Bio Bootcamp
Which of the following lack a true coelom? A. Flatworms B. Annelids C. Echinoderms D. Chordates E. Mollusks
.FLATWORM. A coelom is a cavity lined by an epithelium derived from mesoderm. Mollusks have a reduced, but still true, coelom. A flatworm(also known as planarian) is an acoelomate because it does not have a coelom within its mesoderm layer. Acoelomates: Platyhelminthes Pseudocoelomates: Nematodes, Rotifers Coelomates: Annelids, Mollusks, Arthropods, Echinoderms, Chordates
A scientist translates an enzyme from pre-processed cell mRNA in a test tube (in vitro). However, the in vitro enzyme is found to be inactive compared to the extracted in vivo enzyme from a live cell culture. Which statement is the LEAST likely explanation for this phenomenon?
A nonsense mutation occurred in the extracted mRNA.
What is the function of restriction enzymes in recombinant DNA technology? A. Restrict the cell to transcribe only certain proteins B. Transport the DNA out of the cell C. To anneal sliced DNA fragments D. Cut up the DNA at specific sequences E. Degrade mRNAs with complementary sequences
A restriction enzyme (or restriction endonuclease) is used in recombinant DNA technology to cut up DNA at specific sequences, usually in a staggered manner. Examples of restriction enzymes include EcoRI, TaqI, and BamHI. The one strand that extends beyond the complementary strand is called the sticky end and is where the foreign DNA will be inserted. RNA interference is used to degrade mRNAs with complementary sequences.
Nondisjunction occurring during meiosis II, followed by fertilization, would result in a zygote with which of the following chromosomal descriptions? A. Aneuploid B. Haploid C. Diploid D. Tetraploid E. Disomic
A. When non-disjunction occurs during meiosis II the chromosome is not separated and instead one of the resulting cells produced will have two copies of the same chromosome and one cell will be missing a chromosome. This is referred to as aneuploidy, or the occurrence of having an abnormal amount of chromosomes, either more or less than 23.
A population of lions becomes separated by a river. Which process may eventually diverge them into separate species? A. Allopatric speciation B. Sympatric speciation C. Adaptive radiation D. Disruptive selection E. Natural speciation
A. Allopatric speciation is when a geographic barrier, such as a river, separates a population. Sympatric speciation is when a population forms a new species without a geographic barrier; this can proceed via hybridization, polyploidy, or balanced polymorphism. Disruptive selection is a process where extreme values for a trait are favored over intermediate values, and often contributes to sympatric speciation. Adaptive radiation is the rapid diversification of new organisms, often due to a change in the environment and new available resources.
Which of the following components of the immune system responds to specific antigens? A. B cells B. Interferons C. Phagocytes D. Cilia E. Lysozyme
A. B-Cells. The distinguishing characteristic of B cells is that they all possess a B cell receptor (BCR), which binds to specific antigens, making this answer correct. Formed in the bone marrow, B cells are important because they can differentiate into memory B cells, which can produce antibodies for pathogens that have already been encountered. There are two parts to the immune system: specific and nonspecific defense. Specific defense responds to antigens, such as the toxin from an insect sting, or a molecule on the plasma membrane of a pathogen. Nonspecific defense is not specialized for a particular pathogen; it defends against all pathogens in general. Examples of nonspecific defenses include: skin, interferons, phagocytes, cilia, and lysozyme. Interferons are molecules secreted by cells invaded by viruses that stimulate other cells to help defend against viruses. Phagocytes are white blood cells that engulf pathogens. Cilia line the lungs and help sweep pathogens out of the lungs. Lysozyme is a protein that breaks down cell walls in bacteria.
Which of the following is able to split a molecule of water during plant photosynthesis? A. P680 B. ATP synthase C. RuBisCO D. Magnesium E. NADP+ reductase
A. P680 (photosystem ii) is able to split water to liberate electrons for use in the light dependent reactions.The light dependent reactions take place in the thylakoids, along the thylakoid membrane. In the light reactions, photons power electrons to travel along an electron transport chain within the thylakoid membrane, to produce NADPH and ATP. ATP synthase uses the power of the chemiosmotic gradient of hydrogen to power ATP production. The ATP synthase step comes much later in the process, after the splitting of water. RuBisCO is the enzyme that fixes carbon into bonds of glucose during the light independent reactions Magnesium is the ion that is complexed within the chlorophyll pigment, important in photon capture NADP+ reductase is used to reduce NADP+ into NADPH.
A scientist wants to detach a peripheral membrane protein from the exterior of a cell membrane. Which is the best method to do so? A. Change the salt concentrations. B. Perform a light centrifuge. C. Add a detergent. D. Change the temperature of the solution. E. Run a small current through the solution.
A. Peripheral membrane proteins are held in place by electrostatic interactions and hydrogen bonding. They are generally hydrophilic. Changing the salt concentration (a "salt wash") or the pH would disrupt both of these types of bonds and release the peripheral membrane protein from the cell membrane. A light centrifuge will precipitate cells and nuclei at most, only heavy centrifuges extract small soluble proteins. Adding a detergent is a method used to extract integral proteins because they are more hydrophobic in nature. The hydrophobic detergent will destroy the membrane and expose the hydrophobic integral protein. Changing the temperature will denature the protein. Running a current through the cell isn't a common or viable method.
The ribozyme A. is a complex of molecules of RNA that are capable of catalysis B. aids mRNA in folding into alpha helix or beta pleated sheet C. the sugar component of an RNA nucleotide D. is the protein component of the ribosome E. a protein that condenses RNA into heterochromatin
A. Ribozymes are RNA molecules that can perform biological catalysis in the same manner as protein enzymes.
During embryonic development, a hollow sphere of cells is called a: A. blastula. B. morula. C. chorion. D. yolk sac. E. gastrula.
A. The blastula is the stage of embryonic development where liquid fills the inside of a morula to push the cells outward, forming a hollow sphere of cells. A morula is a solid ball of cells formed after cleavage. A gastrula is a 3-layered blastula (3 layers for the ectoderm, mesoderm, and endoderm), and is formed when a group of cells invaginate into the blastula. The chorion fuses with maternal tissue to form the placenta. The yolk sac is empty in placental mammals, but it is used to give nutrients to the embryo in birds and reptiles.
The cell wall of fungi is composed of A. chitin B. cellulose C. glycogen D. starch E. peptidoglycan
A. The cell wall of fungi is composed of chitin.
Which part of the brain monitors the body's temperature? A. Hypothalamus B. Pons C. Medulla D. Cerebral cortex E. Cerebellum
A. The hypothalamus controls the body's temperature, hunger, thirst, sleep, and circadian cycles. One of its most important functions is that it links the nervous system to the endocrine system through the pituitary gland. The pons relays signals from the forebrain to the cerebellum. The medulla controls autonomic functions, such as respiration, digestion, and the pumping of the heart. The cerebral cortex is a complex portion of the brain that is involved in higher-level thinking and sensory perception. Lastly, the cerebellum is involved in motor control, such as balance and coordination.
Which of the following describes the law of parsimony? A. The phylogenetic tree that has the least amount of assumptions is the most preferred. B. The driving force for evolution is divergent evolution. C. Homoplasy can help us develop phylogenetic trees. D. The individual with more fitness will ultimately outcompete others. E. Life evolved from the oceans, to land, and then air.
A. The law of parsimony, or Occam's Razor, says that when choosing between competing hypotheses, the one that makes the least amount of assumptions is the most preferred. Another way to say it is that the simplest explanation is probably the most accurate. When developing phylogenetic trees, the tree that explains the evolution of organisms with the least amount of assumptions is most likely the correct one.
What is the role of calcium in muscle cells? A. To expose the binding sites on actin filaments B. To initiate a membrane potential C. Increase Na+/K+ ATPase activity D. Increase osteoblast activity E. Regulate transcription of myosin
A. To expose the binding sites on actin filaments. During a muscle contraction, a neuron releases acetylcholine which triggers an action potential on the muscle cell. This signal is propagated by T tubules and releases Ca2+ from the sarcoplasmic reticulum and initiates contraction of the muscle cell. The calcium binds to actin filaments called troponin, which allows it to change its shape and expose binding sites for myosin. The myosin binds to the actin by using ATP and shortens, creating a contraction. When the action potential passes, the calcium gets removed from the troponin and the binding sites are no longer available, relaxing the cell.
An insect moves randomly at different speeds depending if it is in a favorable environment or not. Which of the following describe this insect's movement pattern? A. Kinesis B. Taxis C. Migration D. Longitudinal flow E. Phototaxis
A.Animals typically have three types of movement. The first is kinesis, where the animal will move in a random direction. The animal will slow down if it is in a favorable environment and speed up if it is in an unfavorable environment. This way, the animal will spend more time in a favorable environment. Taxis is when an animal moves in a specific direction after receiving a stimulus. The animal can move either towards or away from the stimulus. A type of taxis is phototaxis, which is exemplified by flies being attracted towards lightbulbs at night. Migration is the long distance movement of animals based on the season. Birds will often migrate from the north towards the south to avoid cold winters with a lack of resources.
Which of the following is a fundamental step in the cloning of an animal? A. Revert a somatic cell into a totipotent state. B. Extracting mRNA of all transcribed genes. C. Differentiate pluripotent cells into totipotent cells. D. Revert totipotent cells into embryonic germ layers. E. Revert a pluripotent cell to a somatic cell.
A.Cloning is the process of taking a somatic cell from an animal and producing a genetic copy from that cell. It is different from fertilization in that there is no genetic variation; each clone is a genetic replica of the parent animal. This was best characterized by Dolly, the cloned sheep.Somatic cells contain the full genome of an organism, but are usually specialized based on the tissue they are a part of. In contrast, totipotent cells can give rise to any and all human cells, and even an entire functional organism. To clone an animal with this method, a somatic cell would need to be reverted to its less specialized totipotent state such that it could give rise to a new, genetically identical animal.
Glycolysis is best described as what type of process? A. Exergonic B. Endergonic C. Isotonic D. Hypertonic E. Hypotonic
A.Glycolysis requires the use of energy when the glucose molecule is broken into two pyruvates. The two steps in which ATP is used can be considered endergonic, however, overall glycolysis produces energy to be consumed by the cells. If energy is released, then the reaction is exergonic. The concentration terms, isotonic, hypertonic, and hypotonic refer to the relative concentrations of different environments and this is not related to cell thermodynamics or a cell's use or production of energy
What is the function of lacteals in the digestive system? A. Absorb fats in the small intestine. B. Neutralize acidic chyme from the stomach. C. Mechanically separate food in the stomach. D. Absorb water in the large intestine. E. Emulsify fats in the small intestine.
A.Lacteals are lymphatic capillaries that absorb dietary fats in the villi of the small intestine. Villi are small finger-like projections that increase the surface area of absorption in the small intestine. Bile (which is not an enzyme because it does not change anything) is released from the gallbladder to emulsify fats. This means it breaks up large fat globules into smaller fat globules for easier absorption by lacteals.
In a food chain that contains four trophic levels, which level has the greatest biomass? A. Producers B. Primary consumers C. Secondary consumers D. Tertiary consumers E. In a successful food pyramid, each trophic level has similar biomass
A.Producers always have the highest biomass in a food chain. biomass shrinks as we go from producers, to primary, secondary, tertiary, etc. consumers. Trophic levels must shrink in biomass as we go higher up the food chain because of this low percentage of energy transfer. The biomass must be larger in the lower trophic levels to be able to sufficiently support higher up trophic levels.
An experiment is designed to track the movement of DNA within a cell. Which radioactive isotope would be the most useful to mark a nucleic acid? A. 32P B. 35S C. 15N D. 13C E. 15O
A.The structure of DNA contains a phosphate backbone, making the radioactive isotope 32P ideal for tracking DNA as it is not found in substantial amounts in other biomolecules, so the answer choice is correct. Recall that in the Hershey-Chase experiment, DNA was proven to be the genetic material of bacteriophages by incorporating 32P into phage DNA and observing that the radioactive phosphorus (as part of DNA) was transferred inside infected bacterial cells (while 35S, incorporated in the protein coat of the bacteriophage, remained in the liquid surrounding cells).
Which of the following is an example of negative feedback? A. Regulation of blood pH B. Release of oxytocin during child birth C. Rising levels of estrogen stimulate a surge of LH D. Blood platelet accumulation in blood vessels E. Release of oxytocin during lactation
A.When blood pH falls too low (and the blood becomes too acidic), buffering systems raise the blood pH back to a normal physiological range. Likewise, when blood pH becomes too high (and the blood is too basic), buffering systems lower it. This is an example of negative feedback, a form of regulation where a normal physiological range is maintained by raising the concentration of a substance when it is too low, and lowering it when it is too high. Positive feedback is much more rare in biology than negative feedback. Oxytocin is released during childbirth to stimulate more contractions, and the increased contractions stimulate more release of oxytocin until the child is born. Similarly, the body produces more prolactin to promote the development of the mammary glands once lactation begins. Blood clotting is a positive feedback mechanism as well - damaged tissue releases a signal to attract platelets, and each platelet releases a signal to attract more platelets until a clot is achieved.
A bacterial cell has its cell wall removed and is placed in distilled water. Which of the following will happen? A. The bacterial cell will lyse because it is hyperosmotic to the water. B. The bacterial cell will lyse because it is hypoosmotic to the water. C. The bacterial cell will shrivel because it is isotonic to the water. D. The bacterial cell will shrivel because it is hypoosmotic to the water. E. The bacterial cell will shrivel because it is hyperosmotic to the water.
A.You should be familiar with osmosis for the DAT. The rigid cell wall of bacteria is designed to protect it from changing osmolarities in the environment. Underneath the cell wall is a permeable plasma membrane. Placing the cell in distilled water will cause water to rush in, ultimately lysing the cell. This is because the cell has a higher osmolarity than the surrounding water, making it hyperosmotic to the water. Water will diffuse from areas of high concentration to areas of low concentration. The higher the osmolarity, the lower the concentration of water. This is similar to freshwater fish in a lake - water constantly enters the fish because they have a higher osmolarity.
Where is ADH stored in the body? A. Thyroid B. Pancreas C. Pineal gland D. Posterior pituitary E. Anterior pituitary
ADH is produced in the hypothalamus. The posterior pituitary stores oxytocin and ADH (also known as vasopressin). The pineal gland produces melatonin to help regulate our sleep patterns. The anterior pituitary produces the following, you can remember most of them with the acronym FLAT, for: FSH, LH, ACTH, and TSH.
Autocrine
Autocrine glands send extracellular signals to themselves. White blood cells are a common example of autocrine stimulation, as they release factors that stimulate themselves.
Which of the following are best characterized by brackish water? A. A river emptying into an inland lake. B. A mangrove leading to an estuary. C. A stream in a tropical forest. D. A freshwater marsh and lake. E. Seawater washing onto a beach.
B. Brackish water means a mix between salt and fresh water, which would be found in an estuary. An estuary is a specific area where freshwater meets seawater. A mangrove swamp often grows near an estuary and is characterized by a mix of salt and freshwater. Some marshes can be brackish, but D specifically stated that this marsh was freshwater, and thus not characterized by brackish water.
Which is the most correct definition of competitive inhibition? A. Another enzyme completes the same reaction and uses the available reactant. B. An inhibitor binds directly to the active site and prevents the reactant from binding. C. A metal cofactor prevents the binding of the reactant by binding at the active site. D. An inhibitor binds to the enzyme at a binding site, and prevents the enzyme from catalyzing the reaction. E. ATP releases its energy and drives the reactant to form the product.
B. Metal cofactors and ATP are often used to help boost enzyme activity, and are not competitive inhibitors. Non-competitive inhibition (D) occurs when an inhibitor is able to prevent the enzyme from binding with the reactant by binding to the enzyme at a site away from the active site, and change the enzyme's conformation so it cannot bind to the reactant. Competitive inhibition occurs when the inhibitor competes directly with the reactant at the active site, and this substrate takes the place of the reactant and prevents the reaction from occurring.
During which step of translation does translocation occur? A. Initiation B. Elongation C. Termination D. Migration E. Extension
B. Translation is the process of a ribosome reading mRNA and synthesizing a protein. There are 3 steps in translation. The first is initiation, when the small ribosome unit attaches to the 5' end of mRNA, the first tRNA attaches, and the larger ribosome unit attaches to form the complete ribosomal complex. The second step is elongation, where the ribosome continues down the codons of mRNA and moves the tRNAs from the entry site to the bonding site, and from the bonding site to the exit site. This phenomenon is known as translocation and takes place during elongation. Termination occurs when a stop codon is reached and no amino acid is joined to the growing peptide. Choice [D], migration, is not a term used in translation. Choice [E], extension, is also not a term used in translation, although both of these are great examples of possible distractors you may see on the DAT.
All of the following mutations would result in a change in phenotype EXCEPT for one. Which one is the EXCEPTION? A. Frameshift mutation B. Silent mutation C. Nonsense mutation D. Missense mutation E. Inversion mutation
B. A silent mutation is one where the mutation does not cause a change in the amino acid sequence that is coded. This is because the genetic code is degenerate, meaning that multiple codons can code for a single amino acid. So if we change only one base pair, we may still code for the same amino acid and no change in the phenotype would occur. A nonsense mutation is when an effective codon is converted into a stop codon, which immediately truncates the protein at that location. This is a lethal mutation. A missense mutation occurs when one base is directly substituted for another, causing a change in that amino acid codon.
Why does cartilage take a considerable amount of time to heal? A. Cartilage does not consist of cells and therefore cannot be healed quickly. B. Cartilage lacks a direct blood supply. C. Similar to bones, cartilage heals slowly because it is a rigid structure. D. Cartilage is a complex tissue that cells cannot quickly synthesize. E. Cartilage can only be formed in utero while the body is flexible.
B. Cartilage consists of living tissue in close proximity to bone. However, it does not have its own blood supply. As a result, nutrients can only access cartilage through slow diffusion, hence why it takes a considerable amount of time to heal. It is not as rigid as bone and can continually be formed throughout an organism's life.
A human embryo is a deuterostome. In deuterostomes, the first opening that forms gives rise to what anatomical structure? A. Mouth B. Anus C. Head D. Back E. Genitalia
B. Deuterostomes and Protostomes are classifications of animals that differ in their development of the mouth and the anus. The blastospore or the opening in the archenteron (the primitive gut that forms during gastrulation) gives rise to the anus in deuterostomes. In protostomes, the blastospore evolves to become the mouth of the embryo. Neither head, back, nor gentalia are biological terms used to differentiate a deuterostome, nor do they evolve directly from the blastospore.
Which of the following directly contributes to cellular recognition? A. Clathrin-coated membrane B. Membrane glycoproteins C. Membrane cholesterol D. Degree of unsaturation in membrane fatty acids E. Resting membrane potential
B. Membrane glycoproteins are fundamental to cellular recognition.
All of the following are connective tissues EXCEPT for one. Which one is the EXCEPTION? A. Adipose B. Neurons C. Cartilage D. Bones E. Blood
B. Neurons. There are four general classes of biological tissues: connective, epithelial, muscular, and nervous. Neurons, although connected, are not a connective tissue in the musculoskeletal system. Adipose, or body fat, is a connective tissue. Cartilage connects bones to other bones. Bones are a connective tissue as well. Blood, interestingly enough, is considered a connective tissue. Blood is derived from the mesoderm and connects the body systems together by providing nutrients and removing waste.
What process is described by an animal's ability to involuntarily contract a skeletal muscle without receiving a direct signal from the brain? A. Peristalsis B. Reflex Arc C. Refraction D. Redirection E. Reflection
B. Reflex Arc. A reflex arc is a nervous system process whereby the stimulus causes a motor movement that is coordinated by the spinal cord and not the brain. Sensory neurons are able to capture the environmental stimuli and send the afferent signal to the spinal cord, which is able to send an efferent (motor) signal directly to the effector, a muscle, which then moves. Refraction refers to the refractory period after a neuron fires and cannot respond to new stimuli. Redirection is not an accurate term and is not used in biology. Peristalsis is the contraction of smooth muscle in the digestive system, not in skeletal muscle.
A species of desert plant secretes a chemical into the surrounding soil that kills seeds from any other species of plant that attempts to germinate in that area. What is this an example of? A. Commensalism B. Allelopathy C. Exploitation competition D. Apparent competition E. Intraspecific competition
B. The correct answer is B. Allelopathy is type of interference competition, where the establishment of other individuals who would compete for a mutual resource is prevented, in this case using a toxic chemical. Intraspecific competition (E) occurs when competition occurs within the same species; in this case the plant is competing with all the other species of plants in the area.
A muscle cell that is in a sustained state of contraction is said to be in: A. Reflex B. Tetanus C. Refraction D. Activation E. Twitch contraction
B. When muscle cells contract, the contraction is followed by a period of cell relaxation. During this refractory period the cell cannot contract again. A muscle cell that has sustained a contraction lasting longer than the normal length of contraction is said to be in tetanus. This is a symptom of "lock jaw," or the medical term tetanus, which may result from getting cut or punctured with a rusty metal object. Reflex is not relevant to the question being asked. Activation, though a biology term, is not directly related to the question being asked. A twitch contraction is a short burst of stimulation, but the duration of the contraction is so short that the muscle begins to relax before reaching peak force. Therefore, the correct answer is B.
β pleated sheet first forms in what level of protein structure? A. Primary structure B. Secondary structure C. Tertiary structure D. Quaternary structure E. Quintary structure
B. β pleated sheet and α helix first form in the secondary structure of a protein. is caused by hydrogen bonding in the protein backbone but does NOT include hydrogen bonding in the amino acid's R groups (functional group). This causes the polypeptide to coil into an alpha helix or fold into a beta pleated sheet.
All of the following are assumptions in Hardy-Weinberg equilibrium EXCEPT for one. Which one is the EXCEPTION? A. No mutations B. Equal inflow and outflow of individuals C. Random mating D. No random increases or decreases of alleles. E. Sufficiently large population
B... Large populations to minimize the effects of genetic drift. Genetic drift is the random increase or decrease of allele frequencies. A special type of genetic drift is the "founder effect", which occurs when a group of emigrating individuals do not reflect the allele frequencies of the original population. Random mating. Individuals do not seek a particular type of individual to mate with, for example they do not mate only with nearby individuals or express sexual selection. No Mutation: There cannot be any mutations to introduce new allels in the population. No Natural selection: The environment is not impacting the allele frequencies, and all traits are neutral. No Migration: This can also be written as no gene flow. The population must be isolated. This is why [B] is wrong, no amount of gene flow into or out of the population can occur.
Which enzyme in replication unzips the DNA to produce a replication fork? A. Topoisomerase B. Helicase C. Primase D. Ligase E. Telomerase
B.At the beginning of replication, helicase unzips the DNA to produce a replication fork. The replication fork is held in place by single-strand binding proteins. As helicase unwinds the DNA upstream, further downstream the DNA actually becomes positively supercoiled. Topoisomerase removes these twists and knots induced by helicase. Telomerase is an enzyme that extends the template strand to add a short sequence of nucleotides to the replicated strand. This is because eukaryotes have linear DNA molecules and cannot replicate the ends of the original DNA, because no primer can be placed.
The ingestion of which of the following would stimulate the release of cholecystokinin? A. Carbohydrates B. Fats C. Nucleic acids D. Cellulose E. Inorganic compounds
B.Cholecystokinin is a hormone produced by the small intestine in response to fats. It stimulates the gallbladder to release bile, which helps in the emulsification of fats, and stimulates the pancreas to release lipases. Gastrin is produced once the nervous system sees or smells food, which stimulates the stomach to produce gastric juices. Secretin is produced in the small intestine and stimulates the pancreas to produce bicarbonate to neutralize the acidity of the chyme.
In which of the following conditions would two animals be most closely related to each other? A. If they belonged to the same class B. If they belonged to the same genus C. If they belonged to the same order D. If they belonged to the same species but not the same genus E. If they belonged to the same family
B.Genus is the closest relation. It is impossible to be in the same species but not the same genus ([D] is not a valid answer).
If a human cell has 46 chromosomes at the beginning of meiosis, then at the end of meiosis I each cell would have: A. 23 chromatids B. 46 chromatids C. 46 chromosomes D. 92 chromatids E. 92 chromosomes.
B.Meiosis will take a diploid cell and produce two haploid cells. This means that our chromosome number will decrease to 23 chromosomes for each daughter cell. However, each of these chromosomes have two chromatids, so they will also have 23 x 2 = 46 chromatids.
Which of the following mRNA transcripts represents a stop codon? A. 5' TCC 3' B. 5' UAA 3' C. 5' UGT 3' D. 5' CCC 3' E. 5' AUU 3'
B.Stop codons are 5' UAA 3', 5' UGA 3', and 5' UAG 3'.
Pancreatic beta cells secrete insulin into the body. Which organelle would you expect to be heavily expressed in beta cells? A. Nucleus B. Golgi apparatus C. Mitochondria D. Lysosomes E. Flagella
B.The Golgi apparatus is a group of flattened sacs that coordinate with the endoplasmic reticulum. The Golgi specializes in modifying and packaging proteins for secretion. Cells that secrete hormones often have a high expression of Golgi complexes to aid in protein secretion.The Golgi apparatus is responsible for transport of various substances in vesicles, and is a necessary organelle for cell secretions. One would expect this organelle to be heavily expressed in pancreatic beta cells, due to their secretion of insulin into the body which would first have to be packaged into vesicles,
Which of the following is the pathway for gas transport to and from the developing bird embryo? A. Umbilical cord B. Allantois C. Yolk D. Amnion E. Placenta
B.The allantois provides a path for gases to reach the developing bird embryo. The chorion is just beneath the shell of the egg and allows gases for respiration to diffuse in and out of the egg. An umbilical cord connects a developing fetus to its mother's placenta in placental mammals. The yolk is intraembryonic (part of the embryo). The yolk is not to be confused with the yolk sac, an extraembryonic structure. In birds, reptiles, fish, and monotremes (like the platypus), the yolk sac encloses the yolk; the yolk provides nourishment to the cell.
Which two structures form the placenta? A. Chorion and allantois B. Chorion and endometrium C. Yolk sac and allantois D. Oviduct and yolk sac E. Ovary and amnion
B.The chorion is an extraembryonic membrane formed during development. The chorion allows for gas exchange in birds and reptiles, while in mammals it attaches to the endometrium and develops into the placenta. The placenta is a structure that allows for the exchange of gases, nutrients, and wastes from the embryo and the mother.
Which germ layer produces the notochord? A. Ectoderm B. Mesoderm C. Endoderm D. Epiderm E. Hypoderm
B.The mesoderm produces the notochord, so the answer choice is correct. The mesoderm also produces the musculoskeletal system, circulatory/lymphatic system, excretory system, gonads, connective tissue, portions of the digestive & respiratory system, somites, kidney, dermis of skin, and the adrenal cortex.
Which of the following best defines a notochord? A. A component that eventually develops into the spinal cord. B. A length of cartilage extending along the body, which will become part of the spinal discs. C. That which will become the pharynx, gills, or other feeding system in the animal. D. A muscular tail extending behind the anus. E. A groove located in the underside of the pharynx that produces mucus in filter-feeding species.
B.The notochord is the feature that will eventually develop into a part of the spinal discs. The spinal cord begins as the dorsal neural tube. Pharyngeal slits are present in all chordates at some point during their development. For fish they will become gills, in other animals it will evolve into the pharynx, and in urochordates they are part of the filter-feeding system. The muscular tail that extends behind the anus is known at the post-anal tail. The endostyle is what produces mucus for filter feeders. Because it also stores iodine, it is believed to be the pre-cursor for the thyroid gland. Chordates share four main features during their development that are important to know: Notochord Dorsal hollow nerve cord Pharyngeal gill slits Muscular post-anal tail
Which of the following is correct regarding the trp operon? A. Humans utilize the trp operon to manufacture tryptophan B. The trp operon is an example of a repressible operon C. The trp operon codes for proteins which digest tryptophan D. The trp operon is the site where trp repressor binds E. The trp operon does not have an upstream promoter sequence
B.The trp operon is an example of a repressible operon. This means the operon will be on, unless it is turned off (repressed). the lac operon produces proteins to digest lactose, whereas the trp operon produce proteins to synthesize tryptophan.
A queen honeybee's unfertilized egg developing into a viable organism is an example of A. sexual reproduction B. budding C. parthenogenesis D. regeneration E. fragmentation
C A.n unfertilized egg developing into a viable (living) organism is the definition of parthenogenesis, a form of asexual reproduction. Honeybees are a common example of this.
A triglyceride is composed of A. Three fatty acid chains B. Three fatty acid chains that each have one double bond C. Three fatty acid chains attached to a glycerol molecule D. A single fatty acid chain with three double bonds E. A single fatty acid chain with three double bonds attached to a glycerol molecule
C.
The proteome is best described as A. the protein component of the ribosome B. a nuclease which can degrade mRNA C. all the proteins expressed by one type of cell under one set of conditions D. cellular machinery for recycling proteins E. the extracellular export of proteins modified and packaged through the Golgi apparatus
C.
Chromosomes align on a cell's equatorial plane during which stages of meiosis? A. Prophase II and Metaphase I B. Anaphase II and Telophase II C. Metaphase I and Metaphase II D. Prophase I and Prophase II E. Prophase I and Telophase I
C. Meiosis I: During the first stage of meiosis, homologous chromosomes pair at the equatorial plate and eventually migrate to opposite poles (no separation of sister chromatids). Prohase I: nucleus disassembles: nucleolus disappears and nuclear envelope breaks down, chromatin condenses, spindle develops. Microtubules begin attaching to kinetochores. Crossing over occurs here: this means genetic recombination occurs, and the nucleotide sequence of the chromosomes may be changed Metaphase I: homologous pairs are spread across metaphase plate. Microtubules attached to kinetochores of one member of each homologous pair. Microtubules from other site attach to 2nd member of pair. Anaphase I: homologues within tetrads uncouple and pulled to opposite sides (disjunction). Telophase I: nuclear membrane develops. Each pole forms a new nucleus that has half the number of chromosomes. Meiosis II: chromosomes spread across metaphase plate and sister chromatids separate and migrate to opposite poles. It is similar to mitosis. Prohase II: nuclear envelope disappears and spindle develops etc. No chiasmata and no crossing over. Metaphase II: chromosomes align on plate like in mitosis but now with half the number of chromosomes (no extra copy). Anaphase II: each chromosome is pulled into 2 separate chromatids and migrates to opposite poles of cell Telophase II: nuclear envelope reappears and cytokinesis occurs => 4 haploid cells (each chromosome = 1 chromatid).
All of the following hormones are derived from cholesterol EXCEPT one. Which one is the EXCEPTION? A. Aldosterone B. Cortisol C. Epinephrine D. Testosterone E. Progesterone
C. Cholesterol is characterized by 4 rings and is the precursor to many steroid hormones. Aldosterone, testosterone, and progesterone all sound very similar, and these are all steroids that are derived from cholesterol. Cortisol is another steroid that is released by the adrenal cortex and involved in stress adaptation.
Sickle-cell disease is caused by a defective hemoglobin gene, resulting in several phenotypic outcomes. Which of the following describes sickle-cell disease? A. Dominant B. Polygenic inheritance C. Pleiotropy D. Epistasis E. Linked genes
C. Pleiotropy occurs when a single gene has multiple phenotypic outcomes. In sickle-cell disease, a single mutation produces abnormal hemoglobin molecules. This results in damage to many organs and also results in several disorders. In contrast, polygenic inheritance is when many genes contribute to one phenotypic outcome. A great example is the height of humans, which is controlled by many genes and results in one phenotype. Epistasis occurs when one gene affects the expression of the second gene.
Blood in the pulmonary vein would be best characterized as which of the following? A. High in CO2 B. Low in O2 C. High in O2 D. Low in iron E. High in NaCl
C. Blood enters the heart on the right side, from the superior and inferior vena cava. This blood is deoxygenated. It circulates from the right atria to the right ventricle, then goes out through the pulmonary artery to the lungs. At the lungs, the blood disposes of CO2 and absorbs O2 and then returns to the heart through the pulmonary vein. Therefore the blood in the pulmonary vein should be high in O2, or answer choice [C]. The terms "vein" and "artery" only describe if blood is moving towards or away from the heart, it has nothing to do with whether they're oxygenated or not. The pulmonary artery has a low concentration of oxygen and the pulmonary vein has a high concentration of oxygen. Fun fact: the pulmonary and umbilical veins are the only veins that carry oxygenated (rather than deoxygenated) blood under normal conditions. Likewise, the pulmonary artery is the only artery that carries deoxygenated (rather than oxygenated) blood.
Defects in the ectoderm during development could lead to damage of what organ? A. Stomach B. Lungs C. Brain D. Heart E. Kidneys
C. Brain
The direct role of chaperonins is to A. help eliminate reactive oxygen species from the cell B. correct errors that occur during DNA replication C. assist newly synthesized proteins in correct folding D. formation of coated vesicles in receptor mediate endocytosis E. assist in cellular digestion through their internal hydrolytic enzymes
C. Chaperonins help ensure newly synthesized proteins are folded in the correct way. All of the other choices do not describe chaperonins. Chaperonins are proteins found in both prokaryotic and eukaryotic cells. Chaperonins assist newly synthesized polypeptides to fold into their correct shape.
Enzymes that are placed in temperatures above their ideal conditions will: A. Increase activity B. Be regulated C. Denature D. Become proteins E. Act as operons
C. Enzymes are highly specific and have optimal temperature and pH ranges in which they have the highest enzymatic activity. If an enzyme is taken outside of these conditions, its ability to catalyze reactions will change, usually decreasing dramatically. At higher than ideal temperatures, enzymes, which are proteins, lose their quaternary structure and denature. Although enzymes can be regulated, they are often regulated with the presence of inhibitors, both competitive and non-competitive, not with extreme temperature changes. Likewise, an operon is not directly related to the function of an enzyme and instead is involved in regulating gene expression.
In mammals, which of the following structures aides the embryo in gas exchange and the disposal of liquid waste? A. Yolk B. Amnion C. Allantois D. Chorionic Villi E. Yolk Sac
C. In mammals, the chorionic villi eventually form the placenta, but the villi are finger-like sections that burrow into the wall of the uterus near the mother's blood vessels. The allantois disposes of wastes, and forms part of the umbilical cord to carry waste away from the embryo and towards the mother's blood vessels. The amnion is a thin sac that surrounds the embryo and produces amniotic fluid to provide cushion for the growing embryo. Mammals do not have yolk, and the yolk sac contains only fluid to cushion the growing embryo and has blood vessels in it that give rise to the vascular system of the embryo. In birds, the yolk sac serves to nourish the embryo throughout its development.
What cell type forms the axonal myelin sheath within the central nervous system of humans? (The central nervous system (CNS) is the brain and spinal cord). A. Schwann cells B. Microglial cells C. Oligodendrocytes D. Astrocytes E. Central nervous system axons have no myelin sheath
C. Oligodendrocytes form the axonal myelin sheath in the central nervous system. Schwann cells form the axonal myelin sheath in the peripheral nervous system. Microglial cells are defensive cells in the central nervous system Astrocytes serve a protective but non-insulating role for nerves in the central nervous system. Central nervous system axons are covered in myelin sheath, essential to proper function.
The majority of the cytoplasm in a developing zygote is provided from where? A. Allantois B. Sertoli cells C. Oocyte D. Sperm E. Endometrium
C. The oocyte is the female egg and provides the majority of the cytoplasm in a developing zygote. This means the mother provides the original organelles of a zygote, including ribosomes, mitochondria, etc. Sperm contribute very little cytoplasm to the zygote. The allantois transfers waste products from the zygote to the placenta and later becomes the umbilical cord. Sertoli cells are located in the seminiferous tubules to help sperm mature. The endometrium is the inside lining of the uterus.
Which of the following pairs of structures target the same organ with different hormones? A. Pancreas and thyroid B. Testes and posterior pituitary C. Posterior pituitary and adrenal cortex D. Adrenal medulla and parathyroid E. Adrenal cortex and thyroid
C. The posterior pituitary stores antidiuretic hormone (ADH) and oxytocin produced by the hypothalamus; ADH targets the kidney, while oxytocin targets the mammary glands and uterus. The adrenal cortex produces glucocorticoids (such as cortisol) that affect the body on a general level to increase blood glucose, and mineralocorticoids (such as aldosterone) that target the kidney. Since the posterior pituitary produces ADH that targets the kidney, and the adrenal cortex produces a different hormone (aldosterone) that targets the kidney, the answer choice is correct. ADH increases reabsorption of water, while aldosterone increases reabsorption of Na+ and excretion of K+. The origin and effects of hormones is a common topic on the DAT. Here, we are looking for two structures that target the same organ with different hormones. The posterior pituitary releases ADH, which allows the kidneys to reabsorb more water. The adrenal cortex releases mineralocorticoids, such as aldosterone, which affects the kidney to increase salt reabsorption (which in turn increases water absorption as well due to changes in osmolarity). The pancreas releases glucagon (increase blood glucose) from alpha cells and insulin (decrease blood glucose) from beta cells. The thyroid controls general metabolism and releases calcitonin, which lowers blood calcium. The parathyroid releases PTH (parathyroid hormone), which increases blood calcium. The anterior pituitary releases FSH, LH, ACTH, TSH, prolactin, and growth hormone. The testes produce testosterone.
In total, how many autosomes does the nucleus of a human cell have? A. 23 B. 36 C. 44 D. 46 E. 53
C. These are 44 autosomes, and two sex chromosomes (X and Y). Each gamete contains 22 autosomes and 1 sex chromosome (either an X or a Y). When the gametes merge, the developing person will have 44 autosomes and 2 sex chromosomes.
All of the following are digestive enzymes EXCEPT one. Which one is the EXCEPTION? A. Amylase B. Pepsin C. Acetylcholinesterase D. Chymotrypsin E. Trypsin
C.Acetylcholinesterase is a protease that hydrolyzes the neurotransmitter acetylcholine. It is mainly found at neuromuscular junctions and brain synapses. Amylase is a digestive enzyme in the mouth that digests carbohydrates. Pepsin breaks down proteins in the stomach and is produced by chief cells. Chymotrypsin and trypsin are digestive enzymes secreted by the pancreas and break down proteins.
In angiosperms, the ovary, style, and stigma are collectively known as the: A. stamen. B. anther. C. pistil. D. filament. E. sepal.
C.Angiosperms are flowering plants and the most advanced of all plants. The pistil is the female reproductive structure and is made of an ovary, style, and stigma. The male reproductive system is called the stamen and is made of a pollen containing anther and filament. A sepal is analogous to a petal and functions to attract pollinators. The stamen is the male reproductive structure of flowering plants. In contrast, the ovary, style, and stigma (collectively known as the pistil) are female reproductive structures of flowering plants;.The stamen includes the pollen-bearing anther that sits on top of a stalk known as the filament. The anther is a part of the stamen, which is the male reproductive structure of flowering plants. In contrast, the ovary, style, and stigma (collectively known as the pistil) are female reproductive structures of flowering plants; The anther contains the microsporangia that go through meiosis to produce haploid gametes in plant reproduction. The pistil is the collective term for the ovary, style, and stigma which are female reproductive structures of flowering plants; therefore the answer choice is correct. The ovary contains the ovules (which themselves contain the female gametophytes of the plant), the stigma receives pollen, and the style is a tube through which the contents of the pollen are transferred to the ovary. The filament is a part of the stamen, which is the male reproductive structure of flowering plants. In contrast, the ovary, style, and stigma (collectively known as the pistil) are female reproductive structures of flowering plants; therefore the answer choice is incorrect. The filament is a stalk that supports the pollen-bearing anther that sits on top of it. The sepal is a leaf-like structure that functions in the protection of the flower. This is unrelated to the female reproductive structures of the plant - collectively known as the pistil (which includes the ovary, style, and stigma); therefore the answer choice is incorrect. Monocots have sepals in multiples of three, while dicots have sepals in multiples of four or five.
All of the following are ways genetic variation can be introduced to bacteria EXCEPT for one. Which one is the EXCEPTION? A. Heat shock with CaCl2 B. Electroporation C. Binary fission D. Transduction E. Conjugation
C.Binary fission is a form of asexual reproduction in prokaryotes and some organelles within eukaryotes (mitochondria and chloroplasts). The DNA is duplicated and then the two copies migrate to opposite sides of the cell, and the cell then splits into two. The consequence of this is that all the bacteria and progeny are genetically identical.
Why do steroid hormones like testosterone and estrogen bind to protein carriers when travelling through the blood? A. Steroid hormones are soluble in the blood, and will dissolve if not bound a protein carrier B. Steroid hormones would activate non-target cells if not bound to a protein carrier C. Steroid hormones are nonpolar and require a protein carrier to shield them from polar blood D. The protein carriers will act as transmembrane protein channels for the steroid hormone, at the target cell E. Protein carriers protect the steroid from being electronically reduced by dissolved oxygen
C.Blood is polar, and nonpolar steroids would be immiscible in blood if not bound to a protein carrier.Steroid hormones are nonpolar and are in fact insoluble in the blood (a polar solvent). The steroid is composed of hydrocarbons, and fused rings - this makes it hydrophobic.
Epinephrine's effects on tissues of the body is an example of what type of cell signaling? A. Paracrine B. Neuronal C. Endocrine D. Exocrine E. Autocrine
C.Endocrine signaling is when hormones are secreted into the blood vasculature, and travel throughout the body. The hormone will be recognized and received by any cell that has a complementary target receptor. The sympathetic nervous system directly stimulates the adrenal medulla. The adrenal medulla then releases epinephrine (adrenaline) and norepinephrine (noradrenaline) into the blood. Epinephrine and norepinephrine will travel through the blood and act on any cell that has complementary adrenergic receptors.
All of the following statements about cyanobacteria are true EXCEPT one. Which one is the EXCEPTION? A. They are also known as blue-green algae B. They are prokaryotic C. They are obligate anaerobes D. They perform nitrogen fixation E. They are autotrophic
C.Obligate anaerobes will die in the presence of oxygen. Cyanobacteria are photosynthetic organisms that produce oxygen as a byproduct of photosynthesis. If they were obligate anaerobes, the oxygen they produce would kill them.
An increase in calcitonin would lead to which of the following? A. Increase calcium concentration in blood B. Decrease calcium reabsorption in bones C. Stimulate osteoblast activity D. Stimulate osteoclast activity E. An increase in muscle contractions
C.Osteoblasts are cells that aid in bone production. They use calcium and other nutrients in the blood as raw materials for building new bone tissue. This leads to a decrease in serum calcium, which is the same effect as increased calcitonin. Two hormones regulate calcium levels in blood: calcitonin (produced by the thyroid), and parathyroid hormone (produced by the parathyroid). Calcitonin serves to lower calcium levels in blood. It does this by stimulating osteoblast activity, which builds up bone, which requires using calcium in the blood. Parathyroid hormone is the opposite, if calcium levels are too low in the blood, it will stimulate osteoclast activity to release calcium from the bones to the blood.
Parathyroid hormone has what direct effect on the nephron? A. It increases reabsorption of potassium ions B. It increases secretion of sodium ions C. It increases reabsorption of calcium ions D. It increases secretion of chloride ions E. It increases reabsorption of water
C.Parathyroid hormone increases calcium levels in blood. It does this in part by stimulating the kidney to reabsorb more calcium. It also causes the bones release calcium. Human (typically) have four parathyroid glands on the back of the thyroid gland. The parathyroid glands release parathyroid hormone (PTH), which stimulates the kidney to reabsorb more calcium. PTH also causes the bones to release calcium by indirectly stimulating osteoclasts. Osteoclasts are the bone resorbing (breaking down) cells. If bone is being resorbed, calcium is being liberated, and blood calcium levels increase. Calcitonin is a hormone which lowers calcium levels in the blood (calcitonin 'tones down' calcium). Calcitonin is secreted by the parafollicular cells of the thyroid gland. Calcitonin limits calcium reabsorption in the kidney's nephrons and limit calcium absorption in the intestines. Calcitonin also causes bones to take up calcium by stimulating osteoblasts to build more bone (osteoblasts build bone). Building bone consumes calcium phosphate, lowering calcium in the blood. Calcitonin also inhibits osteoclasts. If less bone breakdown is occurring, less calcium is being released from bone.
Cytosine (C) accounts for approximately 16% of an organism's DNA. What percentage of its bases would consist of adenine (A)? A. 16 B. 32 C. 34 D. 68 E. 72
C.The amount of adenine must equal the amount of thymine, and the amount of cytosine must equal the amount of guanine. Hence: A%=T% ; C%=G% Therefore, 16% of the DNA consists of C, and 16% must also consist of G. So 32% of the DNA consists of C and G. The other 68% must consist of A and T. We divide this by 2 and find that 34% of the DNA consists of A and 34% also consists of T. Checking our work, we see that C + G + A + T = 16% + 16% + 34% + 34% = 100%.
What anatomical structure serves as a passageway for urine from the kidneys to the urinary bladder? A. Afferent arteriole B. Renal artery C. Ureter D. Urethra E. Uterus
C.The ureter is the connecting passageway between the kidneys and the urinary bladder. The afferent arteriole is the arteriole that enters into Bowman's capsule, and supplies the glomerular capillaries.The afferent arteriole branches off the renal artery and enters into Bowman's capsule, and is the source of the glomerular capillaries. The glomerular capillaries then exit Bowman's capsule, and are now known as the efferent arterioles. The renal artery is the artery that the afferent arterioles branch off of. The urethra connects to the urinary bladder and exits out the penis or the vagina to evacuate urine. Completely different system (reproductive) and does not directly interface with the renal-urinary system
What type of cell junction is most common between digestive tract cells? A. Desmosomes B. Gap junctions C. Tight junctions D. Plasmodesmata E. Anchor junctions
C.Tight junctions prevent the passage of materials between digestive tract cells in animals. This way, the body must absorb the food through intracellular space. Desmosomes are a type of anchoring junctions that provide mechanical stability and are often seen in animal skin cells. They consist of the protein keratin to bind adjacent cells together. Gap junctions are narrow protein channels between animal cells that allow for the exchange of ions and small molecules, but not cytoplasm. They are often used in cell-to-cell communication by the exchange of materials or electrical impulse. Plasmodesmata are narrow protein channels between plant cells.
Which of the following will have a significant effect in stimulating development of cancer? A. A base-pair mismatch during DNA replication which has been repaired B. A cell that has one mutated allele of a tumor suppressor gene C. p53 failing to activate D. A cell that has two copies of proto-oncogenes E. A decrease in reactive oxygen species
C.p53 is the tumor suppressor guardian of the cell; its failure to activate will encourage cancer. p53 is the most well-known and well studied tumor suppressor gene, consider the guardian of the cell. It has numerous roles in cancer prevention, and is upregulated (more of it is transcribed and translated) in response to cell stress. If p53 fails to activate, the cell will have lost its protector, and this will encourage cancerous growth. For the DAT, you should also know p21. It is possible you hadn't read about p21 before, but you definitely should have studied p53. Don't be tempted to pick an answer choice just because you aren't sure whether it's correct or not. Unless you can definitively eliminate every other answer choice, don't just pick an answer because you're unfamiliar with it. p21 is a cyclin dependent kinase (CDK) inhibitor. I've talked about CDK before: CDK stimulates cell division. If p21 inhibits CDK, then p21 prevents cell division. Increasing the activity of p21 will increase the amount of inhibition of CDK, and p21 will decrease the amount of cell division. Another tumor suppressor which has come up before on the DAT is retinoblastoma protein abbreviated rb. Being a tumor suppressor, it follows the two-hit hypothesis of inactivation.
Catabolism can be described as a(n):
Catabolism is the breaking down of materials to smaller units, such as when glucose is broken down to release energy. If we're breaking down glucose, we're releasing energy, so this is an exergonic reaction. It is the opposite of anabolism, a set of metabolic pathways to create molecules from smaller units. Think of anabolic steroids, they develop bigger muscles because they build up molecules. It takes energy to build up those muscles, so anabolism is an endergonic process.
Clathrin
Clathrin is a protein which aids in receptor mediated endocytosis. Endocytosis is when the cell membrane forms a vesicle (a package that is surrounded by plasma membrane) around something extracellular that the cell wants to internalize. When a membrane receptor binds certain substrates that the cell wants to internalize, the receptor signals for clathrin lattice formation. Clathrin forms a lattice around the incoming vesicle in pits, and this is known as a clathrin coated pit. Clathrin coating occurs intracellularly and has nothing to do directly with cell recognition.
Sperm must mature while inside the female reproductive tract, before they are able to fertilize an egg. This process occurs over several hours and includes changes in membrane lipids, proteins and permeability to calcium. What is the name of this process? A. Ovulation B. Cleavage C. Acrosome reaction D. Capacitation E. Binary fission
D. Ovulation is the release of an egg from an ovarian follicle. Cleavage is the rapid cell division of the embryo that occurs after fertilization. The acrosome reaction is the release of enzymes from the acrosome region of the sperm's head that digests the egg's protective coat, allowing fertilization to occur. Capacitation is the final stage of sperm maturation that happens inside the female reproductive tract. Capacitation is the step before the acrosome reaction and fertilization. The vitelline layer is a layer of glycoproteins that surrounds the egg. The zona pellucida is the glycoprotein coat that surrounds the egg in mammals. Binary fission is the asexual reproduction of prokaryotes.
There are many shared traits between fungi and the other four kingdoms. Of the five statements below, which one is unique to fungi? A. Some fungi are bioluminescent. B. Fungi have a cell wall, vacuoles, use sexual and asexual means of reproduction and produce spores. C. Fungi undergo an alternation of generations. D. Fungi cell walls are made of glucans and chitin. E. Fungi are heterotrophic, lack chloroplasts and are reliant on organic compounds for energy sources.
D. This is a question where it would be easier to eliminate wrong answer choices to find the correct answer. Bioluminescence is found among plants and animals. Plants can undergo an alternation of generations. Plants also have chloroplasts allowing them to create their own energy sources, while animals and fungi lack that ability. Plants have cell walls, vacuoles, and use different means of reproduction to produce spores. Animals are heterotrophic, lack chloroplasts, and are reliant on organic compounds for energy sources. Plant cell walls are known to contain glucans, and some animal exoskeletons contain chitin. However, fungi are the only organism known to use both, making this feature unique to fungi only. Strategy tip: If you notice, B and C are somewhat similar in that the alternation of generations usually has a spore stage and B talks about spores, so since they are similar they both can be eliminated as potential answer choices.
Assuming independent assortment, how many different gametes can be produced from the genotype AaBbCc? A. 3 B. 4 C. 6 D. 8 E. 16
D. 8 For these types of problems use the formula 2n = # of combinations, where 2 is the number of alleles in each gene and n is the number genes. We have 2 alleles and 3 genes, so 2(3) = 8 combinations. We could also write out all possible combinations: ABC, ABc, AbC, Abc, aBC, aBc, abC, abc
All of the following statements are part of modern cell theory EXCEPT one. Which one is the EXCEPTION? A. An organism's activity is dependent on the activity of its independent cells. B. Metabolism and biochemistry occur within cells. C. Hereditary information is stored in cells and is shared between cells during cell division. D. All cells contain a nucleus for the storage of genetic material. E. All cells in organisms of similar species have similar chemical compositions.
D. It is true that all cells have hereditary material (DNA), but not all cells have a membrane bound nucleus. In eukaryotic cells the cell nucleus serves to protect the DNA of the organism. Prokaryotic cells do not have a centralized nucleus and do not have many of the other cell organelles that eukaryotic cells have with the exception of ribosomes. Prokaryotes have a nucleoid region.
The main extracellular buffer system in humans consists of: A. amphipathic proteins B. phosphate C. sulfate D. bicarbonate E. histamines
D. The main extracellular buffer is bicarbonate. This is how CO2 is transported throughout the body. The body uses pH sensors to determine how much we have to breathe. If we are exercising vigorously then our cells will produce large amounts of CO2, which will lower our extracellular pH (make it more acidic due to the CO2), which will make us breathe more to expel the excess CO2. Phosphate and other proteins are used as the main intracellular buffer inside cells.
Channel proteins allow particles to cross the cell membrane during what non-energy consuming process? A. Active Transport B. Simple Diffusion C. Saltatory Conduction D. Facilitated Diffusion E. Osmosis
D. here are three different methods for particles to get through the cell membrane. They include: simple diffusion, facilitated diffusion and active transport. With simple diffusion, particles are able to move directly through the phospholipid bilayer. This is only applicable for very small, uncharged particles. With facilitated diffusion, particles are able to cross the membrane but with the help of integral proteins that span the length of the cell membrane. Active transport occurs when particles are pumped or forced across the membrane against their concentration gradient. This transport requires the use of ATP or energy. The question specifies that this is a "non-energy consuming process", thereby the correct answer is D. Saltatory conduction refers to the action potential of a neuron jumping along the axon and osmosis is the process of water movement.
If 2n=8, how many chromosomes are present during anaphase?
D. 16 In a cell with a diploid number of 8, we expect to see 8 chromosomes (as chromatid pairs) aligned at the equatorial plane at metaphase. During anaphase of mitosis, the chromatid pairs split apart. Each chromatid is now considered a separate chromosome, but since the cells have not yet separated, this means there are twice the number of chromosomes present as the diploid number - a total of 16
Which biome is characterized as the largest biome on Earth with long harsh, snowy winters, short rainy and humid summers and with a landscape dominated by conifers? A. Deciduous forest B. Savanna C. Tundra D. Taiga E. Chaparral
D. Deciduous forests do have winters, but they are not characterized as harsh or very snowy and this biome is known for having 4 distinct seasons each year. The savanna biome has small grasses, small shrubs, scattered trees, and have both dry and rainy seasons. The tundra biomes are best defined as regions that have short growing season, cold temperatures all year round and have a layer of permafrost over the soil. The taiga biome has long, cold winters and very short rainy seasons. Taiga does have vegetation with most of the tree covering being provided by conifers like spruce, fir and pine trees. Tropical deserts are characterized as having extremely high temperatures with sporadic rainfall. The only biome that accurately fits the description in the question is D.
Two plants that are both monohybrid are crossed. If the phenotypic ratio seen in the F1 offspring is in a 1:2:1 ratio, this is indicative of This would produce a genotypic ratio of 1 AA: 2 Aa: 1 aa A. complete dominance B. true breeding parents C. genetic drift D. incomplete dominance E. homozygous parents
D. Incomplete dominance is intermediate dominance. If this species of plant showed incomplete dominance of this gene, a genotypic ratio of 1 AA: 2 Aa : 1 aa would have produced a phenotypic ratio of 1:2:1Incomplete dominance phenotypically appears IN the middle of the two traits (or Intermediately to the two phenotypes). Classic example is a white flower mixed with a red flower, producing a pink flower (color is IN the middle to white and red). If A was completely dominant to a, the genotypic ratio of 1 AA : 2 Aa : 1 aa would have produced a phenotypic ratio of 3:1 A true breeding organism is pure breeding, ie. it is homozygous for its traits. By definition, a monohybrid cross is a cross of heterozygous parents. Genetic drift is an ecological process where random chance changes the allele frequency of a population. This has nothing to do with the question By definition, a monohybrid cross is a cross of heterozygous parents.
Insulin is a protein (peptide) hormone, and most directly promotes cells to uptake glucose by A. increasing glucose transporter protein translation by acting as a transcription factor in the nucleus B. increasing exocytosis of glucose into the vascular circulation C. making the phospholipid bilayer directly permeable to glucose diffusion D. stimulating translocation of vesicles containing glucose transporters to the cellular membrane E. stimulating the hypothalamus to increase the body's temperature
D. Insulin stimulates premade vesicles (membrane bound packages) of glucose transporter to translocate and fuse with the membrane. This increases the cell's efficiency at bringing glucose into the cell.
Oligodendrocytes are best associated with: A. Beta cells of the pancreas B. G cells of the stomach C. Nerves in the peripheral nervous system D. White matter of the brain E. Spermatogonia of the testes
D. Oligodendrocytes are responsible for laying down the myelin sheath surrounding neurons in the central nervous system, so choices [A], [B] and [E] can be eliminated. Remember, the central nervous system includes the brain and the spinal cord. Schwann cells perform the same function in the peripheral nervous system (PNS). Myelination insulates the neurons (like the plastic around an electrical wire) and allows the neurons to transmit electrical impulses more quickly and efficiently. Without myelination, your neurons will not be able to properly communicate together, resulting in a variety of diseases, such as multiple sclerosis.
Which of the following is an example of Batesian mimicry? A. The Phasmatodea insect, which looks like a stick B. Two different species of the poisonous Heliconus genus of butterfly, which have similar tiger striping C. The vibrant blue color of an Anura poision dart frog D. The harmless Erastalis fly's yellow and black striping which is similar to that of a Anthrophila stinging bee E. A stinging Anthrophila bee and a stinging Hymenoptera wasp, which have similar coloring and body size
D. is when a non-harmful animal mimics the coloring of a harmful animal. This is the case of a harmless fly which mimics the coloring of a stinging bee. An insect looking like a stick to avoid detection is an example of camouflage. Aposematic coloration is the vibrant, bright coloration of poisonous animals which warns predators that they are poisonous. This is the case of a bright blue frog. Mullerian mimicry is when different poisonous species have a similar appearance, and therefore they cumulatively appear to be a toxic species with more members, which makes them more intimidating to potential predators. This is the case of the poisonous butterflies and the bee with the wasp.
What does it mean if a bacteria is competent? A. It can transfer genes through transduction B. It can transfer genes through transformation C. It can receive genes through transduction D. It can receive genes via transformation E. It can transfer and receive genes via conjugation
D. it can pick up naked DNA from the environment.
A scientist discovers small particles inside a cell and wishes to know what they are. Radioactive aminoacyl-tRNAs are microinjected into the functioning cell. The measured amount of radioactive aminoacyl-tRNAs decreases over time, while the amount of radioactive polypeptides increases. What are the small particles? A. siRNA B. Lysosomes C. Mitochondria D. Ribosomes E. Histones
D.A polypeptide is a protein, and proteins are made of amino acids. Ribosomes read mRNA and synthesize polypeptides out of aminoacyl-tRNAs. Aminoacyl-tRNAs are how amino acids are carried to the ribosome for elongation in translation. siRNA, or small interfering RNA, are small snippets of double stranded RNA that interfere with the expression of certain genes. Lysosomes digest material in the cell and are known for breaking down polypeptides into amino acids. Mitochondria produce ATP for the cell. Histones are proteins associated with eukaryotic DNA and archea DNA.
All of the following directly use an electrochemical gradient EXCEPT one. Which one is the EXCEPTION? A. Flagella rotation B. Mitochondria C. Chloroplasts D. Aquaporins E. Neurons
D.Aquaporins are integral membrane proteins that allow for the facilitated diffusion of water across the cell membrane. The only gradient involved in facilitated diffusion is movement down a concentration gradient, not electrochemical
What are the two abiotic factors that determine the distribution of terrestrial biomes? A. soil and sunlight B. sunlight and temperature C. rainfall and sunlight D. rainfall and temperature E. soil and temperature
D.Biomes are classified based on the biological effects of temperature and rainfall on vegetation. The majority of biomes are dependent on these two factors. For example, deserts have a lack of rainfall and very high temperatures, giving them their characteristics. In contrast, rainforests have lots of rainfall and warm temperatures, providing an environment for a biologically diverse biome.
All of the following statements about muscle contraction are true EXCEPT one. Which one is the EXCEPTION? A. ATP is hydrolyzed B. The H zone of the muscle fiber shortens C. Myosin and actin bind D. Sodium ions bind to troponin E. The action potential spreads quickly via transverse tubules (T tubules)
D.Calcium ions bind to troponin which results in exposure of the myosin binding site of tropomyosin.
Which of these Animalia phyla has a true coelem? A. Nematoda B. Cnidarian C. Platyhelminthes D. Mollusca E. Porifera
D.Coelom is a fluid filled body cavity that has a lining derived from the mesodermal layer. The mesodermal lining of the coelom is known as the peritoneum. Coelom is a fluid filled body cavity that has a lining derived from the mesodermal layer. The mesodermal lining of the coelom is known as the peritoneum. We can use the DATgenius Animalia mnemonic to remember which animals contain a coelom. Privileged - Porifera Children - Cnidarian Play - Platyhelminthes Nicely - Nematoda And - Annelida Maturely - Mollusca Arthur - Arthropoda Ensures - Echinodermata Cooperation - Chordata With this DATgenius mnemonic, anytime there is a letter that occurs twice (like P, C, A) the beginning of the word has some hint in it for the animal it represents. PR...ivileged... - PoRifera Ch...ildren - Cn...idarian (Ch looks like Cn) PLAY - PLAtYhelminthes Nicely - Nematoda (only one N in the mnemonic) ANd - ANNelida Maturely - Mollusca (only one M in the mnemonic) ARTHur - ARTHropoda Ensures - Echinodermata (only one E in the mnemonic) Cooperation - CHOrdata Everything before Nematoda is acoelomate (lack a coelom). Everything after Nematoda is coelomate (contains a coelom). Nematoda are considered pseudocoelomate ('fake' coelomate). Pseudocoelom is a body cavity that does not contain a full peritoneum. This pseudocoelom helps with nematode motility - they use the pseudocoelom as a hydrostatic skeleton. A hydroskeleton provides rigidity through fluid pressure.
If a strand of DNA contains the sequence 5' GTAT 3', which of the following would be the complementary DNA strand? A. 5' CAUA 3' B. 3' CAUA 3' C. 5' CATA 3' D. 3' CATA 5' E. 5' TATG 3'
D.DNA is antiparallel (meaning the two strands run in opposite 5' to 3' directions) and in DNA, adenine binds to thymine (whereas in RNA, thymine is replaced by uracil).
Which of the following stores the most amount of energy, gram for gram? A. Starch B. Glycogen C. Polypeptides D. Fats E. Glucose
D.Fats store the most amount of energy in the body. They store roughly double the amount of energy carbohydrates (starch, glycogen, cellulose) store, gram for gram. The reason our body prefers to burn glucose is because it is easier to use in respiration and it is more readily available.
All of the following processes result in genetic variation EXCEPT for one. Which one is the EXCEPTION? A. Mutation B. Crossing over C. Meiosis D. Linked genes E. Independent Assortment
D.If genes are linked they travel together during meiosis and are likely to be expressed together in an organism's phenotype. An example of linked genes is hair color and eye color, with some combinations dominating over others, i.e. dark hair, dark eye color. This decreases the amount of genetic variation as multiple organisms may have both the same genotype and phenotypes for linked traits because of the presence of linked genes. All of the other answer options are sources of genetic variation both on a molecular and an organism level.
If a host cell is infected by a virus, what might that host cell release to warn other nearby host cells of the viral infection? A. Epinephrine B. Immunoglobulin C. Major histocompatibility complex (MHC) molecules D. Interferon E. C5b and C6 from the complement system
D.Interferon is a cytokine that infected host cells can release to warn other nearby cells that a pathogen (usually a virus) has infected that cell. Interferons help ready neighboring cells for defense. Epinephrine is neurotransmitter involved in the sympathetic nervous system. Immunoglobulin is a protein antibody produced as part of adaptive immunity. Major histocompatibility complex is a cell surface molecule involved in the immune response and self vs non-self cell recognition. C5B and C6.T he complement system is a group of blood proteins which are part of the innate immune response. The complement system aids the body in clearing pathogens.
Which of the following is INCORRECT about jellyfish? A. It does not have a vertebral column B. It is radially symmetrical C. It contains cnidocytes D. It is triploblastic E. It contains a gastrovascular cavity
D.Jellyfish are cnidarians. Both poriferan (sponges) and cnidarians (hydra and jellyfish) are diploblastic, meaning they only have two germ layers: ectoderm and endoderm.
During cellular respiration, in which of these stages is NADH produced? A. Glycolysis, pyruvate decarboxylation B. Glycolysis, citric acid cycle C. Pyruvate decarboxylation, citric acid cycle D. Glycolysis, pyruvate decarboxylation, citric acid cycle E. Glycolysis, pyruvate decarboxylation, citric acid cycle, electron transport chain
D.NADH is produced during glycolysis, pyruvate decarboxylation, and the citric acid cycle.One glucose molecule enters. An investment needs to be made: the energy of activation for glycolysis is 2 ATP. The cell invests 2 ATP into glycolysis to phosphorylate intermediates, as part of the reaction. Therefore, while glycolysis makes 4 ATP, the process only net produces 2 ATP (as 2 ATP were invested in). Additionally, it produces 2 NADH and 2 pyruvate.
What is the fundamental niche of an organism? A. The organism's specific role in an ecosystem B. Environmental conditions where the organism lives C. The organism's place in an ecosystem's foodweb D. The environmental conditions where an organism can potentially live E. The habitat an organism occupies in the environment
D.Note that this question asks about the "fundamental niche" of an organism, not just the "niche". The fundamental niche of an organism is simply the range of environmental conditions an organism can live in, where there is no influence from predators. The realized niche is where the organism actually lives in the environment.
The shaft of the long bone is called the: A. metaphysis. B. periosteum. C. epiphysis. D. diaphysis. E. medullary cavity.
D.The diaphysis is the name of the shaft of a long bone, which is made of compact bone. The epiphysis is the rounded end of a long bone. The metaphysis is the wider portion of a long bone situated near the epiphysis, this is where the majority of growth happens during puberty. The periosteum is a membrane that covers the surface of all bones, except at the joints of long bones. It provides nourishment and sensation to the bones. The medullary cavity is the central cavity of bone shafts. It usually contains red bone marrow, which produces blood cells, and yellow bone marrow, which consists of adipose tissue.
Which of the following describes the evolution of fish, from earliest to latest ancestor? A. Jawless fish -> Lobe-finned fish -> Cartilaginous fish B. Cartilaginous fish -> Lobe-finned fish -> Jawless fish C. Bony fish -> Cartilaginous fish -> Lobe-finned fish D. Jawless fish -> Cartilaginous fish -> Lobe-finned fish E. Cartilaginous fish -> Jawless fish -> Bony fish
D.The first fish to evolve did not have jaws and looked like eels. Afterwards, cartilaginous fish (such as sharks) evolved. Lastly, lobe-finned fish developed, from which terrestrial organisms developed.
Which of the following best describes the position of a gene on a chromosome? A. Chiasma B. Allele C. Genotype D. Locus E. Genome
D.The locus is the location of a gene on a chromosome The chiasma is the structure formed when homologous chromosomes cross over during prophase I of meiosis. An allele is one variant form of a gene that has different forms. Aa Genotype is the actual genetic composition of an organism The genome is all of the DNA within a cell.
Which layer of the skin helps the body conserve heat and protects the body from injury by acting as a "shock absorber"? A. Epidermis B. Dermis C. Endodermis D. Subcutaneous layer E. Mesoderm
D.The subcutaneous layer contains a network of fat cells and collagen. It is the deepest layer of skin and the fat cells help insulate the body and act as a shock absorber to protect it from minor damage. The top layer of skin is the epidermis, which usually contains dead skin cells and contains melanocytes (produce melanin). The dermis is the middle layer and is highly vascularized. The dermis contains blood vessels, hair follicles, sweat glands, and nerves. Fun fact: The dermis is where tattoo machines inject their ink.
If blood pressure is low, which of the following is true? A. Antidiuretic hormone release is inhibited B. Renin will partially cleave angiotensin II to activate it C. Angiotensin II production would further decrease blood pressure D. Vasoconstriction will increase total peripheral resistance E. The kidneys would lower plasma salts levels
D.The total peripheral resistance is the total amount of resistance that blood faces when flowing through the vasculature of the body. Vasoconstriction increases the resistance to blood flow.
All of the following statements about action potentials are true EXCEPT one. Which one is the EXCEPTION? A. An action potential is less likely to occur if the neuron is hyperpolarized B. Potassium voltage gated ion channels open after sodium voltage ion gated channels C. Myelin sheath helps the action potential propagate faster D. The Na+/K+ ATPase helps stimulate action potential firing E. Action potentials can only travel in one direction
D.This is a false statement and therefore the answer choice is correct. The Na+/K+ ATPase makes the cell more negative which makes firing an action potential less likely.Mnemonic to remember relative concentrations of ions in/around the neuron: Salty Banana - imagine salt on the outside of a banana.Salt is high on the outside. Salt is NaCl, sodium chloride.Banana on the inside. Bananas are rich in K+, potassium.So we have higher NaCl outside the neuron than inside it. And we have higher K+ inside the neuron than outside it.
Which of the following are true regarding blood clotting components? A. Platelets contain multiple nuclei B. Fibrin converts prothrombin into thrombin C. Platelets are the cell fragments of old red blood cells D. Exposed collagen in damaged blood vessels activates platelets E. Vitamin K aggregates to plug damaged blood vessels
D.When a blood vessel is damaged, collagen fibers from the blood vessel wall that previously were internal are now exposed to the blood circulating through that vessel. Platelets that are circulating past this area are activated and bind. This begins the coagulation cascade.
he diastole phase of circulation is associated with the: A. contraction of the ventricles. B. closing of the AV valves. C. opening of the semilunar valves. D. closing of semilunar valves. E. relaxation of the atriums.
D.When the heart contracts, the ventricles force blood through the semilunar valves and into our arteries. Also during this time, the AV valves are shut to prevent the blood from being forced back into the atriums. When the ventricles relax, the semilunar valves are shut to prevent backflow from the blood they just forced into the arteries, and the AV valves are reopened; this is called the diastole phase. The opening and closing of the AV valves and semilunar valves causes the "lub-dup" sounds in the heart.
All of the following are statements that support the endosymbiotic theory EXCEPT one. Which one is the EXCEPTION? A. Mitochondria and chloroplasts reproduce by a process similar to binary fission. B. The thylakoid membranes of chloroplast resemble the photosynthetic membranes of cyanobacteria. C. The DNA of mitochondria and chloroplasts is circular and lacks proteins. D. Mitochondria and chloroplasts both produce energy. E. Mitochondria and chloroplasts have two membranes that consist of a lipid bilayer separated by an intermembrane space.
D.While it is true that mitochondria and chloroplasts both produce energy, this statement does not support the endosymbiotic theory that these organelles were originally independent prokaryotic cells that were incorporated as organelles into what eventually came to be known as eukaryotic cells. It simply states their function, which does not provide a strong link to their potential ancestry
What is the purpose of SDS (sodium dodecyl sulfate) in protein analysis?
Denature non-covalent bonds in a protein SDS denatures the non-covalent bonds in a protein, which removes the tertiary structure of the protein and linearizes it. SDS (sodium dodecyl sulfate) has three primary effects on protein: Denatures the protein, Linearizes the protein, Adds negative charge to the protein
Mesoderm
Dermis of skin, muscle, skeleton, circulatory system, gonads, kidneys, respiratory tracts, notochord
A. Streptococcus B. Staphylococcus C. Streptobacillus D. Spirilla E. Diplococcus
Diplo-: pairs Strep-: chain Staph-: grape-like clusters -coccus: spherical -bacillus: rod-like Spirilla/spirochetes: spirals
A child is suspected to have Down Syndrome, or trisomy 21. Which of the following tests can substantiate this diagnosis? A. Gel electrophoresis B. Polymerase Chain Reaction C. DNA fingerprinting D. Northern Blotting E. Karyotyping
E. Down Syndrome, also known as "Trisomy 21", occurs when there are 3 copies of the 21st chromosome. This abnormal number of chromosomes would best be determined using a karyotype. A karyotype is a digital image of the size, shape, and number of chromosomes of an organism, allowing us to observe if there is a third copy of the 21st chromosome. Gel electrophoresis is a laboratory technique used to identify similarities between organisms and the identity of an unknown DNA sample. Polymerase Chain Reaction ("PCR") is a technique used to replicate and amplify a DNA sample in vitro. Northern blotting is a laboratory technique used to identify the sequence of messenger RNA and to study gene expression. DNA fingerprinting is the process of keeping a database of each individual's DNA sequences and/or makeup for forensic or genetic reasons. The only biological test relevant for this scenario is the karyotype, [E].
Colorblindness, a recessive X-linked trait, is far more common in men than women. Which of the following statements explains this phenomenon? A. Women inactivate both of their X chromosomes B. Men carry more genes for colorblindness than women C. Colorblindness is activated by increased testosterone D. Men have two X chromosomes while women have one E. Men carry no genes for color blindness on their Y chromosome
E. Women do not experience color blindness as often because they carry two X chromosomes. In contrast, men have one X chromosome and one Y chromosome. If men inherit the colorblind gene, they cannot rely on their Y chromosome to have a dominant allele for normal color vision like women do with their second X chromosome. This results in X-linked traits affecting men more than women.
After ejaculation, what process must sperm undergo before they are competent to fertilize an oocyte? A. Acrosome reaction B. Oogenesis C. Metamorphosis D. Sperm meiosis E. Capacitation
E. Capacitation. Capacitation is the penultimate step of development of sperm. It occurs in the oviduct. It involves the destabilizing of the acrosome to allow for better binding between the sperm and oocyte. The acrosome reaction is when the tip of the sperm reacts with the zona pellucida of the egg to fuse together. Metamorphosis is the process of additional development that usually refers to the process of larva turning into an adult insect. Sperm meiosis is completed in the seminiferous tubules.
A toxin is released into the body that promotes the degeneration of microfilaments. Which of these structures is most likely to be directly affected? A. Spindle fibers radiating from centrioles B. Lysosomes C. The extracellular matrix D. Chromosomes E. Muscle cells
E. Our muscles are made of long chains of cytoskeleton comprised of two filaments - actin and myosin. Of these, actin is a microfilament, while myosin is a motor protein. If actin degenerates, then our muscles would not contract, thus, our answer is E. The spindle fibers radiating from the centrioles are microtubules. A lysosome is an organelle that is involved in phagocytosis. The extracellular matrix consists of protein fibers and glycosaminoglycans. Chromosomes are made of nucleic acids.
All of the following were observed by Miller-Urey in their classic experiment to check the hypothesis of the "chemical origins of life" EXCEPT for one. Which one is the EXCEPTION? A. Methane B. Amino acids C. Ammonia D. Organic compounds E. Nucleic acids
E. The Miller-Urey experiment used ammonia, methane, water and hydrogen sealed in a sterile arrangement of tubes and flasks with connecting loops. One flask was half-filled with liquid water and the other with 2 electrodes (to simulate lighting in early earth). The flask with water was heated to simulate the temperature of early Earth, and sparks were fired from the electrodes to simulate lightning. After 2 weeks, they observed several organic compounds, amino acids (11 out of 20) and their base starting materials. However, no complete nucleic acids were observed.
Which of the following is a method marine fish use to maintain homeostasis? A. Swim towards freshwater. B. Rarely drink water. C. Absorb salts through gills. D. Constantly urinate. E. Constantly drink water.
E. smoregulation examples in marine and freshwater fish have been common topics on the DAT. A marine fish is hypoosmostic to its environment, meaning that it is less salty than the concentrated saltwater surrounding it. Therefore, it will constantly lose water to the environment. To make up for this, the marine fish must constantly drink water. It also rarely urinates to not waste any water, and it secretes the salts it acquires from constantly drinking. In contrast, freshwater fish are hyperosmotic, or saltier than their environment. Therefore, water will constantly flow into the fish. The fish must constantly urinate to get rid of the excess water. It also rarely drinks, and absorbs salt through its gills to maintain homeostasis. SUMMARY Fish in freshwater environments: Are hyperosmotic relative to their environment Drink very little water Salt enters the gills via active transport Produce large volume of urine In contrast, fish in saltwater environments (i.e. marine fish): Are hypoosmotic relative to their environment Constantly drink Salt leaves the gills via active transport Produce low volume of urine
Which of the following techniques would best allow a scientist to determine which genes are and are not expressed in a cell? A. ELISA B. Gel Electrophoresis C. Karyotyping D. PCR E. DNA microarray
E.A DNA microarray is a method to determine which genes are expressed and which genes are not expressed in a sample. This is useful in cancer research because we can see which genes are over/under expressed as compared to a normal cell. ELISA is a technology to determine if a specific antigen exists. Antibodies are placed into a microtiter plate, and if they bind to their specific antigen there will be a color change in the microtiter plate, indicating that a specific antigen exists. Gel electrophoresis is a technique to separate macromolecules (DNA, RNA, proteins) by size and charge. Shorter macromolecules will move faster than longer macromolecules and travel further. Karyotyping is a useful tool to count the number of chromosomes in a cell. This is useful in the diagnosis of trisomy diseases, or an abnormal number of chromosomes. PCR is used to amplify the amount of DNA available, usually as an intermediate step of other genetic techniques.
Why does yeast undergo anaerobic respiration in the absence of oxygen? A. To produce ethanol as a backup electron acceptor B. To reduce NAD+ to NADH C. To release CO2 D. To release oxygen from pyruvate E. To oxidize NADH to NAD+
E.In the absence of oxygen, yeast undergo anaerobic respiration to oxidize NADH to NAD+, which allows glycolysis to continue (and the production of ATP, which is critical to cell function), so the answer choice is correct. When oxygen is present, NADH is oxidized to NAD+ via the electron transport chain, where oxygen acts as the final electron acceptor. Without anaerobic respiration or oxygen, NADH would accumulate and the cell would die from a lack of ATP.
All of the following can be found in the filtrate from the Bowman's capsule EXCEPT for one. Which one is the exception? A. Glucose B. Salts C. Vitamins D. Nitrogen wastes E. Proteins
E.In the kidney system, blood enters from an afferent arteriole into the glomerulus, where pressure forces water and solutes through the capillary walls into the Bowman's capsule, like a sieve. Small particles can be pushed through the capillary walls, but red blood cells and proteins cannot pass through and remain in the blood. The filtrate in the Bowman's capsule will then travel through the nephron, where the majority of salts, water, and glucose will be reabsorbed.
What is the name of the structure that allows bacteria to stick to a surface? A. Flagella B. Clathrin C. Nucleoid region D. Teichoic acids E. Pili
E.Pili are small short "hairs" called fimbriae on the surface of bacteria that can be used in the exchange of genetic material between bacteria and in cell adhesion. Bacterial flagellum is a long "tail" made of flagellin that provides locomotion to a bacterial cell. In eukaryotes, flagellum is made of microtubules. Clathrin is a receptor protein on the surface of a cell. A nucleoid region is where the DNA exists in a bacterial cell as it does not have a nucleus. Teichoic acids are found only on gram-positive bacteria and help keep the cell wall rigid.
All of the following phyla have a complete digestive system EXCEPT for one. Which of the following is the EXCEPTION? A. Nematoda B. Annelida C. Mollusca D. Echinodermata E. Platyhelminthes
E.Platyhelminthes do not have a complete digestive system, so the answer choice is correct (it is important to know that Cnidaria also lack a complete digestive system - both Cnidaria and Platyhelminthes instead have a gastrovascular cavity in which two way digestion takes place, rather than the one way digestion through an alimentary canal seen in other classes with digestive systems). Platyhelminthes are triploblasts with bilateral symmetry, and are acoelomate. Examples include flatworms, tapeworms, and flukes.
What are the products of the light-dependent reactions in photosynthesis? A. C6H12O6, NADPH, and ATP B. C6H12O6, NADP+, and ADP C. CO2, NADPH, ATP D. O2, NADP+, and ADP E. O2, NADPH, and ATP
E.The light-dependent reactions of photosynthesis occur in the thylakoid membranes of chloroplast. Here, cyclic photophosphorylation produces ATP through an electron transport chain, and noncylic photophosphorylation produces NADPH. Water is split during these reactions, releasing O2. These products, along with CO2 and rubisco, will become the reactants in the light-independent reactions of photosynthesis, which will produce C6H12O6, NADP+, and ADP.The light-dependent reaction of photosynthesis produces the ATP and NADPH needed to power the Calvin cycle (also known as C3 photosynthesis, the dark reaction) which ultimately fixes CO2 to produce glucose. The O2 is emitted into the atmosphere.
Which biome is best described as the largest terrestrial biome, that has very cold winters, and many cone bearing trees? A. Temperate deciduous forest B. Temperate grasslands C. Tundra D. Tropical rain forest E. Taiga-boreal forest
E.The taiga-boreal forest is the largest terrestrial biome, characterized by cold winters (it has a far northern latitude) and coniferous (cone bearing) trees.
Ectoderm
Epidermis of skin, hair, nails, nervous system, lens of eye, enamel of teeth
Exocrine
Exocrine hormones are secreted from glands through a duct. Examples include sweat, salivary, mammary glands, and some of the pancreas and liver function.
Which of the following pairs of classification levels are most closely related? A. Kingdom and Order B. Family and Genus C. Phylum and Order D. Family and Species E. Class and Genus
Family and Genus A genus is the level of organization directly below family in taxonomic rank,
In the alternation of generations, what do spores directly give rise to? A. Gametes B. Zygotes C. Gametophyte D. Sporophyte E. Seeds
Gametophyte In the alternation of generations, spores produced by the sporophyte go through mitosis and form the multicellular gametophyte structure
Gastrulation of the Blastula
Gastrulation of the blastula does not involve apoptosis; therefore the answer choice is incorrect. Gastrulation occurs when a group of the blastula's cells begins to fold inward, resulting in: Formation of three germ layers (endoderm, mesoderm, ectoderm) Formation of the archenteron (a center cavity completely surrounded by endoderm cells that eventually gives rise to the gut) Formation of the blastopore, the opening into the archenteron that becomes the mouth in protostomes and anus in deuterostomes
Which organelle modifies products from the endoplasmic reticulum and is responsible for protein packaging?
Golgi complex The golgi complex is responsible for the transport of various substances in vesicles, and modifies the products of the endoplasmic reticulum: proteins can be glycosylated, phosphorylated, or sulfonated in the golgi complex so the answer choice is correct. The golgi complex consists of flattened sacs called cisternae.
Endoderm
Lining of digestive and layer of respiratory tracts, liver, pancreas
Which of the following statements accurately describes cytokinesis in mammals?
Microfilaments encircle the center of the cell and shorten. During cytokinesis of animal cells, actin and myosin microfilaments encircle the center of the cell and shorten, pulling the plasma membrane towards the center of the cell, eventually resulting in two separate cells. This is the only option that describes a set of events specific to cytokinesis in mammals, so the answer choice is
Mitochondrial matrix
Mitochondrial matrix, citric acid cycle The arrow in the image is pointing towards the mitochondrial matrix, correctly answering the first part of the question. The mitochondrial matrix is also the site of the citric acid cycle (Krebs cycle), so the answer choice is correct. The mitochondrial matrix is also the site of pyruvate decarboxylation and the breakdown of fatty acids via beta-oxidation.
Digestive enzymes Summary
Mouth: salivary amylase (carbohydrates) Stomach: Pepsin (proteins) Pancreas: pancreatic amylase (carbohydrates), pancreatic trypsin and chymotrypsin (proteins), carboxypeptidase (proteins), nucleases (DNA, RNA), lipase (fats) [Note: these digestive enzymes are secreted by the pancreas but carry out their function in the small intestine] Small Intestine: Disaccharidases (carbohydrates), dipeptidases and aminopeptidases (proteins), nucleotidases (nucleotides), nucleosidases (nucleosides)
Myelin sheath
Myelin sheath is a fatty insulation of the axon of the neuron and helps the action potential to propagate faster down the neuron. Myelin sheath is formed by oligodendrocytes in the central nervous system Schwann cells in the peripheral nervous system. Myelin sheath insulates the axon from undergoing ion exchange, and the action potential ion exchange process can only occur where there are gaps in between myelin. These gaps are known as nodes of Ranvier. By promoting ion exchange at the nodes of Ranvier (gaps), the action potential jumps from one node to the next - and this is much faster than having ion exchange down the entire length of the axon.
Electron transport chain:
NADH and FADH2 are electron carriers. They harness the energy of redox reactions occurring in the earlier steps of cellular respiration (glycolysis, pyruvate decarboxylation, Krebs cycle) and brings these electrons to the electron transport chain.At the end of the electron transport chain in cellular respiration, O2 is the final (terminal) electron acceptor. O2 combines with two hydrogens and the electrons exiting the electron transport chain, and is reduced to form H2O (water).
Neuronal
Neuronal signaling is direct communication between neurons via the use of neurotransmitters being sent across a synapse.
An animal cell was lysed, placed in a test tube, and centrifuged. Which organelle would pellet from the centrifuge first?
Nucleus If an animal cell was lysed and centrigufed, the nucleus would be expected to centrifuge first since it is the largest and most dense organelle; Centrifugation works by spinning a tube of components at high velocities to create a force. The heavier a component is, the faster it will pellet out of the solution. The nucleus is the largest and most dense organelle in the cell and will pellet first. All the other organelles are smaller and less dense than the nucleus and will pellet later or not at all depending on the speed of the centrifuge.
Germ layer
Organ development
Paracrine
Paracrine signaling is when a cell signals to other cells in its surrounding vicinity. Examples include blood clotting factors and tissue healing.
What is the original source of energy used to drive the light independent reactions of photosynthesis?
Photons absorbed by chlorophyll
Prolactin
Production of milk in mammary glands
Pyruvate decarboxylation
Pyruvate decarboxylation is the step of cellular respiration that takes the 3 carbon pyruvate generated during glycolysis and processes that pyruvate to form a 2 carbon acetyl CoA, CO2, and NADH. In the Krebs cycle (aka citric acid cycle), the two acetyl CoAs from pyruvate decarboxylation enter. Each 2C acetyl CoA will join a four carbon oxaloacetate, and form a six carbon citrate (hence the alternative name for the Krebs cycle called citric acid cycle). For every acetyl CoA, Krebs cycle produces 2 CO2, 3 NADH, 1 FADH2, and 1 ATP. So for every two acetyl CoA that enters the Krebs cycle: 4 CO2, 6 NADH, 2 FADH2, and 2 ATP are produced.
A researcher extracts a biomolecule from a cell and finds its molecular makeup is comprised of a large amount of nitrogen, no sulfur, and is found in both the cytoplasm and the nucleus. Which of the following is most likely the biomolecule the researcher extracted?
RNA.Do not let the application style of the question overwhelm you; answering this question is a straightforward matter of identifying which of the biomolecules presented in the answer choices match the criteria of the question. RNA is abundant in nitrogen (due to the nitrogenous bases that are part of nucleotide structure). Additionally RNA contains no sulfur and is found in both the nucleus (as a result of transcription) and the cytoplasm (where mRNA, tRNA, and rRNA are all found in the process of translation). As RNA is the only biomolecule that fits all the criteria specified in the question, it is the most likely biomolecule extracted by the researcher, there the answer choice is correct.
Luteinizing Hormone
Regulate development, growth, and reproduction. Acute increase in LH triggers ovulation and develops corpus luteum. In males it stimulates Leydig cells to produce testosterone. It acts synergistically with FSH.
Follicle stimulating hormone
Regulate development, growth, and reproduction. FSH helps develop a primary follicle. It acts synergistically with LH.
Human growth hormone
Regulates protein synthesis and cell division
All of the following are methods of post-translational modification of polypeptides EXCEPT one. Which one is the EXCEPTION? A. Glycosylation B. Protease activity C. Acetylation D. Removal of introns E. Methylation
Removal of introns is a post transcriptional modification, not a post-translational modification.
What is the name of an enzyme that cuts DNA at specific sequences?
Restriction endonuclease
Adrenocorticotropic Hormone
Stimulates adrenal cortex
Thyroid-stimulating hormone
Stimulates the thyroid
What would you expect to happen to a cell in a hypertonic solution?
The cell would shrivel as water leaves it]
Chaparral
The chaparral biome is characterized by highly seasonal precipitation, with rainy winters and dry summers. The scattered vegetation in this biome consists primarily of shrubs, grasses, and herbs. Animals include deer and goats. The chaparral biome is found along the California coastline, and many California fires happen here.
During the mammalian fertilization process, what component of the oocyte is responsible for the binding of the sperm? A. Vitelline membrane B. Centriole C. Zona pellucida D. Progesterone E. The uterine wall
The correct answer is [C]. Vitelline is a similar component in the egg cells of sea urchins, and is responsible for much of the same function. Progesterone plays a role in leading the sperm to the egg, but not in the binding. The zona pellucida is the outer layer of the egg that is responsible for the initial binding of the sperm to the egg. The ZP3 protein is responsible for the species-specific binding of the sperm to the egg, but is more important for helping galactosyltransferase (GaIT) activate the acrosome reaction. Without it, the sperm will not be able to bind to the egg.
Deciduous Forest
The deciduous forest biome is characterized by cold (but not particularly harsh) winters, warm summers, and moderate levels of precipitation. It has deciduous trees that shed their leaves during the winter, not coniferous trees; Due to the shedding of leaves, the soil in deciduous forests is rich. This biome is characterized by vertical stratification (plants and animals live on the ground, in low branches, and high in treetops).
Female Hormonal Cycle
The female hormonal cycle begins in the hypothalamus, which monitors the amount of estrogen and progesterone in the blood. If there is a low amount of these hormones, the hypothalamus will secrete GnRH, which stimulates the anterior pituitary to secrete FSH (follicle stimulating hormone) and LH (luteinizing hormone). FSH will stimulate the development of the follicle and oocyte, and the follicle will secrete estrogen. Positive feedback from estrogen will cause a surge of LH, which will cause ovulation. The follicle now becomes a corpus luteum and develops from the help of LH, and will secrete both estrogen and progesterone. High levels of estrogen and progesterone will thicken the endometrium in the uterus for implantation of a fertilized egg. However, the high levels of estrogen will cause the hypothalamus to stop producing GnRH, which will stop the anterior pituitary from releasing FSH and LH. Now, if the corpus luteum is unfertilized, then it will deteriorate, as the body is no longer supporting it, and menstruation occurs. If the egg is fertilized, it will implant into the endometrium and produce HCG (human chorionic gonadotropin) to support the corpus luteum, which will continue to secrete estrogen and progesterone to maintain the endometrium, and pregnancy will continue.
A color blind man without hemophilia (both X-linked traits) marries a woman who is a carrier for both traits. What is the probability they will have a son with both color blindness and hemophilia? Hemophilia and color blindness are unlinked genes. A. 1/1 B. 1/16 C. 1/8 D. 1/4 E. 3/16
The man's genotype is XcY and the woman's genotype is XcX / XhX. The traits of hemophilia and color blindness are unlinked, meaning they are on either different X chromosomes or far enough apart on the same X chromosome so that they assort independently. In this case, since the mother can only donate one X chromosome (since the father will donate his Y chromosome for a male child), the genes must be far enough apart on the same X chromosome so that they assort independently, and are thus unlinked. We want three things to happen, the man must donate the Y chromosome (1/2 probability), the woman must donate Xh (1/2 probability), and she must also donate Xc (1/2 probability). We just multiply these chances together to find (1/2)(1/2)(1/2) = 1/8.
Savanna
The savanna biome is characterized by warm temperature year-round, with some small seasonal variation. There is very little precipitation in terms of rainfall, and the dry season can last many months each year. Fires are common during the dry season. Plants in this biome consist of grasses and scattered trees with small leaves. Animals in this biome consist primarily of large plant-eating mammals (e.g. zebras) and their predators (e.g. hyenas).
If a cell homogenate is spun in a centrifuge, the homogenate is fractionated into parts based on relative differences in: I. mass II. density III. shape
The sedimentation rate of a particle in a centrifuge tube will increase as the object increases in mass and density and as the shape becomes more compact. Therefore, all three of these features in the answer choice influence how a cell lysate is separated in centrifugation.
The tundra
The tundra biome is characterized by cold winters (to the point that the top layer of soil freezes). In the summer, the top layer thaws, but deeper soil (permafrost) remains frozen year-round. The summers are still relatively cold (generally average less than 50° F), and there is very little precipitation or vegetation; Plants in this biome consist of shrubs, grasses, mosses, and lichens (permafrost restricts the growth of plant roots). Animals in this biome include musk oxen, caribou, arctic hares, and arctic foxes.
Fungi often grow alongside plant roots and receive some products of photosynthesis. In return, the fungus grows to retrieve nutrients from the soil and returns them to the plant. This is an example of: A. Commensalism B. Parasitism C. Amensalism D. Mutualism E. Selection
This is an example of mutualism because both the fungus and the plant benefit. The fungus gets products of photosynthesis so it does not need to find an energy source, and the plant gets necessary nutrients such as phosphorous and nitrogen. This is called a mycorrhizal interaction and is extremely important for the majority of plants today.
Proto-oncogenes
are the genes that regulate growth function within the cell. A proto-oncogene is the noncancerous version of the gene that has a regular and an important role within the cell. Proto-oncogenes affect different processes such as cell growth and differentiation - but if these processes go awry, this will lead to cancer. Proto-oncogene → mutation → oncogene
Hardy Weinberg Equilibrum No selection No mutation Large population
p+q=1 p2 + 2pq + q2=1 P(dominant allele) Q(recessive allele)
During cellular respiration, does the pH of the intermembrane space become higher or lower?
pH becomes lower, due to the build-up of H+]
