AP Biology Fall Semester Final Exam Review

A mouse skin cells containing 40 chromosomes undergoes mitosis. This process results in the formation of

Two daughter nuclei, each with 40 chromosomes

Which of the following describes the most likely way in which two water molecules will interact?

A hydrogen bond will form between the hydrogen atom of one water molecule and the oxygen atom of the other water molecule.

Which of the following observations could be best explained by water's high surface tension?

A leaf floats on the surface of a puddle.

The tobacco mosaic virus (TMV) is a plant virus that infects a wide range of plants, including tobacco. In order to enter and travel through the cells of a plant, TMV produces a movement protein. This protein helps the virus travel directly between the cytoplasms of interconnected plant cells. Which of the following best predicts how the movement protein modifies plant cells in order to help TMV travel from cell-to-cell?

The movement protein modifies the plasmodesmata between plant cells.

A student uses a microscope to compare a human skeletal muscle cell and a human epithelial cell. The student observes that the muscle cell has more mitochondria than the epithelial cell. Which of the following conclusions is best supported by this observation?

The muscle cell requires more ATP than the epithelial cell.

The diagram above represents a model of a signal transduction pathway in a cell that is targeted by two different ligands,L1 and L2. When L1 binds with membrane receptorR1start subscript, 1, end subscript, the pathway is activated, and CDK activity in the cell increases. Alternatively, when L2 binds with membrane receptor R2, downstream signaling by the pathway is inhibited. Based on the model above, what would most likely result if a mutation prevents the binding of L2 with R2?

The signal transduction pathway would proceed unchecked, resulting in increased cell division.

Cowpox is classified as a DNA virus because its genome, or genetic material, consists of double-stranded DNA. Which of the following claims is best supported by the information above?

Uracil nucleotides are not found in the cowpox genome.

Human immunodeficiency virus (HIV) is classified as an RNA virus because its genome, or genetic material, consists of a single strand of RNA. Which of the following claims is best supported by the information above?

Uracil nucleotides are present in the HIV genome.

Which of the following best describes the role that water plays in the reaction depicted above? (the water is a product and comes out of the reaction)

When water condenses out of the reaction, a dimer is created as a covalent bond forms between two monomers.

In order to develop antibiotics, scientists need to understand how bacteria grow, divide, and spread during an infection. An essential part of bacterial growth is RNA synthesis because RNA must be synthesized before proteins can be assembled. If RNA synthesis is blocked, bacteria will not be able to survive and reproduce. Which of the following questions will best direct an investigation on how an antibiotic that inhibits RNA synthesis in bacteria can be developed?

Which chemical compounds block the 3' end of a growing RNA strand?

Which of the following statements accurately describes an energy-releasing process that is coupled to an energy-requiring process in the cell?

The movement of motor proteins is powered by the formation of ADP and inorganic phosphate from ATP.

The image above depicts the signal transduction pathway of epinephrine. During one step in the pathway, the enzyme glycogen phosphorylase is phosphorylated, which activates the enzyme. If an inhibitor prevents glycogen phosphorylase from being activated during this pathway, which of the following will most likely occur?

Blood glucose level will not increase in response to epinephrine.

Which of the following statements is true for both prokaryotic and eukaryotic cells?

Ribosomes synthesize proteins using mRNA sequences.

To complete external fertilization in fish, sperm cells must swim through open water in order to fertilize egg cells. During this process, females release a substance called ovarian fluid, which helps guide the sperm cells toward the egg cells. Researchers hypothesized that sperm cells are mainly attracted by ovarian fluid released from the same species. To test this hypothesis, researchers performed an experiment in which they studied the effects of salmon ovarian fluid and trout ovarian fluid on salmon sperm. In each trial within the experiment, the researchers placed salmon sperm on one side of a porous membrane and either salmon ovarian fluid, trout ovarian fluid, or water on the other side. After two minutes, the researchers counted how many salmon sperm had passed through the membrane and into the fluid. The results are presented in the graph below. Which of the following conclusions is best supported by the data above?

Salmon sperm respond more strongly to long-distance signaling molecules in salmon ovarian fluid than to those in trout ovarian fluid.

Which of the following best describes how the Calvin cycle and the light reactions of photosynthesis function together?

The Calvin cycle uses ATP and NADPH generated by the light reactions to synthesize carbohydrates.

Which organelle has malfunctioned? ___________ plant would not be able to stand up

cell wall

Which organelle has malfunctioned? ___________ plants can't make food & will starve

chloroplasts

All the internal structures are suspended (floating) in what substance?

cytoplasm

Which organelle has malfunctioned? ____________ organism won't have a distinct body shape

cytoskeleton

Which organelle has malfunctioned? ___________ organism won't be able to break down food it eats

lysosomes

Which of the following shows the most likely way that two water molecules will bond with each other?

*(picture not inserted. hydrogen bonding to the oxygen atom between two molecules)

A group of biology students weighed several potato cubes and placed them in open beakers containing various sucrose solutions at 45∘C. The following day, the students weighed the potato cubes again and calculated the differences in mass. It was determined that solute potential equilibrium was reached at 0.50 M. What is the solute potential of the potential cubes? (-iCRT) i = 1.0 for sucrose. C = molar concentration. R = pressure constant (0.0831 x bar x mol^-1 x K^-1)

-13 bar

A student places a zucchini into an open container containing a 0.70 M sucrose solution. The temperature of the solution is kept steady at 20∘C. What is the water potential of the zucchini cube? (-iCRT) i = 1.0 for sucrose. C = molar concentration. R = pressure constant (0.0831 x bar x mol^-1 x K^-1)

-17 bar

The solute potential of a plant cell is -12 bar, and it pressure potential is 3 bar. The plant cell is placed into a solution with a water potential of -10 bar. What is the water potential of the cell, and in which way will water move? Water potential = Pressure potential - solute potential

-9 bar; water will move out of the cell

Humans are made up of many types of cells, and these cells have a broad range of sizes. For example, a type of fat cell called an adipocyte has a radius of approximately 50μm, while a type of heart muscle cell called a cardiomyocyte has a radius of about 15μm. Surface area of a sphere: A = 4πr2A Assuming both cell types are perfectly spherical, approximately how many times larger is the surface area of an adipocyte compared to the surface area of a cardiomyocyte? Round your answer to the nearest integer.

11 times

The figure above depicts an agar cube with a side length of 13mm. In an experiment, students submerged the cube in orange dye for 12 hours. The orange dye permeated 1mm on each side, as indicated by the shading in the figure. Calculate the volume of the agar cube that remained unpenetrated by the orange dye.

1331 mm^3

Cell X has a surface are of 60μm2 and a volume of 15μm3. Cell Y has a surface area of 36μm2 and a volume of 12μm3. Using the information, determine the surface area to volume ratio of each cell. What is the SA:V ration of the cell that will exchange materials with its environment at the fastest rate of diffusion?

4μm

Which of the following mutated proteins is most likely to cause a cell to become cancerous?

An overactive version of a protein that stimulates cell division

The physical characteristics of a cell influence how it functions. For example, the surface area and volume of a cell affect how efficiently waste is removed from the cell via diffusion. The table below shows data for four different cuboidal cells. Using the information from the table, which cell can remove waste via diffusion most efficiently?

A (cell A = 3)

In the reaction above, two glucose monomers combine to form the dimer maltose. Which of the following best explains the process of this reaction?

A covalent bond forms through dehydration synthesis, which results in the formation of maltose and water.

The human oral microbiota contains over 700 species of bacteria. One species often found in the oral cavity is Streptococcus mutans, an anaerobic bacterium strongly associated with the formation of dental cavities. S. mutans metabolizes glucose and other dietary sugars remaining in the mouth after a meal, producing lactic acid as a byproduct. Over time, high levels of lactic acid can erode tooth enamel, eventually leading to the formation of dental cavities.

A drug that prevents the conversion of glucose into pyruvate

Thyroid-stimulating hormone (TSH) is a long-distance signaling molecule released by the anterior pituitary gland. Once released, TSH travels through the bloodstream to the thyroid gland, where it binds to G protein-coupled receptors called TSH receptors. This binding initiates signal transduction pathways that produce two thyroid hormones, T3 and T4. In individuals with hypothyroidism, TSH is released by the pituitary gland normally, but these individuals have consistently low levels of T3 and T4. Which of the following best explains why individuals with hypothyroidism have low levels of T3 and T4?

A mutation in their TSH receptors decreases TSH recognition, resulting in decreased signal transduction.

Which of the following best explains how the light reactions of photosynthesis generate ATP?

A proton gradient drives the formation of ATP from ADP and inorganic phosphate via ATP synthase.

Which of the following best describes the cell communication occurring in the figure above?

A signal-emitting cell communicates with a nearby cell by releasing local regulators.

Which of the following best describes the process of induced fit?

A substrate binds to the active site of an enzyme, causing the conformation of the active site to change slightly.

Bacteroides is the predominant genus of bacteria found in the human gut microbiota. As anaerobic bacteria, Bacteroides undergo fermentation in the gut, converting otherwise nondigestible carbohydrates into fermentation products that are used by the host for energy. Which of the following toxins would be most likely to disrupt carbohydrate metabolism in Bacteroides species?

A toxin that inhibits the function of an enzyme during glycolysis

The information below shows and describes the initial steps of the MAPK/ERK signaling cascade. When epidermal growth factor (EGF) ligands bind to their receptors, the receptors pair up and act as kinases, attaching phosphate groups to one another's intracellular tails. The activated receptors then trigger a series of events that activate the kinase Raf. Which of the following toxins will most likely inhibit the activation of MEK?

A toxin that prevents the kinase activity of Raf

The information below shows and describes the intermediate steps of the MAPK/ERK signaling cascade. After MEK is activated, it phosphorylates and activates ERK. ERK goes on to phosphorylate and activate a variety of target molecules, including transcription factors like c-Myc that promote cell growth and division. Which of the following toxins will most likely inhibit the phosphorylation of c-Myc?

A toxin that prevents the phosphorylation of ERK

Acetylcholine (ACh) is an important signaling molecule in the nervous system. After it transmits a signal, ACh is broken down by the enzyme acetylcholinesterase (AChE) in a reaction known as ACh hydrolysis. Which of the following best describes the effect AChE has on the hydrolysis of ACh?

AChE decreases the activation energy of ACh hydrolysis, increasing the rate of this reaction.

Which of the following best indicates that the light reactions of photosynthesis have completed and that the Calvin cycle has begun?

ATP and NADPH accumulate in the stroma.

The cytochrome complex is an integral thylakoid membrane protein that forms an electrochemical gradient by pumping protons. In an experiment, researchers apply a toxin to a plant cell that inhibits the cytochrome complex. Which of the following explains the most likely effect of this toxin on the light reactions of photosynthesis?

ATP synthesis will not occur.

Acetylcholine is a neurotransmitter that helps control muscle contraction. This neurotransmitter functions differently depending on which type of muscle it interacts with. For example, acetylcholine promotes muscle contraction in skeletal muscle but inhibits contraction in heart muscle. Which of the following best explains why acetylcholine leads to different cellular responses in skeletal and heart muscle?

Acetylcholine binds to different types of receptors in skeletal and heart muscle.

In humans, red blood cells contain hemoglobin, which is an oxygen-binding protein. Hemoglobin helps provide oxygen to the body's tissues. Each molecule of hemoglobin is made up of four subunits. The human genome encodes multiple variations of the hemoglobin subunit, including the alpha, beta, and gamma chains. The specific subunits that make up the dominant form of hemoglobin in a person's body are determined by the person's age and genetic background. The hemoglobin that is present in a fetus, or fetal hemoglobin, has a different functional profile than the hemoglobin present after birth, which is called adult hemoglobin. This difference can be seen in Figure 1, which shows how strongly each type of hemoglobin binds to oxygen. Both adult and fetal hemoglobin contain alpha chain subunits. According to the information provided, which of the following diagrams is the most likely representation of fetal and adult hemoglobin?

Adult (pink and gray) and Fetal (pink and orange)

A group of students are conducting an experiment on Elodea canadensis, a species of aquatic plant. In order to test the effect of light intensity on the rate of photosynthesis, they place each Elodea canadensis plant into an aquarium tank and place each tank at a different distance from a light source. After a few minutes, oxygen bubbles begin to form in each of the tanks. The students count the number of oxygen bubbles released during a 555 minute period for each tank. The results of their experiment are shown below.

An increase in light intensity increases the rate of photosynthesis.

Which of the following best describes the role that water plays in the reaction depicted above? (The water is going into the reaction)

As a reactant, water cleaves the covalent bond that holds the dimer together.

A researcher claims that increased atmospheric carbon dioxide levels cause increased growth rates in plants. Which of the following statements best supports the researcher's claim?

Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing sugars and other organic compounds.

RuBisCO catalyzes the joining of carbon dioxide with RuBP during carbon fixation. In an experiment, researchers apply a toxin to a plant cell that inhibits RuBisCO. Which of the following explains the most likely effect this toxin will have on the Calvin cycle?

Carbon dioxide will not be converted into sugar.

Most species of shark are strict carnivores. However, bonnethead sharks (Sphyrna tiburo) have been observed consuming seagrass within their natural habitat. Like other plants, seagrasses contain cellulose within their cell walls. Based on the information above, which of the following best supports the claim that bonnethead sharks are capable of hydrolyzing cellulose during digestion?

Cellulose is consumed as a linear polysaccharide and is broken down into glucose monosaccharides during digestion.

A lack of water can cause plant cells to become flaccid. This gives the plant a wilted appearance as shown in the figure below. Which of the following cell structures is most likely responsible for the plant's wilted appearance?

Central Vacuole

Chlorophyll a is a pigment that absorbs light energy from the sun and gives plants their green color. Which of the following plant cell structures is most likely to contain chlorophyll a?

Chloroplast

Methotrexate is a drug that is commonly used to treat cancers and autoimmune diseases in humans. It functions by binding to the active site of the enzyme DHFR, preventing both DNA synthesis and excess cell proliferation. Which of the following terms best describes methotrexate?

Competitive inhibitor

Which of the following statements accurately describes a similarity between the nucleotides of DNA and RNA?

Correct answer: The nucleotides of DNA and RNA contain a five-carbon sugar bonded to a phosphate group and a nitrogenous base.

Cyanide poisoning is a type of poisoning caused by exposure to certain cyanide-containing compounds, such as hydrogen cyanide or cyanide salts. Inhalation or consumption of these compounds can cause histotoxic hypoxia, a condition in which cells are no longer able to take up or utilize oxygen during cellular respiration. As a result, ATP production during respiration is significantly reduced. Based on the information above, which of the following is the most likely explanation for how cyanide causes histotoxic hypoxia?

Cyanide inhibits the transfer of electrons to the final acceptor in the electron transport chain.

Which of the following statements accurately describes a difference between DNA and RNA?

DNA is usually double-stranded, but RNA is usually single-stranded.

The diagram above depicts how the eukaryotic cell cycle is regulated by cyclins and cyclin-dependent kinases (CDKs). Based on the diagram, which of the following best describes the effect of a toxin that prevents the production of the G1cyclin?

DNA replication would be inhibited, causing the cell to stop dividing.

A group of biology students wants to study the effects of pH on enzyme activity. They measure the activity of enzymes A and B at various pHs and record their data in the graph below. A solution of enzyme A has pH of 8. Based on the graph, which pH change would result a higher enzyme activity?

Decreasing the pH of the solution to 6

The following excerpt and image come from a scientific paper written by Ebrahimi & Chess. They discuss the role of G proteins in olfaction, or the sense of smell. Each mammalian olfactory neuron appears to use the same machinery for transducing signals from its odorant receptor molecules. Upon odorant binding, the receptor is thought to activate G'olf', a G protein. G'olf' mediated activation of adenylate cyclase III then raises intracellular cAMP levels, causing a cyclic-nucleotide-gated channel to open. The influx of cations through this channel ultimately leads to the formation of an action potential, which allows the primary neuron to signal to the brain. A mutation in a component of this signal transduction pathway prevents the cyclic-nucleotide-gated channel from opening. Which of the following scientific questions would best help researchers understand how the mutation prevents the cyclic-nucleotide-gated channel from opening?

Does the mutation block the activation of adenylate cyclase III?

Adenoviruses are a family of highly contagious viruses that most commonly cause illnesses of the respiratory system, such as bronchitis or pneumonia. In the first phase of an adenovirus infection, the host cell expresses several viral proteins. One of these proteins, E1B-55k, inhibits the activity of the host protein p53, a tumor suppressor that arrests the cell cycle or induces apoptosis when DNA damage is detected. Which of the following claims is best supported by the information above?

E1B-55k decreases the likelihood of apoptosis in infected cells.

Given the structure of water, H2O which of the following must be true?

Each water molecule can form four hydrogen bonds.

The following is an excerpt from a scientific paper by Jean-Pierre Raufman. Cholera, an infectious disease that can kill humans within a matter of hours, is a manifestation of a highly efficient and specific toxin delivery mechanism. This mechanism, which is shared by several bacteria, delivers a potent toxin to activate selectively the adenylyl cyclase system of human intestinal secretory cells. This increases production of the ''second messenger'' cyclic adenosine monophosphate (cAMP) that activates an intestinal crypt cell chloride ion channel, thereby resulting in massive fluid and electrolyte secretion into the lumen of the gut. Raufman, J. P. (1998). Cholera. Am. J. Med. 104, 386-394. Based on the information above, which of the following is most likely to be observed in the intestinal environment of a person infected with cholera?

Elevated levels of extracellular chloride ions

Pancreatic amylase is a digestive enzyme found in the small intestine. It helps break down large starch molecules later in the digestive process. Pancreatic amylase is unable to break down lipids. Which of the following best explains why pancreatic amylase is able to break down starches, but not lipids?

Enzymes bind only to their specific substrates.

A partial hepatectomy, or the surgical removal of a section of the liver, is often performed to treat tumors or other abnormal growths in the liver. Following a partial hepatectomy, resting liver cells re-enter the cell cycle, duplicating until the excised portion of the liver has been regenerated. According to the information above, performing a partial hepatectomy causes liver cells to

Exit G0 and enter G1 phase

Only animal cells have chloroplasts to generate energy for cellular respiration.

False

The enzyme glutamine synthetase facilitates the use of energy to combine glutamate and ammonia (NH4), forming glutamine. This process occurs in two steps, as represented in the following diagram. Which of the following statements best describes the process carried out by glutamine synthetase?

Glutamine synthetase uses an exothermic reaction to drive an endothermic one by catalyzing the formation of a phosphorylated intermediate.

A cell is treated with a toxin that prevents the synthesis of new lysosomes. However, the cell continues to produce the hydrolytic enzymes normally found in lysosomes. In which of the following structures are the hydrolytic enzymes most likely to accumulate?

Golgi Apparatus

Which organelle has malfunctioned? ____________ enzymes & chemical messengers won't be ready to be used

Golgi Apparatus

During step 3 of the Krebs cycle, the enzyme isocitrate dehydrogenase (IDH) catalyzes the conversion of isocitrate α-ketoglutarate. This step is represented in the model below. IDH is allosterically activated by ADP at high concentrations. Which of the following best describes how this interaction helps regulate the Krebs cycle?

High levels of ADP stimulate the Krebs cycle, leading to the increased conversion of ADP to ATP during oxidative phosphorylation.

In order to develop antibiotics, scientists need to understand how bacteria grow and reproduce. One factor that is essential for bacterial growth and reproduction is protein synthesis. By understanding how bacteria synthesize proteins, scientists can then attempt to develop antibiotics that block bacterial protein synthesis during an infection. Which of the following questions will best direct an investigation on how to develop an antibiotic that inhibits protein synthesis in bacteria?

How can the carboxyl (-COOH) terminus of a growing polypeptide chain be blocked?

In order to develop antibiotics, scientists need to understand how bacteria grow and reproduce. One factor that is essential for bacterial growth and reproduction is protein synthesis. By understanding how bacteria synthesize proteins, scientists can then attempt to develop antibiotics that block bacterial protein synthesis during an infection. Which of the following questions will best direct an investigation on how to develop an antibiotic that inhibits protein synthesis in bacteria?

How can the formation of covalent bonds between amino acids be blocked?

Enzymes often play a major role in signal transduction pathways. For example, enzymes can help convert an extracellular signal into an intracellular response. Specifically, adenylyl cyclase is an enzyme that catalyzes the conversion of ATP to cyclic AMP (cAMP). One competitive inhibitor of adenylyl cyclase is called MANT-ITP. Which of the following questions would best direct an investigation on how MANT-ITP impacts a signal transduction pathway?

How does MANT-ITP affect the response to intracellular signals?

Based on the reaction depicted above, which of the following statements is true?

If water is not added to the reaction, hydrolysis will not occur.

The endocrine system maintains homeostasis in the body through the release of various hormones. For example, the pancreas releases the hormone insulin to help regulate blood glucose homeostasis. Which of the following best describes the role of insulin in regulating blood glucose homeostasis?

Insulin is released in response to high blood glucose levels. This release triggers a negative feedback loop that returns blood glucose levels back to normal.

Which of the following best describes how substances move across the cell membrane?

Ions move across the cell membrane through embedded channel proteins.

Which of the following questions would a researcher most likely ask if they wanted to know whether a hydrolysis reaction or a dehydration synthesis reaction is occurring?

Is water a reactant or product of the reaction?

Water has a boiling point of 100.0 ∘C, which is unusually high compared to many other liquids. Which of the following properties allows water to have a high boiling point?

It can form hydrogen bonds.

The gastric H/K ATPase is a membrane protein that uses energy from ATP hydrolysis to transport hydrogen ions (H+) and potassium ions (K+) against their concentration gradients. The steps of ion exchange carried out by the H/K ATPase are depicted in the following diagram. Given the concentration gradient established by the H/K ATPase, which of the following movements can occur?

K+ can move out of the cell without using energy from ATP hydrolysis.

The model below depicts the movement of several ions across a cell membrane. For each ion or molecule, the relative concentration on each side of the membrane is shown. Which of the following statements accurately describes one of the movements shown in the model?

K+ movement into the cell requires ATP

The model below shows how potassium ions (K+), sodium ions (Na+), and hydrogen ions (H+) move between the blood, a parietal cell, and the gastric pit lumen in the stomach. The relative concentrations of K+, Na+, and H+ inside and outside the parietal cell are indicated. Based on the model, which of the following does NOT require an input of energy?

K+ moving out of a parietal cell into the gastric pit lumen

Gastric acid is a digestive fluid that is made with the help of parietal cells in the stomach lining. The parietal cell plasma membrane maintains a concentration gradient of potassium ions (K+) between the cell cytoplasm and the extracellular fluid. During the formation of gastric acid, (K+) moves down this gradient, passing from the cytoplasm into the extracellular space. Which of the following is the most likely mechanism by which K+ moves across the plasma membrane of a parietal cell during gastric acid formation?

K+ passes through membrane channel proteins.

Consider a reaction in which reactants X and Y combine to form the product Z. The diagram below compares the reaction coordinates for the catalyzed and uncatalyzed pathways of this reaction. Which of the following statements about letter B is true?

Letter B represents the activation energy of the catalyzed reaction pathway.

Consider a reaction in which reactants X and Y combine to form the product Z. The diagram below compares the reaction coordinates for the catalyzed and uncatalyzed pathways of this reaction. Which of the following statements about letter C is true?

Letter C represents the activation energy of the uncatalyzed reaction pathway.

Tay-Sachs disease is a genetic disorder that causes certain lipids known as gangliosides to accumulate in the neurons of the brain and spinal cord. As the gangliosides build up, neurons rapidly degenerate. Which of the following cell structures is most likely associated with the accumulation of gangliosides?

Lysosomes

Maltase is an enzyme found in the small intestine. It helps break down maltose during the process of digestion. Which of the following best describes what happens when maltose binds with maltase?

Maltose binds to the active site of maltase, causing the conformation of the active site to change slightly.

Which organelle has malfunctioned? ___________ organism won't have energy to perform everyday functions

Mitochondria

If ATP hydrolysis (ATP production) is inhibited, which of the following types of movement across a cell membrane would likely also be inhibited?

Movement of an ion against its concentration gradient

The model below depicts the movement of several ions across a cell membrane. For each ion, the relative concentration on each side of the membrane is shown. Which of the following statements accurately describes one of the movements shown in the model?

Na+ movement into the cell does not require an input of energy.

Which of the following statements about feedback mechanisms is most accurate?

Negative feedback mechanisms return a system to its set point.

Which of the following correctly describes how positive and negative feedback are different?

Negative feedback reverses changes in a system, while positive feedback amplifies changes in a system.

During cell communication in the nervous system, chemical messengers called neurotransmitters travel between neurons. As they travel, neurotransmitters send messages from one neuron to another. Which of the following best describes the role of neurotransmitters in neuron-to-neuron communication?

Neurotransmitters are local regulators that allow neurons to communicate over short distances.

Where do you find the DNA in each cell in Model 2?

Nucleus

Which organelle has malfunctioned? ___________ organism won't have traits

Nucleus

Neurons transmit information in the form of electrical signals called action potentials. When at rest, a neuron has a membrane potential of approximately -−70mV with respect to the inside of the cell. However, during an action potential, an influx of positively charged ions causes the membrane to depolarize. Immediately following depolarization, the membrane potential of the neuron is approximately 30m with respect to the inside of the cell. Which of the following diagrams best represents the membrane potential of a neuron immediately after depolarization?

Outside of neuron = - Inside of neuron = +

In mitochondria, the rate of ATP synthesis during oxidative phosphorylation is tightly coupled to the movement of electrons through the electron transport chain (ETC). When ADP levels rise and the demand for ATP synthesis increases, electron flow through the ETC also increases. Based on the information above, which of the following best describes an effect of rising ADP levels in mitochondria?

Oxygen consumption will increase.

Pepsin, a proteolytic enzyme found in the stomach, is essential for digestion. Pepsin functions optimally at approximately 37∘C Which of the following would most likely result if pepsin's environmental temperature was lowered from 37∘C to 25∘C?

Pepsin would be less efficient at catalyzing reactions.

The following graph shows how cellular DNA content changes over the course of a typical mitotic cell cycle in rapidly proliferating human cells. Based on the graph, which of the following labeled phases corresponds to S phase of the cell cycle?

Phase B, because the amount of cellular DNA is doubled during this phase

What is different about the outermost boundary in a plant cell compared to an animal cell?

Plants have a cell wall

Unlike most other cells in the human body, mature red blood cells (RBCs) do not contain a nucleus or mitochondria. This allows RBCs to carry more hemoglobin, and therefore oxygen, through the bloodstream. Based on the information above, which of the following is most likely true about RBCs?

RBCs generate lactate as a waste product.

Mutations within genes coding for G protein-coupled receptors (GPCRs) can lead to one of two major outcomes—a loss-of-function or a gain-of-function. Loss-of-function mutations prevent signaling in GPCR pathways, even in the presence of signaling molecules. Gain-of-function mutations activate signaling in GPCR pathways, even in the absence of signaling molecules. Which of the following is most likely to result from a loss-of-function GPCR mutation?

Signal transduction pathways that are inactive even if ligand-to-receptor binding occurs

Based on your answer to the previous question, what might you infer about the absence of this structure in the other two bacteria cells?

Since this structure is important for movement, the other two cells would lack locomotion abilities.

Which of the following is true about the transportation of substances across the lipid region of the cell membrane?

Small nonpolar molecules can freely dissolve across the lipid region of the cell membrane

Which of the following best describes the permeability of the cell wall?

Some substances pass across the cell wall because it is a semipermeable structural boundary.

In the reaction depicted above, maltose is broken down into two molecules of glucose. Which of the following best explains the process of this reaction?

The addition of a water molecule cleaves the covalent bond holding maltose together.

Which of the following statements best describes the selective permeability of the cell membrane?

The cell membrane regulates the transport of specific substances into and out of the cell.

Lactose is a dimer sugar composed of two monomeric subunits (galactose and glucose). In an investigation, researchers placed intestinal cells in a nutrient medium containing lactose. The researchers determined that the lactose had broken down to galactose and glucose in the manner depicted in the reaction below. The cells were then modified and re-exposed to the lactose medium. The researchers were no longer able to detect the presence of galactose and glucose. Which of the following conclusions best explains an outcome of this modification?

The cells were unable to hydrolyze the lactose dimer into its monomeric subunits.

Many species of bacteria regulate gene expression using a cell signaling system known as quorum sensing (QS). In this system, bacteria synthesize QS signaling molecules and release them into the surrounding environment. The effects of these molecules on gene expression depend on the density of the bacterial population. Which of the following best describes what occurs as the density of a QS bacterial population increases?

The concentration of QS signaling molecules increases, eventually triggering a change in gene expression throughout the bacterial population.

If water was removed from the reaction depicted above, which of the following describes the most likely outcome of this removal?

The covalent bond that holds the dimer together would not be cleaved because hydrolysis would not occur.

Glycogen is a highly branched macromolecule usually stored in liver and muscle cells. If blood glucose levels decrease, glycogen breaks down to release glucose in a process called glycogenolysis. In this process, the glycogen polysaccharide goes through hydrolysis and breaks down into glucose monosaccharides. If a toxin were to inhibit glycogenolysis, which of the following statements best predicts a consequence of this inhibition?

The covalent bonds between individual glucose monomers will not be cleaved.

A new dish soap claims that it is able to remove grease from pots and pans while still fully dissolving in the dishwasher water. Which of the following best explains the ideal structure of the dish soap molecule?

The dish soap molecule must be nonpolar at one end to dissolve grease, and polar at the other end so it can dissolve in water.

A single-step reaction is represented below: A + B --> AB + heat Which of the following best explains how the addition of an enzyme would affect the above reaction?

The enzyme would decrease the activation energy of the reaction, increasing its rate.

The image below depicts how the bacterial protein barnase undergoes modifications that involve changing its conformation, or shape. In order to function in the cell, barnase has to be folded from a nonfunctional conformation into a functional conformation. Based on the information above, which of the following best describes the functional conformation of barnase?

The functional conformation of barnase has a tertiary structure because it consists of a polypeptide chain folded into a three-dimensional shape.

A student is examining a whitefish blastula cell under a microscope. Based on the observations, the student proposes that the whitefish blastula cell is in interphase. Which of the following pieces of evidence would best support the students claim?

The genetic content of the cell exists as dispersed chromatin

During the humoral immune response, helper T-cells activate B-cells through cell communication. This process is shown in the image below. During an experiment, researchers introduced a substance that caused the T-cell receptor to break down. Which of the following best describes how the humoral immune response will be affected?

The helper-T cell will no longer bind to the B-cell, as a result, B-cell will not be activated.

The air temperature ranges of several Southern California cities in August are shown in the table below. Which of the following best explains why coastal cities like San Diego often have a smaller air temperature range than inland cities?

The high heat capacity of water allows the ocean to moderate the temperature of nearby air and land.

Bodies of water, such as ponds, freeze from top to bottom, forming a floating sheet of ice. This can help aquatic organisms survive during cold winter months. Which of the following statements explains why the ice floats on the surface of the pond?

The increased number of hydrogen bonds in ice compared to liquid water causes the water molecules in ice to be further apart.

During the cell-mediated immune response, killer T-cells target and kill infected cells. This process is shown in the image below. During an experiment, researchers introduced a substance that caused the Class I MHC molecule to break down. Which of the following best describes how the cell-mediated immune response will be affected?

The killer T-cell will no longer bind to the infected cell, and as a result, the infected cell will not be killed.

A mutation causes the extracellular domain of a G protein-coupled receptor (GPCR) to be misfolded. The misfolded GPCR is packaged into a vesicle that travels to the cell membrane. Upon reaching the cell membrane, the vesicle deposits the misfolded GPCR, which fuses with the cell membrane and functions as a membrane receptor. Which of the following best predicts what will occur whenever the misfolded GPCR is in the presence of its specific ligand?

The ligand-binding domain of the misfolded GPCR will not bind with its specific ligand.

A team of virologists has isolated a nucleic acid sample from a newly discovered virus. In order to classify the virus, they need to figure out whether the viral nucleic acid is DNA or RNA. Which of the the following characteristics of the nucleic acid sample would best help classify the viral nucleic acid as DNA or RNA?

The nucleotides of the virus contain deoxyribose.

A team of virologists has isolated a nucleic acid sample from a newly discovered virus. In order to classify the virus, they need to figure out whether the viral nucleic acid is DNA or RNA. Which of the the following characteristics of the nucleic acid sample would best help classify the viral nucleic acid as DNA or RNA?

The nucleotides of the virus contain uracil.

In the early 1950's, a team of researchers led by Erwin Chargaff conducted a series of experiments related to deciphering the chemical composition of DNA. In one experiment, Chargaff's team examined samples of DNA from different species of sea urchins. The results of this experiment are summarized in the table below. Which of the following results from the experiment is most consistent with the base-pairing rules of DNA?

The percentage of adenine nucleotides is roughly equal to the percentage of thymine nucleotides across all species in the experiment.

A student places a potato cube into a beaker of distilled water as shown below. The potato cube has a pressure potential of 7.2 bar and a solute potential of -9.8 bar. Assuming standard atmospheric pressure, which of the following is true?

The potato cube has a water potential of -2.6 bar and the distilled water has a water potential of 0 bar

Several scientists are studying the effect of initial substrate concentration on the activity of an enzyme. They perform a series of enzyme-controlled reactions, keeping the concentration of enzyme constant but increasing the initial concentration of substrate in each trial. The graph below shows their results. Based on the data above, which of the following best describes what happens to the rate of product formation at higher initial substrate concentrations?

The rate of product formation levels off because nearly all of the enzyme is bound to substrate.

A researcher wants to identify a newly isolated DNA strand. The first step in identifying the DNA strand is to measure its length. To do this, the researcher wants to develop a fluorescent tag that emits light once it binds to both ends of the strand. Which of the following best describes how the researcher should develop a fluorescent tag with an ability to bind to both ends of the strand?

The tag should have an affinity to bind only free 3' hydroxyl (-OH) and 5' phosphate (-PO4) functional groups.

In the cell membrane, carbohydrate chains can be covalently linked to membrane proteins to form glycoproteins. They can also be covalently linked to membrane phospholipids to form glycolipids. These two cell membrane structures are shown in the image below. During an investigation, researchers discover a new toxin that enters a cell after binding to a carbohydrate on the cell membrane. Which of the following best describes how the toxin attaches to the cell membrane?

The toxin attaches to specific monosaccharides on the cell membrane.

Which of the following best describes what will result when a glucose-fed yeast cell is placed in an anaerobic environment?

The yeast cell will produce ATP through fermentation, generating CO2​ and ethanol as byproducts.

Researchers studying cell cycle regulation in budding yeast have observed that a mutation in the CDC15 gene causes cell cycle arrest in telophase when the yeast cells are incubated at an elevated temperature. Which of the following statements best predicts the effect of the cell cycle arrest on proliferating yeast cells?

The yeast cells will replicate their chromosomes but will fail to complete cytokinesis

The human body is capable of digesting the complex polymer starch into simpler subunits. This digestive process requires the presence of water and the enzyme amylase in order to break down starch into maltose. This is depicted below. Which of the following statements best describes the digestion of starch into maltose?

This is a hydrolysis reaction that requires water to break down a complex polymer into simpler subunits

In the reaction depicted above, two amino acids have combined to form a dipeptide. Which of the following best explains the process occuring in this reaction?

Through dehydration synthesis, a covalent bond forms to connect the dipeptide together, and a water molecule forms as a product.

In the image above, a thymine nucleotide and cytosine nucleotide are connected together as a dinucleotide. A single guanine nucleotide is also shown. Which of the following best predicts how the free guanine nucleotide will attach to the dinucleotide?

Through dehydration synthesis, the guanine nucleotide will form a covalent bond at the 3' hydroxyl (-OH) of the cytosine nucleotide.

What role do the highlighted hydroxyl group (-OH) and hydrogen atom (H) play in the depicted reaction above?

Through dehydration synthesis, they condense out of the reaction as a water molecule and a covalent bond forms in their place.

In response to critically low nutrient levels, yeast cells often enter into a dormant, non-dividing state. This state allows yeast cells to survive until nutrient levels are restored, at which point the cells typically re-enter the cell cycle. According to the intormation above, critically low nutrient levels cause yeast cells to

Transition from G1 to G0 phase

Both cells have a nucleus

True

Both cells have mitochondria

True

A neuron stimulates muscle contraction by sending signals across the neuromuscular junction, or the point of contact between a neuron and a muscle cell. The signaling process begins when membrane-bound structures inside the neuron fuse with the cell membrane, releasing signaling molecules into the neuromuscular junction. These molecules then diffuse through the junction and binds to receptors on the surface of the muscle cell, leading to muscle contraction. Botulism is a rare illness caused by a toxin produced by the bacterium Clostridium botulinum. This toxin, called botulinum toxin, inhibits the process by which signaling molecules are released from neurons at the neuromuscular junction. This disrupts the neuron-muscle cell signaling pathway, resulting in temporary paralysis. Based on the information above, which of the following cell processes does botulinum toxin most likely inhibit?

Vesicle fusion during exocytosis

In the reaction depicted above, two amino acids have combined to form a dipeptide. Which of the following best describes the role of water in the reaction?

Water is a product that forms as a result of a dehydration synthesis reaction between the two amino acid monomers.

When light is absorbed by pigments in photosystem II (PSII), energy is passed inward from pigment to pigment until it reaches the reaction center. Electrons are then boosted to a high energy level and captured by the primary electron acceptor. Which of the following occurs immediately after the electrons from PSII are captured by the primary electron acceptor?

Water is broken down.

Which of the following best describes water's ability to dissolve certain substances such as glucose, but remain separate from other substances such as oils?

Water molecules are polar, consisting of two partially positive hydrogen atoms, and one partially negative oxygen atom.

Which of the following examples explains how a biological activity relies on water's adhesive properties?

Water travels through vascular tissue from the roots to the leaves of a plant.

Which statement best describes why water is an effective solvent?

Water's polarity allows it to dissolve ionic and polar compounds.

Which of the following gives water its cohesive properties?

Water's polarity makes it attracted to other charged molecules.

The following excerpt describes a potential origin of the first living cells on earth. We have proposed that a simple primitive cell, or protocell, would consist of two key components: a protocell membrane that defines a spatially localized compartment, and an informational polymer that allows for the replication and inheritance of functional information. Schrum, J. P., Zhu, T. F., & Szostak, J. W. (2010). Based on this excerpt, which of the following questions would best direct an investigation on whether the "informational polymer" is DNA or RNA?

Which nitrogenous bases are present in the structure of the informational polymer?

One of the bacteria in Model 1 has a tail-like structure. What is this structure called?

flagella

Which organelle has malfunctioned? ___________ organism can't make chemical reactions because cell won't import get monomers, O2, water, ions

plasma (cell) membrane

In response to stress, the hypothalamic-pituitary-adrenal (HPA) axis coordinates the release of the steroid hormone cortisol, as summarized in the figure above. Inhaled corticosteroids (ICS) are a class of synthetic steroid hormones that are commonly used in the long-term treatment of persistent asthma. Assuming that ICS function in the same way as naturally occurring cortisol, it is most likely that long-term, high-dose ICS use would

reduce cortisol production

What is represented by the small dots found in each of the bacteria cells?

ribosomes

Which organelle has malfunctioned? ___________ organism won't be able to export out the proteins made

vesicles

The solute potential of a plant cell is -15 bar, and its pressure potential is 7 bar. The plant cell is placed into a solution with a water potential of -8 bar. What is the water potential of the cell, and in which way will water move? Water potential = Pressure potential - solute potential

−8 bar; there will be no net movement of water