Past Tests Questions: Final review

What is the expected percent change in the DNA content of a typical eukaryotic cell as it progresses through the cell cycle from the start of the G1 phase to the end of the G2 phase?

+100%

to test the hypothesis that a particular plant synthesizes storage lipids by using glyceraldehyde 3-phosphate (G3P) from photosynthesis, a researcher plans to use radiolabeled precursors to track the molecules through the biosynthetic pathway. Which of the following radiolabeled precursors is most appropriate for the researcher to use?

14C-labeled CO2, because atmospheric carbon dioxide is fixed to carbohydrates by photosynthesis

The diagram below shows a developing worm embryo at the four-cell stage. Experiments have shown that when cell 3 divides, the anterior daughter cell gives rise to muscle and gonads and the posterior daughter cell gives rise to the intestine. However, if the cells of the embryo are separated from one another early during the four-cell stage, no intestine will form. Other experiments have shown that if cell 3 and cell 4 are recombined after the initial separation, the posterior daughter cell of cell 3 will once again give rise to the normal intestine. Which of the following is the most plausible explanation for these findings?

A cell surface protein on cell 4 signals cell 3 to induce formation of the worm's intestine.

The graph above shows changes in glucagon and insulin secretions at different concentrations of blood glucose. Which of the following feedback mechanisms is best supported by the data?

A low glucose level causes the release of glucagon, which stimulates the release of more glucose from tissues, which in turn lowers the amount of glucagon being released.

The figure above shows a model of a ligand precursor being cleaved to produce an active ligand that binds to a specific receptor. Which of the following is most likely to reduce the binding of the active ligand to its receptor?

A mutation in the receptor gene that causes a substitution of a charged amino acid for a nonpolar amino acid in the ligand binding site of the receptor

Which of the following correctly illustrates a dipeptide and an amino acid in the optimal position to form a tripeptide?

A. demonstrates an ability to refine and/or interpret a representation to explain the synthesis of a biological polymer

Simple cuboidal epithelial cells line the ducts of certain human exocrine glands. Various materials are transported into or out of the cells by diffusion. (The formula for the surface area of a cube is 6 X S2, and the formula for the volume of a cube is S3, where S = the length of a side of the cube.) Which of the following cube-shaped cells would be most efficient in removing waste by diffusion?

A.) 10 um

In mammals, an increase in the concentration of sodium in the blood triggers the release of antidiuretic hormone (ADH) from the pituitary gland. As the concentration of sodium in the blood returns to previous levels, the release of ADH from the pituitary gland is reduced. Based on the information presented, which of the following describes the most likely role of ADH in maintaining blood osmolarity?

ADH promotes an increase in the movement of water into the bloodstream.

Damaged tissue releases chemicals that activate platelets and stimulate the formation of blood clots. Which of the following predictions about the activity of platelets best describes a positive feedback mechanism?

Activated platelets release chemicals that activate more platelets.

The endocrine system incorporates feedback mechanisms that maintain homeostasis. Which of the following demonstrates negative feedback by the endocrine system?

After a meal, blood glucose levels become elevated, stimulating beta cells of the pancreas to release insulin into the blood. Excess glucose is then converted to glycogen in the liver, reducing blood glucose levels.

Which of the following groups of cellular components are found in eukaryotic cells but not prokaryotic cells?

An endoplasmic reticulum, mitochondria, and a nucleus

Which of the following best describes the numbered areas?

Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules.

A researcher claims that only a portion of the light energy captured by green plants is available for growth and repair. Which of the following observations best helps justify the researcher's claim?

As light energy is converted to chemical energy by metabolic processes, some of the energy is lost as heat.

Evolved from a photoautotrophic prokaryote? A.) Mitochondria B.) Chloroplast C.) Golgi Apparatus D.) Cell Membrane E.) Vacuole (large)

B.) Chloroplast

Which of the following is a characteristic of mitochondria and chloroplasts that suggests the endosymbiotic theory?

Both contain DNA molecules

Butterflies of the genus Colias live in the Rocky Mountains, where they experience a wide range of temperatures. Different variants of a particular glycolytic enzyme in the flight muscles are optimally active at different temperatures. Within the same population, some individual butterflies fly most effectively at 29°C, while others fly most effectively at 40°C. Still, others can be equally active at both temperatures. Which of the following claims is most consistent with the observed butterfly behavior?

Butterflies that express two variants of the enzyme are active over a greater range of temperature

Site of modification and packaging of proteins and lipids prior to export from the cell? A.) Mitochondria B.) Chloroplast C.) Golgi Apparatus D.) Cell Membrane E.) Vacuole (large)

C.) Golgi Apparatus

Two different models of a living cell are represented. Of the two cells represented in the figure, which would likely be more efficient and exchanging substances with the surrounding environment?

Cell A, because it has the larger surface area to volume ratio

Figure 1 shows the number of chromosomes observed in an actively dividing human cell at each stage of cell division. Which of the following presents a correct interpretation of the changes in chromosome number depicted in Figure 1 ?

Chromosomes enter metaphase containing two chromatids attached by a centromere. During anaphase, the chromatids are separated, each becoming a chromosome. Cytokinesis distributes the chromosomes into two separate cells.

Based on the results of the experiment, which of the following types of molecules did the bacteriophages most likely inject into the bacteria cells?

DNA

A pathogenic bacterium has been engulfed by a phagocytic cell as part of the nonspecific immune response. Which of the following illustrations best represents the response?

Diagram C: Bacterium getting engulfed and the lysosomes working

The diagram below shows energy changes in a specific chemical reaction with and without the addition of an enzyme to the reaction. Which of the following questions can best be answered by the diagram?

Does the addition of an enzyme reduce the activation energy required for a reaction?

A scientist claims that Elysia chlorotica, a species of sea slug, is capable of photosynthesis. Which of the following observations provides the best evidence to support the claim?

Elysia chlorotica will die if not exposed to light.

All eukaryotic cells contain at least one Golgi complex, typically located in the cytoplasm and near the endoplasmic reticulum. Which of the following best describes a process that occurs within the Golgi complex?

Enzymatic modification of newly synthesized integral membrane proteins.

Epinephrine is a protein hormone found in many animals. Epinephrine stimulates a signaling pathway that results in the breakdown of glycogen to glucose in the liver cells. Which of the following describes the initial steps in the process whereby epinephrine stimulates glycogen breakdown?

Epinephrine binds to a cell-surface receptor; the activated receptor stimulates production of the second messenger, cAMP.

Which of the following is responsible for the cohesive property of water?

Hydrogen bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule.

Cyanobacteria contain a variety of pigment molecules, as shown in Table 1. As a result, the color of cyanobacteria cultures can vary significantly based on the relative amount of each pigment produced. A researcher placed a culture of cyanobacteria under green lights. Within a few weeks, the appearance of the cyanobacteria changed from green to red. The researcher claimed the color change in the culture was the result of an adaptation allowing greater photosynthesis. Which of the following provides the best reasoning to justify the researcher's claim?

In green light, more phycoerythrin molecules are produced, allowing more green light to be absorbed, thus increasing photosynthesis.

The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1. Based on figure 1, which of the following statements best describes the epinephrine signaling pathway?

In involves enzymes activating other enzymes

Researchers performed an experiment to determine the effect of certain genetic mutations on mitosis in tropical fruit fly embryos. They determined the percentage of cells in each of four phases of mitosis as shown in Figure 1.Which of the following patterns is shown by the data?

In mutant 3 cells, more time is spent in prophase/prometaphase than in the later stages of mitosis.

Which of the following questions will best direct an investigation of the mechanism of ATP synthase?

Is the phosphorylation of ADP by ATP synthase dependent on the formation of a proton gradient

In a certain signal transduction pathway, the binding of an extracellular molecule to cell-surface protein results in a rapid increase in the concentration of cyclic AMPAMP inside the cell. The cyclic AMPAMP binds to and activates cytosolic enzymes that then activate other enzymes in the cell. Which of the following statements best describes the role of cyclic AMPAMP in the signal transduction pathway?

It acts as a second messenger that helps relay and amplify the signal within the cell.

Which of the following is most directly responsible for water's unique properties?

It forms hydrogen bonds

The CFTR protein is made up of 1,480 amino acids linked together in a chain. Some humans produce a version of the CFTR protein in which phenylalanine (an amino acid) has been deleted from position 508 of the amino acid chain. Which of the following best predicts how the amino acid deletion will affect the structure of the CFTR protein?

It will affect the primary, secondary, and tertiary structures of the CFTR protein.

Ethylene causes fruits to ripen. In a signaling pathway, receptors activate transcription factors, which ultimately lead to ripening. Which of the following best supports the claim that ethylene initiates the signal transduction pathway that leads to the ripening of fruit?

Loss-of-function mutations in ethylene receptors result in changes to the ripening process.

Which of the following processes is most likely to occur as a result of an animal cell receiving a signal to initiate apoptosis?

Lysosomes will release digestive enzymes into the cytosol

Changing the shape or morphology of the mitochondrial inner membrane can change the efficiency of mitochondrial function. Which of the following outcomes will most likely result from a change in the shape of the mitochondrial inner membrane from a highly folded surface to a smooth, flat surface?

Mitochondria will become less efficient because the surface area of the inner mitochondrial membranes will decrease.

An intermediate electron acceptor for oxidations that occur in both glycolysis and in Krebs cycle reactions

NAD+

This group of questions refers to the following groups of biological compounds.(A) Proteins (B) Carbohydrates (C) Nucleic acids (D) Lipids (E) Steroids Used to carry the genetic code

Nucleic Acids

Directions: This group of questions consists of five lettered headings followed by a list of phrases or sentences. For each phrase or sentence, select the one heading to which it is most closely related. Each heading may be used once, more than once, or not at all. This group of questions refers to the following groups of biological compounds. Synthesized at the ribosome

Nucleic acids

Membrane-bound organelles have been an important component in the evolution of complex, multicellular organisms. Which of the following best summarizes an advantage of eukaryotic cells having internal membranes?

Organelles isolate specific reactions, increasing metabolic efficiency.

Based on the molecular structures shown in the figure, which molecule is likely to be solid at room temperature?

Palmitic acid, because the absence of carbon-carbon double bonds allows the molecules to pack closely together.

Protein digestion in humans is primarily carried out by three enzymes. Pepsin is found in the stomach (pH2), where it aids in the breakdown of large proteins into smaller peptides, while trypsin and chymotrypsin are found in the small intestine (pH8), where they aid in the further breakdown of the proteins into amino acids and dipeptides that can be absorbed into the bloodstream. Graph 1 shows the effect of pH on the activity levels of the three enzymes. Graph 1. Relative activity of pepsin, trypsin, and chymotrypsin at pH 0 through 11. Which of the following best predicts how the structure and function of pepsin will change as it enters the small intestine?

Pepsin will change in shape because of the basic environment of the small intestine; therefore, its enzymatic activity will decrease.

Based on the data shown, changes in the light intensity resulted in changes in the rate of which of the following processes?

Photosynthesis

What most likely causes the trends in oxygen concentration shown in the graph above?

Photosynthesis produces more oxygen than is consumed by respiration during the day

Which of the following experimental designs should the students use as a control for the experiment?

Place a catalase-soaked disk in a beaker of water.

Which of the following statements most directly supports the claim that different species of organisms use different metabolic strategies to meet their energy requirements for growth, reproduction, and homeostasis?

Plants generally use starch molecules for storage while animals use glycogen and fats for storage.

Which of the following statements best describes how organisms such as rabbits obtain the carbon necessary for building biological molecules?

Rabbits eat plants and break down plant molecules to obtain carbon and other atoms that they rearrange into new carbon-containing molecules

Which of the following can be used to determine the rate of enzyme-catalyzed reactions?

Rate of disappearance of the substrate

Prokaryotic and eukaryotic cells generally have which of the following features in common?

Ribosomes

Cells contain smaller components called organelles that are necessary for a cell's survival. Organelle functions have often been compared to components of larger systems. Which of the following functional differences between the rough and smooth endoplasmic reticulum (ER) is explained by the structural differences between them?

Rough ER can synthesize and package proteins for export, and smooth ER cannot.

The sequences for two short fragments of DNA are shown above. Which of the following is one way in which these two segments would differ?

Segment 1 would become denatured at a lower temperature than would segment 2 because A-T base pairs have two hydrogen bonds whereas G-C base pairs have three.

The salinity of a small inland lake has recently started to increase. Researchers are planning to study the lake over several decades to investigate how freshwater organisms survive significant changes in their natural habitat. Which of the following physiological mechanisms will the researchers most likely observe among the surviving organisms in the lake?

Single-celled organisms will use various mechanisms to counteract the increased flow of water from cells to the environment.

A student analyzed a viral genome and found that the genome had the following nucleotide composition. • 28% adenine • 20% thymine • 35% cytosine • 17% guanine Which of the following best describes the structure of the viral genome?

Single-stranded Dna

The relative amount of DNA in a cell at various stages of the cell cycle is shown in Figure 1.Which of the following best describes how the amount of DNA in the cell changes during M phase?

The amount of DNA is halved as the cell divides into two daughter cells.

Based on the model of eukaryotic cell cycle regulation shown in the figure, which of the following best describes the effect of a drug that blocks the production of the mitotic cyclin?

The cell would be prevented from entering mitosis, and the cell would stop dividing.

Intravenous (IV) solutions administered to patients are normally isotonic. Which of the following is most likely if an IV of distilled water is administered to a patient?

The cells that are exposed to hypotonic solutions will expand as water moves osmotically into the cells from the blood

A team of biologists develops a new drug, and one team member hypothesizes that the drug is incapable of freely passing across the plasma membrane and requires the help of membrane proteins to enter cells. Alternatively, another biologist on the team hypothesizes that the drug can diffuse passively across the plasma membrane-like O2 and CO2 can. Which of the following, if true about the drug, best supports the alternative hypothesis that the new drug will exhibit simple diffusion across plasma membranes?

The drug is a small nonpolar molecule

Cancer cells behave differently than normal body cells. For example, they ignore signals that tell them to stop dividing. Which of the following conditions will most likely cause a normal body cell to become a cancer cell?

The environment contains mutagens that induce mutations that affect cell-cycle regulator proteins.

Which of the following characteristics of Figure 1 best shows that the fragment is RNA and not DNA?

The identity of each nitrogenous base

A researcher designs an experiment to investigate the effect of environmental temperature on the function of an enzyme. For each trial included in the experiment, the researcher will add the enzyme and its substrate to an aqueous buffer solution and then measure the amount of product formed over 20 minutes. Which of the following must remain the same for all trials of this experiment?

The initial concentration of the substrate

The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1. Which of the following outcomes will most likely result from the irreversible binding of GDP to the G protein.

The intracellular concentration of glycogen will increase.

Figure 1 shows a model of a signal transduction cascade, initiated by the binding of a ligand to the transmembrane receptor protein A. A DNA mutation changes the shape of the extracellular domain of transmembrane receptor protein A produced by the cell. Which of the following predictions is the most likely consequence of the mutation?

The molecule that normally binds to protein AA will no longer attach, deactivating the cellular response.

Which of the following statements best helps explain the reaction specificity of an enzyme?

The shape and charge of the substrates are compatible with the active site of the enzyme

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.

Which of the following best describes the structures of carbohydrates?

They occur as monomers, chains of monomers, and branched structures.

Which of the following statements best justifies the inclusion of test tubes 3 and 7 in the experiment?

They will show whether the isolated cellular contents have enzymatic activity.

The synthesis of protein or carbohydrate polymers always produces which of the following as a byproduct?

Water

Which of the following scientific questions is most relevant to the model represented in the figure above?

Which molecular substance is actively transported across the plasma membrane?

A feature of organic compounds NOT found in inorganic compounds is the presence of

carbon atoms covalently bonded to each other

Simple diffusion and facilitated diffusion are related in that both

depend on a concentration gradient

DNA replication occurs

during the S phase of the cell cycle

A student placed 20 tobacco seeds of the same species on moist paper towels in each of two petri dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both dishes. The dishes were examined after 7 days, and the opaque cover was permanently removed from dish A. Both dishes were returned to the light and examined again at 14 days. The following data were obtained. According to the results of this experiment, germination of tobacco seeds during the first week is

increased by exposure to light

Oxygen consumption can be used as a measure of metabolic rate because oxygen is

necessary for ATP synthesis by oxidative phosphorylation

All of the following cell components are found in prokaryotic cells EXCEPT

nuclear envelope

Which of the following statements best explains active and passive transport?

passive transport is the net movement of substances down a concentration gradient that doesn't require metabolic energy. active transport is the movement of substances up a concentration gradient that requires energy.

During respiration, most ATP is formed as a direct result of the net movement of

protons down a concentration gradient