Life Science 7C Spring 2020

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(T/F) A cell that utilizes NHEJ to repair a double-stranded DNA break which occurred in the open reading frame of a gene is susceptible to indels resulting in a frame shift mutation and ultimately a non-functional protein.

(T/F) Biochemical, evolutionary, and genetic evidence of functionality can help identify single nucleotide polymorphisms (SNPs) that are important in controlling gene expression or contributing to disease progression.

(T/F) CRISPR/Cas9 can be used to insert, delete, or replace DNA in any model system.

(T/F) CRISPR/Cas9 cannot be used to introduce mutations into specific organs such as the lungs or the brain.

(T/F) Cancer is a disease of cell division.

(T/F) Chromatin immunoprecipitation and DNA sequencing (ChIP-seq) can determine which parts of our genome are associated with regulatory proteins such as p53 tumor suppressor factor.

(T/F) Epigenetic measurements found in neurons will be the same as those found in T cells.

(T/F) Gene models represent protein coding regions of the genome. The direction of transcription 5' ---> 3' is indicated by the direction of arrows.

(T/F) If a human DNA sequence is not evolutionary conserved, it does not have any important functions.

(T/F) In a specific cell type, high H3K27 acetylation would indicate gene expression is turned OFF in that cell.

(T/F) In addition to introducing mutations in a gene, DNA editing by means of CRISPR can also correct mutations in a gene.

(T/F) Researchers can change the sequence of small guide RNA (sgRNA) to cut DNA at a specific location in the genome.

(T/F) Sequences that are conserved, that is, similar in many different organisms, are unlikely to be functionally important.

(T/F) Single nucleotide polymorphisms (SNPs) may indicate genetic variance observed in a population of individuals or mutations found in a cancer genome.

(T/F) Strong conservation of a sequence of nucleotides in the human genome can help identify important genes or regulatory regions of the genome.

(T/F) The UCSC Genome Browser includes not only genetic information, but also epigenetic information of a gene and its regulatory elements.

(T/F) The light blue arrow indicates an intergenic region of the genome in the diagram below

(T/F) The open reading frame starts at exon 2.

(T/F) There are 7 introns in this gene model.

(T/F) Using an evolutionary approach, conservation of a specific DNA sequence among species can determine if that sequence is important for the expression of a nearby gene.

(T/F) Using current DNA-sequencing technology, the sequence of an entire chromosome (for example, human chromosome 1, 250 million nucleotides) is read from one long molecule.

(T/F) Using the Cas9 system, a potential regulatory sequence of DNA and a reporter gene (GFP) is introduced into a model organism such as zebra fish. Examining the expression of the reporter gene can tell us whether that regulatory sequence is important for gene expression.

1. signaling cell; responding cell; receptor protein

A _________ expresses a gene or genes that direct production of the signaling molecule, and the _______________ expresses a gene or genes that direct production of the _________________. 1. signaling cell; responding cell; receptor protein 2. responding cell; signaling cell; receptor protein 3. signaling molecule; responding cell; signaling cell 4. responding cell; receptor protein; signal protein

4. The orchid might produce a pheromone similar to that produced by female wasps.

A botanist working in the Amazon rain forest discovers a new species of orchid. Interestingly, males, but not females, of a certain wasp species keep visiting the flowers of these orchids. Why? 1. Male wasps are likely attracted to the bright colors of the orchids' flowers. 2. Male wasps are likely attracted by growth factors produced by the orchid. 3. Male wasps are likely attracted to the sweet nectar produced by the orchid. 4. The orchid might produce a pheromone similar to that produced by female wasps. 5. Male wasps are likely attracted by paracrine signals produced by the orchid.

B. False

A cell can only respond to signals from other cells, not from the physical environment. A. True B. False

B. False

A cell in a chick embryo is tested to determine whether it is a stem cell of some kind. The results of these tests find: 1.The SR receptor is present 2.DIV genes are on 3.The DIFF (skin) genes are blocked 4.TF of the neural pathway is in the cytoplasm 5.Transducer 2 of the skin pathway is not phosphorylated Based on these results, answer True or False for the following statement. The cell will no longer expresses ID genes. A. True B. False

A. True

A cell in a chick embryo is tested to determine whether it is a stem cell of some kind. The results of these tests find: 1.The SR receptor is present 2.DIV genes are on 3.The DIFF (skin) genes are blocked 4.TF of the neural pathway is in the cytoplasm 5.Transducer 2 of the skin pathway is not phosphorylated Based on these results, answer True or False for the following statement. The transcription factor of the Skin pathway is in the cytoplasm. A. True B. False

A. True

A cell in a chick embryo is tested to determine whether it is a stem cell of some kind. These tests find: 1. The SR receptor is present 2. DIV genes are on 3. The DIFF (skin) genes are blocked 4. TF of the neural pathway is in the cytoplasm 5. Transducer 2 of the skin pathway is not phosphorylated Based on these results, the transcription factor of the Skin pathway is in the cytoplasm. A. True B. False

2. DIV genes

A cell is determined because it received the Self Renewal signal. Which genes that were on, would be turned off if the cell then receives the skin signal? (Assume the SR signal is still present.) 1. DIFF (skin) genes 2. DIV genes 3. DIFF (neural) genes 4. DET genes

A. True

A chromosomal mutation in which a segment is missing is called a deletion. A. True B. False

2. inversion.

A chromosomal mutation where a segment breaks off, flips, and then reattaches itself is called a(n): 1. duplication. 2. inversion. 3. translocation. 4. deletion. 5. reciprocal translocation.

1. translocation

A chromosomal segment that breaks off and attaches to another chromosome is what type of mutation? 1. translocation 2. inversion 3. reciprocal translocation 4. duplication 5. deletion

B. False

A gain-of-function mutation in a tumor suppressor gene would result in abnormal cell proliferation and growth. A. True B. False

3. Cytotoxic T cell 5. MHC I

A host cell infected by a virus will activate the adaptive immune response involving (Select all that apply) 1. Dendritic cell 2. MHC II 3. Cytotoxic T cell 4. Macrophages 5. MHC I 6. Helper T cell

4. LH and FSH are released cyclically in females, but nearly continuously in males. In females, FSH and LH control the periodic maturation and release of eggs from the ovary. In humans, this occurs about once per month. These same hormones function in males to support development and release of sperm. However, in males, sperm are produced continuously.

A key difference between hormonal regulation of the reproductive systems of human males versus human females is that: 1. LH and FSH are released only in males. 2. LH is released continuously in males and FSH is released cyclically in females. 3. LH and FSH are released only in females. 4. LH and FSH are released cyclically in females, but nearly continuously in males. 5. LH is released in males and FSH is released in females.

3. phagocytosis.

A macrophage destroys a pathogen by: 1. secretion of histamine. 2. production of antibodies. 3. phagocytosis. 4. production of antigens.

4. by cytokines secreted by the initial phagocyte

A man is scratched by his cat. A phagocyte near the scratch site recognizes and engulfs a bacterium. Shortly thereafter, more phagocytes arrive in the tissue surrounding the scratch. How are the additional phagocytes recruited to the site of the scratch? 1. by antigens secreted by the initial phagocyte 2. by cytokines produced by the bacteria 3. by antigens secreted by the bacteria 4. by cytokines secreted by the initial phagocyte

2. on the axon reaching threshold and the opening of voltage-gated sodium channels, allowing sodium to enter the axon.

A neuron's ability to generate action potentials depends: 1. on the immediate opening of voltage-gated potassium channels once threshold has been reached, allowing potassium to enter the axon. 2. on the axon reaching threshold and the opening of voltage-gated sodium channels, allowing sodium to enter the axon. 3. on the axon reaching threshold and the opening of voltage-gated sodium channels, allowing sodium to leave the axon. 4. on the immediate opening of voltage-gated potassium channels once threshold has been reached, allowing potassium to leave the axon.

5. a steroid hormone

A new hormone has been isolated from an organism. Although the structure of the hormone has not yet been determined, the hormone is known to exert its effects by forming a hormone-receptor complex that acts as a transcription factor within target cells. What type of hormone is this most likely to be? 1. a peptide hormone 2. either a steroid or a peptide hormone 3. either a steroid hormone or an amine hormone 4. either an amine or a peptide hormone 5. a steroid hormone

1. changes in metabolism

A newly developed drug works by blocking thyroid hormone receptors throughout the body. Which result would be expected to occur in a patient taking this drug? 1. changes in metabolism 2. production of more dilute urine 3. inability to release cortisol 4. increased uptake of glucose by body cells 5. decreased resorption of bone

2. connective tissue.

A pathologist is carrying out an autopsy. Upon opening the chest cavity, the pathologist sees a thick, fibrous tissue surrounding the heart. This is likely: 1. muscle tissue. 2. connective tissue. 3. epithelial tissue. 4. neural tissue.

1. Water uptake by the distal convoluted tubule will increase. 3. Circulating concentrations of renin will increase.

A person's blood pressure falls. Which of the answer choices would you expect to occur? Select all that apply. 1. Water uptake by the distal convoluted tubule will increase. 2. Circulating concentrations of angiotensin II will decrease. 3. Circulating concentrations of renin will increase. 4. Circulating concentrations of aldosterone will decrease.

1. nonsynonymous (missense) mutation.

A point mutation that causes an amino acid replacement is called a: 1. nonsynonymous (missense) mutation. 2. stop mutation. 3. nonsense mutation. 4. synonymous (silent) mutation. 5. transition mutation.

4. nonsense mutation.

A point mutation that changes a UAC codon into a UAG codon is a: 1. missense mutation. 2. frameshift mutation. 3. silent mutation. 4. nonsense mutation.

2. nonpolar; pass through

A receptor that is inside the cell would require a __________ signal molecule that can ____________________ the plasma membrane. 1. polar; bind to 2. nonpolar; pass through 3. nonpolar; bind to 4. polar; pass through

3. Sarcomere size is relatively constant in vertebrates. As a result, mouse and elephant sarcomeres will likely be equal in size. Muscle anatomy is conserved across vertebrates. The size of actin and myosin filaments are approximately the same in vertebrates. Because actin and myosin length are conserved, the length of the sarcomere is relatively constant in vertebrates as well.

A researcher is comparing the size of sarcomeres in mice to those in elephants. What will he find? 1. Sarcomere size is inversely proportional to animal size; sarcomeres in mice will be much larger than sarcomeres in elephants. 2. It is impossible to determine sarcomere size in elephants and mice, given that sarcomeres are dynamic and are constantly changing in length and diameter. 3. Sarcomere size is relatively constant in vertebrates. As a result, mouse and elephant sarcomeres will likely be equal in size. 4. Sarcomere size is proportional to the size of the animal; sarcomeres of elephants will be much larger than sarcomeres in mice.

1. a receptor kinase Phosphorylation is performed by kinase activity that can be part of the function of a receptor kinase or of protein kinases present in the cytoplasm.

A researcher is using a small molecule inhibitor that prevents phosphorylation as a tool to manipulate a signaling pathway. What is the most likely target of this small molecule inhibitor? 1. a receptor kinase 2. a phosphatase 3. a G protein α subunit 4. a ligand-gated ion channel 5. a G protein-coupled receptor

1. fibrinogen growth factors (FGFs)

A researcher is working with mutant mice that demonstrate defects in the formation of connective tissue. These mice likely carry a mutation in a gene encoding what type of growth factor? 1. fibrinogen growth factors (FGFs) 2. neurotransmitters 3. bone morphogenetic proteins (BMPs) 4. nerve growth factors (NGFs) 5. histamine

1. 10%

A retrotransposon known as Alu1 is about 300 base pairs in length and is present in the human genome in about 1 million copies. Approximately what percentage of the human genome is accounted for by this transposon? 1. 10% 2. 1% 3. 30% 4. 0.1% 5. 0.03%

3. 17%

A retrotransposon known as LINE1 is about 1000 base pairs (bp) in length and is present in the human genome in about 516,000 copies. Approximately what percentage of the human genome is accounted for by this transposon? 1. 0.17% 2. 0.017% 3. 17% 4. 1.7% 5. 0.0017%

1. high rates of ATP hydrolysis Muscle fibers can increase in diameter due to increased training. The change in diameter is caused by increases in myosin and actin within each muscle fiber. High rates of ATP hydrolysis are indicative of fast-twitch muscle. ATP hydrolysis is responsible for returning the myosin head back to its relaxed state, where it is ready to bind actin and generate the power stroke. The faster ATP is hydrolyzed, the faster another cross-bridge cycle, and sarcomere shortening, can occur.

A sample of muscle tissue shows large-diameter fibers that are white in color. Which characteristic would also be associated with this tissue? 1. high rates of ATP hydrolysis 2. abundant mitochondria 3. greater resistance to fatigue 4. aerobic respiration

1. the affinity of hemoglobin for O2 has decreased. A shift to the right would mean that at higher partial pressures of oxygen less oxygen is bound to hemoglobin. This reflects a decreased affinity for oxygen because the percent saturation is lower even at higher partial pressures of oxygen.

A shift to the right in the hemoglobin dissociation curve means that: 1. the affinity of hemoglobin for O2 has decreased. 2. less O2 is released by hemoglobin to the body cells. 3. the CO2 levels in the blood have decreased. 4. the pH of the blood has increased. 5. the hemoglobin protein has denatured.

3. replacement of multiple correct amino acids with alternative amino acids

A single base deletion within the open reading frame of a gene's DNA sequence can result in ____________. 1. all of the above 2. replacement of a correct amino acid with an alternative amino acid 3. replacement of multiple correct amino acids with alternative amino acids 4. replacement of a correct amino acid with a premature stop codon

4. motor unit.

A single motor neuron and the population of muscle fibers that it innervates is called a(n): 1. twitch fiber. 2. excitation-contraction coupling. 3. neuromuscular junction. 4. motor unit. 5. motor endplate.

1. DET genes 2. DIV genes 3. ID genes

A stem cell is fate determined once it has received the Self Renewal signal. As result, which genes are newly expressed? (Check all that apply) 1. DET genes 2. DIV genes 3. ID genes 4. DIFF (skin) genes 5. SR genes 6. DIFF (neural) genes

1. DET genes 2. DIV genes 3. ID genes

1. loss of balance and coordination The cerebellum is responsible for motor function, including posture and balance. If there was a stroke in this region, these functions would be impaired. The inability to speak would result from damage to a region of the frontal lobe. Damage to the occipital lobe would affect vision. Damage to the cerebrum would affect sensory perception.

A stroke occurs when blood flow to a region of the brain is interrupted, damaging the cells in that region. What symptoms might you see if a person suffered a stroke in their cerebellum? 1. loss of balance and coordination 2. loss of sensory perception 3. visual impairment 4. difficulty speaking

5. cocking of the myosin head to its high-energy position

ATP hydrolysis allows for what component of skeletal muscle contraction? 1. the actin head to bind to tropomyosin 2. calcium levels in the cytoplasm to rise 3. the reorientation of tropomyosin and troponin 4. the myosin head to bind to actin 5. cocking of the myosin head to its high-energy position

About _____ of the human genome is protein coding sequences. 1% 100% 50% 10% 30%

75%

About ________ of our human genome is transcribed into RNAs. 50% 15% 1% 75% 20%

50%

About _________ of our human genome is composed of repetitive sequences. 75% 20% 15% 1% 50%

1. the temporary hyperpolarization of the axon membrane following the action potential spike

Action potentials typically move in one direction along the neuron away from the cell body. This is due to which answer choice? 1. the temporary hyperpolarization of the axon membrane following the action potential spike 2. the movement of sodium ions out of the cell through voltage-gated potassium channels 3. the myelination of the axon membrane 4. the temporary inactivation of sodium and potassium channels following the action potential spike

3. G protein-coupled receptors on the surface of heart muscle cells.

Adrenaline stimulates an increase in heart rate by binding to: 1. G proteins on the cytosolic face of the plasma membrane. 2. adenylyl cyclase. 3. G protein-coupled receptors on the surface of heart muscle cells. 4. regulatory regions in genes that code for muscle cell proteins. 5. nuclear transport proteins that allow adrenaline to be taken into the nucleus to act as a transcription factor.

4. The more molecules that share the responsibility of passing the signal to activate the effector the more quickly and efficiently the message can spread.

After a signal binds to a signal receptor, the next step is transduction. Why is the signal transduction step necessary? 1. The signal transduction pathway is not necessary since the signal can directly activate the effector. 2. The efficiency increases when less molecules share the responsibility of moving the signal from one molecule to the next to activate the effector. 3. Transmission of the signal through multiple relay molecules before activating an effector is not efficient. 4. The more molecules that share the responsibility of passing the signal to activate the effector the more quickly and efficiently the message can spread.

2. Computer programs are used to automate finding sequence overlaps.

After completing the sequencing reactions, how is the entire genome from an organism assembled? 1. Researchers manually piece together the fragments looking for areas of overlap. 2. Computer programs are used to automate finding sequence overlaps.

2. the proximal convoluted tubule.

After leaving Bowman's space, the filtrate, which contains electrolytes and wastes such as urea, enters: 1. Bowman's capsule. 2. the proximal convoluted tubule. 3. the glomerulus. 4. the endothelial cells.

B. False

After the SR receptor binds its signal molecule, the DET genes are expressed. For the following statement answer True or False. Expression of receptors and transducers of differentiation will cause stem cells to differentiate. A. True B. False

3. The person would lose the ability to hear high-pitched sounds. The frequency of sound waves determines pitch—the more frequent the waves, the higher the pitch, and vice versa. As sound waves travel through the fluid of the inner ear, they move the basilar membrane. If the basilar membrane becomes stiff, it is less affected by the movement of that fluid. This reduces the amount of movement in structures attached to the basilar membrane, such as hair cells and stereocilia. Because the stereocilia will not move as much, there is a decrease in stimulation of the mechanoreceptors on these cells, which makes sounds more difficult to detect.

Aging can sometimes lead to an increase in the stiffness at the base of the basilar membrane. What effect would this have on a person's hearing? 1. The person would lose the ability to hear low-pitched sounds. 2. The person would not be able to distinguish the amplitude of a sound. 3. The person would lose the ability to hear high-pitched sounds. 4. The person would only be able to hear loud sounds.

4. The person would lose the ability to hear high-pitched sounds. The frequency of sound waves determines pitch—the more frequent the waves, the higher the pitch, and vice versa. As sound waves travel through the fluid of the inner ear, they move the basilar membrane. If the basilar membrane becomes stiff, it is less affected by the movement of that fluid. This reduces the amount of movement in structures attached to the basilar membrane, such as hair cells and stereocilia. Because the stereocilia will not move as much, there is a decrease in stimulation of the mechanoreceptors on these cells, which makes sounds more difficult to detect.

Aging can sometimes lead to an increase in the stiffness at the base of the basilar membrane. What effect would this have on a person's hearing? 1. The person would only be able to hear loud sounds. 2. The person would not be able to distinguish the amplitude of a sound. 3. The person would lose the ability to hear low-pitched sounds. 4. The person would lose the ability to hear high-pitched sounds.

2. Aldosterone is lipid-soluble and, therefore, easily crosses the phospholipid bilayer of the plasma membrane. Aldosterone is derived from cholesterol and is hydrophobic. Aldosterone can cross the plasma membrane, while insulin is hydrophilic and cannot cross the plasma membrane.

Aldosterone is a hormone secreted by the adrenal cortex, and insulin is a peptide secreted by the pancreas. Refer to the figures shown. When aldosterone contacts a target cell, it binds to an intracellular receptor and migrates to the nucleus. Insulin binds to extracellular receptors on the plasma membrane. What is the most likely reason for this difference? 1. Aldosterone is too small to bind extracellular receptors on the plasma membrane. 2. Aldosterone is lipid-soluble and, therefore, easily crosses the phospholipid bilayer of the plasma membrane. 3. Insulin is too large to interact chemically with DNA. 4. Aldosterone is hydrophilic and, therefore, must enter the aqueous environment of the cytoplasm to have an effect.

B. False

All DNA sequences are transcribed into RNA. A. True B. False

4. establish concentration gradients—higher Na+ outside and higher K+ inside the cell.

All cells of the body contain Na+/K+ pumps in their cell membranes. The Na+/K+ pumps function to: 1. maintain equal concentrations of K+ inside and outside of the cell. 2. transport glucose from the lumen of the intestine into the epithelial cells. 3. maintain equal concentrations of Na+ inside and outside of the cell. 4. establish concentration gradients—higher Na+ outside and higher K+ inside the cell.

B. False

All neurons have either a sensory or a motor function. A. True B. False

3. Yeast

All of the following are model systems that would be best to understand gene function in the context of cell differentiation or organ formation EXCEPT: 1. Mice 2. Worm 3. Yeast 4. Zebrafish 5. Fly

1. responds to harmless nonself molecules and cells.

Allergies result when the immune system: 1. responds to harmless nonself molecules and cells. 2. does not respond to self molecules and cells. 3. responds to harmful nonself molecules and cells. 4. responds to self molecules and cells.

A. True

Although animal nervous systems differ in complexity, their nerve cells are still remarkably similar. A. True B. False

4. a collection of cells that lines cavities or outside surfaces.

An epithelial tissue is defined as: 1. a network of cells that use chemical communication. 2. a collection of contractile cells. 3. a few cells embedded into an extensive extracellular matrix. 4. a collection of cells that lines cavities or outside surfaces.

1. cannot be synthesized by an organism's cellular biochemical pathways.

An essential amino acid is defined as one that: 1. cannot be synthesized by an organism's cellular biochemical pathways. 2. is necessary for building proteins. 3. functions as a vitamin. 4. cannot be obtained through the diet. 5. is required in large amounts.

4. ADH (antidiuretic hormone)

An increase of _____ increases the permeability of the collecting duct to water. 1. alcohol 2. diuretic drug 3. caffeine 4. ADH (antidiuretic hormone)

2. higher; cortisol Cortisol levels increase with stress

An individual who is experiencing a prolonged period of stress would likely have _____ levels of circulating _____ than an individual who was not experiencing stress. 1. higher; ADH 2. higher; cortisol 3. lower; ACTH 4. lower; ADH 5. lower; cortisol

5. difficulty absorbing sufficient amounts of calcium from their diet.

An individual with vitamin D deficiency will experience: 1. bleeding gums and loss of teeth. 2. slow wound healing. 3. nervous system disorders. 4. anemia. 5. difficulty absorbing sufficient amounts of calcium from their diet.

2. temporal summation Sensory neurons can receive thousands of post-synaptic potentials. However, whether the sensory neuron will get stimulated or not is decided by two different mechanisms. Some sensory neurons will reach the threshold when they receive a number of post-synaptic potentials simultaneously from many other neurons. You may think of an individual exposed to cold environment. Whether he feels cold or not, and how much cold the individual feels depends on how many of his body parts are exposed to cold. If a large surface of his body is exposed to cold, his body may start shivering even in a relatively less cold environment. This is an example of spatial summation. A different mechanism is that of temporal summation. Here, if the sensory neuron receives repeated post-synaptic potentials from one or few neurons, it gets stimulated and the firing rate of the receiving neuron is proportional to the number of signals received from the sensory neuron. You may think of an individual with very little of his body exposed to severe cold. The severe cold-sensation results in repeated firing of the neurons from a very small part of the body which may also suffice to induce shivering. This is an example of temporal summation.

An interneuron may receive multiple stimuli from the same sensory neuron over a very short period of time. The firing rate of the receiving neuron is proportional to the number of signals received from the sensory neuron over time. Of which process is this an example? 1. action potential 2. temporal summation 3. spatial summation 4. hyperpolarization

2. translocation 5. deletion 7. duplication

Aneuploidy can result due to which type of mutation(s). 1. frame shift mutation 2. translocation 3. nonsense mutation 4. base substitution 5. deletion 6. base insertion 7. duplication

3. concentrated urine; reabsorption and secretion

Animals that survive in very dry habitats will likely have a more _________ as a result of the _________steps of the excretory process. 1. dilute urine; filtration and secretion 2. concentrated urine; filtration and secretion 3. concentrated urine; reabsorption and secretion 4. dilute urine; reabsorption and secretion

1. water.

Antidiuretic hormone (ADH) controls the permeability of the collecting ducts to: 1. water. 2. urea. 3. electrolytes. 4. wastes.

B. False

As cells differentiate, they lose their ability to become other cell types because they delete subsets of genes. A. True B. False

1. the length of the vessel 2. the radius of the vessel 4. the viscosity of the fluid

As fluid moves through a vessel, which factors determine the flow resistance? Select all that apply. 1. the length of the vessel 2. the radius of the vessel 3. the pressure exerted by the heart 4. the viscosity of the fluid

3. amniotic eggs

As they evolved, animals faced challenges when moving from water to land. What was the most important adaptation that enabled the uncoupling of reproduction and the need for an aquatic habitat? 1. internal fertilization 2. flagellated sperm 3. amniotic eggs

2. increases.

As water leaves the descending limb of the loop of Henle, the solute concentration of the filtrate: 1. decreases. 2. increases. 3. stays the same.

A. True When blood pressure decreases, the juxtaglomerular apparatus releases renin. Renin converts angiotensinogen to angiotensin I. ACE (angiotensin converting enzyme) from the lungs converts angiotensin I to angiotensin II. The presence of angiotensin II causes the release of aldosterone from the adrenal glands and stimulates the distal convoluted tubule to take up more salt and water. The increased uptake of salt and water increases blood volume and blood pressure.

Assume that blood pressure drops in a person because of an injury, and given the drop in blood pressure, indicate whether the statement on the body's responses is true or false. Circulating levels of aldosterone will increase. A. True B. False

B. False When blood pressure decreases, the juxtaglomerular apparatus releases renin. Renin converts angiotensinogen to angiotensin I. ACE (angiotensin converting enzyme) from the lungs converts angiotensin I to angiotensin II. The presence of angiotensin II causes the release of aldosterone from the adrenal glands and stimulates the distal convoluted tubule to take up more salt and water. The increased uptake of salt and water increases blood volume and blood pressure.

Assume that blood pressure drops in a person because of an injury, and given the drop in blood pressure, indicate whether the statement on the body's responses is true or false. The sympathetic nervous system stimulates the adrenal glands. A. True B. False

Assume that blood pressure drops in a person because of an injury, and given the drop in blood pressure, indicate whether the statement on the body's responses is true or false. Water absorption by the distal convoluted tubule will decrease. A. True B. False

1. Glucagon release from the pancreas will increase.

Assume you haven't eaten in the last 24 hours. Which of the statements would you predict? 1. Glucagon release from the pancreas will increase. 2. Glycogen storage by the liver will increase. 3. Glucagon release from the pancreas will decrease. 4. Insulin release from the pancreas will increase.

5. Points a and e have similar composition.

Assuming that active transport of electrolytes stop in the ascending limb, what would you predict the comparative composition would be of the filtrate at points a and e in the figure? 1. Point a has more NaCl than point e. 2. Point a has more water than point e. 3. Point e has more water than point a. 4. Point e has more NaCl than point e. 5. Points a and e have similar composition.

1. more positive inside than out.

At the moment that the action potential has reached its maximum height, the potential (or voltage) difference across the nerve membrane is: 1. more positive inside than out. 2. zero or equal on both sides. 3. more negative inside than out.

3. C

At which point on the phylogeny shown did the amnion first appear? 1. A 2. B 3. C 4. D 5. E

4. the left atrium from the left ventricle and the right atrium from the right ventricle.

Atrioventricular valves separate: 1. the right atrium from the left atrium and the right ventricle from the left ventricle. 2. the right and left ventricles. 3. the aorta from the left ventricle. 4. the left atrium from the left ventricle and the right atrium from the right ventricle.

2. They can consume complex and simple sugars through specific transporters and enzymes present in their membrane.

Bacteria are able to utilize energy sources present in their extracellular environment because: 1. They can absorb complex and simple sugars in their extracellular environment through simple diffusion. 2. They can consume complex and simple sugars through specific transporters and enzymes present in their membrane. 3. They can consume complex and simple sugars through exocytosis 4. They can consume complex and simple sugars through endocytosis

A and C The researchers found support for their hypothesis that muscle force depends on the overlap between actin and myosin. These data and the follow-up work support the hypothesis that muscle length changes when actin and myosin slide relative to each other.

Based on the Results and Follow-up Work sections, which statement is correct? (A) Researchers found experimental support for their hypothesis that muscle force depends on the overlap of actin and myosin filaments allowing cross-bridge formation within a sarcomere. (B) Researchers found experimental support that muscles change length when they contract through shortening of myosin filaments. (c)Researchers found experimental support that muscles change length by the relative sliding of adjacent actin and myosin filaments. (D) Researchers found no support for their experimental hypothesis. A and C B and D

Exon 2

Based on the diagram below, which exon would contain the start codon (AUG)? Exon: 1 2 3 4 5 6

5, 1, 4, 3, 6, 2

Beginning at the synapse of a neuron, place the events in neuronal signaling in the correct sequence. 1. Ion channels bind the ligand and open. 2. Na+ is pumped out of the cell, and the membrane potential is restored. 3. Acetylcholinesterase breaks down acetylcholine. 4. Na+ enters the postsynaptic cell, and the membrane potential changes. 5. Acetylcholine is released into the synapse. 6. Na+ ion channels close. 1, 2, 3, 4, 5, 6 6, 4, 3, 1, 2, 5 5, 1, 4, 3, 6, 2 3, 4, 6, 1, 5, 2 4, 5, 1, 2, 6, 3

5. hemoglobin releases more of its bound O2 than it would without BPG. BPG causes the same response as increased proton concentrations. BPG would cause the affinity of hemoglobin to oxygen to decrease and shift the oxygen binding curve to the right. This results in release of more oxygen at the tissues.

Bisphosphoglyceric acid (BPG) is a byproduct of glycolysis released into the bloodstream when an animal's supply of oxygen is low. Like protons, it decreases hemoglobin's affinity for O2. The effect of high BPG levels would be that: 1. hemoglobin picks up more O2 in the lungs than it would without BPG. 2. hemoglobin now binds more oxygen at low partial pressures than at high partial pressures. 3. hemoglobin holds on to more of its O2 than it would without BPG. 4. hemoglobin loses its cooperative binding of oxygen. 5. hemoglobin releases more of its bound O2 than it would without BPG.

4. autonomic nervous system.

Body functions such as heart rate, blood flow, and digestion are controlled by the: 1. somatic nervous system. 2. voluntary nervous system. 3. automatic nervous system. 4. autonomic nervous system.

1. small molecules to enter the proximal convoluted tubule.

Bowman's capsule acts as a filter that allows: 1. small molecules to enter the proximal convoluted tubule. 2. large molecules to enter the proximal convoluted tubule.

1. cell adhesion molecules found in cell junctions.

Cadherins are: 1. cell adhesion molecules found in cell junctions. 2. proteins involved in attachment of cells to the extracellular matrix. 3. proteins involved in attachment of cells to the basal lamina. 4. proteins that provide a pathway for molecules to move between cells.

4. both intermediate filaments and microfilaments

Cadherins bind to which type of cytoskeletal element(s)? 1. microfilaments only 2. microtubules only 3. intermediate filaments only 4. both intermediate filaments and microfilaments

2. troponin

Calcium is necessary to initiate muscle contraction. Which molecule binds calcium? 1. tropomyosin 2. troponin 3. myosin 4. actin

2. No, she should not worry about her children because this did not occur in a germ-line cell. - Somatic mutations cannot be passed to the next generation.

Cancer can be caused by mutations. Genetic analysis of a tumor found in a patient shows that the cell proliferation was triggered by a somatic mutation in the MYC gene, causing this gene to be inappropriately activated. The patient is concerned about passing this cancer on to the children she plans to have in the future. Should she be concerned? 1. Yes, she should worry because tumor growth was triggered by a genetic change, and mutations are passed on through cell divisions. 2. No, she should not worry about her children because this did not occur in a germ-line cell. 3. No, this is not something to worry about because mutations in cancer cells cannot be passed on in cell division.

1. no change in the targeted gene 2. deletions of the targeted gene 3. loss-of-function mutations within the targeted gene 4. the insertion of a DNA sequence into the targeted gene 5. mutations that result in changes to the open reading frame (ORF) of the targeted gene

Cas9 cleaves both strands of the target DNA. Which of the following could occur when cells will try to repair the damage after cleavage by Cas9? (Select all that apply.) 1. no change in the targeted gene 2. deletions of the targeted gene 3. loss-of-function mutations within the targeted gene 4. the insertion of a DNA sequence into the targeted gene 5. mutations that result in changes to the open reading frame (ORF) of the targeted gene

3. Because of the decreased number of cone cells, cats have (relatively) poor color vision. Nocturnal organisms need to be able to see in low light conditions. The more rods they have, the more cells they have in their eyes that are specific for sensing light intensity differences because they all have the same opsin. Color vision is not as important for nocturnal organisms as it is for diurnal organisms, and the higher number of cones in diurnal organisms results in their having fewer rods.

Cats and other nocturnal predators have a greater number of rod cells in their eyes compared to cone cells. What would you predict about the color vision of cats? 1. Cats have (relatively) poor color vision, but this is independent of the number of rod or cone cells. 2. Because of the decreased number of cone cells, cats have excellent color vision. 3. Because of the decreased number of cone cells, cats have (relatively) poor color vision. 4. Because of the increased number of rod cells, cats have excellent color vision.

A. True

Cells can regulate their internal osmotic pressure by controlling the solute concentration inside of the cell. A. True B. False

1. gene regulation.

Cells differentiate through: 1. gene regulation. 2. timing. 3. growth. 4. the cell cycle.

4. reabsorb; higher

Cells of the excretory tubule _________water by osmosis, from which we can conclude that the solute concentration in these cells must be _________ than in the filtrate. 1. excrete; lower 2. reabsorb; lower 3. excrete; higher 4. reabsorb; higher

2. being bound by cytotoxic T cells.

Cells with class I major histocompatibility complex (MHC) proteins that contain a foreign antigen will be destroyed after: 1. stimulating the membrane attack complex (MAC). 2. being bound by cytotoxic T cells. 3. releasing histamine. 4. being bound by helper T cells.

1. undergo irreversible repression. 2. become more densely packed with nucleosomes.

Cellular differentiation progressively restricts cell fate because the unexpressed genes in the cell: Select all that apply. 1. undergo irreversible repression. 2. become more densely packed with nucleosomes. 3. accumulate near the centromeres. 4. accumulate point mutations. 5. are deleted from the genome.

3. All of these choices are correct.

Certain medications can cause potassium levels in the body to decrease. Which symptom would be consistent with a low concentration of potassium? 1. muscle weakness 2. irregular heartbeat 3. All of these choices are correct. 4. fatigue

2. It makes sense because tissues that are more actively working produce more CO2 and, therefore, need more O2. During cellular respiration, carbon dioxide is produced as sugars are oxidized.

Chemoreceptors in the circulatory system detect changes in circulating pCO2. If CO2 concentrations get too high, the rate of ventilation increases. Why does this make sense? 1. It makes sense because hemoglobin carries CO2 and, therefore, blocks oxygen binding to the heme site, creating an oxygen deficiency. 2. It makes sense because tissues that are more actively working produce more CO2 and, therefore, need more O2. 3. It makes sense because CO2 is formed from O2 and, therefore, CO2 is a sign that oxygen is being consumed. 4. Actually, it does not make sense. There is no relationship between CO2 and ventilation rate.

3. Bacteria in the developing microbiome consume complex sugars and degrade them in to simple sugars in their intracellular environment while bacteria in the mature microbiome mostly degrade complex sugars in the extracellular environment and consume the simple sugars that result.

Choose the correct statement that describes bacterial feeding strategies in the developing and mature microbiome: 1. Humans are born with the greatest amount of unique microorganism Bacterial feeding strategies of the developing microbiome is the same as the mature microbiome 2. Bacteria present in the developing microbiome utilize a feeding strategy in which they degrade complex sugars in the extracellular environment and consume the simple sugars that result. 3. Bacteria in the developing microbiome consume complex sugars and degrade them in to simple sugars in their intracellular environment while bacteria in the mature microbiome mostly degrade complex sugars in the extracellular environment and consume the simple sugars that result. 4. Bacteria present in the mature microbiome utilize a feeding strategy in which they consume complex sugars and degrade them in to simple sugars in their intracellular environment.

1. Humans gain a gut microbiota from the birthing process.

Choose the correct statement that describes how humans gain a gut microbiota: 1. Humans gain a gut microbiota from the birthing process. 2. Bacteria colonize the human gut while they are in the womb 3. Humans gain a gut microbiota from the first foods they eat. 4. Bacteria can but usually don't colonize the human gut during birth.

4. Humans are born with the least amount of unique microorganism species in their gut and have greatest amount of unique species once they develop in to adulthood.

Choose the correct statement that describes the development of the human gut microbiome: 1. Humans have the same type and number of microorganism species present in their gut at birth and at death. 2. Humans are born with the greatest amount of unique microorganism species in their gut and as they get older specific microbial species are eliminated through competition for resources. 3. Humans are born with the least amount of unique microorganism species in their gut, but by the time they reach an elderly age they have the greatest amount of unique microorganism species. 4. Humans are born with the least amount of unique microorganism species in their gut and have greatest amount of unique species once they develop in to adulthood.

4. Beneficial microbes develop a symbiotic relationship with the host and pathogenic microbes do not and cause disease symptoms in the host.

Choose the correct statement that refers to either beneficial or pathogenic microbes: 1. Pathogenic bacteria help hosts utilize food sources, which they are not normally able to use. 2. All microbes are beneficial but some are considered pathogenic because the host immune system does not recognize it. 3. All microbes are pathogenic but we still tolerate some species without showing disease symptoms. 4. Beneficial microbes develop a symbiotic relationship with the host and pathogenic microbes do not and cause disease symptoms in the host.

2. Antibiotics can directly kill most of the bacterial species present in the gut but the ones that survive the antibiotic treatment can then increase their population sizes after the antibiotic treatment is finished.

Choose the correct statement that refers to human gut microbiome resilience after antibiotic exposure: 1. Antibiotics educate the host immune system to defend against only the bacteria that are causing the disease so after the antibiotic treatment only beneficial microbes are present. 2. Antibiotics can directly kill most of the bacterial species present in the gut but the ones that survive the antibiotic treatment can then increase their population sizes after the antibiotic treatment is finished. 3. Antibiotics are food sources for beneficial microbes only and allow their population sizes to increase due to the greater amount of food that is available for only these beneficial bacteria. 4. Antibiotics can directly kill all of the bacterial species present in the gut and the observed resilience of the microbiota is due to new bacteria we introduce from the food we eat or other environmental exposure events.

2. Biochemical approach

Chromatin immunoprecipitation and DNA sequencing (ChIP-seq) can be used to identify regions of the genome that can indicate promoters, enhancers, and transcription factor-binding motifs. ChIP-seq is an example of: 1. All of these approaches 2. Biochemical approach 3. None of these approaches 4. Evolutionary approach 5. Genetic approach

Circle plots show changes in cancer genomes vs. the reference genome. Use the circle plot below to answer the following question. T/F: Regions of the genome with higher tumor/normal cell read copy ratios are more likely to be associated with intrachromosomal rearrangements.

A. True

Color vision in vertebrates is made possible by cone cells. A. True B. False

2. rod cells.

Cone cells most likely evolved from: 1. ommatidia. 2. rod cells. 3. retinal. 4. rhodopsin.

1, 3, 4, 2, 6, 5

Consider the events in muscle contraction. 1. ATP binds to myosin head. 2. Myosin head interacts with actin. 3. ATP is converted to ADP and Pi. 4. Myosin head is cocked back. 5. Myosin head pivots in the power stroke. 6. ADP and Pi are released from myosin. Place the following events in muscle contraction in the correct sequence from first to last. 1, 2, 4, 3, 6, 5 1, 2, 3, 4, 5, 6 1, 3, 6, 2, 4, 5 1, 3, 4, 2, 6, 5

3. II, I, V, III, IV

Consider the events involved in the stimulation of heart muscle. Arrange the events in the stimulation of heart muscle in sequence. Note that this question does not list every step in the pathway, but the steps presented should be arranged in order. I. Activation of adenylyl cyclase II. Activation of G proteins III. Activation of protein kinase A IV. Phosphorylation of proteins that induce contraction in muscle cells V. Conversion of ATP into cyclic AMP 1. I, II, IV, V, III 2. I, III, II, IV, V 3. II, I, V, III, IV 4. III, II, I, V, IV

A. True

Consider the figure shown of an electrocardiogram (EKG) trace and the typical action potential of cells in the left ventricle. Indicate whether the statement is true or false. Atria are emptying at the interval labeled 4 on the action potential figure. A. True B. False

B. False The plateau phase on the action potential figure helps inhibit tetanus in the heart. Diastole is when the heart is filling and ventricles are relaxed. Notice that the graph wave shown in the EKG figure represents ventricular contraction and systole of the cardiac cycle. At point 4 on the action potential figure, the atria are emptying into the ventricles, which are relaxed, and readying the ventricles for contraction.

Consider the figure shown of an electrocardiogram (EKG) trace and the typical action potential of cells in the left ventricle. Indicate whether the statement is true or false. Ventricular diastole occurs at the interval labeled 2 on the action potential figure. A. True B. False

Consider the genome browser data associated with TP53. T/F: Track A provides genetic evidence of functionality

Consider the genome browser data associated with TP53. T/F: Tracks B and C provide evolutionary evidence of functionality.

Consider the graph. Which letter under the graph shown corresponds to increased mitotic division in memory B cells?

2. increased

Consider the image. Muscle contractions have _____ force at slower shortening velocities compared to higher shortening velocities. 1. equal 2. increased 3. less stable 4. decreased

1. The left ventricle must contract with more force in order to send blood to the body's extremities. The right ventricle only needs to push blood through the pulmonary arteries to the lungs. The distance to the lungs from the heart is very short, so a large amount of pressure is not needed. Because the pressure necessary to get blood to the lungs is low, the muscular wall of the right ventricle does not need to be as thick as the left ventricle that must generate enough pressure to push blood throughout the body.

Consider the mammalian heart. Why is the muscular wall of the left ventricle thicker than that of the right ventricle? 1. The left ventricle must contract with more force in order to send blood to the body's extremities. 2. This difference stems from the fact that frogs have a thicker left ventricular muscle mass. 3. The left ventricle has more nerve endings for contraction, and more muscle mass must be there to accommodate the extra neurons. 4. The ventricle wall must be thicker to inhibit diffusion between the right and left ventricle.

3. Na+; Na+-glucose cotransporter

Continued glucose transport into cells lining the lumen of the small intestine requires a _________ concentration gradient and a transmembrane protein that is a _________. 1. Na+; K+-glucose cotransporter 2. K+; glucose channel protein 3. Na+; Na+-glucose cotransporter 4. glucose; glucose channel protein 5. K+; K+-glucose cotransporter

2. myosin; actin filaments

Contraction of muscles is an example of how the motor protein _______ interacts with the cytoskeletal elements called _____________ to produce movement. 1. kinesin; microtubules 2. myosin; actin filaments 3. dynein; microtubules 4. myosin; dynein 5. actin; dynein

2. No, these motor proteins are specific to microtubules and cannot move along microfilaments. Dynein and kinesin are molecular motors that are only capable of moving along microtubules. They cannot move along microfilaments.

Could melanin granules be moved by dynein and kinesin along an actin microfilament? 1. Yes, motor proteins all use ATP to cause a conformation change. 2. No, these motor proteins are specific to microtubules and cannot move along microfilaments. 3. Yes, melanin granules would be moved by these motor proteins along microfilaments.

1. decreases the amount of water leaving the descending limb of the loop of Henle.

Decreasing the amount of solute leaving the proximal convoluted tubule: 1. decreases the amount of water leaving the descending limb of the loop of Henle. 2. does not change the amount of water leaving the descending limb of the loop of Henle. 3. increases the amount of water leaving the descending limb of the loop of Henle.

1. All of these choices are correct.

Defects in cell signaling can lead to a cancerous cell as a result of: 1. All of these choices are correct. 2. overproduction of a receptor that triggers cell division. 3. a defective signal transduction protein that stays in the activated state and triggers cell division continuously. 4. a defective receptor that stays in the activated state and triggers cell division continuously. 5. overproduction of signals that trigger cell division.

1. delete amino acids in a polypeptide chain.

Deletions that eliminate a multiple of three nucleotides can: 1. delete amino acids in a polypeptide chain. 2. All of these choices are correct. 3. cause frameshift mutations in an open reading frame. 4. cause nonsense mutations in an open reading frame.

2. A Phosphatase activated by Transducer 2 of the skin pathway would target Transducer 2 of the Neural pathway

Differentiating cells receiving the Skin signal becomes skin, but never neurons. How could this property of a cell becoming only one or the other of these two cell types be achieved? 1. A Kinase activated by Transducer 2 of the skin pathway would target Transducer 1 of the Neural pathway 2. A Phosphatase activated by Transducer 2 of the skin pathway would target Transducer 2 of the Neural pathway 3. Activation of Transducer 1 of the neural pathway would cause degradation of TF of the Skin pathway 4. DIFF (skin) genes could include transcription factors that activate the DIFF (neural) genes

4. capillaries

Diffusion of materials between the blood and body tissues occurs at which of the blood vessels? 1. arterioles 2. arteries 3. veins 4. capillaries 5. venules

3. the sympathetic division of the autonomic system.

Dilated pupils, inhibited digestive activity, increased respiratory rate, and release of glucose from the liver are all signs of activity of: 1. the somatic nervous system. 2. both divisions of the autonomic nervous system. 3. the sympathetic division of the autonomic system. 4. the parasympathetic division of the autonomic system.

4. flexion; extension

During _____ bone segments move closer together, whereas during ______ bone segments move further apart. 1. contraction; extension 2. rotation; flexion 3. extension; flexion 4. flexion; extension 5. contraction; flexion

3. decreased stimulation of chemoreceptors in the brainstem 4. increased blood pH, greater than 7.2

During certain stressful moments, some individuals will begin to hyperventilate—that is, their breathing will be very shallow and quick. A by-product of hyperventilation is much lower levels of CO2 in the blood. Which effect would you also expect to find? Select all that apply. 1. increased stimulation of chemoreceptors in the brainstem 2. decreased blood pH, less than 7.2 3. decreased stimulation of chemoreceptors in the brainstem 4. increased blood pH, greater than 7.2

2. approximately 20% Start at the x-axis and find 20 mmHg. From there, draw a line up to the curve. From the point where that line intersects the curve, draw a straight line to the y-axis to determine percent saturation.

During heavy exercise, the pO2 in muscle may drop to 20 mmHg. Considering the oxygen-hemoglobin dissociation curve shown, what is the approximate percent O2 saturation of hemoglobin in venous blood returning from skeletal muscles during heavy exercise? 1. approximately 100% 2. approximately 20% 3. approximately 50% 4. approximately 75% 5. nearly 0%

A. True

During starvation, humans and other animals deplete glycogen and fat reserves first, followed by protein. A. True B. False

4. feature of microtubules.

Dynamic instability is a: 1. feature of intermediate filaments. 2. feature of microfilaments. 3. universal feature of the cytoskeleton. 4. feature of microtubules. 5. feature of microtubules and microfilaments.

1. None of the above

Epigenetic modification is a change in ________________. 1. None of the above 2. DNA sequence 3. RNA sequence 4. Protein sequence

4. Filtration removes water from the blood. 5. Filtration removes substances dissolved in the blood.

Filtration is usually the first step in the excretory process. What types of filtration typically occur? Select all that apply. 1. Filtration removes blood cells. 2. Filtration removes CO2 from the blood. 3. Filtration removes blood proteins. 4. Filtration removes water from the blood. 5. Filtration removes substances dissolved in the blood.

4. The chloride cells actively remove ions from the body and water follows by osmosis.

Fish in a marine environment must maintain a relatively constant ion concentration in their tissues and blood. How do the chloride cells in the gills aid fish in the removal of excess ions? 1. The chloride cells actively move ions into the body and water follows by osmosis. 2. The chloride cells create a countercurrent system where ions are lost from the body and water is absorbed to dilute other ions. 3. The chloride cells create a countercurrent system where water is lost from the body and chloride ions are absorbed. 4. The chloride cells actively remove ions from the body and water follows by osmosis.

False

For your summer internship you decide to help farmers characterize the microbiotas of their pigs. Below is a graphical representation of the diversity observed after sampling and sequencing the microbiotas present in the small intestine (jejunum and ileum) and large intestine (cecum) of their fattest pigs. Reference the data presented below to address the following statement. T/F: Each point on the graph above represents one microbial species present in the either the small intestine or the large intestine.

True

For your summer internship you decide to help farmers characterize the microbiotas of their pigs. Below is a graphical representation of the diversity observed after sampling and sequencing the microbiotas present in the small intestine (jejunum and ileum) and large intestine (cecum) of their fattest pigs. Reference the data presented below to address the following statement. T/F: Points that cluster together have greater 16s rRNA gene sequence similarity than points that are farther apart.

3. Freshwater fish have chloride cells that actively move chloride ions into the gills, with sodium ions following. To keep ion balance, freshwater fish pump chloride ions, with sodium ions following, into the body through chloride cells on the gills. This also compensates for the water freshwater fish take in from living in a hypotonic environment. As well, freshwater fish produce large volumes of urine to remove excess water.

Freshwater fish are in a hypotonic environment. In which direction do their gill chloride cells move chloride ions in this environment? 1. Freshwater fish have chloride cells that actively move chloride ions into the gills, with sodium ions moving in the opposite direction. 2. Freshwater fish have chloride cells that actively move chloride ions out of the gills into the surrounding water, with sodium ions following. 3. Freshwater fish have chloride cells that actively move chloride ions into the gills, with sodium ions following. 4. Freshwater fish have chloride cells that actively move chloride ions out of the gills into the surrounding water, with sodium ions moving in the opposite direction.

1. sarcomeres.

Functional unit of skeletal muscles are called: 1. sarcomeres. 2. muscle bundles. 3. muscle fibers. 4. myofibrils.

3. on the cell surface.

G protein-coupled receptors are found: 1. on the nuclear membrane. 2. inside the nucleus. 3. on the cell surface. 4. in the cytoplasm.

A. True

Ganglia were the evolutionary precursor to the centralized concentration of neurons that we now call a brain. A. True B. False

4. They both allow direct transport of materials between cells. Gap junctions occur between animal cells and are formed from connexin proteins. Plasmodesmata are junctions formed by the cell walls of adjacent plant cells, and these cells have one continuous plasma membrane.

Gap junctions and plasmodesmata have what feature in common? 1. They both are made up of protein subunits located in the plasma membrane. 2. They are both found in plant cells. 3. They both attach to the cytoskeleton. 4. They both allow direct transport of materials between cells.

3. none of these

Genome annotation includes all of the followings except: 1. conserved sequences 2. start codons 3. none of these 4. regulatory sequences 5. locations of genes

1. the ability to secrete large amounts of protein.

Given the plasma cell's role in the adaptive immune response, it is reasonable to assume that a plasma cell has: 1. the ability to secrete large amounts of protein. 2. All of the answer options are correct. 3. more genes than normal cells. 4. high levels of cell motility.

2. 20 - 30 - 40 - 50 - 60

Given the temperature readings in the topmost tube (in the system diagrammed), which would be reasonable temperatures for points 1 to 5 in the lower tube? 1. 0 - 10 - 20 - 30 - 40 ' 2. 20 - 30 - 40 - 50 - 60 3. 50 - 40 - 30 - 20 - 10 4. 90 - 80 - 70 - 60 - 50

1. 90 - 80 - 70 - 60 - 50

Given the temperature readings in the topmost tube (in the system diagrammed), which would be reasonable temperatures for points 1 to 5 in the lower tube? 1. 90 - 80 - 70 - 60 - 50 2. 20 - 30 - 40 - 50 - 60 3. 50 - 40 - 30 - 20 - 10 4. 40 - 30 - 20 - 10 - 0

2. Glucose is co-transported with Na+, which moves down its concentration gradient into the cell.

Glucose enters the epithelial cells of the small intestine against its concentration gradient. Select the best explanation from the statements. 1. Glucose is transported through a glucose pump in the apical membrane that hydrolyzes ATP to ADP and Pi. 2. Glucose is co-transported with Na+, which moves down its concentration gradient into the cell. 3. Glucose is co-transported in the Na+/K+ pump. 4. Glucose follows the water that is pumped into the cell. 5. Glucose enters by diffusion.

1. a glucose channel protein on the cell surface facing the blood 5. a higher concentration of glucose in the intestinal cells

Glucose transport out of intestinal cells into the bloodstream requires which of the following? Select all that apply. The general chemical nature of a hormone can be used to predict: 1. a glucose channel protein on the cell surface facing the blood 2. a Na+ channel connecting the intestinal cell to the blood stream 3. a Na+ concentration gradient between the blood and the intestinal cell 4. a Na+-glucose cotransporter in the membrane facing the blood 5. a higher concentration of glucose in the intestinal cells

3. paracrine signaling.

Growth factors such as platelet-derived growth factor (PDGF) function in: 1. contact-dependent signaling. 2. autocrine signaling. 3. paracrine signaling. 4. endocrine signaling.

3. Host epithelial cell components

Gut microbial food sources do not include: 1. Bacterial produced simple sugars 2. Host consumed complex sugars 3. Host epithelial cell components 4. Host produced intestinal mucosal complex sugars

1. releasing neurotransmitters.

Hair cells function by: 1. releasing neurotransmitters. 2. firing action potentials directly. 3. stabilizing homeostasis. 4. using chemosensory receptors.

2. beta; insulin

High blood glucose stimulates the _________ cells in the pancreas to secrete _________. 1. beta; glucagon 2. beta; insulin 3. alpha; glucagon 4. alpha; insulin

4. by movement of the tympanic membrane, the bones in the middle ear, and the fluid-filled region covered by the oval window. The tympanic membrane vibrates when the soundwave strikes its surface. The tympanic membrane's vibrations are transmitted to the inner ear bones, which then vibrate and send the sound waves across the oval window into the fluid-filled cochlea. Each time the waves are transmitted they are amplified.

How are sound vibrations amplified in a vertebrate ear? 1. by movements of the basilar membrane induced by fluid vibrations 2. by differences in the surface area of the pinna versus the oval window 3. by movement of the cochlea and fluid vibrations 4. by movement of the tympanic membrane, the bones in the middle ear, and the fluid-filled region covered by the oval window.

4. The sequence of exons complements mRNA molecules in the cell.

How can researchers distinguish exons from introns in a segment of DNA? 1. Exons have a characteristic sequence. 2. Only exons contain three-base sequences that can code for amino acids. 3. Primers will not bind to introns. 4. The sequence of exons complements mRNA molecules in the cell.

1. through integrins

How do cells connect to the extracellular matrix? 1. through integrins 2. through cadherins 3. through tight junctions 4. through gap junctions

4. Phosphatases remove phosphate groups. MAP kinase is activated upon phosphorylation of kinases responding to Ras activation. In order to stop the activation, the phosphates must be removed by phosphatases.

How do mitogen-activated protein (MAP) kinases get deactivated? 1. Ligand diffuses away from the ligand-binding site. 2. Ras hydrolyzes GTP to GDP. 3. Receptor kinases move apart in the membrane. 4. Phosphatases remove phosphate groups.

2. from a series of mutations that arise in the descendants of a single somatic cell

How do most cancers arise? 1. from mutations arising in a single cell that are then transmitted to other cells in the body 2. from a series of mutations that arise in the descendants of a single somatic cell 3. from multiple mutations arising simultaneously in a single cell 4. from a single mutation arising simultaneously in a cluster of cells

1. Mutations arise randomly and independent of other mutations in the cell.

How do mutations arise? 1. Mutations arise randomly and independent of other mutations in the cell. 2. Mutations arise simultaneously, where whole sets of mutations occur in a single event. 3. Mutations arise in a specific sequence where a mutation in one gene directly leads to a mutation in a specific second gene. 4. Mutations in cancer cells arise because they need to divide faster.

1. Fragments from different regions of the chromosomes may appear identical if they contain the same repeated sequence. 2. The repeated sequences may appear in many fragments. 3. Regions of sequence overlap may occur between fragments not actually adjacent in the genome.

How do repeated sequences in the genome complicate assembly of fragments? Select all that apply. 1. Fragments from different regions of the chromosomes may appear identical if they contain the same repeated sequence. 2. The repeated sequences may appear in many fragments. 3. Regions of sequence overlap may occur between fragments not actually adjacent in the genome.

4. It generates a population of memory cells that speed up the response to an actual infection. Vaccine is composed of dead or heat killed Organism that doesn't cause infection but immune system detect them as enemy and produce antibodies. After passing of threat, though the antibody will be denatured but the memory cells will persist. Next time when this antigen will encounter, memory cells automatically activated and started producing Antibody quickly to damaged the antigen.

How does a vaccination help to prevent a disease? 1. It generates a population of plasma cells that increase the concentration of antibody in the bloodstream. 2. It reduces the severity of symptoms to a disease. 3. It establishes defenses that prevent a pathogen from entering the body. 4. It generates a population of memory cells that speed up the response to an actual infection.

1. through a conformational change of the receptor

How does an "activated" receptor transfer information into the cell? 1. through a conformational change of the receptor 2. by increased translation of the receptor 3. by altering the ligand-binding site of the receptor 4. by decreased phosphorylation of the receptor

1. A genomic sequence is broken into small fragments of a few hundred base pairs.

How is DNA sequencing accomplished? 1. A genomic sequence is broken into small fragments of a few hundred base pairs. 2. Whole chromosomes are sequenced in one piece. 3. Each gene is separated from the others and individually sequenced. 4. The DNA is converted to RNA.

1. Synaptic signaling specifically involves neurotransmitters that are released from neurons.

How is synaptic signaling different from paracrine signaling? 1. Synaptic signaling specifically involves neurotransmitters that are released from neurons. 2. Synaptic signaling requires receptors to elicit a response in the target cell. 3. Synaptic signaling acts over a longer distance than paracrine signaling. 4. Synaptic signaling is longer in duration than paracrine signaling. 5. All of these choices are correct.

3. They are analyzed in a machine that determines the base sequence.

How is the actual base sequence of DNA fragments determined? 1. They are carefully lined up with known sequences from other organisms. 2. They are translated into proteins and the amino acid sequence is determined. 3. They are analyzed in a machine that determines the base sequence. 4. They are analyzed in a powerful microscope.

3. The base sequences are aligned by matching short regions at the ends that overlap.

How is the order of DNA fragments determined to obtain the sequence of the entire genome? 1. They are converted into sentences that are then assembled. 2. They are sorted by size using gel electrophoresis. 3. The base sequences are aligned by matching short regions at the ends that overlap. 4. They are matched up to chromosomes prepared from the nucleus.

2. 10^-3 times as long

How long does an action potential last compared to one second? 1. 0.1 times as long 2. 10^-3 times as long 3. 10 times as long 4. the same time 5. 1/100th times as long

How many molecules of O2 can a single hemoglobin molecule carry when fully saturated? 2 16 4 1 8

How many synapses are involved in the contraction of the knee extensor muscles in the knee-jerk reflex? 1 2 3 4

How many synapses in total are involved in the knee-jerk reflex? 1 2 3 4

2. change the concentration of K+ ions in the solution bathing the axon In order to identify which ion (1) leaves the inside of the cell and (2) causes the decrease in voltage, a researcher would manipulate a positive ion such as K+.

How might researchers experimentally test what ion leaves the axon, causing the axon to become re-polarized after firing an action potential? 1. create a short-circuit across the axon's membrane so that the membrane potential remains at 0 volts 2. change the concentration of K+ ions in the solution bathing the axon 3. change the concentration of Cl- ions in the solution bathing the axon

1. change the concentration of Na+ ions in the solution bathing the axon In order to identify which ion (1) enters the cell from outside and (2) causes the increase in voltage, a researcher would want to manipulate a positive ion such as Na+.

How might researchers identify which ion enters the cell from outside, causing the rapid rise in membrane potential that initiates the action potential in additional experiments? 1. change the concentration of Na+ ions in the solution bathing the axon 2. change the concentration of Cl- ions in the solution bathing the axon 3. create a short-circuit across the axon's membrane so that the membrane potential remains at 0 volts

2. Complexity arises from different combinations of proteins.. 3. Complexity arises from differential gene expression. 4. Many human genes can encode multiple proteins.

Humans do not have significantly more genes than some other animals, for instance, the nematode worm C. elegans. What accounts for the diversity of cell types and functions in humans relative to C. elegans or D. melanogaster? Select all that apply. 1. Most genes in the other animals are inactive. 2. Complexity arises from different combinations of proteins.. 3. Complexity arises from differential gene expression. 4. Many human genes can encode multiple proteins. 5. Humans cells frequently gain more genes through horizontal gene transfer.

1. The adrenal glands will not release cortisol.

If ACTH secretion is inhibited, which of the outcomes will result? 1. The adrenal glands will not release cortisol. 2. The thyroid gland will not release thyroid hormone. 3. The posterior pituitary gland will not release ADH. 4. The anterior pituitary gland will not release TSH.

B. False

If a hemoglobin molecule comes into close contact with a respiring cell, the presence of CO2 in the environment will cause hemoglobin to bind to more oxygen molecules (if it is not already bound to four). A. True B. False

3. 5000 10 mm = 10,000 µm. The number of sarcomeres is therefore 10,000 µm /2 µm = 5,000 sarcomeres.

If a muscle fiber is 10 mm long and its sarcomeres average 2.0 µm in length (close to their maximal force generation), how many sarcomeres are in series along the fiber's length? 1. 50 2. 2000 3. 5000 4. 200

3. It constantly signals its pathway to be "on."

If a mutation caused the G protein to become permanently bound to GTP, what result can be predicted? 1. It is unable to signal subsequent steps in the pathway. 2. It constantly signals its pathway to be "off." 3. It constantly signals its pathway to be "on." 4. It is unable to separate from the beta and gamma subunits.

1. Cadherins in desmosomes would no longer be anchored to intermediate filaments Cadherin cytoplasmic domain binds to microfilaments in adherens junctions and to intermediate filaments in desmosomes.

If a mutation occurred in the cadherin gene so that the cytoplasmic domain no longer attached to the cytoskeleton, which of the following would occur? 1. Cadherins in desmosomes would no longer be anchored to intermediate filaments 2. Cadherins in adherens junctions would no longer be anchored to microtubules 3. Cadherins in hemidesmosomes would no longer be anchored to intermediate filaments 4. Cadherins in desmosomes would no longer be anchored to microfilaments

4. Cadherins in desmosomes would no longer be anchored to intermediate filaments. Cadherin cytoplasmic domain binds to microfilaments in adherens junctions and to intermediate filaments in desmosomes.

If a mutation occurred in the cadherin gene so that the cytoplasmic domain no longer attached to the cytoskeleton, which of the following would occur? 1. Cadherins in adherens junctions would no longer be anchored to microtubules. 2. Cadherins in hemidesmosomes would no longer be anchored to intermediate filaments. 3. Cadherins in desmosomes would no longer be anchored to microfilaments. 4. Cadherins in desmosomes would no longer be anchored to intermediate filaments.

2. actin and myosin in the sarcomeres will remain bound. ATP is required to break the association between actin and myosin. If there is no ATP available, then myosin will stay bound to actin and the sarcomere will maintain its shortened state.

If a skeletal muscle is no longer able to make enough ATP, then: 1. there will be low levels of acetylcholine at the motor endplate. 2. actin and myosin in the sarcomeres will remain bound. 3. actin and myosin in the sarcomeres are in the unbound state. 4. the muscle will be unable to shorten.

4. Solution X is hypotonic relative to solution Y.

If solution X has a 2% concentration of salt (NaCl) and solution Y has an 8% concentration of NaCl, which of the statements is correct? 1. Solution X has a higher osmotic pressure than solution Y. 2. Solution X is hypertonic relative to solution Y. 3. Solution X has a higher solute concentration than solution Y. 4. Solution X is hypotonic relative to solution Y. 5. Solution X has a lower concentration of water than solution Y.

2. There will be a net diffusion of oxygen from outside the cell to inside the cell. Gases will move from areas of higher partial pressure to areas of lower partial pressure for that gas. The partial pressure of oxygen is higher outside the cell, so oxygen will move into the cell.

If the partial pressure of oxygen outside of a cell is 100 mmHg and the partial pressure of oxygen inside of a cell is 25 mmHg, which of the statements is correct? 1. There will be a net diffusion of carbon dioxide into the cell. 2. There will be a net diffusion of oxygen from outside the cell to inside the cell. 3. There will be a net diffusion of oxygen from inside the cell to outside the cell. 4. There will be a net diffusion of carbon dioxide out of the cell. 5. There will be no net diffusion of oxygen in either direction.

2. toward the plus; kinesin

If the vesicle being carried in the figure (in an animal cell) contains content that is to be excreted from the cell at the plasma membrane, it is probably being transported toward the __________ by the motor protein ____________. 1. toward the minus; kinesin 2. toward the plus; kinesin 3. toward the minus; dynein 4. toward the plus; dynein

4. All of these choices are correct.

If two signaling pathways are activated simultaneously: 1. one may inhibit the other. 2. they may inhibit each other. 3. they may strengthen each other. 4. All of these choices are correct.

If you were to use CRISPR to cleave DNA at sites flanking a gene, and in this way produce a deletion of the gene, how many sgRNAs would you need? 1 2 3 4

1. there is a higher concentration of cone cells in the center of the retina in an area called the fovea.

Images that you see in your peripheral vision are not as sharp as those directly in front of you because: 1. there is a higher concentration of cone cells in the center of the retina in an area called the fovea. 2. the lens cannot focus images well on areas of the retina where images from the periphery are projected. 3. the rod cells in the periphery are sensitive to blue and green light only. 4. there are fewer rod cells in areas of the retina where images from the periphery are focused.

2. missense

Imagine a gene in which the sequence that is transcribed has a GAG codon, which specifies glutamic acid. If the codon mutated to GUG, which specifies valine, what type of mutation would it be? 1. nonsense 2. missense 3. silent 4. base pair deletion 5. frameshift

3. The sequence is contained in a retrovirus that has infected both species. 4. The sequence encodes a gene that is critical for life and that cannot retain its function if mutated.

Imagine a genomic researcher who is analyzing the genome of different types of cats. She finds that a particular sequence in the North American Bobcat genome is identical to a sequence found in the common house cat, whereas most other sequences between the genomes of these cats differ at many nucleotides. Bobcats and house cats diverged an estimated 6.8 million years ago, plenty of time for mutation to generate DNA sequence variation. Which statements could explain the identical sequence in these otherwise differing genomes? Select all that apply. 1. The sequence encodes a protein critical for the production of fur color. 2. The sequence is from an intron of a gene that encodes a muscle protein. 3. The sequence is contained in a retrovirus that has infected both species. 4. The sequence encodes a gene that is critical for life and that cannot retain its function if mutated.

B. False

Imagine that a doctor encounters a patient carrying a mutation that reduces collagen production. As a result, the arteries of this patient will likely be stronger and more resistant to aneurysms compared to arteries in an individual not carrying this mutation. A. True B. False

1. More sequences are conserved between rabbits and humans than between humans and mice.

Imagine that a researcher is comparing the sequence of seven protein-coding genes among mice, rabbits, and humans. She finds that for five of these genes the rabbit sequences are more similar to the human sequences than are the mouse sequences. What can she deduce? 1. More sequences are conserved between rabbits and humans than between humans and mice. 2. Mice and rabbits do not share a common ancestor. 3. Mice and humans share a more "recent" common ancestor than do rabbits and humans. 4. Humans and mice do not share a common ancestor.

2. All of these choices are correct. Memories are formed through changes in synapses in neural circuits. The formation of these neural circuits requires repeated excitation in order to be maintained in long-term memory. Cramming for a test commits information to short-term memory but does not produce strong neural circuits necessary for long-term memory.

Imagine that a student studies all night for an exam the next day. The student remembers (almost) everything for her test, but within a week, she forgets most of what she studied. Why? 1. The student has not studied the material she was tested on repeatedly. 2. All of these choices are correct. 3. The student's short-term memories regarding the test material were not successfully transformed into long-term memories. 4. New neural circuits were not formed (or strengthened) in the student's brain.

1. The injury will make it more difficult to increase negative air pressure in her chest cavity, making inhalation more difficult. Contraction of the diaphragm expands the thoracic cavity, creates negative pressure, and aids the movement of air into the lungs. Relaxation causes the diaphragm to move up under the lungs and helps with exhalation.

Imagine that a young girl suffers a horseback riding injury and one of her ribs punctures her diaphragm. How will this injury affect the girl's breathing? 1. The injury will make it more difficult to increase negative air pressure in her chest cavity, making inhalation more difficult. 2. The injury will not affect her at all, as intercostal muscles are responsible for breathing. 3. The injury will make it more difficult to decrease negative air pressure in her chest cavity, making inhalation more difficult. 4. The injury will make it easier to increase negative air pressure in her chest cavity, making inhalation easier.

2. The progenitor cell will become a type 1 cell. Because loss of function mutations result in decreased or absent signaling, you would expect the cell not to differentiate into a type 2 cell.

Imagine that there is a loss-of-function mutation in the gene for the Notch receptor in the progenitor cell of C. elegans. How does that mutation affect vulva development? Refer to the figure shown. 1. The progenitor cell will remain a type 2 cell. 2. The progenitor cell will become a type 1 cell. 3. The progenitor cell will become a type 2 cell. 4. The type 2 cell will differentiate into a type 1 cell.

1. The cells of the epidermis would not be properly connected to form a water-resistant barrier. The basal lamina is made and maintained by the cells that sit on it. It acts as a point of attachment for cells. However, it can also have other function such as a permeability barrier in the glomerulus (urine production). The basal lamina underlies and supports all epithelial tissues and is the foundational layer for keratinocytes

Imagine that you are examining a mouse that does not produce basal lamina in the skin. How will this mouse be different from a normal, wild-type mouse? 1. The cells of the epidermis would not be properly connected to form a water-resistant barrier. 2. The dermis will be disorganized and will lack blood vessels. 3. All of these choices are correct. 4. Cellular junctions will fail to form between the cells of the epidermis. 5. The epidermis and dermis will be strongly connected.

4. No, the somatic nervous system is responsible for voluntary responses and is not subdivided into sympathetic and parasympathetic components.

Imagine that you are talking with one of your friends about your biology course. He states that the somatic nervous system is subdivided into sympathetic and parasympathetic components and is responsible for involuntary responses. Is this statement correct? 1. No, although the somatic nervous system does have both sympathetic and parasympathetic subdivisions, it is responsible for voluntary responses. 2. No, although the somatic nervous system controls involuntary responses, it is the autonomic nervous system that is subdivided into parasympathetic and sympathetic components. 3. Yes, this statement is correct. The somatic nervous system has both sympathetic and parasympathetic components and controls involuntary responses. 4. No, the somatic nervous system is responsible for voluntary responses and is not subdivided into sympathetic and parasympathetic components.

1. returning to resting potential after the hyperpolarization phase of an action potential 3. maintaining resting potential 4. the hyperpolarization phase of an action potential

Imagine you created a toxin such that binds to the sodium-potassium pump. The toxin binds immediately to the sodium-potassium pump at the peak of the action potential but does not alter the function of sodium and potassium channels. Which of the processes would the toxin prohibit in the neuron? Select all that apply. 1. returning to resting potential after the hyperpolarization phase of an action potential 2. the depolarization phase of an action potential 3. maintaining resting potential 4. the hyperpolarization phase of an action potential

3. No action potential would be generated. The simultaneous movement of positively charged ions into and out of the cell would result in a change in membrane potential that would not reach threshold potential and no action potential would be generated.

Imagine you genetically engineered a neuron to produce voltage-gated Na+ and K+ channels that opened at the same time in response to a change in voltage. How would that change the recording shown in the figure? 1. The peak would occur over a longer period of time. 2. The peak voltage would be higher. 3. No action potential would be generated. 4. Threshold values would increase. 5. The period of hyperpolarization would be longer.

2. the adaptive immune system.

Immunological memory is a feature of: 1. the innate immune system. 2. the adaptive immune system.

2. cleave target DNA. 3. bind target DNA. 4. bind guide RNA.

In DNA editing by means of CRISPR, the function of the CRISPR-associated protein is to: Select all that apply. 1. translate guide RNA. 2. cleave target DNA. 3. bind target DNA. 4. bind guide RNA. 5. transcribe guide RNA.

A. True

In DNA sequencing, the newly synthesized DNA strand that is complementary and anti-parallel to a template DNA strand is called a sequence read. A. True B. False

4. potassium leaves cell, cell repolarizes

In a typical neuron, what happens during an action potential when a voltage-gated potassium channel opens? 1. potassium enters cell, cell depolarizes 2. potassium enters cell, cell repolarizes 3. potassium leaves cell, cell depolarizes 4. potassium leaves cell, cell repolarizes

4. one muscle undergoes flexion, whereas the other undergoes extension.

In an antagonistic muscle pair: 1. both muscles undergo extension simultaneously. 2. both muscles undergo flexion simultaneously. 3. the two muscles combine forces to produce similar motions. 4. one muscle undergoes flexion, whereas the other undergoes extension. 5. None of the other answer options is correct.

1. remove nitrogenous wastes from the circulating blood 2. maintain water balance in the body 3. maintain electrolyte balance in the body

In general, excretory organs function to do which of the statements? Select all that apply. 1. remove nitrogenous wastes from the circulating blood 2. maintain water balance in the body 3. maintain electrolyte balance in the body 4. remove excess sugar from the circulating blood

B. False

In mammals, bulk flow only refers to the movement of oxygen (either into or out of the lungs and within the bloodstream). Bulk flow never refers to the movement of carbon dioxide. A. True B. False

3. receptor activation. When receptors bind to their signaling molecules, receptor activation results from a change in shape of the receptor that activates enzyme activity of the receptor or allows binding of other proteins to the receptor.

In many signaling pathways, once a signaling molecule binds to a receptor, the receptor becomes phosphorylated. This initial phosphorylation step best demonstrates: 1. either cellular response or signal transduction. 2. signal transduction. 3. receptor activation. 4. cellular response. 5. termination.

A. True

In most organisms, the excretion of wastes is closely tied to the maintenance of water and electrolyte balance. A. True B. False

5. noncoding DNA.

In organisms with large genomes, inversions are more likely to be tolerated if the breakpoints occur in: 1. open reading frames. 2. reciprocal translocations. 3. closed reading frames. 4. coding DNA. 5. noncoding DNA.

2. testosterone.

In response to LH and FSH, testes secrete: 1. ejaculate. 2. testosterone. 3. estrogen. 4. TDF. 5. sperm.

1. -54 mv Mean or average = (-55+-40 + -70 + -60 + -45)/5 = -54mV

In separate studies of other nerve cells in other animals, researchers have recorded values for the resting membrane potential of the different nerve cells: -55 mv, -40 mv, -70 mv, -60 mv and -45 mv. What is the mean resting membrane potential of these cells? 1. -54 mv 2. -40 mv 3. -60 mv 4. -50 mv 5. +40 mv

2. intermediate filaments Hemidesmosomes are cell junctions between integrins on the cell surface, the intermediate filaments in the cell, and the extracellular matrix.

In skin, the cells of the epidermis connect to the basal lamina through cellular junctions known as hemidesmosomes. Select the cytoskeletal element that helps maintain the integrity of this connection. 1. microtubules only 2. intermediate filaments 3. both intermediate microtubules and microfilaments 4. microfilaments only

3. The direction of a reversible reaction is influenced by the concentrations of reactants and products. In pulmonary circulation, the low CO2 concentration favors the formation of CO2 and H2O. The direction of a reversible reaction is influenced by the concentrations of reactants and products. In pulmonary circulation, the low CO2 concentration favors the formation of CO2 and H2O.

In systemic tissue fluids, the enzyme carbonic anhydrase catalyzes the reaction CO2 + H2O → H2CO3 (which then can dissociate into H+ and HCO3-). In fact, CO2 released from cells is converted to HCO3- ions and travels in that form in the bloodstream. HCO3- is reconverted to CO2 + H2O in the pulmonary capillaries by the same enzyme, and there the CO2 is exhaled. How is it possible for the same enzyme to catalyze reverse reactions? 1. There must be two forms of carbonic anhydrase. One form catalyzes the forward reaction CO2 + H2O → H2CO3 and the other catalyzes the reverse reaction H2CO3 → CO2 + H2O. 2. The lungs contain an allosteric inhibitor that prevents the formation of carbonic acid. 3. The direction of a reversible reaction is influenced by the concentrations of reactants and products. In pulmonary circulation, the low CO2 concentration favors the formation of CO2 and H2O.

In systemic tissue fluids, the enzyme carbonic anhydrase catalyzes the reaction CO2 + H2O → H2CO3 (which then can dissociate into H+ and HCO3-). In fact, CO2 released from cells is converted to HCO3- ions and travels in that form in the bloodstream. HCO3- is reconverted to CO2 + H2O in the pulmonary capillaries by the same enzyme, and there the CO2 is exhaled. How is it possible for the same enzyme to catalyze reverse reactions? 1. The lungs contain an allosteric inhibitor that prevents the formation of carbonic acid. 2. There must be two forms of carbonic anhydrase. One form catalyzes the forward reaction CO2 + H2O → H2CO3 and the other catalyzes the reverse reaction H2CO3 → CO2 + H2O. 3. The direction of a reversible reaction is influenced by the concentrations of reactants and products. In pulmonary circulation, the low CO2 concentration favors the formation of CO2 and H2O.

1. a signaling molecule that binds to the receptor

In the context of cell signaling, to what does the term ligand refer? 1. a signaling molecule that binds to the receptor 2. the extracellular domain of a receptor protein 3. the proteins activated as part of a signal transduction pathway 4. a type of gated channel

1. the return of excess interstitial fluid to the bloodstream If the vessels were occupied by worms, then the amount of fluid that can enter the vessel would be reduced. The reduction of fluid entering the lymph vessel would result in decreased fluid returned into the circulatory system at the venae cava to the heart.

In the disease elephantiasis, lymph vessels become blocked because of infection with parasitic worms. Which of the processes would be impacted by this disease? 1. the return of excess interstitial fluid to the bloodstream 2. the flow of water back into the capillaries by osmosis 3. the generation of pressure to filter materials through the capillary walls 4. the diffusion of water and small molecules across the wall of the capillary 5. the exchange of oxygen and other materials between the blood and body cells

100; 1,010,000

In the example of adrenaline signaling used in the animation, suppose each amplification step produces hundredfold active molecules. A signaling pathway resulting from a single activated signal receptor results in the consumption of _______ molecules of GTP and _______ molecules of ATP. 10,000; 1,000,000 100; 1,000,000 100; 1,010,000 1; 100

1,000,000

In the example of adrenaline signaling used in the animation, suppose each amplification step produces hundredfold active molecules. How many total modified protein target molecules result from a single activated signal receptor? 1,000,000 100,000,000 300 10,000 900

4. activated receptor activates G proteins, activated adenylyl cyclase produces cAMP, active protein kinase A phosphorylates target proteins

In the example of adrenaline signaling, which steps represent an amplification of the signal? 1. receptor signal binding, activated adenylyl cyclase producing cAMP, active protein kinase A phosphorylating target proteins 2. activated receptor activates G proteins, G protein binding by GTP, cyclic AMP activation of protein kinase A 3. receptor signal binding, activated receptor activates G proteins, activated adenylyl cyclase producing cAMP 4. activated receptor activates G proteins, activated adenylyl cyclase produces cAMP, active protein kinase A phosphorylates target proteins

A. True

In the figure shown, digestion in the small intestine is aided by secretions from the liver, gallbladder, and pancreas. Secretin, a hormone produced by cells lining the duodenum, stimulates the pancreas to release bicarbonate ions. A. True B. False

3. Hyperpolarization of the rod cell in the light inhibits release of a neurotransmitter. Rod cells release neurotransmitter in the dark. When light hits a rod, there is a conformational change in retinal that causes a change in membrane potential, and it hyperpolarizes. This reduces the amount of neurotransmitter released and changes the signals sent to the postsynaptic cell.

In the figure shown, panel a depicts a photoreceptor and its postsynaptic cell in the dark and panel b depicts both cells in the light. What causes the change observed in this figure? 1. Hyperpolarization of the rod cell in the dark causes release of a neurotransmitter. 2. This figure is incorrect; dark and light are reversed. 3. Hyperpolarization of the rod cell in the light inhibits release of a neurotransmitter. 4. Depolarization of the rod cell in the light inhibits release of neurotransmitter.

4. ligand H Of the four receptors, the activation of H receptor is the only one that results in the activation of S and the inhibition of T. So, if ligand H binds the H receptor, T is inhibited, preventing the activation of V, and S is activated, causing the activation of U.

In the figure shown, there are four ligands (M, H, K, and L) and their corresponding receptors along with four genes (S, T, U, and V), whose activity the receptor controls through signal transduction. The arrows indicate gene activation, the T-bars indicate gene repression. Which ligand acts as a signal resulting in gene U being active and V inactive? 1. ligand L 2. ligand M 3. ligand K 4. ligand H 5. None of the other answer options is correct.

2. ligand K Of the four receptors, the activation of K receptor is the only one that results in the activation of T and the inhibition of S. So, if ligand K binds the K receptor, T is activated, causing the activation of V, and S is inhibited, preventing the activation of U.

In the figure shown, there are four ligands (M, H, K, and L) and their corresponding receptors along with four genes (S, T, U, and V), whose activity the receptor controls through signal transduction. The arrows indicate gene activation, the T-bars indicate gene repression. Which ligand acts as a signal resulting in gene U being inactive and gene V being active? 1. ligand M 2. ligand K 3. ligand H 4. ligand L 5. None of the other answer options is correct.

3. testosterone Steroid hormones are hydrophobic and able to cross the plasma membrane. Furthermore, hormones derived from cholesterols, like testosterone, are able to cross the plasma membrane and have intracellular receptors.

In the figure shown, what could the hormone indicated by the small hexagon in the red circle be? 1. growth hormone 2. ADH 3. testosterone 4. insulin

5. nucleus; cell body

In the figure, arrow B is pointing at the _____ in the _____. 1. nucleus; glial cell 2 . vesicle; dendrite 3. neurotransmitter; synaptic cleft 4. synaptic cleft; neuron 5. nucleus; cell body

Point C

In the figure, at which labeled location will NaCl be at its highest concentration relative to the other solutes in the filtrate?

Point e

In the figure, where will urea be at its highest concentration relative to the other solutes in the filtrate?

Point c

In the figure, where would you predict you would find the highest concentration of solutes in the filtrate?

Point a & b

In the figure, which of the letters represents a region of the loop of Henle where water diffuses out of the filtrate? Select all that apply.

1. It is going toward the minus.

In the image of a microtubule shown here, the plus and minus ends are labeled. If the motor protein shown is dynein, what can you say about the direction in which the vesicle is being carried? 1. It is going toward the minus. 2. It can go in either direction on microtubules. 3. The direction cannot be determined from the data provided. 4. It is going toward the plus.

A and B The percent muscle length is what is being changed in the experiment, so it is the independent variable. The percent force is being measured, so it is the dependent variable.

In the results for percent force graphed versus percent muscle length: (a) percent force is the dependent variable. (b) percent muscle length is the independent variable. (c) percent force is the independent variable. (d) percent muscle length is the dependent variable. A and B C and D

4. hypothalamus

In vertebrates, the nervous system directly interacts with the _________ to control endocrine function in the body. 1. adrenal cortex 2. anterior pituitary 3. posterior pituitary 4. hypothalamus

4. myelinating the axon

In vertebrates, the speed of transmission along a neuron can be increased by which answer choice? 1. myelinating the dendrites 2. the presence of additional voltage-gated potassium channels 3. the presence of additional voltage-gated sodium channels 4. myelinating the axon

1. Saltatory conduction in non-myelinated neurons slows the process of transmission.

In vertebrates, the speed of transmission along neurons is much faster in myelinated neurons compared to unmyelinated neurons. Which answer choice is not true of transmission along myelinated neurons? 1. Saltatory conduction in non-myelinated neurons slows the process of transmission. 2. Action potentials are generated only in the nodes of Ranvier. 3. Sodium and potassium channels are concentrated at nodes of Ranvier.

1. the hypothalamus

In vertebrates, which structure frequently serves as the first intermediary between the areas of the brain that perceive sensory stimuli and the rest of the endocrine system? 1. the hypothalamus 2. the adrenal glands 3. the thyroid gland 4. the posterior pituitary gland 5. the anterior pituitary gland

4. if the homologous chromosome lacks the deletion

In what situation can a harmful deletion in a chromosome persist in a population? 1. if the deletion is in the centromere 2. if it is homozygous 3. if a transposon replaces the deleted region 4. if the homologous chromosome lacks the deletion

2. canines

In which of the groups of vertebrates listed below would you expect to find the fewest number of different photopigments? 1. birds 2. canines 3. humans

4. right atrium and right ventricle

In which of the heart chambers would deoxygenated blood be found? 1. left atrium and left ventricle 2. right atrium and left ventricle 3. left atrium and right ventricle 4. right atrium and right ventricle 5. right atrium and left atrium

1. ovaries

In which of the structures are oocytes produced? 1. ovaries 2. uterus 3. cervix 4. fallopian tubes 5. vagina

2. the release of the ligand from the receptor ligand binding site.

Inactivation of a cell-surface receptor depends on: 1. the concentration of ligand surrounding the cell. 2. the release of the ligand from the receptor ligand binding site. 3. the binding affinity of the receptor. 4. the activity of phosphatases in the cytosol.

4. reciprocal inhibition.

Inhibition of the flexor muscle during the knee-extension reflex is an example of: 1. negative feedback. 2. homeostasis. 3. All of these choices are correct. 4. reciprocal inhibition.

B. False

Inhibitory postsynaptic potentials (IPSPs) are associated with membrane depolarization, whereas excitatory postsynaptic potentials (EPSPs) are associated with hyperpolarization. A. True B. False

4. None of the other answer options is correct.

Innate immunity activation depends on: 1. major histocompatibility complex (MHC) class II proteins. 2. previous exposure to a foreign antigen. 3. diversity of antibodies in the blood stream. 4. None of the other answer options is correct. 5. memory B cells.

1. open

Insects possess _____ circulatory systems, circulatory systems in which hemolymph completely "bathes" the organs and is not typically contained in distinct arteries or veins. 1. open 2. closed 3. fluid 4. solid

1. cause frameshift mutations.

Insertions and deletions of single nucleotides: 1. cause frameshift mutations. 2. cause cancer. 3. add or delete amino acids to or from the normal polypeptide. 4. shorten chromosomes. 5. cause missense mutations.

2. injecting too much insulin

Insulin injections are an important treatment for some diabetics. A serious potential side effect of insulin injections is hypoglycemia (low blood sugar). This would most likely occur under which of the circumstances? 1. failure to inject enough insulin 2. injecting too much insulin 3. failure to inject any insulin

3. All of these choices are correct.

Intermediate filaments: 1. undergo little change in length in comparison to microtubules and microfilaments. 2. play an important role in maintaining cell shape. 3. All of these choices are correct. 4. have a diameter that is larger than a microfilament, but smaller than a microtubule. 5. play an important role in preventing skin from tearing by shear stress.

3. decrease kisspeptin synthesis.

Kisspeptin is a protein in humans that has an important role in initiating secretion of the releasing factor gonadotropin-releasing hormone (GnRH). Endocrinologists are finding that the protein kisspeptin and its receptor are central to sexual maturation at puberty. Neurons that release kisspeptin carry estrogen receptors. If this is a negative feedback system, high levels of estrogen would be expected to: 1. neither increase nor decrease kisspeptin synthesis because steroid hormones do not affect protein synthesis. 2. increase kisspeptin synthesis. 3. decrease kisspeptin synthesis.

1. grew better in cell culture containing blood serum containing proteins released by platelets during clotting. In plasma, less mitogenic activity was obtained for the proliferation of fibroblasts. Growth promoting factor is not present as precursor molecule in plasma then it must have been released during the clotting process. Platelets increases the stimulation of cell proliferation by 5 folds. The content of the protein released by platelet is the source which promotes the growth of normal fibroblasts. Kohler and Lipton found that blood serum that was derived from clotted blood, in which platelets had released their contents to drive blood clotting, enhanced growth of fibroblasts better than blood plasma, in which platelets were still intact.

Kohler and Lipton first discovered platelet-derived growth factor (PDGF) by observing that fibroblasts: 1. grew better in cell culture containing blood serum containing proteins released by platelets during clotting. 2. grew better in cell culture blood plasma without the proteins released by platelets. 3. grew at the same rate in cell culture containing either blood plasma or serum.

3. the postsynaptic cell becomes more responsive to subsequent stimulation. 4. molecular or structural changes occur at the synapse.

Learning and memory involve changes in neural circuits within specific regions of the brain. At the cellular level, repeated stimulation of a presynaptic neuron may result in learning if: Select all that apply. 1. the postsynaptic cell produces action potentials with greater maximum voltage. 2. the stimulated cell produces action potentials with greater maximum voltage. 3. the postsynaptic cell becomes more responsive to subsequent stimulation. 4. molecular or structural changes occur at the synapse. 5. the amount of neurotransmitter released from postsynaptic vesicles of the stimulated cell decreases.

4. B cells binding to antigens on host cells and targeting their degradation

Lupus is an autoimmune disorder. Which of the qualities would you expect to be a symptom of lupus? 1. increased phagocytosis of bacterial pathogens in the body 2. an increase in ciliary action of the esophagus 3. increased blood clotting if the skin is cut 4. B cells binding to antigens on host cells and targeting their degradation

1. Minus end; dynein Dynein is a minus end-directed motor protein that carries vesicles along microtubules.

Macrophage cells undergo a process called phagocytosis in which material is brought into a cell in the form of membrane vesicles and then transported along microtubules toward the cell center. Assuming that the centrosome is near the cell center, you can predict that these vesicles are moving to the _____ end of microtubules using the motor protein _____. 1. minus end; dynein 2. plus end; kinesin 3. minus end; kinesin 4. plus end; dynein

1. minus end; dynein Dynein is a minus end-directed motor protein that carries vesicles along microtubules.

2. endocrine

Mammalian steroid hormones are signaling molecules that function in which type of cell signaling? 1. autocrine 2. endocrine 3. paracrine 4. All of these choices are correct.

1. Birth control pills maintain constant levels of estrogens and/or progesterone so that there is no surge in FSH and ovulation does not occur.

Many birth control pills release a constant amount of synthetic estradiol and progesterone for 21 days, followed by 7 days during which no hormones are ingested. Which of the statements describes the effects of birth control pills? 1. Birth control pills maintain constant levels of estrogens and/or progesterone so that there is no surge in FSH and ovulation does not occur. 2. Birth control pills inhibit the development of the uterine lining so that implantation of a fertilized oocyte cannot occur. 3. The 7 days without hormones prevent the uterine lining from thickening to the point that a fertilized oocyte can implant.

3. the sarcomere is at intermediate length before contraction begins.

Maximum force is generated by a muscle contraction when: 1. intracellular calcium levels are low. 2. there is excessive overlap between actin and myosin. 3. the sarcomere is at intermediate length before contraction begins. 4. overlap between actin and myosin is low.

3. difference in concentration of ions and charged molecules on the two sides of a cell's plasma membrane.

Membrane potential is determined by the: 1. concentration of cholesterol in a membrane. 2. number and type of phospholipids present in a membrane. 3. difference in concentration of ions and charged molecules on the two sides of a cell's plasma membrane. 4. number and types of ion-channel proteins present in the plasma membrane of a cell.

1. cerebrum and hippocampus

Memory and learning take place in which area of the brain? 1. cerebrum and hippocampus 2. pons and medulla 3. hypothalamus 4. cerebellum

5. the urine produced in both systems is more dilute than the body fluids.

Metanephridia differ from protonephridia in all of the following ways EXCEPT that: 1. fluid from the body cavity enters protonephridia without first being filtered. 2. metanephridia are surrounded by an extensive capillary network, whereas protonephridia are not. 3. fluid enters metanephridia through a funnel-shaped opening. 4. selective reabsorption of materials occurs via cells lining the tubules in protonephridia and via capillaries in metanephridia. 5. the urine produced in both systems is more dilute than the body fluids.

A. True

Metanephridia differ from protonephridia in that selective reabsorption of materials occurs via cells lining the tubules in protonephridia and via capillaries in metanephridia. A. True B. False

4. are able to leave the tumor where they originated and travel to distant locations to begin new tumors at distant sites.

Metastatic cancer cells: 1. only need to cross a single layer of capillary endothelial cells to form tumors at distant sites. 2. All of these choices are correct. 3. become malignant when they grow rapidly. 4. are able to leave the tumor where they originated and travel to distant locations to begin new tumors at distant sites. 5. have lost their adhesion to the extracellular matrix, freeing them from the original tumor.

3. All the microorganisms that inhabit a location as well as all their functional genes and metabolites.

Microbiome refers to: 1. An organism and all its symbiotic microorganisms. 2. All the functional genes within microorganisms that inhabit a location. 3. All the microorganisms that inhabit a location as well as all their functional genes and metabolites. 4. All the microorganisms that inhabit a location.

4. repeating actin subunits; a thin double-helix

Microfilaments are composed of ____________ in ____________ arrangement. 1. polymers of tubulin; a double-helix 2. polymers of actin protein; a hollow tube-like 3. alpha and beta dimer subunits; a double-helix 4. repeating actin subunits; a thin double-helix

2. maintain its size and shape.

Microfilaments help a cell ____________________ 1. separate chromosomes during anaphase of mitosis. 2. maintain its size and shape. 3. strengthen the plasma membrane.

1. dynamic; polymerize

Microtubules are __________ because they __________ and depolymerize at their ends. 1. dynamic; polymerize 2. unstable; hydrolyze 3. stable; polymerize 4. dynamic; hydrolyze

1. both plus and minus ends; both plus and minus ends

Microtubules can grow by addition of tubulin dimers to _______________, and they can shorten by removal of dimers from ______________. 1. both plus and minus ends; both plus and minus ends 2. the minus end; the plus end 3. the plus end; the minus end 4. the plus end; both plus and minus ends 5. both plus and minus ends; the minus end

1. alpha-tubulin; beta-tubulin; hollow tube

Microtubules form from dimers of _____ and ______ subunits that polymerize into a ____________. 1. alpha-tubulin; beta-tubulin; hollow tube 2. +tubulin; -tubulin; double helix 3. an amino acid; phosphate; double helix 4. beta-tubulin; gamma-tubulin; beta sheet

4. The enrichment of select microbes during development that can degrade human milk oligosaccharides.

Milk-oriented Microbiota refers to: 1. The type of baby formula invented that includes human milk oligosaccharides. 2. The difference between lactose tolerant and lactose intolerant human microbiot 3. The presence of microbes in store bought milk made from dairy cows. 4. The enrichment of select microbes during development that can degrade human milk oligosaccharides.

B. False Most signaling molecules bind to the ligand binding domain of their receptors through polar interactions and do not form covalent bonds with the receptor.

Most ligands form covalent bonds with their associated receptors, these complexes are more or less permanent and can only be broken through the hydrolysis of ATP. A. True B. False

3. urea; ammonia; uric acid

Most mammals excrete _____; most aquatic animals excrete _____; birds, insects, and many reptiles excrete _____. 1. uric acid; urea; ammonia 2. urea; uric acid; ammonia 3. urea; ammonia; uric acid 4. uric acid; ammonia; urea 5. ammonia; urea; uric acid

4. All of these choices are correct.

Motor proteins cause movement by: 1. harnessing energy from ATP. 2. undergoing a conformational change. 3. binding to the cytoskeleton. 4. All of these choices are correct.

1. taking up glucose and storing it as glycogen.

Muscle and liver cells respond to insulin by: 1. taking up glucose and storing it as glycogen. 2. breaking down glycogen and storing glucose. 3. breaking down glucose and releasing glycogen 4. breaking down glycogen and releasing glucose.

3. less often than

Mutation rate in germ-line cells occur___________________ in somatic cells. 1. at the same rate as 2. more often than 3. less often than

3. APC, Ras, p53

Mutations arise in which order in the colon cancer example shown in the animation? 1. APC, p53, Ras 2. p53, Ras, APC 3. APC, Ras, p53 4. Ras, APC, p53

4. microfilaments.

Myosin is a motor protein that associates with: 1. intermediate filaments. 2. vimentin. 3. microtubules. 4. microfilaments.

3. The vertebrate hypothalamus plays a role that is similar to neurosecretory cells located in the brain of insects, which release peptide hormones that act on the corpora allata.

Neurosecretory cells underlie nervous system communication with the endocrine system. Which of these statements reflects this coordinated function between the nervous and endocrine systems? Select all that apply. 1. Neurosecretory cells within the vertebrate hypothalamus release steroid hormones that act directly on the posterior pituitary gland. 2. Neurosecretory cells within the vertebrate hypothalamus secrete hormones into blood vessels that are transported to cell receptor targets located within the anterior pituitary gland. 3. The vertebrate hypothalamus plays a role that is similar to neurosecretory cells located in the brain of insects, which release peptide hormones that act on the corpora allata. 4. Neurosecretory cells within the vertebrate hypothalamus release peptide hormones that act directly on the anterior pituitary gland. 5. Neurosecretory cells within the insect brain release steroid hormones that act directly on the corpora allata and prothoracic gland. 6. Neurosecretory cells within the insect brain release peptide hormones that act directly on the corpora allata and prothoracic gland.

2. Notch is a receptor, and Delta is a signaling molecule. Delta binds to Notch on neighboring cells, activating Notch and causing signal transduction to prevent neuronal development in Notch-activated cells.

Notch and Delta are both transmembrane proteins involved in cell communication in the developing nervous system of vertebrate animals. What makes Notch different from Delta? 1. Notch is required at higher density than Delta to alter cell fate. 2. Notch is a receptor, and Delta is a signaling molecule. 3. Notch is a signaling molecule, and Delta is a receptor. 4. All of these choices are correct.

2. the semicircular canals

On a space station, without gravity, the function of which system(s) is(are) least affected? 1. The statocyst chambers and the semicircular canals are equally affected. 2. the semicircular canals 3. the two statocyst chambers of the vestibular canal

Once all the sequencing data is collected, individual sequence reads must be mapped to the reference genome. For this question the reference sequence is shown in blue. 5'- GGCGTCTATATCTCGGCTCTAGGCCCTCATTTTTT- 3' How many single nucleotide polymorphisms (SNPs) are present in this sequencing dataset? 1 6 2 5 4 3 0

3. The cell does not divide.

One example of a cellular response to a signal is the triggering of cell division. If a mutation occurred in the gene for the signal receptor in this pathway that caused the receptor to reject binding of the signal, what response can be predicted? 1. The cell divides repeatedly without the signal. 2. The signal is not produced. 3. The cell does not divide.

4. enzymes that catalyze the hydrolysis of carbohydrates are active.

One of the effects of the hormone secretin is to stimulate the release of bicarbonate ions into the duodenum, which neutralizes the acid that enters the duodenum with food from the stomach. One consequence of neutralizing the pH in the intestine is that: 1. the enzymatically catalyzed hydrolysis of carbohydrates that began in the stomach is halted in the duodenum. 2. carbohydrates are not as easily broken down in this neutral environment. 3. enzymes that catalyze the hydrolysis of carbohydrates are denatured. 4. enzymes that catalyze the hydrolysis of carbohydrates are active.

A. True Carbon dioxide coming from the body moves into the cells of the tubule and is converted to bicarbonate to help buffer tissue surrounding the tubules and excrete hydrogen ions. The active transport of hydrogen ions into the lumen drives the reaction to the right, with CO2 and H2O.

One of the roles of the kidneys is to help buffer body fluids so that they are not too acidic or too basic. The cells of the renal tubule secrete H+ into the tubule lumen and absorb bicarbonate (HCO3-), passing it into the tissue fluid. Consider the reaction catalyzed by the enzyme carbonic anhydrase, shown in the accompanying figure. During heavy exercise, the reaction shifts to the right in the tubule lumen of the nephron. A. True B. False

B. False

One of the roles of the kidneys is to help buffer body fluids, to keep fluids from becoming too acidic or too basic. The cells of the renal tubule wall secrete H+ into the tubule lumen and absorb bicarbonate, passing it into the tissue fluid. Consider the reaction catalyzed by the enzyme carbonic anhydrase, shown in the accompanying figure. During heavy exercise, the reaction shifts to the right in the renal tubule cell of the nephron. A. True B. False

3. have different

Osmoregulators _____ internal solute concentrations compared to their external environment. 1. have the same 2.always have higher 3. have different 4. always have lower

1. The uterus has receptors for oxytocin, but not for cholecystokinin.

Oxytocin and cholecystokinin are transported through the bloodstream and arrive at the uterus at the same time. Why does oxytocin cause the uterus to contract, whereas cholecystokinin has no effect? 1. The uterus has receptors for oxytocin, but not for cholecystokinin. 2. Oxytocin blocks the activity of cholecystokinin. 3. Unlike cholecystokinin, oxytocin alters gene expression patterns. 4. Oxytocin is at a higher concentration in the bloodstream than cholecystokinin. 5. Unlike cholecystokinin, oxytocin is able to diffuse through the plasma membrane of uterine cells.

2. engulf many different pathogens. 3. present foreign antigens that stimulate adaptive immune responses.

Phagocytic cells are an important part of the innate immune system because of their ability to: Select all that apply. 1. produce multiple antibodies. 2. engulf many different pathogens. 3. present foreign antigens that stimulate adaptive immune responses. 4. attack cells infected by a virus.

A. True

Pheromones are generally detected by the vomeronasal organ in most mammals, reptiles, and amphibians. A. True B. False

3. The response of the cell would last longer than it normally would. Phosphatases remove phosphate groups added by kinases and terminate their activating effect. Without phosphatases, phosphorylation and activation would persist.

Phosphatases are a family of enzymes that remove phosphate groups from specific proteins; these phosphate groups had been added to the proteins by protein kinases. Vanadate is an inhibitor of phosphatases in eukaryotic cells. What effect would vanadate have on the response of cells to signals received by receptor kinases? 1. The response of the cell would be shorter than it normally would. 2. The signal would still bind the receptor, so there would be no effect. 3. The response of the cell would last longer than it normally would.

2. tumor suppressor gene. - Normal, non-mutant tumor suppressor genes have functions that block the development of cancer.

Phosphorylated p53 is a protein that accumulates in the nuclei of cells that have damaged DNA where it functions to block the cell cycle and activate DNA repair. The p53 gene that encodes this protein is an example of a(n): 1. oncogene. 2. tumor suppressor gene. 3. protein kinase. 4. proto-oncogene.

True

Phylogenetic analysis of 16S rRNA-encoding gene sequences from fecal microbiota of control or patients with C. difficile associated diarrhea (both initial and recurrent episodes) are shown below. T/F: Bacteroides are reduced in patients with recurrent CDI.

False

Phylogenetic analysis of 16S rRNA-encoding gene sequences from fecal microbiota of control or patients with C. difficile associated diarrhea (both initial and recurrent episodes) are shown below. T/F: People with recurrent CDI have more resilient microbiomes.

(6)-(1)-(5)-(3)-(4)-(2)

Place the events in the correct order. (1) opening of voltage-gated calcium channels (2) change in membrane potential of the postsynaptic neuron (3) fusion of secretory vesicles with the plasma membrane of axon terminal (4) binding of neurotransmitters to receptors on the postsynaptic neuron (5) increase in cytosolic calcium levels in the presynaptic neuron (6) arrival of action potential at the axon terminal of the presynaptic neuron (2)-(1)-(5)-(4)-(3)-(6) (6)-(2)-(1)-(5)-(3)-(4) (1)-(5)-(2)-(3)-(4)-(6) (6)-(1)-(5)-(3)-(4)-(2)

1. nonsynonymous codon 3. nonsense codon 4. shift in reading frame

Point mutations can impair a protein if they result in which of the answer choices? Select all that apply. 1. nonsynonymous codon 2. synonymous codon 3. nonsense codon 4. shift in reading frame

5. All of these choices are correct.

Positive feedback loops: 1. are activated by a stimulus. 2. continue until interrupted or broken by an external signal. 3. cause a response in the same direction as the initial stimulus. 4. move the system further and further away from the set point. 5. All of these choices are correct.

4. The membrane potential would become more positive.

Predict what would happen to a neuron's resting membrane potential if the number of sodium ion channels increased. 1. The membrane potential would remain the same due to the activity of the sodium-potassium pump. 2. The membrane potential would become slightly more negative. 3. The membrane potential would become more negative. 4. The membrane potential would become more positive.

A. True

Principal Coordinate (PC) analysis plots are a tool that can provide information on the similarities and differences between microbiome samples. A. True B. False

2. The concentration of positively charged ions present inside the cell must increase to produce the positive spike of the action potential. 5. The decrease in voltage after the action potential spike results from the movement of positive ions from the inside to the outside the nerve cell.

Refer to the graph in the figure. Which statements are true? Select all that apply. 1. The decrease in voltage after the action potential spike results from the movement of positive ions back into the nerve cell. 2. The concentration of positively charged ions present inside the cell must increase to produce the positive spike of the action potential. 3. The concentration of positively charged ions present inside the cell must decrease to produce the positive spike of the action potential. 4. The concentration of negatively charged ions present inside the cell must increase to produce the positive spike of the action potential. 5. The decrease in voltage after the action potential spike results from the movement of positive ions from the inside to the outside the nerve cell.

2. tight junctions

Referring to the figure shown, identify which type of cell-cell interaction is most likely to force the products of digestion to be absorbed across microvilli of intestinal cells, rather than allowing them to leak between cells. 1. desmosomes 2. tight junctions 3. hemidesmosomes 4. plasmodesmata 5. gap junctions

2. sequences containing repeats longer than the DNA fragments to assemble

Repeated DNA sequences represent a special challenge in genome sequence assembly. Which would be harder to assemble correctly, assuming the number of copies of the repeat can be determined? 1. sequences containing repeats shorter than the DNA fragments to assemble 2. sequences containing repeats longer than the DNA fragments to assemble

3. "remember" the first time it was infected with a virus. 4. identify viral DNA by complementary base pairing with RNA. 6. transcribe RNA that combines with a protein that has a DNA-cleaving function.

Researchers noted that about half of all species of bacteria contain small segments of DNA of about 20-50 base pairs derived from plasmids or viruses. The phrase clustered regularly interspaced short palindromic repeats (CRISPR) describes the organization of these viral DNA segments in the bacterial genome. Bacteria use CRISPR to: (Select all that apply.) 1. identify viral DNA by complementary base pairing with template DNA. 2. transcribe RNA that combines with a protein that has a RNA-cleaving function. 3. "remember" the first time it was infected with a virus. 4. identify viral DNA by complementary base pairing with RNA. 5. copy part of the bacteria genome and incorporate it into a viral genome. 6. transcribe RNA that combines with a protein that has a DNA-cleaving function.

4. carbohydrates in the mouth.

Salivary amylase starts the chemical digestion of: 1. proteins in the stomach. 2. fats in the mouth. 3. carbohydrates in the stomach. 4. carbohydrates in the mouth. 5. proteins in the mouth.

5. All of these choices are correct.

Second messengers: 1. are small intracellular molecules that participate in signal transduction. 2. play a role in activation of intracellular signal transduction. 3. are removed in order to terminate a cellular signaling response. 4. amplify the effects of the signal. 5. All of these choices are correct.

1. stretch-gated channel Ligand-gated channels only open when a ligand binds. Voltage-gated channels only open when there is a change in membrane potential. Stereocilia are situated at a fixed distance from adjacent stereocilia. Movement of fluid in the cochlea or semicircular canals causes movement of the hair cells, bringing some stereocilia closer together but stretching others further apart. This stretching causes ion channels to open and depolarization of the sensory nerves associated with the hair cell.

Select the type of channel that is associated with ion transport in stereocilia. 1. stretch-gated channel 2. ligand-gated channel 3. voltage-gated channel

1. Sensory cells and sensory neurons have electrically excitable membranes that change in charge potential in response to binding an environmental signaling molecule. 4. Sensory cells and sensory neurons have protein receptors linked to intracellular or membrane-based signaling pathways that alter ion channel permeability.

Sensory cells and sensory neurons allow multicellular animals to sense physical and chemical cues from their environment. What key properties of these cells enable them to perform this function? Select all that apply. 1. Sensory cells and sensory neurons have electrically excitable membranes that change in charge potential in response to binding an environmental signaling molecule. 2. Sensory neurons have myelinated dendrites that serve as nerve endings. 3. All sensory cells and sensory neurons fire action potentials when they bind a signaling molecule. 4. Sensory cells and sensory neurons have protein receptors linked to intracellular or membrane-based signaling pathways that alter ion channel permeability.

1. muscle contraction.

Sensory neurons are involved in all of the processes except: 1. muscle contraction. 2. taste. 3. vision. 4. hearing.

4. All of these choices are correct.

Sensory transduction requires: 1. a change in membrane potential. 2. alteration of the conformation of a channel protein. 3. reaction of a receptor protein with a stimulus. 4. All of these choices are correct.

A. True

Sequencing reads can be aligned to a reference genome (i.e., human genome) to identify single nucleotide variants and potential mutations. A. True B. False

Sequencing results can determine SNPs in cancer cells or provide evidence for large-scale mutations. You sequenced a tumor genome and a healthy tissue genome, then aligned your sequences with a reference genome. T/F: The blank region indicated by the arrow means that there are more reads in cancer cells compared to healthy cells.

2. single nucleotide deletions 3. large scale chromosome mutations such as a translocation and inversion 4. point mutations such as base substitutions

Sequencing the genome of cancer cells from patients can detect: Select all that apply: 1. all of these 2. single nucleotide deletions 3. large scale chromosome mutations such as a translocation and inversion 4. point mutations such as base substitutions 5. protein isoforms 6. none of these

4. several mutations affecting proto-oncogenes and/or tumor suppressor genes. - Cancer is the result of multiple mutations that accumulate over time.

Several years ago, a man noticed a small mole on his wrist. Years later, the mole grew in size and the man was diagnosed as having metastatic melanoma. This was likely the result of: 1 a single mutation inactivating a tumor suppressor gene. 2. None of the other answer options is correct; cancers arise spontaneously, independent of mutations. 3. a single mutation affecting one proto-oncogene in a cell. 4. several mutations affecting proto-oncogenes and/or tumor suppressor genes.

2. the lumen of the small intestine

Shortly after eating a candy bar, where would the increased concentration of glucose be first evident? 1. the blood flowing past the basal membrane of the epithelial cells of the lumen 2. the lumen of the small intestine 3. the cytoplasm of the epithelial cells lining the lumen of the small intestine

2. ligand K 3. ligand M 4. ligand H

Shown are four ligands (M, H, K, and L) and their corresponding receptors along with three genes (U, V, and W), whose activity the receptor controls through signal transduction. The arrows indicate gene activation, the T-bars indicate gene repression. If either U or V is required to activate W, which ligands result in W being active? Select all that apply. 1. ligand L 2. ligand K 3. ligand M 4. ligand H 5. None of the other answer options are correct.

2. ligand M 4. ligand H 5. ligand K

Shown here are four ligands (M, H, K, and L) and their corresponding receptors along with three genes (U, V, and W) whose activity the receptor controls through signal transduction. The arrows indicate gene activation, the T-bars indicate gene repression: If either U or V is required to activate W, which ligand (or ligands) result in W being active? (Select all that apply.) 1. ligand L 2. ligand M 3. None of the answer options is correct. 4. ligand H 5. ligand K

3. polar; on the surface

Signal molecules that are _______ usually have their corresponding receptor ______________ of the cell. 1. nonpolar; on the surface 2. polar; in the cytoplasm 3. polar; on the surface

1. sequential phosphorylation of proteins in the cytoplasm.

Signal transduction in development is often amplified by: 1. sequential phosphorylation of proteins in the cytoplasm. 2. methylation of the target cell's DNA. 3. opening and closing of nuclear pores. 4. histone modification in chromosomes.

3. an extracellular molecule activates a membrane protein, which in turn activates molecules inside the cell.

Signal transduction is the process by which: 1. a single master gene, or signal, activates a series of downstream genes that lead to cell differentiation. 2. a specific combination of transcription factors determines the developmental pathway in a cell or group of cells. 3. an extracellular molecule activates a membrane protein, which in turn activates molecules inside the cell. 4. transcription factors bind to cis-regulatory regions of DNA and either activate or repress transcription. 5. None of the other answer options are correct.

3. travel by diffusion. Paracrine signals are released by cells and diffuse to affect nearby cells, whereas autocrine signals are released by cells to diffuse and bind to receptors on that cell's own plasma membrane.

Signaling molecules involved in paracrine and autocrine signaling: 1. travel in the circulatory system. 2. remain attached to the plasma membrane. 3. travel by diffusion.

A. True

Signaling pathways have been conserved in a wide range of organisms. A. True B. False

2. actin and myosin

Skeletal muscle appears striated with light and dark regions. Which of the following is found in the dark regions? 1. actin and the Z disc 2. actin and myosin 3. thick filaments, but not the thin filaments 4. myosin and the Z disc

3. Low levels of calcium would result in fewer signals sent between the presynaptic and postsynaptic cell. Extracellular calcium is important because as an action potential reaches the axon terminal of the presynaptic neuron, voltage-gated calcium channels open. An increase in cytosolic calcium causes the vesicles carrying neurotransmitters to bind and release neurotransmitters into the synaptic cleft. If there is not enough circulating calcium to enter the presynaptic cell and facilitate release of neurotransmitter, then many functions controlled by the nervous system may not occur.

Some people have low levels of calcium circulating in the blood, a condition known as hypocalcemia. While for many this disorder has little to no effect, for some it can be life-threatening. How could low levels of calcium harm an individual? 1. Low levels of calcium would cause sustained depolarization of the presynaptic cell. 2. Low levels of calcium would not have any effect on synaptic transmission. 3. Low levels of calcium would result in fewer signals sent between the presynaptic and postsynaptic cell.

2. Low levels of calcium would result in fewer signals sent between the presynaptic and postsynaptic cell. Extracellular calcium is important because as an action potential reaches the axon terminal of the presynaptic neuron, voltage-gated calcium channels open. An increase in cytosolic calcium causes the vesicles carrying neurotransmitters to bind and release neurotransmitters into the synaptic cleft. If there is not enough circulating calcium to enter the presynaptic cell and facilitate release of neurotransmitter, then many functions controlled by the nervous system may not occur.

Some people have low levels of calcium circulating in the blood, a condition known as hypocalcemia. While for many this disorder has little to no effect, for some it can be life-threatening. How could low levels of calcium harm an individual? 1. Low levels of calcium would cause sustained depolarization of the presynaptic cell. 2. Low levels of calcium would result in fewer signals sent between the presynaptic and postsynaptic cell. 3. Low levels of calcium would not have any effect on synaptic transmission.

4. the sensor The sensor would recognize the feeling of hunger, or a need for caloric intake. If the set point is raised to a higher number of daily calories, then the sensor would have to change so that it only responds (by decreasing hunger) when the higher caloric number is consumed.

Some researchers have suggested that obesity is due to a change in "set point" in the brain that is related to the number of calories a person needs. People whose set point has increased eat more than they need and gain weight. Permanently raising the set point would involve a permanent change in which of the answer choices? 1. the response 2. the stimulus 3. the effector 4. the sensor

2. increases. When a person has diarrhea, they fail to reabsorb ions from the small intestine, and fluids entering the large intestine have high solute concentrations. This keeps higher volumes of water in the large intestine. In order to compensate for water loss through the digestive system, vasopressin is released. The presence of vasopressin increases the permeability of the collecting ducts to water, so water is returned to the interstitial fluid. This decreases the amount of water lost through urination.

Sometimes while traveling, people are infected with a protist parasite, Giardia. One of the side effects of Giardia infection is diarrhea. When someone has diarrhea, they lose excessive water and salt from the body. The result is loss of Na+, dehydration that leads to decreased extracellular volume and plasma volume, and decreased arterial blood pressure. Given this, the vasopressin secretion of a person infected with Giardia: 1. decreases. 2. increases. 3. stay the same.

1. a sensory neuron

Stretch receptors in the knee extensor muscles stimulated by the tap of a physician's reflex hammer just below the knee cap directly triggers a nerve impulse in which answer choice? 1. a sensory neuron 2. an interneuron 3. a motor neuron 4. the patellar tendon

1. increased surface area for nutrient absorption.

Structures known as microvilli are associated with: 1. increased surface area for nutrient absorption. 2. communication between cells. 3. adhesion to the extracellular matrix. 4. increased rates of cell division.

3. The strength of tissues would decrease because the integrin could no longer associate with microfilaments. The cytoplasmic domain of integrins binds to microfilaments. This provides a structural attachment of the cytoskeleton to the extracellular matrix that can contain laminin.

Suppose there is a mutation in a laminin-binding integrin gene that causes a loss of function in the cytoplasmic domains of the integrin. Which one of the outcomes would you expect to observe as a result of this mutation? 1. The integrin would function normally because the cytoplasmic domain is not responsible for binding to laminin. 2. The integrin would adhere to laminin and the cytoplasmic domain would adhere to microtubules instead of microfilaments. 3. The strength of tissues would decrease because the integrin could no longer associate with microfilaments.

2. frequency of stimulation of a postsynaptic cell.

Temporal summation is a response to the: 1. location of synapses over the surface of a postsynaptic neuron. 2. frequency of stimulation of a postsynaptic cell. 3. amount of neurotransmitter released from a presynaptic cell. 4. density of ligand-gated channels on the postsynaptic cell.

3. All of these choices are correct. Adrenaline has many effects, including increased heart rate, blood pressure, and respiration. To ensure that these responses do not persist permanently, the termination of adrenaline signaling stops the signaling of this pathway in a matter of minutes to hours.

Termination is an important step in adrenaline signaling because: 1. it allows an appropriate level of response. 2. it allows organisms to respond to new stresses. 3. All of these choices are correct. 4. it prevents an excessive response to adrenaline.

3. GTP bound to the G protein alpha subunit is hydrolyzed to GDP and Pi.

Termination of the adrenaline signal begins when: 1. G protein-coupled receptors are removed from the cell membrane. 2. GDP bound to the G protein is exchanged for GTP. 3. GTP bound to the G protein alpha subunit is hydrolyzed to GDP and Pi. 4. the molecules of adrenaline are transported into the cell and degraded. 5. ATP gets converted into cyclic AMP.

3. a muscle contraction of sustained force resulting from repeated action potentials.

Tetanus is: 1. an abnormal muscle contraction. 2. a contraction that slowly increases in force. 3. a muscle contraction of sustained force resulting from repeated action potentials. 4. a contraction caused by a single action potential. 5. a contraction where the muscle does not change length.

The DNA sequence shown below comes from part of the TP53 gene. It encodes the last amino acids of the p53 protein, which is normally 393 amino acids long. The underlined codon indicates the correct reading frame of this gene. The lower strand of the gene is used as the template during the transcription of mRNA from this gene. ...TTCAAGACAGAAGGGCCTGACTCAGACTGACATTCTCC-3' ...AAGTTCTGTCTTCCCGGACTGAGTCTGACTGTAAGAGG-5' T/F: A mutation that changes the nucleotide at position 23 from C to G is a nonsense mutation.

The DNA sequence shown below comes from part of the TP53 gene. It encodes the last amino acids of the p53 protein, which is normally 393 amino acids long. The underlined codon indicates the correct reading frame of this gene. The lower strand of the gene is used as the template during the transcription of mRNA from this gene. ...TTCAAGACAGAAGGGCCTGACTCAGACTGACATTCTCC-3' ...AAGTTCTGTCTTCCCGGACTGAGTCTGACTGTAAGAGG-5' T/ F A mutation that changes the nucleotide at position 20 from A to G is a silent mutation.

1. the addition of a drug that prevents the final kinase from interacting with its target protein in the nucleus

The Figure shows how normal signaling works with a Ras protein acting downstream of a receptor kinase. You examine a cell line in which Ras is always activated even in the absence of a signaling molecule. This causes constant activation of the kinases in the MAP kinase pathway. Which of the following conditions would be MOST likely to turn off this abnormally active signaling pathway? 1. . the addition of a drug that prevents the final kinase from interacting with its target protein in the nucleus 2. the addition of a drug that prevents the dimerization of the receptor kinase 3. the addition of a drug that increases the binding affinity of Ras for MAP kinase enzymes in the cytoplasm 4. the addition of a drug that prevents the phosphorylation of the receptor kinase

4. duodenum

The _____ is the first section of the small intestine, where food enters from the stomach. 1. jejunum 2. gizzard 3. ileum 4. duodenum

2. the presence of the appropriate receptors on the cells of the target tissue or organ. Cellular response to any signaling requires that receptors are present that are activated by the signaling molecule.

The ability of a specific tissue or organ to respond to the presence of a hormone is dependent on: 1. the membrane potential of the cells of the target organ. 2. the presence of the appropriate receptors on the cells of the target tissue or organ. 3. nothing; all hormones of the body are able to stimulate all cell types because hormones are powerful and nonspecific. 4. the location of the tissue or organ with respect to the circulatory path.

1. depolymerization; polymerization; spindle apparatus

The ability of microtubules to undergo rapid ___________ and slower ____________ is associated with the ability of the ______________ to explore the cell and locate chromosomes. 1. depolymerization; polymerization; spindle apparatus 2. synthesis; hydrolysis; microtubules 3. polymerization; depolymerization; microtubules 4. synthesis; hydrolysis; cytoskeleton elements

5. GDP is exchanged for GTP.

The alpha subunit of a G protein is free to diffuse in the plane of the membrane when: 1. GTP is hydrolyzed into GDP and Pi. 2. cyclic AMP binds to the alpha subunit. 3. the alpha subunit is dephosphorylated. 4. the alpha subunit is phosphorylated. 5. GDP is exchanged for GTP.

3. a specialized form of the extracellular matrix found beneath all epithelial tissues.

The basal lamina is: 1. an area found beneath all connective tissues that helps them adhere to underlying muscle. 2. a specialized form of the extracellular matrix found only in the skin. 3. a specialized form of the extracellular matrix found beneath all epithelial tissues. 4. an area found wherever two different types of tissues meet.

4. a specialized form of the extracellular matrix found beneath all epithelial tissues.

The basal lamina is: 1. an area found beneath all connective tissues that helps them adhere to underlying muscle. 2. an area found wherever two different types of tissues meet. 3. a specialized form of the extracellular matrix found only in the skin. 4. a specialized form of the extracellular matrix found beneath all epithelial tissues.

4. Sharks store enough urea to match the total solute concentration of the surrounding seawater. Urea also contributes to the solute concentrations within a cell. By storing urea in the tissues, osmotic balance can be achieved without storing more sodium than can be tolerated by the shark's body.

The body fluid of sharks has a much lower concentration of sodium chloride than that of the surrounding seawater, and sharks are able to remain in osmotic equilibrium with the external environment. How can this be the case? 1. Sharks are osmoregulators. 2. Sharks maintain high levels of sodium chloride in their skin. 3. Sharks drink large volumes of seawater to compensate for the low salt concentration of their body fluids. 4. Sharks store enough urea to match the total solute concentration of the surrounding seawater. 5. None of the other answer options is correct.

2. The resting membrane potential would become more positive because researchers are taking negatively charged molecules out of the cell. Although there are other properties of nerve cells that help maintain a negative voltage inside of the cell, one of the biggest contributors to the negative resting potential is the normal presence of DNA and negatively charged proteins. Without these negatively charged molecules, the voltage would tend to increase.

The cell contains a number of impermeable molecules that carry negative charges including DNA and proteins. If researchers removed all of the DNA and proteins from the squid giant axon, what do you think would happen to the resting membrane potential of the cell? 1. The resting membrane potential would become more negative because researchers are taking negatively charged molecules out of the cell. 2. The resting membrane potential would become more positive because researchers are taking negatively charged molecules out of the cell. 3. The membrane potential would not change because the voltage is set by the movement of Na+ and K+ ions.

2. muscle fibers.

The cells that make up skeletal muscles are called: 1. myofibrils. 2. muscle fibers. 3. sarcomeres. 4. muscle bundles.

1. proteins circulating in the blood that are activated by antibodies or molecules on pathogens.

The complement system refers to: 1. proteins circulating in the blood that are activated by antibodies or molecules on pathogens. 2. proteins present on macrophages that recognize foreign proteins. 3. proteins that are activated when histamine levels increase. 4. proteins circulating in the blood that are activated by opsonization.

2. proteins circulating in the blood that are activated by antibodies or molecules on pathogens.

The complement system refers to: 1. proteins that are activated when histamine levels increase. 2. proteins circulating in the blood that are activated by antibodies or molecules on pathogens. 3. proteins present on macrophages that recognize foreign proteins. 4. proteins circulating in the blood that are activated by opsonization.

B. False

The complexity of an organism is proportional to the number of genes in its genome. A. True B. False

3. All these choices are correct.

The conformational change in opsin, triggered by the absorption of light by retina, activates a G protein. What do G proteins do in the cell? 1. G proteins contribute to signal pathways. 2. G proteins influence the activity of other proteins and enzymes in a cell. 3. All these choices are correct. 4. G proteins can trigger the synthesis of second messengers.

3. sensory transduction.

The conversion of physical or chemical stimuli into nerve impulses is known as: 1. sensory reception. 2. cellular response. 3. sensory transduction. 4. motor response.

3.active transport of electrolytes out of the ascending limb

The countercurrent arrangement of the two limbs of the loop of Henle becomes a multiplier of electrolyte concentration due to which other characteristic? 1. water permeability of the descending limb 2. thickness of the ascending limb 3.active transport of electrolytes out of the ascending limb 4. water impermeability of the ascending limb

4. All of the answer options are correct. Force is maximal at an intermediate length of muscle. Force is minimal for both very short and very long muscle lengths. At long lengths, actin thin filaments are pulled out beyond their overlap with myosin thick filaments, so that few if any myosin cross-bridges can form. At short lengths, adjacent actin filaments within a sarcomere interfere with each other and thick filaments run into the Z-disc, disrupting the number of myosin cross-bridges that can form.

The data plotted in both graphs show that: 1. force is minimal at both short muscle lengths and long muscle lengths. 2. force is maximal at an intermediate muscle length, which corresponds to maximal actin-myosin overlap within the sarcomere. 3. at long lengths, actin thin filaments are pulled out beyond their overlap with myosin thick filaments so that few, if any, myosin cross-bridges can form. 4. All of the answer options are correct.

2. a single sample over time

The data shown in the graph in the figure represent which data? 1. a continuous sample 2. a single sample over time 3. a qualitative result 4. multiple samples across different nerve cells 5. multiple samples over time

1. This response is not homeostatic.

The digestive tract is well-adapted for digestion and absorption. For most nutrients, once material is in the digestive tract, the digestive system does not vary its rate of absorption according to body needs. 1. This response is not homeostatic. 2. This is an example of a homeostatic negative feedback mechanism. 3. This is an example of a homeostatic positive feedback mechanism.

5. The digestive enzymes back up into the pancreas and may start to digest the pancreas. If the pancreatic duct becomes blocked, pancreatic enzymes would build up in the pancreas and could digest the pancreas.

The duct that connects the pancreas to the duodenum can sometimes become blocked. What is the result? 1. The digestive enzymes are not affected because they are stored in the gallbladder until they are needed in the duodenum. 2. Nothing happens, because the pancreas does not produce digestive enzymes. 3. The digestive enzymes produced by the pancreas enter the large intestine instead, and digestion proceeds as normal. 4. The digestive enzymes produced by the pancreas still enter the duodenum because they travel by the blood to reach the duodenum, not by a duct. 5. The digestive enzymes back up into the pancreas and may start to digest the pancreas.

B and C.

The experiment described was conducted on the squid's giant axon. Which statements are true? A. Additional studies of other neurons cannot be carried out because the membrane properties of other, smaller axons cannot be studied. B. Additional studies of the membrane properties of neurons from other species are needed to test the generality of the findings for a squid's giant axon. B and C. C. This experiment suggests a mechanism that other nerve cells may use to transmit action potentials. D. This experiment shows that all axons use the same movement of ions across their membrane to fire an action potential. A and D.

1. connective

The extracellular matrix is particularly important for which type of tissue? 1. connective 2. epithelial 3. muscle 4. nervous

2. a network of proteins and polysaccharides outside the cell that play a role in structural support.

The extracellular matrix is: 1. a network of proteins found in the cellular membrane that allow for substances to enter the cell. 2. a network of proteins and polysaccharides outside the cell that play a role in structural support. 3. a network of channel proteins found in the cellular membrane that allow for communication. 4. a network of proteins and polysaccharides inside the cell that keep organelles in place.

5. it can give rise to a complete organism.

The fertilized egg is totipotent, which means: 1. it only contains genetic material from the female. 2. it can be removed and donated to a surrogate womb. 3. it forms the membranes that surround and support the developing embryo. 4. the Y chromosome does not create interference to the expression of X-linked genes. 5. it can give rise to a complete organism.

E 1= Water <-- 2= Blood --> Water always has a slightly higher concentration of oxygen than the blood. Water flows over the gill lamellae in the opposite direction of blood flow in the gill lamellae. This maintains a concentration gradient where the water is always at slightly higher concentrations of oxygen than the blood, so that oxygen will move down its concentration gradient into the blood of the fish across the gill lamellae.

The figure shown is of tubes illustrating O2 uptake at the fish gill. The values shown in the tubes indicate percent fluid saturation of O2. Which answer choice identifies the fluid and the direction of flow correctly? A. 1 = Blood --> 2 = Water <-- B. 1 = Water <-- 2 = Blood <-- C. 1 = Water --> 2 = Blood <-- D. 1= Blood <-- 2= Water --> E. 1= Water <-- 2= Blood -->

1. The addition of a drug that prevents the final kinase from interacting with its target protein in the nucleus. If Ras is constantly active, something else downstream in the pathway would have to be blocked to stop the pathway.

The figure shows how normal signaling works with a Ras protein acting downstream of a receptor kinase. You examine a cell line in which Ras is always activated even in the absence of a signaling molecule. This causes constant activation of the kinases in the MAP kinase pathway. Which condition would be most likely to turn off this abnormally active signaling pathway? 1. The addition of a drug that prevents the final kinase from interacting with its target protein in the nucleus. 2. The addition of a drug that increases the binding affinity of Ras for MAP kinase enzymes in the cytoplasm. 3. The addition of a drug that prevents the dimerization of the receptor kinase. 4. The addition of a drug that prevents the phosphorylation of the receptor kinase.

3. dimerization of the receptor. A dimerization is an addition reaction in which two molecules of the same compound react with each other to give the adduct An adduct is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all components. The resultant is considered a distinct molecular species.

The first step following platelet-derived growth factor (PDGF) binding of the receptor is: 1. activation of MAP kinase. 2. activation of gene expression. 3. dimerization of the receptor. 4. phosphorylation of the receptor.

3. translocation

The following are examples of small-scale mutations except: 1. single nucleotide insertion 2. single nucleotide deletion 3. translocation 4. base substitution 5. frame shift mutation

2. in the middle of the contraction when the muscle is at an intermediate length

The force generated by a long muscle varies as it contracts through its range of movement. At which point is the greatest force generated? 1. at the beginning of the contraction when the muscle is at its greatest length 2. in the middle of the contraction when the muscle is at an intermediate length 3. near the end of the contraction when the degree of actin and myosin filament overlap is greatest, and the muscle is at its shortest length

1. the amount of ATP available. 2. the number of cross bridges between actin and myosin in the sarcomeres. 3. the degree of overlap between actin and myosin in the sarcomeres. 4. the number of sarcomeres contracting.

The force generated by a muscle depends on: Select all that apply. 1. the amount of ATP available. 2. the number of cross bridges between actin and myosin in the sarcomeres. 3. the degree of overlap between actin and myosin in the sarcomeres. 4. the number of sarcomeres contracting.

4. All of the answer options are correct. The data from the graph and follow-up experiments show that cross-bridges determine muscle force. So, this information can be used to quantify cross-bridges within the length and width of a muscle fiber. In addition, variation in cross-bridges could be measured by evaluating the peak individual cross-bridge forces.

The force that a muscle fiber produces results from many thousands of myosin cross-bridges binding to actin filaments over time. Given this, which statement(s) are correct. Choose all that apply. 1. The net force produced by the fiber represents the summation of cross-bridge forces across the thickness and length of sarcomeres within the muscle fiber. 2. More cross-bridges are associated with greater force generated by the sarcomere. 3. Variation in cross-bridge force could be assessed by measuring the standard deviation of peak individual cross-bridge forces. 4. All of the answer options are correct.

4. Graphs 2 and 3 In negative feedback, LH should decrease as testosterone increases. This is seen with a slight lag in graph 2, and without the lag in graph 3.

The graphs shown represent relationships between circulating levels of luteinizing hormone (LH) and testosterone in normal men. Which of the graphs indicate negative feedback regulation of testosterone on LH? 1. Graphs 1 and 2 2. Graph 1 3. Graph 3 4. Graphs 2 and 3 5. Graph 4

4. commensalism.

The human body has about 10 bacterial cells for every eukaryotic cell. Bacteria coat our skin, gut, and mouth. Also present are protists, archaeans, and viruses. Collectively, these organisms are our microbiota. For most members of our microbiota, our body provides their environment, or space to live. They, in turn, have no effect on us. This is an example of: 1. mutualism. 2. an antagonistic relationship. 3. predation. 4. commensalism.

4. the posterior pituitary only.

The hypothalamus uses action potentials to directly stimulate hormone release from: 1. the anterior pituitary only. 2. neither the anterior nor the posterior pituitary. 3. both the anterior and posterior pituitary. 4. the posterior pituitary only.

3. nonself; self

The immune system usually responds to _____ cells and molecules but not to _____ cells and molecules. 1. self; nonself 2. host; foreign 3. nonself; self 4. host; self

5. takes place at the SA node.

The initiation of the mammalian heart contraction: 1. takes place at the SA node and requires neural input. 2. takes place at the AV node and requires neural input. 3. takes place at the AV node. 4. requires neural input. 5. takes place at the SA node.

3. proteins and chloride ions.

The interior of a neuron is more negative than the outside due to the presence in the interior of: 1. hydroxyl (OH-) groups. 2. potassium and chloride ions. 3. proteins and chloride ions. 4. sodium and chloride ions.

4. an inhibitory stimulus that prevents contraction of the knee flexor muscles

The interneuron in the spinal cord triggers which answer choice? 1. an inhibitory stimulus that prevents contraction of the knee extensor muscles 2. a stimulatory stimulus that prevents contraction of the knee extensor muscles 3. a stimulatory stimulus that prevents contraction of the knee flexor muscles 4. an inhibitory stimulus that prevents contraction of the knee flexor muscles

4. destroy infected or abnormal host cells.

The job of a natural killer cell is to: 1. trigger inflammation. 2. release histamine. 3. destroy invading pathogens through phagocytosis. 4. destroy infected or abnormal host cells.

3. shorter in the mouse.

The kangaroo rat is a desert mammal that conserves water by producing highly concentrated urine (urine very low in water). You compare the relative lengths of the loops of Henle in the kangaroo rat with those from a mouse species native to a temperate area where water is readily available. You find that the loops of Henle are relatively: 1. shorter in the kangaroo rat. 2. about the same in both. 3. shorter in the mouse.

2. water balance.

The kidney functions to maintain: 1. carbohydrate balance. 2. water balance. 3. protein balance. 4. hormonal balance.

2. making a unique antibody from all other B cells by genomic rearrangement.

The large number of antibodies that can be produced in a single individual is a result of: 1. making multiple unique antibodies by genomic rearrangement. 2. making a unique antibody from all other B cells by genomic rearrangement. 3. being able to produce unique antibodies from both the maternal and paternal alleles. 4. secreting multiple antibodies that will be presented on the surface of other B cells.

B. False

The magnitude of the action potential is correlated with the strength of the stimulating input. A. True B. False

4. homeostasis.

The maintenance of certain physical conditions (blood pH, body temperature, and so forth) within a narrow range of values is termed: 1. sensory responses. 2. reciprocal inhibition. 3. equilibrium. 4. homeostasis.

3. a change in the integrin proteins from the cell's surface. Integrins function in adhesion of cells to the basal lamina. Cancer cells can alter expression of integrins and can release enzymes that modify the composition of the basal lamina.

The most likely reason(s) a metastatic tumor cell might lose its connection to the basal lamina would be: 1. All of these choices are correct. 2. a change in connexins disrupting gap junctions. 3. a change in the integrin proteins from the cell's surface. 4. a change in the cadherin proteins on the cell surface.

3. express different genes.

The muscle cells and nerve cells in a mouse look very different and serve very different functions in the mouse's body. These differences exist because the muscle cells and nerve cells in the mouse: 1. use different genetic codes. 2. have different chromosomes. 3. express different genes. 4. have different ribosomes. 5. copy different genes. 6. have different genes.

4. its fractional contribution to total pressure of the mixture.

The partial pressure of one gas in a mixture is: 1. a measure of how quickly a gas moves across a respiratory surface. 2. equivalent to the total atmospheric pressure. 3. the weight of a given volume of the gas. 4. its fractional contribution to total pressure of the mixture. 5. the difference in concentration of that gas inside and outside of a cell.

2. The scatterplot shows a positive correlation between force and number of cross-bridges. The data plotted here are quantitative data representing discrete data (for example, you cannot have half of a cross-bridge). In addition, that data show a positive correlation between the number of cross-bridges and the percent force. That is, as the number of cross-bridges increases, so does the force.

The percent maximum force that a muscle fiber produces is plotted against the estimated number of myosin cross-bridges formed with actin in the scatterplot. Given this, which statement is correct? 1. The scatterplot shows a negative correlation between force and number of cross-bridges. 2. The scatterplot shows a positive correlation between force and number of cross-bridges. 3. The plotted data represent continuous data. 4. The plotted data are qualitative data. 5. None of the other answer options are correct.

1. ability of an action potential to "jump" from one node of Ranvier to the next.

The phrase saltatory propagation refers to the: 1. ability of an action potential to "jump" from one node of Ranvier to the next. 2. role of ions such as sodium and potassium in producing the action potential. 3. All of these choices are correct. 4. tendency of an action potential to move in one direction.

4. the barrier would block hormone secretion.

The pituitary gland and a part of the hypothalamus are among only a few parts of the brain that are not protected by the blood-brain barrier. One explanation for this could be: 1. they cannot produce sufficient hormone quantity without a blood supply. 2. they are not actually part of the brain. 3. they developed from epithelial cells, not neurons. 4. the barrier would block hormone secretion. 5. the toxic substances blocked by the barrier do not affect them.

3. in that new tubulin or actin subunits are added more quickly.

The plus ends of both microtubules and microfilaments differentiate from the minus ends: 1. in that the end that always grows in the direction the cell is moving. 2. in that new tubulin or actin subunits are added rather than removed. 3. in that new tubulin or actin subunits are added more quickly.

4. sliding of actin relative to myosin filaments

The power stroke corresponds to which event in muscle contraction? 1. cocking of the myosin head 2. detachment of myosin from actin 3. binding of the myosin head to actin 4. sliding of actin relative to myosin filaments

1. Protein such as transcription factors 2. Non-coding RNA (ncRNA) 3. DNA topological domains 4. DNA enhancer sequences

The presence of a gene in the genome does not indicate the expression of that gene. Which of the following elements can control gene expression? (Mark all that apply) 1. Protein such as transcription factors 2. Non-coding RNA (ncRNA) 3. DNA topological domains 4. DNA enhancer sequences

2. excessive cell division.

The presence of excess epidermal growth factor (EGF) receptors can result in: 1. normal cell division. 2. excessive cell division. 3. diminished cell division.

1. allows a large intracellular response from a small number of extracellular signal molecules.

The primary advantage of a signaling cascade is that it: 1. allows a large intracellular response from a small number of extracellular signal molecules. 2. provides a mechanism to use a single signaling molecule to produce a response in multiple cells. 3. allows extracellular molecules to be taken into the cell to initiate a response. 4. limits an abundant extracellular signal to a smaller intracellular response. 5. allows a cell to quickly shut off all phosphorylation events inside that cell without the signaling molecule itself entering the cell.

3. to generate a concentration gradient between the inner medulla and outer cortex.

The primary function of the loop of Henle is: 1. to dilute the filtrate passing through the loop. 2. selective reabsorption of glucose and other solutes into the bloodstream. 3. to generate a concentration gradient between the inner medulla and outer cortex. 4. active secretion of other wastes from the bloodstream. 5. to concentrate the filtrate passing through the loop.

The random thermal motion of molecules results in movement from a region of higher concentration to a region of lower concentration, and this is called diffusion. The rate of diffusion across a barrier is defined by Fick's law of diffusion: Rate of diffusion = k X A X (C2 - C1) L k = diffusion coefficient, which depends on solubility and temperature A = surface area for exchange C2 - C1 = difference in partial pressure of gas on either side of the barrier L = thickness of the barrier to diffusion Consider the structure and function of respiratory membranes. Respiratory membranes 1 and 2 represent membrane barriers between the outside medium and the inside of the organism. Which term in the equation is different between respiratory membranes 1 and 2?

respiratory membrane 2?

The random thermal motion of molecules results in movement from a region of higher concentration to a region of lower concentration, and this is called diffusion. The rate of diffusion across a barrier is defined by Fick's law of diffusion: Rate of diffusion = k X A X (C2 - C1) L k = diffusion coefficient, which depends on solubility and temperature A = surface area for exchange C2 - C1 = difference in partial pressure of gas on either side of the barrier L = thickness of the barrier to diffusion Consider the structure and function of respiratory membranes. Respiratory membranes 1 and 2 represent membrane barriers between the outside medium and the inside of the organism. Which would have the higher rate of diffusion, respiratory membrane 1 or respiratory membrane 2?

3. the competition from the introduction of other bacteria into the gastrointestinal tract keeps C. difficile numbers down.

The reasoning behind the use of fecal transplants from healthy individuals is that: 1. the fecal matter from healthy patients does not have C. difficile. 2. antibiotics are administered with the fecal transplant, thus controlling populations of C. difficile. 3. the competition from the introduction of other bacteria into the gastrointestinal tract keeps C. difficile numbers down. 4. C. difficile feeds on other bacteria that are introduced with the fecal transplant.

2. exocytosis.

The release of neurotransmitter from the presynaptic cell is an example of: 1. phagocytosis. 2. exocytosis. 3. endocytosis. 4. transcytosis.

1. increases in overlap favor more cross-bridges to form, increasing muscle force. The researchers hypothesized that changes in overlap between myosin and actin filaments affect the number of cross-bridges and, therefore, the force a muscle can produce.

The researchers' experimental hypothesis was that changes in actin and myosin overlap would alter the number of myosin cross-bridges that could form within a sarcomere, and specifically that: 1. increases in overlap favor more cross-bridges to form, increasing muscle force. 2. increases in overlap disrupt cross-bridge formation, reducing muscle force. 3. differences in overlap and cross-bridge formation have little effect on muscle force. 4. overlap is minimal at intermediate sarcomere (and muscle fiber) lengths. 5. None of the other answer options are correct.

3. parasympathetic system.

The signal to "rest and digest" comes from the: 1. peripheral system. 2. somatic system. 3. parasympathetic system. 4. sympathetic system.

3. The absence of microorgamism in the environment of a developing fetus.

The sterile womb hypothesis refers to: 1. An old hypothesis that has been proven wrong by recent technological advancements in microbiology research. 2. The strict maternal regulation of microorganism species that are able colonize a child before and after birth. 3. The absence of microorgamism in the environment of a developing fetus. 4. The distinct microbiota present in the developing fetus gut and the newborn child gut.

1. its triple helical structure and bundling.

The strength of collagen comes from: 1. its triple helical structure and bundling. 2. its amino acid sequence. 3. its ability to bind to polysaccharide molecules. 4. its triple helical structure and bundling, as well as its amino acid sequence.

3. countercurrent; more; concurrent

The system diagrammed is an example of _________ flow and is _________ efficient than _________ flow. 1. concurrent; more; countercurrent 2. countercurrent; less; concurrent 3. countercurrent; more; concurrent 4. concurrent; less; countercurrent

2. concurrent; less; countercurrent

The system diagrammed is an example of _________ flow and is _________ efficient than _________ flow. 1. countercurrent; less; concurrent 2. concurrent; less; countercurrent 3. countercurrent; more; concurrent 4. concurrent; more; countercurrent

3. 5'-AATGGCGTCCTGATCCCGG-3'

The three DNA fragments above are about to be sequenced. What is the nucleotide sequence that will be recorded from this synthesis reaction for the bottom (3rd) DNA fragment? 1. 5'-CCGGGATCAGGACGCCATT-3' 2. 5'-AATGGTGACTATTGCCCGG-3' 3. 5'-AATGGCGTCCTGATCCCGG-3' 4. 5'-CCGGGCAATAGTCACCATT-3'

2. 5'-CCGGG-3' 3. 5'-AATGG-3' 4. 5'-GGCCC-3'

The three DNA fragments above are about to be sequenced. Which primers could be used to sequence the following DNA fragments? Select all that apply. 1. 5'-CCATT-3' 2. 5'-CCGGG-3' 3. 5'-AATGG-3' 4. 5'-GGCCC-3'

2. when stereocilia bend against the tectorial membrane, causing hair cell depolarization. The basilar membrane is in contact with the fluid inside the ear that transmits sound waves. As the fluid moves, it causes the basilar membrane to move. The movement of the basilar membrane causes the stereocilia to move up (or down) and bend against the tectorial membrane. When there is contact with the tectorial membrane, the mechanoreceptors on the stereocilia depolarize and the signal is sent through the auditory nerve to the brain.

The transduction of sound waves to changes in membrane potential takes place: 1. in the basilar membrane as it vibrates at different locations. 2. when stereocilia bend against the tectorial membrane, causing hair cell depolarization. 3. within the tectorial membrane as it is stimulated by the hair cells. 4. as the vibrations received by the outer ear cause the eardrum to vibrate. 5. in the oval window, which vibrates at the same frequency as the original sound.

2. amine/peptide hormones and steroid hormones.

The two main classes of hormones are: 1. polysaccharide hormones and protein hormones. 2. amine/peptide hormones and steroid hormones. 3. nucleic acid hormones and lipid hormones. 4. steroid hormones and lipid hormones.

4. myosin; actin

Thick filaments are made of ____________ and thin filaments are made of ____________. 1. actin; myosin 2. actin; myostatin 3. myosin; myostatin 4. myosin; actin

2. it reflects the relative amount of sensory cortex devoted to pressure and touch sensations from a body part.

This map of the somatosensory cortex shows distorted body parts because: 1. it reflects the number of muscle fibers that are devoted to stimulating a particular body part. 2. it reflects the relative amount of sensory cortex devoted to pressure and touch sensations from a body part. 3. that is the only way an illustrator can fit all the parts into the picture. 4. it reflects differences in different people depending on how that person perceives his or her body parts.

B. False

To maintain the accuracy of the genome sequence, the DNA should not be cut into small pieces before sequencing. A. True B. False

1. Viral delivery 2. Direct nucleic acid (plasmid) injection 5. Lipid nanoparticles

Transgenic models can be generated using CRISPR/Cas9 to introduce cancer-related mutations into cells within an organism. Which of the following approaches can produce a transgenic model? (Mark all that apply) 1. Viral delivery 2. Direct nucleic acid (plasmid) injection 3. Patient derived xenografts (PDFs) 4.Knockin a wildtype genetic locus 5. Lipid nanoparticles

2. the movement of potassium ions out of the axon

Transmission of impulses along a neuron in the vertebrate nervous system ordinarily occurs in only one direction because, following passage of an action potential, the neuron is temporarily in a refractory period or hyperpolarized. This is caused by which answer choice? 1. the movement of sodium ions out of the axon 2. the movement of potassium ions out of the axon 3. the movement of sodium ions into the axon 4. the movement of potassium ions into the axon

1. act on other endocrine organs.

Tropic hormones: 1. act on other endocrine organs. 2. are released from the thyroid gland. 3. suppress the immune system. 4. suppress the appetite. 5. regulate the metabolic state of the body.

4. the effect of histamines on blood vessels.

Two of the classic signs of infection, swelling and redness, are a result of: 1. the increase in cell density due to migration of phagocytes. 2. changes in osmotic balance due to the presence of cytokines. 3. All of the answer options are correct. 4. the effect of histamines on blood vessels.

2. There will be no net movement of water molecules between the solutions. Water does not discriminate between the concentrations of specific solutes on either side, but only moves in respect to total solute concentration in one compartment as compared to another. Because the solute concentrations are the same on both sides of the membrane, there would be no net movement of water.

Two solutions of water with dissolved potassium and glucose are separated by a selectively permeable membrane that only permits the passage of water. If the two solutions have the same total solute concentration, but solution 1 has a higher concentration of potassium and a lower concentration of glucose than solution 2, which of the statements is correct? 1. There will be net water movement from solution 1 to solution 2. 2. There will be no net movement of water molecules between the solutions. 3. There will be net glucose movement from solution 2 to solution 1. 4. There will be net potassium movement from solution 1 to solution 2. 5. There will be net water movement from solution 2 to solution 1.

2. potassium; potassium

Under normal (resting) cellular conditions, the _________ concentration is greater inside the cell, and the plasma membrane is most permeable to ______________. 1. potassium; sodium 2. potassium; potassium 3. sodium; sodium 4. sodium; potassium

2. red and white muscle fibers of larger cross-sectional area in Usain Bolt's leg muscles 3. more fast-twitch fibers in Usain Bolt's leg muscles

Usain Bolt, a world champion sprinter, can run a 10-meter split in 0.82 seconds. Say you obtain a quadriceps muscle sample from Usain Bolt and compare it to one from a 25-year-old male long-distance runner. What differences do you expect to observe between those two muscle samples? Select all that apply. 1. more mitochondria in Usain Bolt's leg muscles 2. red and white muscle fibers of larger cross-sectional area in Usain Bolt's leg muscles 3. more fast-twitch fibers in Usain Bolt's leg muscles

Use the Genome Browser information on the TP53 gene below. T/F Histone acetylation near the promoter of the gene is conserved in Zebrafish.

Use the Genome Browser information on the TP53 gene below. T/F: Exon 1 is conserved in mice.

340

Use the UCSC Genome Browser (http://genome.ucsc.edu/) to determine how many amino acids are in the protein encoded by the EFNB3 gene. 340 333 330 346

4. chr 17

Use the UCSC Genome Browser (http://genome.ucsc.edu/) to determine what chromosome is the EFNB3 gene located. 1. chr 13 2. chr y 3. chr x 4. chr 17 5. chr 7

5. Receptor tyrosine kinase (RTK)

Use the UCSC Genome Browser (http://genome.ucsc.edu/) to determine what type of protein is encoded by the EFNB3 gene. 1. Voltage-gated ion channel 2. Intracellular receptor 3. Ligand-gated ion channel 4. G-protein coupled receptor (GPCR) 5. Receptor tyrosine kinase (RTK)

2. VEGF is a paracrine signaling molecule because it binds to receptors on nearby cells, at the site where new blood vessels are needed. Because the effect of VEGF is on nearby blood vessels, it must signal in relatively short distances, which is characteristic of paracrine signaling.

Vascular endothelial growth factor (abbreviated VEGF and pronounced "Veg-F") is a peptide signaling molecule related to platelet-derived growth factor. VEGF is important in the formation of the circulatory system because its signaling pathway causes the formation of blood vessels in developing embryos during normal development. Tumors also produce and secrete VEGF, causing nearby blood vessels to branch and grow to form new blood vessels that supply these tumors. Given what you know about the different kinds of cell signaling and VEGF, which statement is true? 1. VEGF is an endocrine-signaling molecule because it is released from platelets into the bloodstream and is carried throughout the body, causing widespread activation of platelet-derived growth factor receptors on cells in a variety of tissues. 2. VEGF is a paracrine signaling molecule because it binds to receptors on nearby cells, at the site where new blood vessels are needed. 3. VEGF is an endocrine-signaling molecule because it circulates through the bloodstream inside of platelets.

3. calmodulin.

Vertebrate smooth muscle cells are activated when Ca2+ binds to: 1. tropomyosin. 2. troponin. 3. calmodulin. 4. myosin kinase. 5. myosin.

3. cytotoxic T cells

Virus-infected cells are detected and destroyed by which cell-mediated immune response? 1. helper T cells 2. B cells 3. cytotoxic T cells 4. macrophages

1. collecting ducts; antidiuretic hormone

Water levels are adjusted to meet the osmoregulatory needs of the organism in the _____ of the nephron under the control of _____, also called vasopressin. 1. collecting ducts; antidiuretic hormone 2. distal convoluted tubule; antidiuretic hormone 3. collecting ducts; diuretic hormone 4. distal convoluted tubule; diuretic hormone 5. loops of Henle; antidiuretic hormone

4. solute concentration is higher in the interstitial fluid as compared to the solute concentration in the descending limb of the loop of Henle.

Water moves from the descending limb of the loop of Henle to the interstitial fluid because: 1. solute concentration is lower in the interstitial fluid as compared to the solute concentration in the descending limb of the loop of Henle. 2. solute concentration is the same in the interstitial fluid and in the descending limb of the loop of Henle. 3. water is a small molecule and freely crosses membranes. 4. solute concentration is higher in the interstitial fluid as compared to the solute concentration in the descending limb of the loop of Henle.

2. the solute concentration of the interstitial fluid is higher than the solute concentration in the collecting duct.

Water moves out of the collecting duct because: 1. the solute concentration of the interstitial fluid is lower than the solute concentration in the collecting duct. 2. the solute concentration of the interstitial fluid is higher than the solute concentration in the collecting duct. 3. the solute concentration of the interstitial fluid is equal to the solute concentration in the collecting duct.

1. osmosis.

Water moves out of the collecting ducts and into the interstitial fluid by: 1. osmosis. 2. All of the answer options are correct. 3. the action of a water pump. 4. active transport.

3. Because when we exercise, we use more ATP, and additional O2 is necessary to generate sufficient ATP. 4. Because when we exercise, we produce more CO2 and increased ventilation is necessary to rid ourselves of CO2.

We breathe more quickly and deeply when we exercise. Why does this make sense? Select all that apply. 1. Because when we exercise, we hydrolyze more ATP to ADP and Pi, and O2 is necessary for the hydrolysis, so we increase our intake of oxygen. 2. Because when we exercise, we consume more CO2 and must increase ventilation to supply the CO2. 3. Because when we exercise, we use more ATP, and additional O2 is necessary to generate sufficient ATP. 4. Because when we exercise, we produce more CO2 and increased ventilation is necessary to rid ourselves of CO2.

1. a thickness under 10 micrometers 3. a large surface area

What are desirable characteristics for a gas exchange surface, such as the endothelial cells lining the inside of a lung? Select all that apply. 1. a thickness under 10 micrometers 2. a small surface area 3. a large surface area 4. a thickness of 100 micrometers

1. a thickness under 10 micrometers 4. a large surface area

What are desirable characteristics for a gas exchange surface, such as the endothelial cells lining the inside of a lung? Select all that apply. 1. a thickness under 10 micrometers 2. a thickness of 100 micrometers 3. a small surface area 4. a large surface area

4. sensory neurons or cells that are able to respond to environmental stimuli

What are sensory receptors? 1. integral membrane proteins that open channels in response to signal molecules 2. cytosolic proteins that respond to signal molecules 3. interneurons that transmit sensory information 4. sensory neurons or cells that are able to respond to environmental stimuli

1. The α (alpha) subunit catalyzes the hydrolysis of GTP to GDP and inorganic phosphate. The α (alpha) subunit of the G proteins has GTPase activity, and when GTPase functions, it hydrolyzes GTP to GDP and inorganic phosphate, thus deactivating itself.

What causes the inactivation of a G protein? 1. The α (alpha) subunit catalyzes the hydrolysis of GTP to GDP and inorganic phosphate. 2. A phosphatase removes the inorganic phosphate group from GTP. 3. The β (beta) and γ (gamma) subunits trigger the hydrolysis of GTP to GDP. 4. The inactive receptor catalyzes the replacement of GTP by GDP.

4. the change in conformation of voltage-gated calcium channels in the axon terminal membrane

What causes the increase in cytosolic calcium that triggers the fusion of secretory vesicles to the membrane and the release of neurotransmitters into the synaptic cleft? 1. the release of calcium from intracellular calcium stores 2. the opening of ligand-gated calcium channels in the axon terminal membrane 3. the hyperpolarization of the membrane at the axon terminal 4. the change in conformation of voltage-gated calcium channels in the axon terminal membrane

1. a voltage-gated ion channel

What class of membrane-transport protein is associated with triggering an action potential? 1. a voltage-gated ion channel 2. a pump protein 3. a ligand-gated ion channel 4. a sodium-potassium symporter

3. the type of opsin present in the membrane There are different types of opsin found in the membranes of cone cells. Each responds to a different wavelength of light.

What determines the specific wavelength of light absorbed by a cone cell? 1. the location of the cone cell on the retina 2. the type of retinal molecule present 3. the type of opsin present in the membrane 4. the type of retinal molecule and opsin present

2. All of these choices are correct. Ligand-gated channels open to allow ions to pass through the membrane when they bind to their signaling molecule.

What does a ligand-gated channel do? 1. It can be closed and restrict ion flow when signal molecules are absent. 2. All of these choices are correct. 3. It opens a channel through the plasma membrane when signal molecules bind. 4. It allows ions to move across the plasma membrane.

4. pressure

What drives the filtration that occurs in animal excretory systems? 1. passive diffusion 2. active transport 3. passive diffusion for some substances and active transport for others 4. pressure 5. electrochemical gradients

5. passive diffusion for some substances and active transport for others

What drives the reabsorption that occurs in animal excretory systems? 1. electrochemical gradients 2. pressure 3. active transport 4. passive diffusion 5. passive diffusion for some substances and active transport for others

2. active transport

What drives the secretion stage that occurs in animal excretory systems? 1. passive diffusion for some substances and active transport for others 2. active transport 3. passive diffusion 4. pressure 5. electrochemical gradients

2. It causes them to divide more rapidly than normal cells.

What effect does each successive mutation have on the colon cells in the example? 1. It causes them to become non-colon cells. 2. It causes them to divide more rapidly than normal cells. 3. In causes them to become larger and expand in the colon. 4. It causes them to leave the colon and spread to other tissues.

3. They provide elastic rebound of the arterial wall to help smooth out blood flow.

What function do collagen and elastin have in arteries? 1. They form valves to prevent the backflow of blood. 2. They help to control blood flow within the body by contracting with the smooth muscles in the arterial wall. 3. They provide elastic rebound of the arterial wall to help smooth out blood flow. 4. They line the interior to provide a smooth surface for blood flow.

1. All of these choices are correct.

What function does the low pH of the stomach serve? 1. All of these choices are correct. 2. It allows for the activation of pepsinogen into pepsin. 3. It allows gastric enzymes to work. 4. The acidic conditions break down foods directly.

3. a single cell of a muscle

What is a muscle fiber? 1. a group of muscle cells that make up the same muscle group 2. the connective tissue outer covering of a muscle 3. a single cell of a muscle 4. the myosin that makes up the contractile unit of a muscle cell

5. Air moves into the lungs during inhalation and air moves out of the lungs during exhalation.

What is meant by tidal ventilation? 1. Water is pumped back and forth across the respiratory system. 2. None of the answer options is correct. 3. Air moves in a continuous, unidirectional flow through the lungs. 4. The ventilation rate increases and decreases at regular intervals. 5. Air moves into the lungs during inhalation and air moves out of the lungs during exhalation.

1. ATP

What is required to separate actin and myosin during sarcomere contraction? 1. ATP 2. Actin and myosin do not separate during sarcomere contraction. 3. ADP and Pi

1. sarcomere

What is the basic contracting unit of a skeletal muscle? 1. sarcomere 2. myosin 3. actin filament 4. myofibril

4. It lengthens more slowly than the plus end.

What is the best characterization of the minus end of a dynamic filament? 1. It lengthens more quickly than the plus end. 2. It lengthens quickly but can also lose its subunits quickly. 3. It loses subunits quickly. 4. It lengthens more slowly than the plus end.

3. Negative feedback mechanisms return a system to a set point; positive feedback mechanisms amplify a response.

What is the difference between negative feedback and positive feedback mechanisms? 1. Negative feedback mechanisms move a system away from a set point; positive feedback mechanisms stabilize a system at a set point. 2. Negative feedback mechanisms stabilize a system at a set point; positive feedback mechanisms change the set point. 3. Negative feedback mechanisms return a system to a set point; positive feedback mechanisms amplify a response.

3. a change in gene expression

What is the end-result of activating the MAP kinase pathway? 1. phosphorylation of multiple cytosolic proteins 2. synthesis of second messenger molecules 3. a change in gene expression 4. ion flow

3. to bind to surface molecules present on pathogens

What is the function of a toll-like receptor? 1. to facilitate the release of histamine 2. to bind to cytokines 3. to bind to surface molecules present on pathogens 4. to bind to self molecules

4. to convert ATP into cyclic AMP (cAMP)

What is the function of adenylyl cyclase? 1. to form protein kinase A (PKA) 2. to phosphorylate cyclic AMP (cAMP) 3. to phosphorylate protein kinase A (PKA) 4. to convert ATP into cyclic AMP (cAMP)

1. They facilitate antigen recognition by T cell receptors.

What is the function of major histocompatibility complex (MHC) proteins? 1. They facilitate antigen recognition by T cell receptors. 2. They stimulate cell division. 3. They promote phagocytosis by binding to antigens. 4. They trigger endocytosis of the antigen.

3. It maintains the concentration gradient established by the loop of Henle.

What is the function of the vasa recta? 1. It secretes the hormone renin in response to a drop in blood pressure. 2. It helps determine the final concentration of the urine. 3. It maintains the concentration gradient established by the loop of Henle. 4. It filters the blood within the glomerulus.

3. If the genome is randomly broken up, then sequencing the fragments will lead to significant overlap for re-alignment.

What is the hypothesis of the sequencing approach described in the figure? 1. If the genome is randomly broken up, then sequencing the fragments will lead to little overlap for re-alignment. 2. There will be no overlap if the genome is sequenced from random fragments. 3. If the genome is randomly broken up, then sequencing the fragments will lead to significant overlap for re-alignment.

2. to determine the direction of gravity

What is the primary function of a statolith? 1. to amplify sound waves 2. to determine the direction of gravity 3. to detect vibrations in water 4. to determine whether an organism is stationary or moving

2. The three semicircular canals allow the animal to detect motions of the head in three different planes.

What is the purpose of having three semicircular canals in mammalian vestibular systems? 1. The presence of three semicircular canals is an example of a redundant system that ensures appropriate motor adjustments to maintain orientation and balance. 2. The three semicircular canals allow the animal to detect motions of the head in three different planes. 3. The three semicircular canals are sensitive to three intensities of movement, allowing the animal to differentiate between slight, moderate, and substantial changes in orientation. 4. The three semicircular canals provide identical input to the brain, which integrates the information and allows more precise balance and movement.

4. the cytoskeleton The cytoskeleton is responsible for controlling cell size and shape. The endomembrane system does not affect shape, as its location is associated with the nucleus, which also has no bearing on the shape morphology of a nerve cell.

What part of a cell's cytoplasm is responsible for the diversity of nerve cell shape? 1. All of these choices are correct. 2. the nucleus 3. the endomembrane system 4. the cytoskeleton

2. less than 25%

What percentage of oxygen in the air is typically extracted by the mammalian lung when an animal is resting? 1. 76-90% 2. less than 25% 3. 91-100% 4. 26-50% 5. 51-75%

2. All of these choices are correct.

What properties are associated with a malignant cancer? 1. It is fast growing. 2. All of these choices are correct. 3. It is metastatic. 4. It invades surrounding tissue.

2. a sense of angular motion and balance

What senses do the three semicircular canals in the mammalian inner ear provide? 1. a sense of sound pitch and amplitude 2. a sense of angular motion and balance 3. a sense of gravity and body orientation 4. a sense of orientation to the source of sound

3. an impulse from a motor neuron

What stimulates a skeletal muscle cell to contract? 1. auto-depolarizing cells in the membrane of muscle cells 2. hormones 3. an impulse from a motor neuron 4. an impulse from a sensory neuron

5. bacterium

What type of pathogen causes cholera? 1. worm 2. fungus 3. virus 4. protist 5. bacterium

1. mechanoreceptor

What type of sensory receptor is a hair cell? 1. mechanoreceptor 2. pressure receptor 3. electroreceptor 4. chemoreceptor

1. The response to the signal would persist longer after activation. Phosphatases function in termination of signals activated by kinases. Without termination, the cellular response would persist.

What would happen to a signaling pathway if phosphatases had reduced levels of function? 1. The response to the signal would persist longer after activation. 2. The response to the signal would be shorter after activation. 3. There would be no change in the persistence of the response to the pathway.

3. The response to the signal would persist longer after activation. Phosphatases function in termination of signals activated by kinases. Without termination, the cellular response would persist.

What would happen to a signaling pathway if phosphatases had reduced levels of function? 1. There would be no change in the persistence of the response to the pathway. 2. The response to the signal would be shorter after activation. 3. The response to the signal would persist longer after activation.

2. They would be better able to survive in desert or dry habitats than animals with shorter loops. 3. They can produce greater concentration gradients of electrolytes in the deep medulla of the kidney.

What would you predict to be the effect on an animal species of having longer loops of Henle in their kidney structure? 1. They can produce less concentrated urine (one with a higher concentration of water). 2. They would be better able to survive in desert or dry habitats than animals with shorter loops. 3. They can produce greater concentration gradients of electrolytes in the deep medulla of the kidney. 4. They can reabsorb more water, glucose, and amino acids in the ascending limb.

3. GTP; activate another target protein

When a G protein-coupled receptor binds a signal molecule, it activates a G protein. The active G protein is bound to a molecule of _______, and in its active state can _________. 1. GDP; inactivate another target protein 2. GTP; inactivate another target protein 3. GTP; activate another target protein 4. GDP; activate another target protein

2. Curve B Depending on the type of diabetes, patients either fail to produce insulin or are unresponsive to insulin. A patient that drinks a sugary drink will not be able to absorb the glucose into their cells; therefore, the glucose concentration will increase over time, as shown in Curve B. A peak seen in Curve A means that the response to glucose levels is slower, but still decreases over time after the drink.

When a doctor suspects that a patient may have diabetes, she will often have the patient take a glucose challenge test. After the patient drinks a large amount of sugary solution, his blood is drawn, and the circulating levels of glucose in the blood are determined. Review the graph shown. Which curve do you expect from a patient with diabetes? 1. Curve A 2. Curve B 3. Curve C

2. neurotransmitter molecules are released from the axon terminal and bind to receptors on the postsynaptic neuron, causing either an inhibitory hyperpolarization or an excitatory depolarization.

When an action potential reaches the axon terminal: 1. calcium ions are released from the axon terminal, bind to and open the sodium channels on the cell body of the next neuron, and may initiate an action potential in that neuron. 2. neurotransmitter molecules are released from the axon terminal and bind to receptors on the postsynaptic neuron, causing either an inhibitory hyperpolarization or an excitatory depolarization. 3. sodium ions are released from the axon terminal, enter the cell body of the postsynaptic neuron through its sodium channels, and may initiate an action potential in that neuron. 4. neurotransmitter molecules are released from the axon terminal, bind to and open the potassium channels on the cell body of the next neuron, and may initiate an action potential in that neuron.

2. Signal binding causes a conformational change in the cytoplasmic portion of receptor protein.

When an appropriate signal binds to a G protein-coupled receptor, what is the best description of how the information is passed across the plasma membrane? 1. The signal molecule is transported across the plasma membrane by the receptor protein. 2. Signal binding causes a conformational change in the cytoplasmic portion of receptor protein. 3. Binding of the signal molecule triggers the cell to produce G protein.

1. sensory neurons, interneurons, motor neurons

When an environmental stimulus is received, the signal is usually transmitted through three types of nerve cells. In which order is the signal transmitted through these cells? 1. sensory neurons, interneurons, motor neurons 2. motor neurons, sensory neurons, interneurons 3. interneurons, sensory neurons, motor neurons 4. motor neurons, interneurons, sensory neurons 5. sensory neurons, motor neurons, interneurons

5. lipids.

When an individual has an energy surplus, he or she stores the extra energy as: 1. None of the other answer options is correct. 2. carbohydrates. 3. nucleic acids. 4. proteins. 5. lipids.

A. True

When an open reading frame (ORF) is identified, it may not actually correspond to the amino acid sequence of any polypeptide in the cell. A. True B. False

3. signaling molecule; signal receptor

When cells communicate by the signaling process, one cell produces a _________________ that must be received by the ___________ on or in the responding cell. 1. nonpolar signal; nonpolar receptor 2. cell division signal; plasma membrane 3. signaling molecule; signal receptor 4. hydrophilic signal; hydrophilic receptor 5. signaling particle; signal enzyme

5. calcium; inhibited

When circulating _____ levels are too high, production of parathyroid hormone is _____. 1. glucose; stimulated 2. calcium; stimulated 3. cortisol; inhibited 4. glucose; inhibited 5. calcium; inhibited

A. True Oxidative slow-twitch fibers are important for repeated contraction in the muscle with limited fatigue. Slow-twitch muscle is characterized by higher density of myoglobin and mitochondria to fuel oxidative phosphorylation, which provides more ATP for repeated muscle contractions.

When compared to the leg muscles of an Olympic sprinter, the muscles of an Olympic marathoner would likely show a greater proportion of oxidative slow-twitch fibers. A. True B. False

4. increases TSH production

When iodine intake is too low, the anterior pituitary gland _____. 1. increases thyroxine production 2. decreases triiodothyronine production 3. decreases thyroxine production 4. increases TSH production 5. decreases TSH production

2. reciprocal translocation

When nonhomologous chromosomes exchange parts, a(n) _____ has occurred. 1. base exclusion 2. reciprocal translocation 3. inversion 4. closed reading frame 5. mismatch

4. These cells survive despite DNA damage and divide extremely rapidly.

When p53 becomes mutant in cells already mutant for APC and Ras, what occurs? 1. These cells die. 2. These cells expand their chromosome number to 53. 3. These cells remain benign. 4. These cells survive despite DNA damage and divide extremely rapidly.

4. Alcohol decreases the release of ADH. ADH acts on the kidneys to increase water uptake. Inhibiting this hormone results in more water exiting the kidneys into the collecting ducts and increasing urine production.

When people have a few drinks containing alcohol, they often feel the need to urinate. This response suggests interplay between alcohol and antidiuretic hormone (ADH). Which of these statements could explain how alcohol and ADH interact? 1. Alcohol inhibits the binding of ADH to receptors in the brain, so individuals "feel" the need to urinate. 2. Alcohol increases the release of ADH. 3. Alcohol facilitates the binding of ADH to receptors in the brain, so individuals "feel" the need to urinate. 4. Alcohol decreases the release of ADH.

1. flexion.

When skeletal muscles contract such that bone segments move closer together, this action is known as: 1. flexion. 2. tetanus. 3. lengthening contraction. 4. extension.

A. True

When the filtrate reaches the distal convoluted tubule, additional wastes are pumped from the bloodstream into the distal convoluted tubule. A. True B. False

Point d & e

When you examine the cells lining the loop of Henle at the regions labeled in the figure, where do you observe large numbers of mitochondria? Select all that apply.

2. bone marrow

Where do B cells mature in mammals? 1. blood 2. bone marrow 3. thymus 4. lymph nodes

2. All of these choices are correct.

Which activity is a function of the endocrine system? 1. The endocrine system helps an animal respond to the environment. 2. All of these choices are correct. 3. The endocrine system regulates growth. 4. The endocrine system helps synchronize and coordinate body processes. 5. The endocrine system regulates development.

1. the fusion of secretory vesicles with the presynaptic plasma membrane

Which answer choice could be inhibited by greatly decreasing extracellular calcium? 1. the fusion of secretory vesicles with the presynaptic plasma membrane 2. the production of neurotransmitter by the presynaptic neuron 3. the arrival of the action potential at the presynaptic axon terminal 4. the opening of voltage-gated calcium channels on the presynaptic axon terminal

3. the overall net change in membrane potential caused by the combined EPSPs and IPSPs

Which answer choice determines whether or not an action potential is triggered in the postsynaptic neuron? 1. the magnitude of the depolarizing excitatory postsynaptic potentials (EPSPs) 2. the magnitude of the hyperpolarizing inhibitory postsynaptic potential (IPSP) 3. the overall net change in membrane potential caused by the combined EPSPs and IPSPs

2. motor neurons of the knee flexor muscles

Which answer choice is inhibited following a tap of a physician's reflex hammer just below the knee cap? 1. motor neurons of the knee extensor muscles 2. motor neurons of the knee flexor muscles 3. sensory neurons of the knee flexor muscles 4. sensory neurons of the knee extensor muscles

3. Sodium ions enter the neuron through voltage-gated sodium channels.

Which answer choice occurs when a neuron is depolarized? 1. Sodium ions diffuse along the outside of the neuron, bringing nearby regions to threshold. 2. Potassium ions enter the neuron through voltage-gated potassium channels. 3. Sodium ions enter the neuron through voltage-gated sodium channels. 4. Calcium ions enter the cell through voltage-gated calcium channels.

4. All of these choices are correct.

Which are examples of sequence motifs? 1. coding region 2. promoters 3. hairpin structures 4. All of these choices are correct. 5. open reading frame (ORF)

1. They maintain the biconcave shape to maximize gas exchange.

Which best describes a role that microfilaments play in the structure and function of red blood cells? 1. They maintain the biconcave shape to maximize gas exchange. 2. They provide a track for directing O2 to the proper cellular locations. 3. They anchor and orient the O2-bearing hemoglobin protein molecules.

3. limbic system

Which brain region controls drives, instincts, and emotion? 1. cerebrum 2. thalamus 3. limbic system 4. cerebellum

2. temporal lobe

Which brain region is associated with language in humans? 1. parietal lobe 2. temporal lobe 3. frontal lobe 4. occipital lobe

2. cerebellum and pons

Which choice contains structures found in the hindbrain? 1. limbic system 2. cerebellum and pons 3. cerebral cortex 4. thalamus and hypothalamus

4. stimulating a muscle to contract Only motor neurons can directly cause a muscle cell to contract. Interneurons help integrate information between the efferent and afferent components of the nervous system.

Which function is not a role of an interneuron? 1. maintaining homeostasis 2. relaying information from sensory to motor neurons 3. conveying information within the internal environment of an animal 4. stimulating a muscle to contract

4. SR genes

Which genes are expressed in a quiescent stem cell? 1. DIV genes 2. ID genes 3. DET genes 4. SR genes 5. DIFF (skin) genes

5. exon, gene; chromosome; genome

Which group lists the levels of genetic information in order from smallest to largest. 1. exon; chromosome; gene; genome 2. exon; gene; genome; chromosome 3. genome; gene; chromosome; exon 4. gene; chromosome; exon; genome 5. exon, gene; chromosome; genome

1. ecdysone

Which insect hormone acts on the body tissues to stimulate molting and metamorphosis? 1. ecdysone 2. All of these choices are correct. 3. juvenile hormone 4. PTTH 5. brain peptide

3. Protein-coding DNA sequences frequently contain long open reading frames; nonprotein-coding DNA sequences rarely do.

Which is a feature of DNA that could allow you to distinguish between a DNA sequence that is protein coding and a DNA sequence that is not? 1. Protein-coding DNA sequences form hairpin structures, in which the molecule folds back on itself; nonprotein-coding DNA sequences do not form hairpin structures. 2. Protein-coding DNA sequences contain tandem repeats; nonprotein-coding DNA sequences do not. 3. Protein-coding DNA sequences frequently contain long open reading frames; nonprotein-coding DNA sequences rarely do. 4. Protein-coding DNA sequences are single stranded; nonprotein-coding DNA sequences are double stranded. 5. Protein-coding DNA sequences contain U (uracil) and nontranscribed DNA sequences contain T (thymine).

3. All of these choices are correct. Open reading frame (ORF) is a type of sequence identified by gene annotation. Gene annotation is the process of predicting the location of all the genes and other coding sequences within the sequenced genome. This is generally done by finding the ORF (open reading frame). Open reading frame is marked by the initiation codon (AUG) and a termination codon (UAA, UAG or UGA) with a continuous stretch of codons in between them.

Which is a type of sequence identified by gene annotation? 1. open reading frame (ORF) 2. simple-sequence repeat 3. All of these choices are correct. 4. tandem repeat 5. noncoding RNA

2. They both have small particles in the fluid-filled chamber that depress the stereocilia of the hair cells.

Which is not a feature shared by statocysts of some animals and vestibular systems of mammals? 1. They both have hair cells that form synapses with sensory neurons. 2. They both have small particles in the fluid-filled chamber that depress the stereocilia of the hair cells. 3. They both allow the animal to determine its orientation in space. 4. They are both fluid-filled organs lined by hair cells.

2. receptor activation, signal transduction, response

Which is the correct order for these steps in cell signaling? 1. receptor activation, response, signal transduction 2. receptor activation, signal transduction, response 3. signal transduction, receptor activation, response 4. response, signal transduction, termination

Which lettered item in the figure is similar to the payload on a transport vehicle? A B C D E

Which lettered item in the figure is the motor protein? A B C D E

Which lettered item in the figure represents a tubulin dimer? A B C D E

3. a separate stimulating electrode to depolarize the nerve cell to its threshold potential 4. a recording microelectrode placed inside the cell referenced to a second electrode located outside the cell

Which methods were used to record the resting membrane potential and action potential of the squid axon? Choose all that apply. 1. a recording microelectrode placed adjacent to the outside of the cell referenced to a second electrode 2. a separate stimulating electrode to hyperpolarize the nerve cell to its threshold potential 3. a separate stimulating electrode to depolarize the nerve cell to its threshold potential 4. a recording microelectrode placed inside the cell referenced to a second electrode located outside the cell

1. Your lenses become more rounded.

Which most likely happens if you shift your gaze from the TV on the other side of the room to look closely at a stain on the front of the shirt you are wearing? 1. Your lenses become more rounded. 2. Your irises dilate to let more light through the pupil. 3. Your irises constrict to let less light through the pupil. 4. Your lenses become more flattened.

3. glomerulus, capsule, renal tubules, collecting ducts, ureter, bladder

Which of the answer choices correctly describes the path taken by excretory fluid through the mammalian kidney? 1. glomerulus, capsule, collecting ducts, renal tubules, ureter, bladder 2. capsule, glomerulus, collecting ducts, renal tubules, ureter, bladder 3. glomerulus, capsule, renal tubules, collecting ducts, ureter, bladder 4. capsule, glomerulus, renal tubules, ureter, collecting ducts, bladder 5. collecting ducts, glomerulus, capsule, renal tubules, ureter, bladder

1. autocrine, paracrine, endocrine

Which of the answer choices correctly lists the types of cellular communication from shortest to longest distance traveled by the signaling molecule to reach its responding cell? 1. autocrine, paracrine, endocrine 2. autocrine, endocrine, paracrine 3. endocrine, paracrine, autocrine 4. paracrine, autocrine, endocrine

4. All of these choices are correct. Signal transduction can produce many changes in the cell, ranging from changes in gene expression to the release of signals to communicate with other cells.

Which of the answer choices is a cellular response to signal transduction? 1. a change in the activity of an enzyme 2. a change in the proteins found in the cytosol 3. the release of signaling molecules from the cell 4. All of these choices are correct.

2. The concentration of salt in a person's urine increases after that person eats a large bag of salty chips. Negative feedback involves a response that is the reverse of the change detected. It functions to reduce the change or it serves to maintain a normal status of change. Whereas, Positive feedback results in amplification or increase of output signal or response. It keeps the sequence of events going up. Bacterial infection and fever is an example positive feedback. Fever increases the chemical reactions of the body by an average of about 12 per cent for every 1°C rise in temperature. It increases the metabolic rate, which increases heat production, which in turn raises body temperature even more. Consumption of salt increase the plasma salt level. To decrease or reverse the effect, body homeostatic mechanism excrete the salts and thus increase the urine salt concentration. Thus it is an example of negative feedback. Elevated heart rate during course of long run is an example of positive feedback. During a run, body muscle use more oxygen and nutients and to meet the supply heart need to pump more blood. Local chemical changes in muscles stimulates chemoreceptor and signal results in increase heart rate. Here, production of oxytocin is an example of positive feedback. Here, oxytocin increase the level of oxytocin to rise in pregnant women. After a person eats a bag of chips, salt concentration in the blood increases above set point. This would cause an opposite response by the kidneys to remove excess salt from the blood.

Which of the answer choices is an example of negative feedback altering homeostatic control? 1. The production of oxytocin (a hormone) increases in a pregnant woman's body as oxytocin levels in her body rise. 2. The concentration of salt in a person's urine increases after that person eats a large bag of salty chips. 3. A person with a bacterial infection runs a fever and his body temperatures rises and stays elevated for several days. 4. A person's heart rate remains elevated over the course of a long run.

4. increased sweating on a hot summer day The effector receives a signal form the sensor causing it to change its activity. In this case, sweat glands have received a signal to sweat in response to the stimulus of heat.

Which of the answer choices is an example of the effector's role in maintaining homeostasis? 1. decrease in body temperature on a cold day 2. vasodilation on a cold winter day 3. increased body temperature during a workout 4. increased sweating on a hot summer day

4. a protein that forms a channel that allows ions to enter the cell when a ligand binds Ligand-gated ion channels are a type of cell surface receptor. They are transmembrane proteins that are normally closed until the signal binds, which causes the channel to change conformation and allow ions to pass through the membrane.

Which of the answer choices would be considered a cell-surface receptor? 1. a protein that acts as an enzyme that attaches phosphate groups to substrates 2. a protein that causes GDP to be exchanged for GTP in a G protein 3. a protein that binds a nonpolar steroid hormone and activates transcription 4. a protein that forms a channel that allows ions to enter the cell when a ligand binds

2. tight junction

Which of the cell junctions is involved in creating a barrier between cells? 1. desmosome 2. tight junction 3. adherens junction

1. All of these choices are correct. - Oncogenes result from mutations in proto-oncogenes that normally control cell division. The mutations cause them to be hyperactive and make cell division increase in an uncontrolled way.

Which of the choices could be a proto-oncogene? 1. All of these choices are correct. 2. a gene encoding a protein kinase 3. a gene encoding a G-protein 4. a gene encoding a cell-surface receptor 5. a gene encoding a growth factor

3. seminiferous tubules, epididymis, vas deferens, ejaculatory duct, urethra

Which of the choices is the correct path taken by sperm from the site of production to the site of ejection? 1. seminiferous tubules, vas deferens, ejaculatory duct, epididymis, urethra 2. epididymis, seminiferous tubules, vas deferens, ejaculatory duct, urethra 3. seminiferous tubules, epididymis, vas deferens, ejaculatory duct, urethra 4. vas deferens, epididymis, seminiferous tubules, ejaculatory duct, urethra 5. epididymis, seminiferous tubules, vas deferens, urethra, ejaculatory duct

2. the EGF ligand

Which of the choices is the diffusible extracellular element in the process of vulval cell differentiation in C. elegans? 1. the Notch ligand 2. the EGF ligand 3. the EGF receptor 4. the Notch receptor

1. bicarbonate ions to neutralize stomach acid 2. trypsin for further protein digestion 5. lipase for fat digestion

Which of the choices is/are secretions produced by the pancreas? Select all that apply. 1. bicarbonate ions to neutralize stomach acid 2. trypsin for further protein digestion 3. methane from fermentation 4. gastrin to stimulate HCl production 5. lipase for fat digestion

4. the activation of an oncogene and the inactivation of a tumor suppressor gene - Cancer requires multiple mutations, including the activation of oncogenes and the inactivation of tumor suppressor genes.

Which of the choices would be most likely to lead to the development of cancer? 1. the activation of a tumor suppressor gene 2. the activation of an oncogene and the activation of a tumor suppressor gene 3. the activation of a proto-oncogene 4. the activation of an oncogene and the inactivation of a tumor suppressor gene

4. The uterine lining is shed.

Which of the events does not occur during the follicular phase of the menstrual cycle? 1. 10-20 oocytes begin to mature. 2. Progesterone levels increase. 3. FSH levels increase. 4. The uterine lining is shed.

1. an inability to inactivate protein kinase A 2. an inability of a G protein to hydrolyze GTP

Which of the factors could lead to a prolonged increase in heart rate, even in the absence of an external signal? Select all that apply. 1. an inability to inactivate protein kinase A 2. an inability of a G protein to hydrolyze GTP 3. an inability of G protein coupled receptors to bind adrenaline 4. an inability to convert ATP into cyclic AMP 5. an inability of cyclic AMP to activate protein kinase A

3. the deflection of stereocilia in hair cells of the semicircular canals due to changes in position of the head

Which of the following allows the semicircular canals in humans to provide a sense of balance and body position? 1. floating statocysts within the gel of the semicircular canals acting to deflect the hair cells when the head changes position 2. nerve impulses generated based on changes in the density of the gel that surrounds the hair cells in the semicircular canals 3. the deflection of stereocilia in hair cells of the semicircular canals due to changes in position of the head

1. hair cells with stereocilia

Which of the following is a common feature of the lateral line of fish, and statocysts of crustaceans and mammals? 1. hair cells with stereocilia 2. semicircular canals 3. synapses with motor neurons 4. statoliths

1. All of these answer choices are correct.

Which of the following is not a component that contributes to human gut microbiome stability: 1. All of these answer choices are correct. 2. Bacterial competition for resources 3. Direct bacterial defense against other bacterial species 4. Bacterial niche specialization and colonization 5. Host immune system defense against specific of bacterial species

3. Many muscle fibers are packaged into a muscle fibril.

Which of the following is not true of muscle fibers? 1. Muscle fibers have more than one nucleus. 2. Actin and myosin filaments are arranged in parallel along the longitudinal axis on the myofibril. 3. Many muscle fibers are packaged into a muscle fibril. 4. Movement is generated by muscles when actin filaments interact with myosin filaments.

4. a conformational change in myosin

Which of the following is referred to as the power stroke? 1. the sliding of bundles of myosin along actin filaments 2. the hydrolysis by actin of ATP to ADP 3. the hydrolysis by myosin of ATD to ADP 4. a conformational change in myosin

1. birds

Which of the groups of vertebrates below has the greatest number of cone cell types? 1. birds 2. humans 3. canines

1. luteinizing hormone

Which of the hormones surges to trigger ovulation? 1. luteinizing hormone 2. follicle stimulating hormone 3. estrogen 4. testosterone 5. progesterone

3. All of the answer options are correct.

Which of the phrases could be assembled from these fragments? 1. ose is 2. a rose i 3. rose 1. a rose is a rose 2. a rose is 3. All of the answer options are correct. 4. a rose is a rose is a rose is a rose 5. a rose is a rose is a rose

1. one that occurs in a noncoding region of DNA 2. one that creates a new codon code for the same amino acid as the original codon

Which of the point mutations is unlikely to change a protein's ability to function? Select all that apply. 1. one that occurs in a noncoding region of DNA 2. one that creates a new codon code for the same amino acid as the original codon 3. one that creates a new codon that does not code for any amino acid 4. one that occurs in somatic cells 5. one that occurs in germ cells

4. pO2 red blood cell < pO2 blood plasma < pO2 lung

Which of the relationships best describes the partial pressure of oxygen (pO2) in the lung (alveolar air), red blood cells, and blood plasma? 1. pO2 lung < pO2 blood plasma < pO2 red blood cell 2. pO2 red blood cell < pO2 lung < pO2 blood plasma 3. pO2 blood plasma < pO2 lung < pO2 red blood cell 4. pO2 red blood cell < pO2 blood plasma < pO2 lung

1. single excitatory postsynaptic potentials (EPSPs) arriving simultaneously at several different synapses (spatial summation) on the postsynaptic cell 3. multiple excitatory postsynaptic potentials (EPSPs) arriving close in time at a single synapse (temporal summation) on the postsynaptic cell

Which of the scenarios will most likely trigger an action potential? Select all that apply. 1. single excitatory postsynaptic potentials (EPSPs) arriving simultaneously at several different synapses (spatial summation) on the postsynaptic cell 2. an excitatory postsynaptic potential (EPSP) and an inhibitory postsynaptic potential (IPSP) arriving simultaneously on the postsynaptic cell (cancellation) 3. multiple excitatory postsynaptic potentials (EPSPs) arriving close in time at a single synapse (temporal summation) on the postsynaptic cell

1. 1, 5, 6 can be assembled together and 2, 3, 4 can be assembled together

Which of the sentence fragments can be assembled together by matching their overlaps? 1. o matter. Try Again. 4. bility to go from failure to failure with 2. thout losing your enthusiasm. 5. gain. Fail again. Fail better. 3. Success is the abi 6. Ever tried. Ever failed. No 1. 1, 5, 6 can be assembled together and 2, 3, 4 can be assembled together 2. 1, 4, 5 can be assembled together and 2, 3, 6 can be assembled together 3. 1, 2, 3 can be assembled together and 4, 5, 6 can be assembled together 4. None of the other answer options are correct 5. 1, 3, 4 can be assembled together and 2, 5, 6 can be assembled together

1. K-strategists reproduce frequently.

Which of the statements about K-strategists is false? 1. K-strategists reproduce frequently. 2. K-strategists produce few offspring. 3. K-strategists invest considerable parental time and care into raising their offspring. 4. K-strategists evolved in stable environments. 5. K-strategists evolved in environments with intense competition for limited food.

1. The unidirectional flow of air through a bird's lungs maintains a larger concentration gradient for diffusion than can be obtained through tidal breathing.

Which of the statements about bird respiration is true? 1. The unidirectional flow of air through a bird's lungs maintains a larger concentration gradient for diffusion than can be obtained through tidal breathing. 2. Oxygen is exchanged between the air, the bloodstream in the lungs, and the air sacs. 3. Bird lungs receive fresh air only during inhalation. 4. It takes four ventilation cycles for a single breath of air to move through a bird's respiratory system. 5. Air flowing through the air channels in the lungs moves in a tidal fashion.

4. Gastrin secretion is initiated in response to the sight or smell of food.

Which of the statements about gastrin is false? 1. Gastrin is produced by cells lining the stomach. 2. A low pH in the stomach inhibits the secretion of gastrin. 3. Gastrin stimulates the production of HCl. 4. Gastrin secretion is initiated in response to the sight or smell of food.

4. Angiotensin II stimulates the release of antidiuretic hormone, which increases salt and water uptake by the distal convoluted tubule. Angiotensin II is a vasoconstrictor, so it helps to increase blood pressure. Angiotensin II also stimulates the release of aldosterone from the adrenal cortex. Aldosterone causes an increase in sodium reabsorption by the kidneys, causing increased water retention and an increase in blood volume.

Which of the statements about the control of blood volume and blood pressure is false? 1. Inactive angiotensinogen is converted to angiotensin II by an enzyme released from the lungs. 2. Angiotensin II causes the smooth muscle in the walls of the arterioles to contract. 3. A drop in blood pressure stimulates the cells of the juxtaglomerular apparatus to release renin. 4. Angiotensin II stimulates the release of antidiuretic hormone, which increases salt and water uptake by the distal convoluted tubule.

2. The corpus luteum is maintained first by FSH, and then by hCG.

Which of the statements about the corpus luteum is false? 1. Progesterone secreted by the corpus luteum maintains the uterine lining. 2. The corpus luteum is maintained first by FSH, and then by hCG. 3. The corpus luteum is composed of follicle cells that remain in the ovary following ovulation. 4. None of the other answer options is correct. 5. If the egg is not fertilized, the corpus luteum degenerates.

3. Fluid from the body enters the protonephridia without first being filtered.

Which of the statements about the protonephridia of freshwater flatworms is accurate? 1. The urine leaving the body of a freshwater flatworm is more concentrated than its body fluids. 2. Muscular contractions drive fluid movement through the excretory tubules. 3. Fluid from the body enters the protonephridia without first being filtered. 4. The fluid passing through the tubules is not modified before excretion. 5. Protonephridia are surrounded by a capillary network to allow for selective reabsorption and secretion.

3. Frameshift mutations change the amino acid sequence downstream from the site of the mutation.

Which of the statements applies to frameshift mutations? 1. Frameshift mutations are known risk factors in breast cancer, but not colon cancer. 2. Frameshift mutations create a premature stop codon at the site of the mutation. 3. Frameshift mutations change the amino acid sequence downstream from the site of the mutation. 4. Frameshift mutations cause the insertion or deletion of a single amino acid from the polypeptide chain. 5. Frameshift mutations are known risk factors in most forms of cancer, including breast and colon cancer.

1. The pituitary gland acts as the control center for most other endocrine glands in the body. 2. The posterior pituitary gland is under the control of the hypothalamus. 5. The anterior pituitary gland is under the control of the hypothalamus.

Which of the statements are correct descriptions about the pituitary gland? Select all that apply. The general chemical nature of a hormone can be used to predict: 1. The pituitary gland acts as the control center for most other endocrine glands in the body. 2. The posterior pituitary gland is under the control of the hypothalamus. 3. The pituitary gland controls signaling from the hypothalamus. 4. Even though the anterior and posterior pituitary have distinctly different functions, they formed from the same embryonic tissue. 5. The anterior pituitary gland is under the control of the hypothalamus.

2. It results from the sodium-potassium pump moving more Na+ ions out of the cell than K+ ions into the cell. 3. It results from K+ ions diffusing out of the cell.

Which of the statements are true about the resting membrane potential? Select all that apply. 1. It results from voltage-gated sodium channels remaining open for long periods of time. 2. It results from the sodium-potassium pump moving more Na+ ions out of the cell than K+ ions into the cell. 3. It results from K+ ions diffusing out of the cell.

1. Neurosecretory cells of the hypothalamus secrete releasing factors that enter the anterior pituitary via a portal system to cause release of hormones from the anterior pituitary. 3. The action of the neurons from the hypothalamus is direct for the posterior pituitary, that is, the neurons extend from the hypothalamus to the posterior pituitary where the axon terminal releases hormones that go directly into the blood.

Which of the statements are true for the hypothalamus and pituitary gland? Select all that apply. The general chemical nature of a hormone can be used to predict: 1. Neurosecretory cells of the hypothalamus secrete releasing factors that enter the anterior pituitary via a portal system to cause release of hormones from the anterior pituitary. 2. The action of the neurons from the hypothalamus is indirect for the anterior pituitary, that is, the action potentials in the neurons in the hypothalamus cause formation of new action potentials in different neurons in the anterior pituitary. 3. The action of the neurons from the hypothalamus is direct for the posterior pituitary, that is, the neurons extend from the hypothalamus to the posterior pituitary where the axon terminal releases hormones that go directly into the blood. 4. Release factors from neurosecretory cells of the hypothalamus cause release of hormones into the blood from the posterior pituitary gland. 5. Release factors from the posterior pituitary stimulate release of specific hormones into the blood from the anterior pituitary.

2. The hypothalamus connects the nervous system to the endocrine system.

Which of the statements best describes the function of the hypothalamus? 1. The pituitary gland is that part of the hypothalamus that produces hormones. 2. The hypothalamus connects the nervous system to the endocrine system. 3. The hypothalamus produces the hormones that make up the endocrine system. 4. The hypothalamus has endocrine hormone receptors that trigger the action potentials of the neurosecretory cells.

3. A signal present on the outside of the cell leads to a change on the inside of the cell.

Which of the statements best summarizes the function of G protein-coupled receptors? 1. A G protein present on the outside of the cell leads to a change on the inside of the cell. 2. A GTP molecule is bound to the receptor, which causes a conformational change inside the cell. 3. A signal present on the outside of the cell leads to a change on the inside of the cell. 4. A signal molecule on the outside of the cell is transported to the inside of the cell.

3. Insulin and glucagon are good examples of peptide hormones. 4. Most peptide hormones act on cells by binding to receptors on cell surfaces and triggering signaling cascades inside the cell. 5. The action of peptide hormones can cause changes in gene expression or can affect the function of metabolic enzymes in cells.

Which of the statements correctly describe(s) peptide hormones? Select all that apply. 1. Enzymes modify cholesterol compounds to produce peptide hormones. 2. Peptide hormones bind to intracellular receptors and the peptide-receptor complex acts as a transcription factor. 3. Insulin and glucagon are good examples of peptide hormones. 4. Most peptide hormones act on cells by binding to receptors on cell surfaces and triggering signaling cascades inside the cell. 5. The action of peptide hormones can cause changes in gene expression or can affect the function of metabolic enzymes in cells.

1. Steroid hormones have their primary effects in the cell's nucleus. 3. Steroid hormones can change which mRNAs are produced in a cell.

Which of the statements correctly describe(s) the functioning of steroid hormones in the animal endocrine system? Select all that apply. 1. Steroid hormones have their primary effects in the cell's nucleus. 2. In general, peptide hormones are slower to act than steroid hormones and their actions last longer than those of steroid hormones. 3. Steroid hormones can change which mRNAs are produced in a cell. 4. Steroid hormones bind to cell-surface receptors, which then trigger second messengers.

4. Blood pressure is higher in arteries than veins, and the elastic layer helps maintain the structure of the artery. With each heartbeat, there is a volume of blood pushed through the arteries at high pressure. The elastic layer helps to absorb the increase in pressure with some distention of the artery, and the artery is able to return to its normal shape.

Which of the statements explains why there is an elastic layer found in arteries but not veins? 1. Arteries are thicker than veins, and the elastic layer is necessary to support the additional weight of arteries. 2. Valves present in veins provide a mechanism for withstanding high blood pressure flow going through veins. 3. The total length of arteries in the body is more than the total length of veins, and the elastic layer in arteries helps push the blood over the longer length. 4. Blood pressure is higher in arteries than veins, and the elastic layer helps maintain the structure of the artery.

1. Human bodies contain bacteria that are beneficial to certain processes (for example, digestion). 2. Human bodies may contain pathogenic bacteria, but these are often kept in check by other (nonpathogenic) species.

Which of the statements is (are) true regarding bacteria in the human body? Select all that apply. 1. Human bodies contain bacteria that are beneficial to certain processes (for example, digestion). 2. Human bodies may contain pathogenic bacteria, but these are often kept in check by other (nonpathogenic) species. 3. Cholera is caused by a bacterium that infects and disables part of the immune system.

3. Circulation requires a pump to generate pressure to drive flow, whereas ventilation does not.

Which of the statements is accurate? 1. The same amount of oxygen enters the blood through diffusion as is transported by circulation. 2. Ventilation increases the concentration of oxygen in the air on the inside of the respiratory surface. 3. Circulation requires a pump to generate pressure to drive flow, whereas ventilation does not. 4. Larger, more complex animals and smaller, simpler animals rely on bulk flow and diffusion to deliver oxygen to their cells. 5. Only oxygen, not carbon dioxide, moves across the respiratory surface by diffusion.

2. Internal fertilization occurs only in terrestrial animals.

Which of the statements is false? 1. External fertilization occurs outside of an animal's body, whereas internal fertilization takes place inside an animal's body. 2. Internal fertilization occurs only in terrestrial animals. 3. Internal fertilization prevents the gametes from drying out. 4. External fertilization usually involves the production of large numbers of gametes to increase the chances of successful fertilization.

1. High blood glucose levels can result from an overproduction of insulin.

Which of the statements is false? 1. High blood glucose levels can result from an overproduction of insulin. 2. The pancreas releases glucagon into the blood in response to low blood sugar and releases insulin into the blood in response to high blood sugar. 3. In the pancreas, the action of the beta cells opposes the action of the alpha cells in regulating blood glucose levels. 4. The actions of both the beta and alpha cells in the pancreas are stimulated or inhibited by the amount of glucose they detect in the blood as it passes through the pancreas.

3. As food passes through the liver, it is mixed with bile, which breaks large clusters of fats into smaller droplets

Which of the statements is false? 1. Lipases in the small intestine break lipids into glycerol and free fatty acids. 2. Nutrient absorption takes place primarily in the jejunum and ileum. 3. As food passes through the liver, it is mixed with bile, which breaks large clusters of fats into smaller droplets. 4. The hormone cholecystokinin stimulates the release of bile from the gall bladder. 5. None of these answers are false

1. They are more common than electrical synapses. 3. Vesicles fuse with the presynaptic membrane to release neurotransmitters into the synaptic cleft. 4. Once released from postsynaptic membrane receptors, neurotransmitter molecules may be actively returned to the presynaptic cell.

Which of the statements is true of chemical synapses? Select all that apply. 1. They are more common than electrical synapses. 2. Ligands must also bind to ligand-gated ion channels on the presynaptic membrane of the synapse. 3. Vesicles fuse with the presynaptic membrane to release neurotransmitters into the synaptic cleft. 4. Once released from postsynaptic membrane receptors, neurotransmitter molecules may be actively returned to the presynaptic cell.

1. They recognize antigen-MHC complexes. 3. They contain variable and constant regions. 5. They are formed by the rearrangement of V, J, C, and D gene segments.

Which of the statements is true regarding T cell receptors? Select all that apply. 1. They recognize antigen-MHC complexes. 2. They are composed of two heavy (H) chains and two light (L) chains. 3. They contain variable and constant regions. 4. They can be found in the bloodstream independent of T cells. 5. They are formed by the rearrangement of V, J, C, and D gene segments.

1. activation of adenylyl cyclase by active G protein

Which of the steps does not result in an amplification of the signal information? 1. activation of adenylyl cyclase by active G protein 2. activation of G protein by activated receptor 3. phosphorylation of target proteins by protein kinase A 4. production of cyclic AMP by adenylyl cyclase

1. electrolytes 2. vitamins 3. sugars 4. amino acids

Which of the substances are removed from the filtrate and returned to the blood during the reabsorption step? Select all that apply. 1. electrolytes 2. vitamins 3. sugars 4. amino acids 5. proteins

3. muscle

Which of these animal tissue types is directly affected by the type of signaling cascade shown in the video? 1. epithelial 2. nerve 3. muscle 4. connective

2. frog

Which of these animals has a heart in which oxygenated and deoxygenated blood mix? 1. mammal 2. frog 3. bird 4. fish 5. human

5. All of these choices are correct.

Which of these choices increase(s) the amount of oxygen that a fish can extract from the surrounding seawater? 1. gills with a large surface area 2. very thin lamellae 3. countercurrent exchange 4. ventilation of the gills with the aid of an operculum 5. All of these choices are correct.

3. Both ventricles contract.

Which of these events occurs during systole? 1. The left ventricle contracts. 2. Both atria contract. 3. Both ventricles contract. 4. The atria fill with blood. 5. The ventricles fill with blood.

2. salmon

Which of these organisms would be able to extract the greatest percentage of oxygen from their respiratory medium? 1. grasshoppers 2. salmon 3. humans 4. sparrows 5. blue whales

5. filtration

Which of these processes occur within Bowman's capsule? 1. secretion 2. filtration, selective reabsorption, and secretion 3. filtration and selective reabsorption 4. selective reabsorption 5. filtration

4. monozygotic twins

Which pair of people has the exact same genome? 1. father and son 2. dizygotic twins 3. None of the other answer options is correct. 4. monozygotic twins 5. mother and daughter

2. endoderm: multipotent

Which pair of terms correctly matches a cell or group of cells with its ability to differentiate into different specialized cells? 1. mesoderm: pluripotent 2. endoderm: multipotent 3. fertilized egg: multipotent 4. fertilized egg: pluripotent 5. ectoderm: totipotent

3. hindgut

Which part of the digestive tract is the predominant location for water and mineral absorption? 1. foregut 2. crop 3. hindgut 4. midgut

3. the rod cells in the retina

Which photoreceptor cells are primarily responsible for allowing you to read a newspaper in a dimly lit room? 1. the blue-sensitive cone cells in the retina 2. the green sensate cone cells in the retina 3. the rod cells in the retina 4. the blue- and green-sensitive cone cells in the retina

3. hypothalamus

Which portion of the forebrain regulates the endocrine system and body temperature? 1. cerebrum 2. limbic system 3. hypothalamus 4. thalamus

2. hypothalamus

Which portion of the forebrain regulates the endocrine system and body temperature? 1. limbic system 2. hypothalamus 3. cerebrum 4. thalamus

2. protein breakdown during metabolism

Which process is responsible for creating most of an animal's nitrogenous waste? 1. toxins in the environment 2. protein breakdown during metabolism 3. carbohydrate breakdown during metabolism 4. respiration

3. All of these choices are correct.

Which property of transposable elements allows them to contribute to the C-value paradox? 1. Their replication is controlled by genes found on the transposable element itself. 2. Their copy number can increase from one generation to the next. 3. All of these choices are correct. 4. Copies of transposable elements can appear on multiple chromosomes.

4. cerebral cortex

Which region of the brain is larger in humans and primates than in other vertebrates? 1. cerebellum 2. forebrain 3. midbrain 4. cerebral cortex

1. Calcium ions are released from the sarcoplasmic reticulum and bind with troponin to open actin binding sites for myosin, leading to force generation. 2. Calcium ions enter the motor neuron axon terminus to stimulate vesicle fusion and neurotransmitter release into the neuromuscular synapse. 3. Calcium ions are actively pumped into the sarcoplasmic reticulum to cause muscle relaxation by allowing tropomyosin to block actin binding sites.

Which roles are played by calcium ions in coordinating the activation of a muscle by motor neurons? Select all that apply. 1. Calcium ions are released from the sarcoplasmic reticulum and bind with troponin to open actin binding sites for myosin, leading to force generation. 2. Calcium ions enter the motor neuron axon terminus to stimulate vesicle fusion and neurotransmitter release into the neuromuscular synapse. 3. Calcium ions are actively pumped into the sarcoplasmic reticulum to cause muscle relaxation by allowing tropomyosin to block actin binding sites. 4. Calcium ions enter the motor endplate of the muscle fiber, causing depolarization of the muscle cell. 5. Calcium ions diffuse into the sarcoplasmic reticulum to open actin binding sites for myosin, leading to force generation.

2. involuntary, autonomic, sympathetic

Which set of terms belong together? 1. voluntary, autonomic, parasympathetic 2. involuntary, autonomic, sympathetic 3. voluntary, somatic, sympathetic 4. involuntary, somatic, parasympathetic

4. endocrine

Which signaling system involves the longest distance between release of a signaling molecule and activation of a receptor? 1. autocrine 2. contact-dependent 3. paracrine 4. endocrine

1. Kinesin and dynein move substances along microtubules.

Which statement about intracellular transport is true? 1. Kinesin and dynein move substances along microtubules. 2. Kinesin and dynein move substances along microfilaments. 3. Kinesin and myosin move substances along microtubules. 4. Kinesin moves substances along microfilaments.

2. Most skeletal muscles consist of mixtures of fast- and slow-twitch fibers.

Which statement is an accurate comparison of fast-twitch and slow-twitch fibers? 1. Slow-twitch fibers have fewer mitochondria than fast-twitch fibers. 2. Most skeletal muscles consist of mixtures of fast- and slow-twitch fibers. 3. Fast-twitch fibers appear red, whereas slow-twitch fibers appear white. 4. Fast-twitch fibers generate more force per unit cross-sectional area than slow-twitch fibers.

3. Changes in membrane potential depend on movements of ions within cellular compartments. The hypothesis of the experiment is that action potentials are established across the plasma membrane of the cell. An alternative hypothesis is that the action potential is established by changes across intracellular membranes, for example, the endoplasmic reticulum or nuclear membrane.

Which statement is an alternative hypothesis for the experiment? 1. Changes in membrane potential resist movements of charged ions across the membrane. 2. Changes in membrane potential occur rapidly to signal an action potential. 3. Changes in membrane potential depend on movements of ions within cellular compartments. 4. Changes in membrane potential are gradual when a nerve cell transmits an action potential.

4. None of the other answer options is correct. As basal animals, sponges do not have a nervous system of any sort. Anemones do have nerve nets distributed throughout their bodies. The nerve nets of cnidarians contain both sensory and motor neurons, but they do not have a "brain" located in their bodies.

Which statement is true regarding sea anemones? 1. Because sea anemones are "simple" organisms, these animals only possess motor neurons; sensory neurons or interneurons are never found in sea anemones. 2. Sponges, not sea anemones, possess what is considered to be the "simplest" nervous system found in animals. 3. Although sea anemones possess "net-like" nervous systems, these animals have brains located at their bases (near where they would attach to rocks). 4. None of the other answer options is correct. 5. Although sea anemones lack definitive brains, they do possess ganglia that serve a similar function to the paired ganglia of flatworms.

5. All of these choices are correct.

Which statement is true regarding the bacteria present in the stomachs or intestines of humans? 1. Many intestinal bacteria aid in digestion. 2. Intestinal bacteria can produce important vitamins. 3. Intestinal bacteria may play a role in immune system function. 4. Some stomach bacteria have been associated with cancers. 5. All of these choices are correct.

5. All animals sense and respond to the environment.

Which statement is true? 1. It is necessary to have a nervous system to sense and respond to the environment. 2. All animals have a nervous system and sense and respond to the environment, and it is necessary to have a nervous system to sense and respond to the environment. 3. All animals have a nervous system to sense and respond to the environment, but not all animals sense and respond to the environment. 4. All animals have a nervous system. 5. All animals sense and respond to the environment.

1. stimulating the muscle fiber so frequently that it cannot relax at all Tetanus occurs when multiple depolarizing stimuli reach the muscle cell at regular intervals. Each of the stimuli are summed over time and there is no overall relaxation of the muscle in between stimuli. The summation of stimuli results in sustained contraction of the muscle.

Which statement would result in tetanus? 1. stimulating the muscle fiber so frequently that it cannot relax at all 2. stimulating a muscle fiber to contract when it has partially relaxed 3. allowing a muscle fiber to relax for several seconds between twitches 4. stimulating a muscle fiber to contract immediately after it has relaxed

1. whether the hormone interacts with receptors inside the cell. 2. how soluble the hormone is in water. 3. whether the hormone will be able to move through the cell membrane. 4. whether the hormone interacts with receptors on the cell membrane.

Which statements correctly describe(s) the relationship between the classes of hormones and their behavior or function? Select all that apply. The general chemical nature of a hormone can be used to predict: 1. whether the hormone interacts with receptors inside the cell. 2. how soluble the hormone is in water. 3. whether the hormone will be able to move through the cell membrane. 4. whether the hormone interacts with receptors on the cell membrane. 5. whether the hormone will increase or decrease a specific cell function.

1. breaking the DNA into small fragments

Which step comes first in shotgun sequencing? 1. breaking the DNA into small fragments 2. matching regions of overlap 3. sequencing the DNA 4. reconstructing the long sequence of nucleotides 5. putting the sequences in the correct order

1. pupil

Which structure is the opening in the eye through which light passes? 1. pupil 2. lens 3. iris 4. cornea

4. retinal

Which structure is/are the light-absorbing compound(s) used by photoreceptors? 1. rhodopsin 2. both opsin and retinal 3. opsin 4. retinal

4. B cells

Which type of cell produces antibodies? 1. mast cells 2. helper T cells 3. natural killer cells 4. B cells 5. cytotoxic T cells

3. a receptor kinase

Which type of cell-surface receptor undergoes changes in phosphorylation in response to binding of its ligand? 1. a ligand-gated ion channel 2. a G protein-coupled receptor 3. a receptor kinase 4. both the G protein-coupled receptor and the receptor kinase

1. kinase

Which type of protein adds a phosphate group to another molecule? 1. kinase 2. phosphatase 3. phosphorylase 4. G protein

3. plus (+) end growth of microfilaments at the tip of the microvillus but no shrinkage at the minus (-) end

Which would be more likely to cause development of a microvillus on an intestinal epithelial cell? 1. minus end growth of microfilaments at the tip of the microvillus and shrinkage at the plus (+) end 2. plus (+) end growth of microfilaments at the tip of the microvillus and shrinkage at the minus (-) end 3. plus (+) end growth of microfilaments at the tip of the microvillus but no shrinkage at the minus (-) end

1. Responsive cells express a receptor specific for the hormone.

Why are some body cells responsive to a particular hormone, whereas others are not? 1. Responsive cells express a receptor specific for the hormone. 2. Whether or not a cell responds to a hormone depends entirely on what type of cell it is (liver cell vs. fat cell vs. nerve cell), because hormones only activate one type of cell. 3. Responsive cells are located closer to the gland that releases the hormone. 4. Responsive cells have complex signal transduction pathways, whereas cells that do not respond to a particular hormone lack these pathways.

1. Ras activates the MAP kinase signal transduction pathway that regulates cell division. Ras mutations associated with cancer block the GTPase activity and prevent Ras from hydrolyzing GTP to GDP and turning off. Thus, mutant Ras is constantly "on" and activates the MAP kinase pathway, resulting in increased rates of cell division.

Why are some mutations of Ras associated with cancer? 1. Ras activates the MAP kinase signal transduction pathway that regulates cell division. 2. Ras alters ion flow across the cell membrane. 3. Ras is a type of second messenger. 4. Ras binds to growth factor receptors.

4. Ras activates the MAP kinase signal transduction pathway that regulates cell division. - Ras mutations associated with cancer block the GTPase activity and prevent Ras from hydrolyzing GTP to GDP and turning off. Thus, mutant Ras is constantly "on" and activates the MAP kinase pathway, resulting in increased rates of cell division.

Why are some mutations of Ras associated with cancer? 1. Ras is a type of second messenger. 2. Ras binds to growth factor receptors. 3. Ras alters ion flow across the cell membrane. 4. Ras activates the MAP kinase signal transduction pathway that regulates cell division.

1. because voltage-gated sodium ion channels cannot immediately reopen

Why does an action potential travel in one direction down an axon? 1. because voltage-gated sodium ion channels cannot immediately reopen 2. because it needs to reach the synapse to trigger release of neurotransmitters 3. because the diffusion of charge can only occur in one direction 4. because voltage-gated potassium ion channels remain open longer

2. Calcium is needed to activate troponin so that tropomyosin can be moved to expose the myosin-binding sites on the actin filament. Myosin heads must bind to the actin filaments in order for the cross-bridge cycle to occur. At rest in the sarcomere, tropomyosin covers the myosin-binding sites of actin. When calcium binds to troponin there is a change in conformation such that tropomyosin moves and the myosin-binding sites are exposed along the actin filaments. Without this change, cross-bridge formation could not occur.

Why is calcium necessary for muscle contraction? 1. Calcium is needed to allow the muscle fiber to become depolarized. 2. Calcium is needed to activate troponin so that tropomyosin can be moved to expose the myosin-binding sites on the actin filament. 3. Calcium is needed to detach the myosin from the actin. 4. Calcium is needed to cock the myosin head so that it can form a cross-bridge with actin. 5. Calcium functions as a neurotransmitter and is released from the motor neuron.

4. retina.

Within the human eye, photoreceptors (rods and cones) are located within the: 1. lens. 2. cornea. 3. vitreous humor. 4. retina. 5. iris.

3. The B cell with the appropriate antibody is stimulated to divide, producing plasma cells that make antibodies to C. tetani, and memory cells that "remember" C. tetani.

You are a doctor and have a patient who has been injured by a rusty nail. As a precaution, you vaccinate her against tetanus. In response to the vaccine, how does her body produce antibodies against C. tetani and prevent future illness due to tetanus? 1. Every cell in her immune system produces antibodies against C. tetani. 2. Every B cell in her body produces antibodies against C. tetani. 3. The B cell with the appropriate antibody is stimulated to divide, producing plasma cells that make antibodies to C. tetani, and memory cells that "remember" C. tetani. 4. The B cell that produces the appropriate antibody undergoes genomic rearrangement in order to produce other cells that produce the same antibody.

4. activate other immune system cells; kill altered host cells; express on their plasma membrane

You are a doctor examining a patient's blood test reports. You are looking at the ratio of helper T cells to cytotoxic T cells. Helper T cells _____; cytotoxic T cells _____. You can tell them apart by the type of protein they _____. 1. kill altered host cells; activate other immune system cells; express on their plasma membrane 2. activate other immune system cells; kill altered host cells; secrete 3. activate antigens; destroy antigens; digest 4. activate other immune system cells; kill altered host cells; express on their plasma membrane 5. kill altered host cells; activate other immune system cells; secrete

4, 3, 5, 1, 2

You are interested in using CRISPR to edit a particular gene in the genome. Select the correct order of events that must occur to introduce a double stranded DNA break using CRISPR/Cas9. 1. small guide RNA (sgRNA) hybridizes with the target DNA 2. Cas9 cuts DNA 3. Cas9/sgRNA complex binds PAM sequence 4. sgRNA binds Cas9 5. Cas9 unzips DNA 4, 3, 5, 1, 2 5, 1, 4, 3, 2 5, 4, 3, 1, 2 4, 1, 3, 5, 2

1. Neither Region 1 nor 2

You are studying the function of two different noncoding regions of the genome. You conduct a reporter assay to test how these regions affect expression of GFP and you obtain the results shown below. Which region(s) is (are) supported by genetic evidence of functionality to act as a repressor? 1. Neither Region 1 nor 2 2. Both Region 1 and 2 3. Region 2 4. Region 1

4. peptide or amine hormone

You are working with a team of scientists who are investigating the biochemical control system involved in how animals digest fats in their meals. You have evidence that there must be a signal molecule involved that is released soon after the fats are consumed. When this signal molecule is present it triggers activation of appropriate digestive enzymes and cellular uptake transporters until the meal has been fully digested. Based on this information, what type of signal molecule would you predict is involved in this process? 1. protein kinase 2. steroid hormone 3.cAMP 4. peptide or amine hormone 5. hydrophobic hormone

2. hypotonic This organism likely produces ammonia as its nitrogenous waste. This requires a lot of water for excretion. Because the fish is hypotonic, it will constantly take on water from its environment. The kidneys are able to produce copious amounts of dilute urine quickly to deal with the constant absorption of water.

You discover a new type of marine organism that has the kidneys of a fish but no gills. Based on what you know about other aquatic organisms, the newly discovered organism is _____ compared to the surrounding water. 1. hypertonic 2. hypotonic 3. isotonic

3. hypotonic This organism likely produces ammonia as its nitrogenous waste. This requires a lot of water for excretion. Because the fish is hypotonic, it will constantly take on water from its environment. The kidneys are able to produce copious amounts of dilute urine quickly to deal with the constant absorption of water.

4. within the sarcoplasmic reticulum of the muscle fiber Calcium is sequestered in the sarcoplasmic reticulum until the muscle cell depolarizes.

You measure levels of Ca2+ in various locations within a motor neuron and a skeletal muscle fiber when the motor neuron is not depolarized, and the muscle fiber is at rest. Where do you expect to find high levels of Ca2+? 1. in the cytosol of the motor neuron terminus 2. in the synaptic cleft 3. in vesicles within the motor neuron 4. within the sarcoplasmic reticulum of the muscle fiber

3. Contraction still occurs because Ca2+ can enter the cell directly through Ca2+ channels in the plasma membrane and bind to calmodulin. Although a large amount of calcium is sequestered in the sarcoplasmic reticulum, any calcium that enters the cell can bind troponin causing contraction of smooth muscle tissue. The amount of calcium that comes in through calcium channels will be lower than that released from the sarcoplasmic reticulum, but slower, smaller contractions can still occur.

You take a human smooth muscle cell and block the release of calcium from the sarcoplasmic reticulum. What effect does that have on contraction of that smooth muscle cell, and why? 1. Contraction still occurs because contraction in smooth muscle is completely independent of Ca2+ levels. 2. Contraction is completely blocked because calcium binding to calmodulin is required for contraction. 3. Contraction still occurs because Ca2+ can enter the cell directly through Ca2+ channels in the plasma membrane and bind to calmodulin. 4. Contraction still occurs because Ca2+ can enter the cell directly through Ca2+ channels in the plasma membrane and bind to troponin. 5. Contraction is completely blocked because calcium binding to troponin is required for contraction.

Your computer records the raw sequencing data shown below. How many different sequences are represented in this dataset? 1 4 3 2 5 or more

1. 5'-CCGGAT-3' 4. 5'-CCGGAA-3'

Your computer records the raw sequencing data shown below. Which of the following sequences is (are) represented in this dataset? (Mark all that apply) 1. 5'-CCGGAT-3' 2. 5'-TAGGCC-3' 3. 5'-TAAGCC-3' 4. 5'-CCGGAA-3'

3. Pheromones

_____ are chemical signals that, instead of being secreted into the bloodstream, are introduced by animals into their habitats. They can be used to attract mates and mark territories. 1. Hormones 2. Neurotransmitters 3. Pheromones 4. Growth factors

3. Sodium; potassium

_________ concentration is always higher outside the cell. During the peak of the action potential, the plasma membrane is becoming more permeable to _________. 1. Potassium; potassium 2. Potassium; sodium 3. Sodium; potassium 4. Sodium; sodium

1. Collagen

___________ is a component of the extracellular matrix produced by an animal cell. 1. Collagen 2. Cadherin 3. Cellulose 4. All of these choices are correct.

2. All of these choices are correct.

and In the ascending limb of the loop of Henle, urea is concentrated within the loop because: 1. the loop of Henle is impermeable to urea. 2. All of these choices are correct. 3. the ascending limb pumps electrolytes into the interstitial fluid. 4. water moves out of the descending limb by osmosis.

A. True All cells with membranes that experience action potentials have the characteristic shape shown in the graph. When threshold potential is reached, through a stimulus, such as an EPSP or multiple EPSPs, an action potential will fire, and the membrane potential becomes more positive. This begins by the influx of sodium ions into the cell at point 2 in the graph. As the voltage changes, voltage-gated potassium ion channels open and potassium ions leave the cell. At point 3, there is no more influx of sodium ions, and potassium ions are still leaving. Potassium ions continue to leave the cell at point 4, and there is a change in membrane potential to below resting membrane potential. The sodium-potassium pump restores resting membrane potential, and then the membrane can depolarize again.

indicate whether the statement is true or false. An excitatory postsynaptic potential (EPSP) of sufficient strength to reach threshold occurred at point 1 on the figure. A. True B. False

indicate whether the statement is true or false. Different ion channels are responsible for generating the voltage change seen at point 2 and point 4 in the figure. A. True B. False

indicate whether the statement is true or false. Resting potential is generated mainly by the outward movement of K+ ions from inside the cell. A. True B. False

B. False All cells with membranes that experience action potentials have the characteristic shape shown in the graph. When threshold potential is reached, through a stimulus, such as an EPSP or multiple EPSPs, an action potential will fire, and the membrane potential becomes more positive. This begins by the influx of sodium ions into the cell at point 2 in the graph. As the voltage changes, voltage-gated potassium ion channels open and potassium ions leave the cell. At point 3, there is no more influx of sodium ions, and potassium ions are still leaving. Potassium ions continue to leave the cell at point 4, and there is a change in membrane potential to below resting membrane potential. The sodium-potassium pump restores resting membrane potential, and then the membrane can depolarize again

indicate whether the statement is true or false. The changes in voltage shown in the figure are due to ligand-gated ion channels opening and closing along the axon. A. True B. False

indicate whether the statement is true or false. The trace (blue) line in the figure is following the voltage change as it moves down the axon. A. True B. False

A. True feedback a: All cells with membranes that experience action potentials have the characteristic shape shown in the graph. When threshold potential is reached, through a stimulus, such as an EPSP or multiple EPSPs, an action potential will fire, and the membrane potential becomes more positive. This begins by the influx of sodium ions into the cell at point 2 in the graph. As the voltage changes, voltage-gated potassium ion channels open and potassium ions leave the cell. At point 3, there is no more influx of sodium ions, and potassium ions are still leaving. Potassium ions continue to leave the cell at point 4, and there is a change in membrane potential to below resting membrane potential. The sodium-potassium pump restores resting membrane potential, and then the membrane can depolarize again.

indicate whether the statement is true or false. The voltage change shown in the figure is an all-or-nothing response. A. True B. False

indicate whether the statement is true or false. The changes in voltage seen at point 2 and point 4 in the figure are caused by similar movements, in the same direction, of the same ions across the membrane. A. True B. False

indicate whether the statement is true or false. The voltage differences shown in the figure are measured across the plasma membrane. A. True B. False

A. True

indicate whether the statement is true or false. All voltage changes along the plasma membrane of an axon have the characteristic shape shown above. A. True B. False

1. hydrochloric acid 4. enzymes that digest lipids 5. pepsin, an enzyme that digests proteins

n humans, which of the enzymes does the stomach secrete? Select all that apply. 1. hydrochloric acid 2. cellulase 3. amylase 4. enzymes that digest lipids 5. pepsin, an enzyme that digests proteins

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