DAT Biology

Lab techniques: Polymerase chain reaction

- biotechnology process that can quickly and automatically create millions of copies of DNA with no cells required

Lab techniques Enzyme-linked immunosorbent assay (ELISA)

used to determine if a specific antigen exists in a person

lab techniques: Fluorescence recovery after photobleaching (FRAP)

used to see how and where biomolecules are moving in a live cell gives quantitive insight into cell dynamics

Lab Techniques: Scanning electron microscopy

captures electrons that are scattered by atoms found on surface of dehydrated samples - visualizes high resolution 3D images of the sample surface

Glycolysis happens in the

cytoplasm

All of the following labels can be used to describe the AB (+) blood type EXCEPT one. Which one is the EXCEPTION? A. Heterozygous B. Hemizygous C. Codominant D. Universal acceptor E. No blood type antibodies

B. Hemizygous Erythrocytes have antigens on their surface. These antigens are little sugars and proteins that 'mark' our blood cells as a certain type. There are four main blood groups based on the erythrocyte's antigens: Type A blood - has A antigen Type B blood - has B antigen Type AB blood - has both A and B antigens Type O blood - has neither A nor B antigen. ABO blood typing is a classic example of codominance. They do not mask each other's effects. AB contribute to a heterozygous genotype and are codominant. Hemizygous individuals only have 1 copy of an allele instead of 2.

Which germ layer produces the notochord? A. Ectoderm B. Mesoderm C. Endoderm D. Epiderm E. Hypoderm

B. Mesoderm Ectoderm: epidermis of skin, hair, nails, neural tube, lens of eye, enamel of teeth, NERVOUS SYSTEM, jaws, bones of face, etc Mesoderm: dermis of skin, muscle, skeleton, circulatory system, gonads, kidneys, respiratory tracts, notochord Endoderm: lining of digestive and layer of respiratory tracts, liver, pancreas Epiderm: avascular layers of the skin (from outmost inward: stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale) Hypoderm: subcutaneous layer for fat storage and heat insulation

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.

Brackish water means a mix between salt and fresh water which would be found in an estuary. A mangrove swamp often grows near an estuary. Some marshes can be brackish but D specifically stated that the marsh was freshwater.

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 Ectoderm: epidermis of skin, hair, nails, nervous system, lens of eye, enamel of teeth Mesoderm: dermis of skin, muscle, skeleton, circulatory system, gonads, kidneys, respiratory tracts, notocord Endoderm: lining of digestive and layer of respiratory tracts, liver, pancreas

What part of the mitochondrion does the arrow point to, and which process occurs here?

Mitochondrial matrix does citric acid cycle or Krebs cycle. It is also the site of pyruvate decarboxylation and the breakdown of fatty acids via beta oxidation.

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 A or a = 2 B or b = 2 C or c = 2 2*2*2 = 8 2 alleles and 3 genes = 2^3 = 8

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

C. 1/8

H+ accumulates in

the intermembrane space

Which biome is characterized as the largest terrestrial 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. Taiga 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.

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. white matter of the brain. Oligodendrocytes are responsible for laying down the myelin sheath surrounding neurons in the CNS. Schwann cells perform the same function in the peripheral nervous system. They are both types of glial cells.

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

D. Cut up the DNA at specific 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. Key Takeaways: Restriction enzymes are used to cut DNA at specific sites for the purpose of recombinant engineering. EcoR1 is an example of a restriction enzyme that is often used.

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 Fats store the most amount of energy in the body. They store double the amount of carbohydrates (starch, cellulose, glycogen) gram for gram. Our body prefers to burn glucose because it is more readily available and easier to use. Fat>Starch=Glycogen=Glucose=Polypeptides

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

Osmoregulation 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.

Polytomy in a phylogenetic tree

Polytomy/multifurcation is if it is linked to 3+ branches

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.

In response to being startled, an animal involuntarily contracts a skeletal muscle, causing it to shorten. What process is described by an animal's ability to involuntarily contract a skeletal muscle without receiving a direct signal from the brain, and which type of muscle contraction occurred as a result? A. Reflex Arc; eccentric B. Reflex Arc; concentric C. Refraction; isometric D. Redirection; isotonic E. Reflection; isokinetic

B. Reflex Arc; concentric A reflex arc is a motor movement by the spinal cord not the brain. Refraction is the bending of light confused with refractory period. Concentric contractions shorten the muscle. Eccentric lengthens the muscle. Isometric indicates no change. Isokinetic contractions categorize muscle length changes at a constant speed. Isotonic contractions describes any contraction that changes muscle length.

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. Silent mutation Silent mutations does not cause changes in the amino acid sequence. Nonsense mutations is when an affective codon is converted into a stop codon; lethal. A missense mutation is when a change in the amino acid codon is made.

In mammals, which of the following structures aides the embryo in the storage of liquid waste? A. Yolk B. Amnion C. Allantois D. Chorionic Villi E. Yolk Sac

C. Allantois The allantois stores wastes, and forms part of the umbilical cord to carry waste away from the embryo and towards the mother's blood vessels. 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 for gas and waste exchange. 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.

A patient complains about abdominal pain. A healthcare worker determines that the discomfort stems from bile not arriving at their small intestine properly. What part of their digestive system may NOT be functioning as intended? A. Common bile duct B. Pancreatic duct C. Common hepatic duct D. Cardiac sphincter E. Pyloric sphincter

A. Common bile duct Bile is a dark-green-to-yellowish-brown colored fluid that aids in the emulsification of lipids in the small intestine. In humans, bile is produced continuously by the liver, and then stored and concentrated in the gallbladder. The liver secretes bile into passages that carry it toward the hepatic duct, which joins with the cystic duct (carrying bile to and from the gallbladder) to form the common bile duct. The common bile duct opens into the small intestine, specifically the duodenum. Therefore, if the common bile duct were not functioning properly, this would disrupt the passage of bile from the gallbladder to the small intestine. DAT Pro-Tip: Bile is not an enzyme; emulsification is a type of mechanical digestion, not enzymatic breakdown.

What is the purpose of SDS (sodium dodecyl sulfate) in protein analysis? A. Denature non-covalent bonds in a protein B. Decrease the surface area of the protein C. Impart a positive charge on the protein D. To cut the protein at specific sequences E. Dye the proteins to track their run

A. Denature non-covalent bonds in a protein Sodium dodecyl sulfate is a strong detergent used in gel electrophoresis to separate proteins based on their electrophoretic mobility. SDS is used to denature and linearize proteins and to impart a negative charge to the proteins. Key Takeaways: The SDS-PAGE(polyacrylamide gel electrophoresis) is used to separate proteins on the basis of size (molecular weight). Smaller proteins will travel further than large proteins from the negative cathode to the positive anode. SDS (sodium dodecyl sulfate) has three primary effects on protein: Denatures the protein Linearizes the protein Adds negative charge to the protein

Which of the following lack a true coelom? A. Flatworms B. Annelids C. Echinoderms D. Chordates E. Mollusks

A. Flatworms from the phylum platyhelminthes 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. Key Takeaways: Acoelomates: Platyhelminthes Pseudocoelomates: Nematodes, Rotifers Coelomates: Annelids, Mollusks, Arthropods, Echinoderms, Chordates

Which part of the brain monitors the body's temperature? A. Hypothalamus B. Pons C. Medulla D. Cerebral cortex E. Cerebellum

A. Hypothalamus - controls the body's temperature, hunger, thirst, sleep, and circadian cycles -links the nervous system to the endocrine system through the pituitary gland The pons relays messages from the cerebellum to forebrain and controls sleep and dreaming The medulla oblongata maintains heart rate, breathing rate, vomiting, blood pressure Cerebral cortex contains the four lobes of the brain and attributes to higher level thinking The cerebellum is for motor balance and coordination

After the successful implantation of a developing embryo into the uterus, all of the following occur EXCEPT one. Which one is the EXCEPTION? A. Increase in follicle stimulating hormone (FSH) and luteinizing hormone (LH) B. Increase in human chorionic gonadotropin (HCG) C. Maintained high levels of estrogen D. Maintained high levels of progesterone E. Maintenance of the corpus luteum

A. Increase in follicle stimulating hormone (FSH) and luteinizing hormone (LH) After the successful implantation of a developing embryo, the corpus luteum produces estrogen and progesterone which negatively inhibits GnRH. This causes FSH and LH to decrease, not increase.

The main extracellular buffer system in humans consists of A. amphipathic proteins. B. phosphate. C. sulfate. D. bicarbonate. E. histamines.

D. bicarbonate. The main extracellular buffer is bicarbonate and 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 which will make us breathe more to expel the excess CO2. Phosphate and proteins are used as the main INTRACELLULAR buffer inside cells. Amphiphatic proteins are to buffer things like the phospholipid bilayer. Sulfate does not function as a buffer. Histamines do not have any buffer function. Histamine is produced by mast cells and basophils and functions in inflammatory response where it causes vasodilation, which in turn increases the blood flow and temperature to an affected area that can stimulate white blood cells to kill pathogens. Key Takeaways: Bicarbonate is the main extracellular buffer system in humans that is used to regulate pH through the carbonic anhydrase reaction. The phosphate buffer system is mainly used to regulate intracellular pH.

If 2n = 8, how many chromosomes are present during anaphase? A. 2 B. 4 C. 8 D. 16 E. 32

D. 16 Before anaphase, the DNA in a cell has duplicated and condensed, given us 2 chromatids per chromosome. During anaphase, the chromatids split and migrate towards opposites sides of the cell. Because of this, the number of chromosomes during anaphase doubles from the usual count therefore, 16.

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. All cells contain a nucleus for the storage of genetic material. All cells have DNA but not all cells have a membrane bound nucleus. (Eukaryotic cells have nucleus to protect the DNA and prokaryotic cells do not - they have nucleoids.) An organism's activity is dependent on the activity of its independent cells. It states that metabolism and biochemistry occur within cells. Hereditary information is stored in cells and is shared between cells during cell division. And the theory states that all cells in organisms of similar species have similar chemical compositions. Key Takeaways: Cell theory was originally established on the basis of three fundamental statements that you may already be familiar with: All living organisms are composed of one or more cells The cell is the most basic unit of life All cells come from pre-existing, living cells Modern cell theory has expanded on these fundamental statements, and can best be summarized in the following seven statements: All known living things are made up of one or more cells All living cells arise from pre-existing cells by division. The cell is the fundamental unit of structure and function in all living organisms. The activity of an organism depends on the total activity of independent cells. Energy flow (metabolism and biochemistry) occurs within cells. Cells contain DNA which is found specifically in the chromosome; RNA is also found in cells. All cells are basically the same in chemical composition in organisms of similar species

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 An electrochemical gradient is where an electrochemical imbalance exists between a membrane. Flagella use proton spin and give locomotion to bacteria. Mitochondria use a proton force in ATP synthesis as well as chloroplasts where they also produce NADPH. Neurons use Na+/K+ ATPase to create a gradient. Aquaporins are protein structures in the membrane that help water passively flow into or out of the cell known as facilitated diffusion. It uses a concentration gradient, not electrochemical.

Where is ADH stored in the body? A. Thyroid B. Pancreas C. Pineal gland D. Posterior pituitary E. Anterior pituitary

D. Posterior pituitary ADH is produced in the hypothalamus and the posterior pituitary stores oxytocin and ADH (vasopressin). The pineal gland produces melatonin to regulate sleep patterns. The anterior pituitary produces the following FLAT --> FSH, LH, ACTH, TSH.

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 cytosol and the nucleus. Which of the following is most likely the biomolecule the researcher extracted? A. Glycogen B. Actin C. DNA D. RNA E. Cholesterol

D. RNA Glycogen does not contain any nitrogen and is not found in the nucleus. Actin is found in the nucleus and the cytoplasm however it does contain sulfur as an amino acid. Actin is found in microfilaments which play important roles in skeletal muscle contraction, the cleavage furrow, and structures of psuedopods. DNA has a lot of nitrogen but no sulfur and is not present in the cytosol. RNA has a lot of nitrogen, no sulfur, and is in the nucleus and cytosol. Cholesterol does not have any nitrogen.

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

In meiosis II, the individual chromosomes line up on the metaphase plate and are separated by spindle fibers. Each resulting cell should have one of each chromosome. 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 chromosome. This aneuploid gamete will then be fertilized, producing an aneuploid zygote. Disomic is interchangeable with diploid.

A scientist wants to identify a specific DNA sequence from the cells of a lab mouse. Which set of procedures should be performed in order from left to right? A. PCR, Southern blot, FRAP B. Flow cytometry, gel electrophoresis, DNA microarray C. Homogenization, centrifugation, Southern blot D. Electroporation, ELISA, Northern blot E. SEM, Western blot, DNA fingerprinting

In order to identify a specific DNA sequence from the cells of a lab mouse you would need to split open the cells, separate the components, and isolate the DNA. The first step describes homogenization and centrifugation. In differential centrifugation, cells are first split open so that the components can be separated. This process is called homogenization and it is accomplished by the shear forces of a lab blender. The homogenate is the mixture of the split open cells produced by homogenization. When it is centrifuged, the nucleus pellets first because it is most dense, the rest is the supernatant. Next, you do southern blotting which is a technique to IDENTIFY FRAGMENTS OF A KNOWN DNA SEQUENCE IN A LARGE POPULATION OF DNA.

Which layer of tissue 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

The subcutaneous layer contains a network of fat cells and collagen. It is the deepest layer and the fat cells help insulate the body and act as a shock absorber to protect it from minor damage. The top-most layer 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. Epidermis - barrier against pathogens and environmental dangers Dermis - flexible connective tissue - has sensory cells and responsible for supplying nutrients to the epidermis - it can absorb shock but not insulate Endodermis - not a layer for humans but for plants. The endodermis regulates flow of water and nutrients through the symplastic pathway. Subcutaneous layer/hypodermis - insulation and shock absorption and has adipose fatty tissue.

Lab techniques: DNA fingerprinting

identifies individuals through aspects of unique DNA (ex: short tandem repeats)

Adaptive radiation

many new species arise from a single ancestor as they adapt to their respective environments

Lab Techniques: Flow cytometry

method of cell counting cells pass through narrow tube and are counted via detection by laser beam

Lab technique: Electroporation

process where electricity is applied to cells to induce competency which allows transformation to occur

Strepcoccus shape

sphere chains

Lab techniques: Differential Centrifugation

splits open cells so that the components can be separated through homogenization The homogenate is centrifuged over and over to gradually fractionate the cell components

The citric acid cycle occurs in

the mitochondrial matrix

pyruvate decarboxylation occurs in

the mitochondrial matrix

The electron transport chain is in the

inner mitochondrial membrane

Lab technique: Gel electrophoresis

applies electric field to agarose gel and separates fragments by charge and size

Lab techniques: DNA microarray

chip containing thousands of DNA probes that are complementary to a certain gene sequence

Evolution in chordates

1. Notochord first seen in lancelets 2. Head first seen in hagfish 3. Vertebrae column saw in jawless fish (lampreys) 4. Jaw and mineralized skeleton (sharks) 5. Lung derivatives (ray-finned fish) 6. Lobed fins 7. Limbs with digits (amphibians) 8. Amniotic eggs (reptiles) 9. Production of milk (mammals)

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. Change the salt concentrations. Peripheral membrane proteins are held in place by hydrogen bonding and electrostatic interactions and are hydrophilic. Changing the salt concentration or the pH would disrupt both of these bonds. A light centrifuge will disrupt the cell membrane and cause it to break apart and fragment the membrane itself. Centrifuging is often used to break apart cells to separate their organelles on size and shape. Adding a detergent is a method used to extract integral proteins because they are more hydrophobic. Changing the temperature will denature the protein. Running a current isn't a common or viable method.

By which mechanism can some DNA sequences change their position within the genome? A. Transposons duplicating and inserting themselves B. Merging of Okazaki fragments during DNA replication C. Nondisjunction during cell division D. Colocalization between enhancers and silencers E. Transcription factors binding to and moving DNA sequences

A. Transposons duplicating and inserting themselves Transposons are also known as jumping genes and are DNA sequences found in prokaryotes and eukaryotes that can move to different places in the genome. They can cause mutations and make up a significant portion of organism's genome (mostly in eukaryotes) They use a cut and paste method to change their position which requires the presence of a transposase enzyme (acts as scissors) During replicative transposition the transposon is duplicated so that the transposing entity is a copy of the original transposon. During DNA replication, the lagging strand of DNA is synthesized discontinuously therefore the lagging strand is synthesized in short pieces called Okazaki fragments. These fragments are glued together by DNA ligase - ligation does not alter the position of DNA sequences within the genome. Nondisjunction is the failure of 1 or more chromosome pairs to separate properly during anaphase. It does not alter the position of DNA but rather produces daughter cells with the incorrect # of chromosomes. Colocalization between enhancers and silencers (these sites are where transcription factors can bind to.) The DNA loops around so the enhancer or silencer can colocalize with RNA polymerase. This process does not change the position of the DNA sequence within the genome. Transcription factors are regulatory proteins that control transcription rates by binding to enhancer or promoter regions of DNA. They do not involve moving DNA sequences. They have these mechanisms: Stabilizing or blocking the binding of RNA polymerase to DNA Catalyzing the acetylation or deacetylation of histones Recruiting coactivators or corepressors to the transcription factor DNA complex

During embryonic development, a hollow sphere of cells is called a A. blastula. B. morula. C. chorion. D. yolk sac. E. gastrula.

A. blastula. 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 (ectoderm, mesoderm, 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.

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 Allopatric speciation is when a geographic barrier separates a population. Sympatric speciation is when a population forms a new species without a geographical barrier. Disruptive selection is when the extremes are favored for a trait. Adaptive radiation is when there is a rapid diversification of new organisms. Natural speciation is evolution occurring over time.

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. Key Takeaways: Note that calcium binding to troponin is necessary for exposure of the binding sites on actin filaments, which in turn allows binding of the myosin heads. The cross-bridge cycle of contraction is crucial for muscle contraction and movement.

An organism exhibits regulative cleavage. What would occur after the separation of this organism's embryo at the two-cell stage into two distinct masses? A. Formation of dizygotic twins. B. Development of two viable embryos. C. Death of the embryo. D. Development of animals and vegetal poles. E. Initiation of meroblastic cleavage.

B. Development of two viable embryos. Regulative cleavage is the ability of an embryo to overcome a disturbance such as being separated into two cell masses. This ability is what allows mammals to have viability of monozygotic twins. Organisms that don't have regulative cleavage are said to have mosaic development. When an embryo is separated at the 2-cell stage monozygotic twins result. This does not lead to the death of the embryo and instead leads to two viable embryos. Dizygotic twins are fraternal in this case the mother ovulates two eggs and both eggs are individual fertilized by two different sperms (two genetic different material) Holoblastic and meroblastic cleavage is how the embryo divides. Holoblastic occurs when the entire embryo evenly divides the entire embryo into distinct cells (blastomeres.) It is typical of eggs that contain little yolk - sea urchins/humans. Meroblastic cleavage happens in embryos with a lot of yolk such as birds and describes uneven division. In meroblastic cleavage an animal pole (rapid division) and vegetal pole (negligible division) form within the embryo. Since this is regulative cleavage we would not expect meroblastic cleavage nor animal/vegetal poles.

How do enzyme kinetics change in the presence of a competitive inhibitor? A. KM increases, Vmax increases B. KM increases, Vmax stays the same C. KM decreases, Vmax increases D. KM decreases, Vmax stays the same E. KM decreases, Vmax decreases

B. KM increases, Vmax stays the same Competitive inhibition is a form of enzyme regulation, where inhibitors compete with substrates for active sites. As we increase the amount of substrate, there is a higher chance the substrate can bind to the active site. This is why we can outcompete a competitive inhibitor by adding more substrate. The KM (michaelis constant) is the substrate concentration at which the velocity of a reaction is 50% of the maximum reaction velocity (Vmax) As we add more substrate (added competitive inhibitor) the probability that a substrate will occupy the active site over an inhibitor increases so Km increases. V max stays the same. Note: In competitive inhibition, adding more substrate will increase the speed of catalysis until all active sites are occupied. As saturation begins to occur, adding more substrate will have diminishing returns in increasing the speed; this is when a plateau starts to occur.

All of the following diseases may result from nondisjunction during meiosis EXCEPT one. Which one is the EXCEPTION? A. Down syndrome B. Kartagener's syndrome C. Turner syndrome D. Klinefelter syndrome E. Trisomy X

B. Kartagener's syndrome Down syndrome: trisomy (extra copy of chromosome) at chromosome 21 Klinefelter's: sex chromosome in males Triple X: trisomy X, X chromosome trisomy that affects females Turner syndrome: X chromosome monosomy Kartagener's syndrome: autosomal recessive genetic disorder that causes defects in the action of cilia lining the respiratory tract, fallopian tube, and flagellum. It does not result from nondisjunction.

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. tetanus Reflex is not relevant. Activation is not related. A twitch contraction is a short burst of stimulation. Tetanus is the continued state of muscle contraction in which it does not relax. Refraction is the time after an action potential in which a neuron will not respond to a new stimulus. Key Takeaways: During tetanus, muscles remain in a state of constant contraction. Tetanus toxin blocks the release of neurotransmitters from inhibitory neurons; this results in the rapid firing of motor neurons and keeps muscles from being able to relax.

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. A length of cartilage extending along the body, which will become part of the spinal discs. The notochord develops into spinal discs. The spinal cord begins at the dorsal neural tube. Pharyngeal slits are present in all chordates at some point in development. The muscular tail extending behind the anus is known as the post-anal tail. The endostyle is what produces mucus for filter feeders. It also stores iodine and it the pre-cursor for the thyroid gland. The dorsal hollow nerve cord develops into the spinal cord in chordates. The notochord is derived from the mesoderm and defines the primitive axis of the embryo. The post-anal tail is lost during the embryonic development of humans and many other chordates. The endostyle is the groove located in the underside of the pharynx and has mucus to capture food particles. Key takeaways: The dorsal neural tube becomes the spinal cord, while the notochord develops into the spinal discs and spine. 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

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. Allelopathy Allelopathy is a 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 ocurs when competition occurs within the same species which in this case the plant is competing with other species of plants. Interference competition is when individuals are directly prevented from physically establishing themselves in the habitat. Exploitation competition is when 2 predators prey on 1 species. Apparent competition is when 1 predator preys on 2 species. Increase in prey 1 leads to increase in predator which decreases prey 2.

The homeobox of a honeybee embryo's genome is genetically altered. Which of the following might occur as a result? A. Larval organs undergo uncontrollable apoptosis during metamorphosis B. An additional pair of antennae develops at the bee's legs C. An abnormal body axis develops through spiral cleavage D. The notochord fails to induce the formation of the neural tube E. The adult insect only reproduces through parthenogenesisThe homeobox of a honeybee embryo's genome is genetically altered. Which of the following might occur as a result?

B. An additional pair of antennae develops at the bee's legs Homeotic genes act as controllers that decide which part of the embryo develops into what structures. They all contain the 180 nucleotide sequence called a homeobox. Hox genes are a subset of homeobox genes that specify regions of the body plan along the head-tail axis. Metamorphosis is a biological process where an animal physically develops after birth because of an abrupt change in body structure through cell growth and differentiation while certain larval organs undergo apoptosis after metamorphosis (ex: fins in tadpoles) which the homeobox is not responsible for. HOMEODOMAIN PROTEINS DIRECT THE FORMATION OF THE BODY AXES AND BODY STRUCTURES DURING EARLY EMBRYONIC DEVELOPMENT. The homeobox does not regulate the type of cleavage the zygote undergoes. Cleavage is rapid cell division without changing the total mass of cells and is the first step of growth for a zygote. Each small cell from a cleavage is called a blastomere. Spiral cleavage results in misaligned cells from the axis. Deuterostomes undergo radial cleavage and protostomes undergo spiral cleavage. Neuralation marks the beginning of organogenesis where the homeobox is not involved. The embryo at this stage is known as the neurula where the notochord forms a neural plate which folds to form the neural tube. The homeobox does not include the genes that regulate parthenogenesis - which occurs when an unfertilized egg develops into a viable organism. Offspring that arise from unfertilized eggs are haploid male drones in honeybees.

During which step of translation does translocation occur? A. Initiation B. Elongation C. Termination D. Migration E. Extension

B. Elongation Translation is the process of a ribosome reading mRNA and synthesizing a protein. There are 3 steps: 1. 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. 2. elongation: the ribosome continues down the codons of mRNA and moves the tRNAs from entry site to the binding site, then the binding site to the exit site known as translocation. Termination occurs when a stop codon is reached. Migration and extension are distractors.

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

B. Family and Genus Dear King Philip Come Over For Good Soup Domain, kingdom, phylum, class, order, family, genus, species

Which of the following is true of IgG? A. The constant region wraps around the antigen it opsonizes. B. Hydrogen bonding attaches the heavy chains to the light chains. C. Antigen proteins bind to the matching hypervariable regions of the antibody. D. It is unable to activate the complement system. E. It is mainly found in exocrine secretions.

C. Antigen proteins bind to the matching hypervariable regions of the antibody. Antibodies such as immunoglobin IgG consist of a light and heavy chain linked through disulfide bonds. The constant regions have a very similar amino acid coding sequence within a particular class of antibodies. The variable regions bind to different antigens; that is why they have different amino acid sequences. Q: Which of the following is true of IgG? A. The constant region wraps around the antigen it opsonizes. Incorrect. Antibodies are divided into five major classes (IgM, IgA, IgE, IgD, IgG) based on their constant region structure and immune function. The constant region of the antibody determines the mechanism used to destroy the antigen, but it is the variable region that makes direct contact with the antigen. B. Hydrogen bonding attaches the heavy chains to the light chains. Incorrect. Antibodies consist of a light chain and heavy chain linked through disulfide bonds. C. Antigen proteins bind to the matching hypervariable regions of the antibody. Correct. The variable region, more specifically the hypervariable region, of the antibody contains the residues that bind to the corresponding antigen. D. It is unable to activate the complement system. Incorrect. IgG, along with IgM, activates the complement system when it binds antigens. The complement system is part of innate immunity, and consists of ~30 blood plasma proteins that help the immune cells to make the battle against pathogens more effective. E. It is mainly found in exocrine secretions. Incorrect. IgG is the most abundant type of antibody found in blood and extracellular fluid, allowing it to control infection of body tissues.

Which of the following can lead to an increase in cell division? A. A null allele of the p53 gene B. Inhibited cyclin dependent kinase C. Downregulated p21 gene D. Loss-of-function mutations of proto-oncogenes E. Entry to the G0 phase of the cell cycle

C. Downregulated p21 gene Tumor suppressor genes are genes that regulate a cell during cell division and replication. When it is mutated it results in a loss or reduction in function. Loss-of-function mutations in BOTH copies of these genes are required for cancer causing. p21 is a tumor suppressor gene that inhibits cyclin dependent kinase which stimulates cell division. Therefore a downregulation of p21 leads to an increase in cell divsion. p53 is a tumor suppressor gene and it is considered the "guardian of the cell." It is upregulated in response to cell stress. One null allele will not lead to an increase in cell division. Inhibition of CDK leads to a decrease in cell division. P21 inhibits CDK. The downregulation leads to an increase of cell division. Proto-oncogenes are normal genes involved in cell division and regulation. If they experience a gain-of-function mutation, this can cause proto-oncogene to become an oncogene. Oncogenes are genes that can transform a normal cell into a cancerous cell. During the G1 phase of interphase, the cell physically grows in preparation of a future divsion. If in G0 phase it is in a hangout spot where they won't divide.

The image above shows a photomicrograph of a cluster of cells. What type of cell is most likely represented in the image? A. Streptococcus B. Epithelial C. Erythrocyte D. Monocyte E. Myocyte

C. Erythrocyte The cells in the picture lack nuclei and are most likely erythrocytes or red blood cells. Strep - chain coccus - sphere Epithelial - contain a nucleus Monocyte - contain a nucleus and are amoeboid in appearance Myocyte - found in muscle tissue and have nucleus

A grandmother and her granddaughter are the only two members in a family to have a genetically inherited disease. Neither parent of the granddaughter has the disease. The disease is probably inherited as a(n) A. Y-linked dominant disease B. autosomal dominant disease C. autosomal recessive disease D. X-linked dominant disease E. X-linked recessive disease

C. autosomal recessive disease Cannot be Y-linked because does not affect males. It skips a generation so most likely recessive. If the trait was X-linked recessive the granddaughter would inherit at least one normal chromosome from her parents and not be affected.

A student observes a population of 100 eagles in Hardy-Weinberg equilibrium. The eagle's allele for a pointed beak is dominant, and the allele for a rounded beak is homozygous recessive. If 9 eagles were found to have a rounded beak in the population, what is the allele frequency of the pointed beak? A. 0.09 B. 0.30 C. 0.70 D. 0.81 E. 0.91

C. 0.70 pointed peak = p^2 for homozygous dominant 9 eagles display rounded beaks which means they are homozygous recessive for the allele. q^2 gives us homozygous recessive so if 9% is recessive then q=0.3 p+q=1 so p=0.7

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. Epinephrine Cholesterol is made up of 4 rings and is the precursor to many steroid hormones. Aldosterone, testosterone, progesterone (terone) are all steroids derived from cholesterol. Cortisol is also a steroid that is released by the adrenal cortex and involved in stress adaptation. Aldosterone is released from the adrenal cortex and increases reabsorption of Na+ and excretion of K+. Causes blood volume and pressure to rise. Cortisol is a glucocorticoid released from the adrenal cortex and is a stress hormone that raises blood glucose levels. Epinephrine is a catecholamine which are amino-acid derived hormones. They are released from the adrenal medulla and is sometimes referred to as adrenaline. Testosterone is responsible for male secondary sex characteristics and functions in spermatogenesis. Progesterone is produced in the ovaries and functions in the menstrual cycle. Key Takeaway: Cholesterol is the precursor molecule of all the steroid hormones.

In the alternation of generations, what do spores directly give rise to? A. Gametes B. Zygotes C. Gametophyte D. Sporophyte E. Seeds

C. Gametophyte The spores (n) give rise to gametophytes through mitosis, which creates gametes through fusion which creates the zygotes and through mitosis gives up the sporophytes and through meiosis gives us spores.

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. High in O2 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.

Which of the following statements accurately describes cytokinesis in mammals? A. Molecular chaperones pull each cell to opposing ends. B. Vesicles migrate and fuse to form a cell plate. C. Microfilaments encircle the center of the cell and shorten. D. Microtubules pull apart the homologous chromosomes. E. RNA is spliced before it migrates into the cytoplasm.

C. Microfilaments encircle the center of the cell and shorten. Cytokinesis is the last stage of mitosis and begins occurring at the end of anaphase. It is the process of dividing the cytoplasm to form 2 cells. In mammals, a cleavage furrow develops from microfilaments encircling the cell and pulling the plasma membrane into the center. In PLANTS, vesicles from the golgi bodies migrate and fuse to form the cell plate. Microtubules pulling apart the homologous chromosomes refers to anaphase, not cytokinesis.

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. Oocyte The oocyte is the female egg and provides the majority of the cytoplasm in a developing zygote. This means that 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.

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 Pleiotropy occurs when a single gene has multiple phenotypic outcome. In sickle cell disease, a single mutation produces abnormal hemoglobin molecules which results in damage to many organs and also results in several disorders. polygenetic inheritance is when many genes contribute to one phenotypic outcome - like height. Epistasis is when one gene affects the expression of the second gene.

An increase in calcitonin would lead to which of the following? A. Increase calcium concentration in blood B. Decrease calcium reabsorption into bones C. Stimulate osteoblast activity D. Stimulate osteoclast activity E. An increase in muscle contractions

C. Stimulate osteoblast activity Two hormones regulate calcium in the blood: calcitonin (produced by thyroid) & parathyroid hormone (produced by parathyroid) Calcitonin lowers calcium levels in the blood. Increased osteoblast activity comes from an indirect result of decreased osteoclast activity. Increased osteoblast activity builds bones which uses up calcium in the blood. The parathyroid hormone is the opposite where is calcium levels are too low in the blood, osteoclast activity will be stimulated to released calcium from the bones back into the blood.

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

C. Zona pellucida Vitelline is a similar component in the egg cells of sea urchins and is responsible for the same function. Progesterone plays a role in leading sperm to the egg but not in the binding. The zona pellucida is an 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-species binding of the sperm to the egg. The zona pellucida is also responsible for initiating the acrosomal reaction.

Catabolism can be described as a(n) A. isotonic process. B. endergonic process. C. exergonic process. D. endothermic process. E. hypertonic process.

C. exergonic process Catabolism is breaking down of materials into smaller units so there is a release in energy. Anabolism builds up molecules so that is endergonic.

This micrograph was most likely taken with which of the following microscopes? (scale bar = 200 nm) A. Compound Light Microscope B. Stereo Microscope C. Transmission Electron Microscope D. Fluorescence Microscope E. Scanning Electron Microscope

C. transmission electron microscope You can tell it is a TEM because it is a very magnified 2D image of a single bacterial cell. Scanning electron microscopes give us a 3D image. Compound microscopes need images to be dyed with color. Stereo microscopes only offer low magnification to observe the surface. Fluorescence microscope requires bright color. Scanning electron microscope is 3D with high magnification.

Human immunodeficiency virus (HIV) contains reverse transcriptases that promote low-fidelity replication, leading to diverse viral subgroups and major challenges to the development of vaccines. Which of the following mutations most likely contributes to diverse HIV subgroups? A. Silent mutation of viral mRNA B. Silent mutation of viral tRNA C. Missense mutation of host mRNA D. Missense mutation of viral cDNA E. Missense mutation of host tRNA

D. Missense mutation of viral cDNA Point mutations occur when one nucleotide is replaced by a different nucleotide. (A replaced by G). Silent and missense mutations can result from this. In a silent mutation, the change in DNA code results in no change. This is because of the degeneracy of the genetic code. Can also occur because there is less strict base pairing between third base of a codon and anticodon. known as third base wobble. A missense mutation happens when a change in DNA code results in a different amino acid coding. These are non-conservative when the mutated AA doesn ot share the same properties as the unmuted AA. This could result in protein folding incorrectly and function being changed. It is therefore more likely that a missense mutation would contribute to diverse HIV subgroups. Recall that HIV is a retrovirus meaning it stores its genetic material as RNA therefore it infects host cells with RNA. It carries an enzyme called REVERSE TRANSCRIPTASE which allows it to convert RNA INTO CDNA. (cDNA is complementary to RNA it was transcribed from.) HIV cDNA integrates into the host's DNA, which begins the lysogenic cycle. This is beneficial to the virus because its genetic material will be replicated whenever the host's DNA is replicated. Thus, we can conclude that a high mutation rate in HIV cDNA leads to diverse viral subgroups.

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. Jawless fish -> Cartilaginous fish -> Lobe-finned fish The first fish to evolve did not have jaws and looked like eels. Then cartilaginous fish evolved. Then lobe-finned fish from which terrestrial organisms developed.

An otherwise healthy mother who consumes insufficient dietary calcium has three offspring that all produce insufficient insulin. What is the most likely connection? A. There is an epistatic link. B. There is no link between the two events, it was random. C. Both effects are due to a common pleiotropic allele. D. There is an epigenetic link. E. There is a polygenic link.

D. There is an epigenetic link. All 3 offspring produce insufficient insulin suggesting a high hereditary connection. In addition, the mother is otherwise healthy so it can be reasoned that she does not suffer from type 1 diabetes herself but that it is related to her nutritional deficiency. Environmental factors such as diet are not capable of altering the DNA sequence. The mechanisms that allow the genome to interact with environmental factors are called epigenetic changes and can be passed down. Epistatis is the interaction between different genes where one gene can affect expression of another. Pleiotropy occurs when one gene affects many different traits. Polygenic inheritance occurs when multiple genes interact to influence one trait with continuous variation.

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. Facilitated Diffusion The 3 different methods for particles to get through the cell membrane: Simple diffusion: only small and uncharged particles can move through the phospholipid bilayer Facilitated diffusion: particles can cross the membrane with the help of integral proteins example: aquaporins Active transport: particles are pumped or forced across the membrane against their concentration gradient - requires ATP/energy Saltatory conduction: an action potential of a neuron jumping along the axon - describes transmission of A.P down an axon and not simple particles across a membrane Osmosis: simple diffusion of water which does not require channel proteins

There are many shared traits between fungi and the other three eukaryotic 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. Fungi cell walls are made of glucans and chitin. Bioluminescence is found among plants and animals. Plants can undergo alternation of generations. Plants also have chloroplasts, cell walls, and use different means of reproduction to produce spores. Animals are heterotrophic, lack chloroplasts, and are reliant on organic compounds for energy. Plant cell walls are known to contain glucans and some animals are made from chitin exoskeletans. Fungi are the only organism to use both.

Which of the following is true about the temporal isolation of carbon in CAM photosynthesis? A. The light dependent reactions occur at night B. Malate is transferred to bundle sheath cells C. Oxaloacetate is stored in the Golgi apparatus D. Involves the fixation of carbon dioxide into acetyl-CoA E. RuBP carboxylase is active during the day

E. RuBP carboxylase is active during the day Recall that photorespiration occurs when RuBisCo binds oxygen, even though it has much higher affinity for carbon dioxide. When this happens, RuBisCo will oxygenate RuBP and derail the Calvin cycle. To prevent photorespiration, a small percentage of plants undergo CAM photosynthesis. CAM plants utilize temporal isolation, meaning that they do different processes at different times. During the day, CAM plants close their stomata to prevent transpiration. At night, CAM plants open their stomata, allowing carbon dioxide to enter the leaf. In this way, CAM photosynthesis minimizes water loss and photorespiration in extremely hot and dry environments, like a desert. In CAM photosynthesis, during the day, inorganic carbon dioxide and PEP are released from oxaloacetate (step #6 below). The carbon dioxide will be fixed through the usual Calvin cycle, meaning that RuBP carboxylase will be active. Choice [E] is the answer. A. The light dependent reactions occur at night Incorrect. Light dependent reactions occur during the day in plants. B. Malate is transferred to bundle sheath cells Incorrect. This is a characteristic of spatial isolation in plants that perform C4 photosynthesis. This process involves the fixation of inorganic carbon into PEP using the enzyme PEP carboxylase. This produces oxaloacetate, which converts to malate. The malate is then transferred from the mesophyll cells (where the PEP carboxylase reaction occurred) to the bundle sheath cells. C. Oxaloacetate is stored in the Golgi apparatus Incorrect. In CAM photosynthesis, during the night, oxaloacetate converts to malate, which is stored in the vacuole of the mesophyll cell. D. Involves the fixation of carbon dioxide into acetyl-CoA Incorrect. In CAM photosynthesis, PEP carboxylase fixes inorganic carbon dioxide into PEP. This produces oxaloacetate, which converts to malate. Recall that acetyl-CoA is formed during aerobic cellular respiration, specifically during the pyruvate manipulations that occur after glycolysis. Acetyl-CoA goes on to join oxaloacetate to form citrate during the Krebs cycle.

A scientist wishes to create bacterial colonies on an agar plate for observation of growth. Unfortunately, directly adding bacteria from the original culture results in too many bacterial colonies to count. In order to create a solution of proper bacterial concentration for observation, the scientist performs a three-step 1:100 serial dilution of the original bacterial culture. What is the dilution factor of the final solution? A. 10^-9 B. 10^-3 C. 3.0 D. 10^3 E. 10^6

E. 10^6 Since 1:100 dilution , every dilution was multiplied by 10^-2. 3 dilutions = 10^-6. Then we flip to get our answer for the dilution factor. If it was just the concentration it would be 10^-6. Key Takeaways: A dilution factor is the factor by which a solution is diluted. In laboratory settings, dilution factors are usually done in factors of 10 or 100. In the above problem, three consecutive serial dilutions of 1:100 results in a dilution factor of 106

To confirm the genetic similarity or difference between organisms, which of the following biotechnology processes should be used? A. Vectors B. Cloning C. Phrenology D. Cladogram E. Gel Electrophoresis

E. Gel Electrophoresis Vectors are common biological tools used to transform, or insert, DNA for subsequent replication or gene expression. Cloning refers to the duplication of DNA or an entire organism, which does not serve as a genetic comparison. Phrenology, or the study of the contours of the brain, is not related to this question. A cladogram is a way to determine if organisms are related but not on a molecular or gene level. Often cladograms will categorize organisms based on their phenotypes and/or physical appearance. In addition, a cladogram does not provide enough information to determine how different organisms are from each other. Gel electrophoresis is a biotechnology process that allows for the separation of DNA, RNA, or proteins on the basis of size and charge (shorter molecules move further). The banding patterns that result after running the gel electrophoresis on DNA can be used to determine the genetic similarity or differences of organisms. Smaller segments travel further through the gel. Each organism produces a unique banding pattern on the gel that can be used for comparison with the banding patterns of other organisms to determine genetic similarity or difference.

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. Men carry no genes for color blindness on their Y chromosome. 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.

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. Muscle cells Our muscles are made of long chains of cytoskeleton comprised of actin and myosin. Actin is a microfilament while myosin is a motor protein. If actin degenerates then our muscles would not contract. The spindle fibers radiating from the centrioles are MICROTUBULES. A lysosome is an organelle that is involved in phagocytosis. It is produced from the golgi and contain digestive enzymes to break down nutrients, cell debris, and bacteria and do not rely on microfilaments. In plants, the central vacuole carries out lysosome functions. The ECM 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. Nucleic acids The experiment used ammonia, methane, water, and hydrogen sealed in sterile tubes and flasks with connecting loops to stimulate lightning in early earth. They observed several organic compounds, amino acids, and their base starting materials but no nucleic acids. Several organic compounds were found in the collected sample, including amino acids, hydrocarbons, formaldehyde, and hydrogen cyanide. The Miller-Urey experiment was designed to test the "organic soup theory" originally put forward by Oparin & Haldane. Oparin and Haldane put forth the theory that the origin of the Earth's environment was a reducing environment (without O2), allowing for the formation of complex organic molecules from simpler ones. The energy for the synthesis of these molecules came from UV light, lightning, heat, and radiation present in the early atmosphere.

An animal cell was lysed, placed in a test tube, and centrifuged. Which organelle would pellet from the centrifuge first? A. Ribosome B. Lysosome C. Mitochondria D. Golgi complex E. Nucleus

E. Nucleus During a centrifuge, the nucleus is the largest and pellets first and is most dense. The ribosome would expected to pellet out last due to small density and size. Lysosome would not be expected to centrifuge after nucleus but before ribosome. The mitochondria would expect to pellet out after nucleus but before ribosome. Same with golgicomplex.

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. O2, NADPH, and ATP Light dependent reaction: Reactants: H2O, light, ADP, NADP+ Products: O2, ATP, NADPH Light independent reaction (Calvin Cycle): Reactants: CO2+ATP+NADPH Products: Glucose, ADP, NADP+

What is the original source of energy used to drive the light independent reactions of photosynthesis? A. Substrate level phosphorylation B. The breakdown of glucose C. Photolysis of water to release electrons D. ATP produced by mitochondria E. Photons absorbed by chlorophyll

E. Photons absorbed by chlorophyll The energy used to drive photosynthesis comes from light, or photons. The light independent reactions takes energy produced in the light dependent reactions along with CO2 to produce glucose. Substrate level phosphorylation is related to glycolysis or breaking down of glucose. Photosynthesis is meant to produce glucose not to break it down. The energy used in the photolysis of water comes from light as well. Key Takeaways: The energy that is used to drive the light-independent reactions of photosynthesis is obtained from photons being absorbed by chlorophyll. This energy is able to be used to make ATP, a energy storage molecule that should be familiar to you.

All of the following phyla have a complete digestive system EXCEPT for one. Which of the following is the EXCEPTION? A. Arthropoda B. Annelida C. Mollusca D. Echinodermata E. Platyhelminthes

E. Platyhelminthes Arthopoda have a complete digestive system; they are triploblasts with bilateral symmetry and are coelomates. (ex: spiders and scorpions) Annelida have a complete digestive system and are also triploblasts with bilateral symmetry, and are coelomates with segmented bodies and closed circulatory systems. (ex: earthworms and leeches) Mollusca have a complete digestive system; therefore the answer choice is incorrect. They are triploblasts with bilateral symmetry, and are coelomates with open circulatory systems (with exception to cephalopods, which have closed circulatory systems). The tongue of this class is referred to as a radula. Examples of Mollusca include clams, snails, squids, and octopuses. Echinodermata have a complete digestive system; therefore the answer choice is incorrect. They are triploblasts with radial symmetry as adults), and are coelomates with open circulatory systems. They are deuterostomes (like Chordata). Examples of Echinodermata include starfish, sea urchins, and sea cucumbers. 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.

Glycolysis is best described as what type of process? A. Exergonic B. Endergonic C. Isotonic D. Hypertonic E. Hypotonic

Glycolysis requires the use of energy when the glucose molecule is broken into two pyruvates. The two steps in which ATP is used up can be considered endergonic however overall glycolysis releases energy to be stored back into more ATP and consumed by the cell therefore the reaction is exergonic. It is the metabolic breakdown of glucose accompanied by a release of energy used to power the cell. Net products of glycolysis = 2 ATP, 2 NADH, and 2 pyruvate The pyruvate molecules can either enter aerobic cellular respiration if O2 is present or fermentation if no O2 is present. it is usually anabolism (building up molecules from smaller units) that is endergonic. An isotonic process does not exist - refers to the tonicity of solutions (the cell has a solute concentration equal to the surrounding solution) or muscle contractions (where the muscle shortens as it contracts in contrast to an isometric contraction where the muscle contracts but does not shorten) neither is relevant to glycolysis. Hypertonic process does not exist - if a cell is in a hypertonic solution, the surrounding solution has a higher solute concentration than inside of the cell. Does not pertain to glycolysis. Hypotonic processes do not exist it is when the surrounding solution has a lower solute concentration than inside the cell and does not pertain to glycolysis.

Lab techniques: Southern blotting Northern blotting Western blotting

Southern: used to identify fragments of a known DNA sequence in a large population of DNA using DNA probes Northern: same as southern blotting, except this technique identifies fragments of a known RNA sequence using RNA probes Western: similar to Southern/Northern blotting except quantifies the amount of target protein in a sample using SDS PAGE SNOW DROP

A basketball player suffers a severe tear in his Achilles tendon. Which of the following will occur at the site of injury? A. A weaker connection between two bones B. Recovery mainly features secretions from fibroblasts C. Neutrophils release histamine at the injury site D. Swelling occurs due to accumulation of synovial fluid E. Erythrocytes travel to the site of injury through diapedesis

The achilles tendon is in the back of the lower leg. In case of injury, the tendon repair process involves the recruitment of inflammatory cells and fibroblasts from outside the tendon tissue to the injury site. The fibroblasts synthesize extracellular matrix and collagen and play a critical role in adhesion formation and wound healing. Tendons connect muscle to bone, while ligaments connect bones to other bones. A tear in the Achilles tendon results in a weaker connection between muscle and bone. If the Achilles tendon is torn, inflammatory cells migrate to the injury site. However, neutrophils are a type of leukocyte that phagocytize and destroy pathogens; they do not release histamine. Mast cells are another type of leukocyte that are responsible for rally signaling. When there is an injury, the injured tissue and mast cells work together to release histamine, which functions to dilate capillaries and make capillaries more permeable. In the case of injury, an increase in synovial fluid would not occur. Swelling would result from the action of inflammatory cells. When there is an injury, the injured tissue and mast cells work together to release histamine, which functions to dilate capillaries and make capillaries more permeable. This allows immune cells (ex. neutrophils, lymphocytes, monocytes) to rush to the site of injury and begin the battle against pathogens. The process of cells moving from capillaries to tissues is called diapedesis. Erythrocytes do not undergo diapedesis.

Which of the following is true about embryonic development in frogs? A. It undergoes radial, meroblastic cleavage B. Primitive streak is absent during gastrulation C. The dorsal lip develops into the dorsal hollow nerve cord D. The blastopore gives rise to the mouth E. The grey crescent forms at the location of sperm entry

The inner cell mass (ICM) of a blastocyst differentiates into two different layers: the hypoblast and epiblast. The hypoblast: partially contributes to the yolk sac and the epiblast contributes to the main embryo. Epiblast cells thicken to form a structure called the primitive streak which defines the axis for a developing embryo. It is crucial to begin the process of gastrulation which is the formation of a trilaminar embryo. Frog embryos do not have a primitive streak. They have a grey crescent that appears at the opposite end of sperm entry. Because the primitive streak is absent gastrulation begins at the dorsal lip in frog embryos. Another structure called the dorsal lip of the blastopore forms at the gray cresent. Frog embryos undergo radial holoblastic cleavage which occurs in embryos without a lot of yolk. But frogs are an exception as they have a lot of yolk and undergo holoblastic cleavage. Because they do not have a primitive streak, gastrulation begins at the dorsal lip of the blastopore. The dorsal lip is mesodermal tissue that later becomes the notocord. The blastopore becomes the anus in deuterostomes and the mouth in protostomes. Deuterostomes include chordates and echinoderms, protostomes are primitive invertebrates.

This table displays the number of single nucleotide differences between 5 different species. Which cladogram best represents their taxonomic relationship?

The less the nucleotide the closer they are.

Test your knowledge: What is the name of an enzyme that cuts DNA at specific sequences?

[Answer to Test your knowledge: Restriction endonuclease]

Test your knowledge: during aerobic respiration, which processes produce ATP via substrate level phosphorylation, and which processes use oxidative phosphorylation?

[Answer to Test your knowledge: glycolysis and the Krebs cycle produce ATP via substrate level phosphorylation. The electron transport chain produces ATP via oxidative phosphorylation].