EXO Baes <3
Which of the following correctly illustrates a dipeptide and an amino acid in the optimal position to form a tripeptide?
(A) [MISS]
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 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) [cube with 10 micro-meters as side length]
Five new species of bacteria were discovered in Antarctic ice core samples. The nucleotide (base) sequences of rRNA subunits were determined for the new species. The table below shows the number of nucleotide differences between the species. Which of the following phylogenetic trees is most consistent with the data?
(C) [3, 4, 2, 1, 5]
A pathogenic bacterium has been engulfed by a phagocytic cell as part of the nonspecific (innate) immune response. Which of the following illustrations best represents the response?
(C) [Lysosomes]
When DNA replicates, each strand of the original DNA molecule is used as a template for the synthesis of a second, complementary strand. Which of the following figures most accurately illustrates enzyme-mediated synthesis of new DNA at a replication fork?
(D) [In at 3' Out at 5']
Lactose digestion in E. coli begins with its hydrolysis by the enzyme E-galactosidase. The gene encoding E-galactosidase, lacZ, is part of a coordinately regulated operon containing other genes required for lactose utilization. Which of the following figures correctly depicts the interactions at the lac operon when lactose is NOT being utilized? (The legend below defines the shapes of the molecules illustrated in the options.)
(D) [Repressor Protein]
Which of the following best describes the mechanism behind the change in beak size in the finch population?
A change in gene frequencies in the finch population due to selective pressure from the environmental change
During aerobic cellular respiration, oxygen gas is consumed at the same rate as carbon dioxide gas is produced. In order to provide accurate volumetric measurements of oxygen gas consumption, the experimental setup should include which of the following?
A substance that removes carbon dioxide gas
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 statements best supports the claim that organisms share fundamental processes as a result of evolution?
All organisms share a genetic code organized into triplet codons, making it possible for one organism to express a gene from another organism.
The most probable cause for the difference in mean stem length between plants in dish A and plants in dish B is which of the following?
Elongation of seedlings in response to the lack of light
The diagram above shows the progression of ecological events after a fire in a particular ecosystem. Based on the diagram, which of the following best explains why the oak trees are later replaced by other trees?
Eventually the other trees grow taller than the oak trees and form a dense canopy that shades the understory.
Which of the following statements might best explain the increase in average beak size in the finch population during the drought?
Finches with bigger beaks are better able to crack thick-walled seeds and produce more surviving offspring.
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.
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.
The area covered by tropical rain forest is reduced by millions of hectares per year due to agriculture and logging. Which of the following best describes a likely result of tropical rain forest deforestation?
Populations of plants and animals will decrease as more rain forest disappears, leading to a decrease in biodiversity.
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.
A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds. Which of the following procedures was most likely followed to determine the change in beak size?
The beak size in a large number of finches was measured every year from 1981 to 1987.
The following is a food web for a meadow habitat that occupies 25.6 km2. The primary producers' biomass is uniformly distributed throughout the habitat and totals 1,500 kg/km2. Developers have approved a project that will permanently reduce the primary producers' biomass by 50 percent and remove all rabbits and deer. Which of the following is the most likely result at the completion of the project?
The biomass of coyotes will be dramatically reduced.
Paramecia are unicellular protists that have contractile vacuoles to remove excess intracellular water. In an experimental investigation, paramecia were placed in salt solutions of increasing osmolarity. The rate at which the contractile vacuole contracted to pump out excess water was determined and plotted against osmolarity of the solutions, as shown in the graph. Which of the following is the correct explanation for the data?
The contraction rate increases as the osmolarity decreases because the amount of water entering the paramecia by osmosis increases.
Arctic foxes typically have a white coat in the winter. In summer, when there is no snow on the ground, the foxes typically have a darker coat. Which of the following is most likely responsible for the seasonal change in coat color?
The decrease in the amount of daylight in winter causes a change in gene expression, which results in the foxes growing a lighter-appearing coat.
In most freshwater fish, nitrogenous waste is primarily excreted as ammonia, which is highly soluble in water and is toxic at low concentrations. In terrestrial mammals, ammonia is converted to urea before it is excreted. Urea is also highly soluble in water but is less toxic than ammonia at low concentrations. Which of the following best explains why freshwater fish do not convert ammonia to urea for excretion?
The dilution of ammonia by direct excretion into freshwater conserves energy.
The biologist discovered that from 1988 to 1993, the average beak size declined to pre-1981 levels. The reversal in beak size from 1988 to 1993 was most likely related to which of the following events?
The end of the drought
Which of the following best supports the hypothesis that the difference in leaf color is genetically controlled?
The existence of yellow-leaved seedlings as well as green-leaved ones on day 14 in dish B
According to the data, the mice at 10C demonstrated greater oxygen consumption per gram of tissue than did the mice at 25C. This is most likely explained by which of the following statements?
The mice at 10C had a higher rate of ATP production than the mice at 25C
By discharging electric sparks into a laboratory chamber atmosphere that consisted of water vapor, hydrogen gas, methane, and ammonia, Stanley Miller obtained data that showed that a number of organic molecules, including many amino acids, could be synthesized. Miller was attempting to model early Earth conditions as understood in the 1950s. The results of Miller's experiments best support which of the following hypotheses?
The molecules essential to life today could have formed under early Earth conditions.
The FtsZ protein is present in prokaryotes and in chloroplasts. The protein is structurally and functionally similar to tubulin proteins of eukaryotic cells. Which of the following is a likely conclusion to draw from this information?
Tubulin genes are evolutionarily derived from the gene that codes for the FtsZ protein.
A sample of human blood was placed in a test tube containing a physiological saline solution (0.9% sodium chloride). This type of solution is often used intravenously to quickly rehydrate patients. A drop of the blood from the test tube was placed on a slide and red blood cells (RBCs) were observed under a microscope. Three possible outcomes are diagrammed below.
View 2 because the rate of water movement into the RBCs equals the rate of water movement out of the cells
During the infection cycle for a typical retrovirus, such as HIV, which uses RNA as genetic material, the genetic variation in the resulting population of new virus particles is very high because of
errors introduced in the DNA molecule through reverse transcription
According to the results of this experiment, germination of tobacco seeds during the first week is
increased by exposure to light
According to the data, the crickets at 25C have greater oxygen consumption per gram of tissue than do the crickets at 10C. This trend in oxygen consumption is the opposite of that in the mice. The difference in trends in oxygen consumption among crickets and mice is due to their
mode of internal temperature regulation
Additional observations were made on day 21, and no yellow-leaved seedlings were found alive in either dish. This is most likely because
yellow-leaved seedlings were unable to convert light energy to chemical energy
