BIO REVIEW

If 30% of the nucleotides in a single-stranded RNA molecule are adenine, then what percent are expected to be thymine?

0%

To investigate the ability of various enzymes to digest gelatin, a group of students set up an assay involving camera film. The camera film contains gelatin and appears black when exposed to light but turns clear as the gelatin gets broken down. The students incubated pieces of exposed camera film in test tubes, each containing one of three different enzyme solutions (trypsin, lipase, or amylase) as indicated in Figure 1. The students recorded the time it took for the enzymes to digest the gelatin in each test tube, turning the film from black to clear. Which of the following would be the most appropriate control for this experiment?

A test tube containing a piece of exposed camera film submerged in water

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

An endoplasmic reticulum, mitochondria, and a nucleus

In the first step of an experiment, rat liver cells were exposed for 5 minutes to amino acids labeled with a radioactive isotope. The cells were then washed to stop any further incorporation of radioactive amino acids. The cells were sampled periodically thereafter, and the radioactivity of a certain protein (protein X) was measured in various cell components, as shown below. What is the most likely identity of protein X ?

An enzyme that participates in the degradation and recycling of cell components

The following question refers to the following diagram. Match the labeled organelle with its function. Site of glucose synthesis

B (endoplasmic reticulum)

The following molecule has a chemical formula of C6H12O6 and was synthesized during photosynthesis. What classification would this molecule belong to?

Carbohydrate

Which of the following describes the most likely location of cholesterol in an animal cell?

Embedded in the plasma membrane

The illustration shows the active transport of hydrogen ions through a membrane protein. Which of the following best predicts the effect of not having ATP available to supply energy to this process?

H+ ions will stop moving through the protein.

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

Polypeptides are continuously being formed and degraded. One of these processes is shown. Which statement is the most accurate description of the reaction shown in Figure 1?

It represents a polypeptide chain that is broken down through a hydrolysis reaction.

Contains hydrolytic enzymes associated with the intracellular digestion of macromolecules

Lysosome

Scientists examined the folded structure of a purified protein resuspended in water and found that amino acids with nonpolar R groups were primarily buried in the middle of the protein, whereas amino acids with polar R groups were primarily on the surface of the protein. Which of the following best explains the location of the amino acids in the folded protein?

Nonpolar R groups that cannot form hydrogen bonds with water are pushed into the middle of the protein.

Which of the following conclusions is most clearly supported by the representations of nucleic acid #1 and nucleic acid #2 ?

Nucleic acid #1 contains adenine-thymine base pairs, whereas nucleic acid #2 does not.

The molecular structures of linoleic acid and palmitic acid, two naturally occurring substances, are shown in the figure. 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.

A prokaryotic cell has which of the following?

Plasma membrane

Carbon dioxide most likely enters a cell through which of the following processes?

Simple diffusion through the membrane

Which of the following organelles modifies and packages for secretion the materials produced by the ribosomes?

The Golgi apparatus

Which of the following best describes the hydrolysis of carbohydrates?

The addition of a water molecule breaks a covalent bond between sugar monomers.

A student used a microscope to observe a wet-mount slide of red onion epidermal cells that were suspended in a 1% NaCl solution. The student then added a 15% NaCl solution to the slide and observed the changes that occurred. The student's observations are represented in Figure 1. Which of the following most directly explains the changes in the cells?

The movement of water from the central vacuoles of the cells into the solution

Water and ammonia interact to form hydrogen bonds, as represented in the figure. Which statement best helps explain the formation of the hydrogen bond represented in the figure?

The nitrogen has a partial negative charge, and the hydrogen attached to the oxygen has a partial positive charge.

The diagram above represents a typical rod-shaped bacterium. Which of the following best describes a feature shown in the diagram that is unique to archaea and bacteria?

The organism does not have a nuclear membrane surrounding its genetic material.

The following questions refer to an experiment in which a dialysis-tubing bag is filled with a mixture of 3% starch and 3% glucose and placed in a beaker of distilled water, as shown below. After 3 hours, glucose can be detected in the water outside the dialysis-tubing bag, but starch cannot. From the initial conditions and results described, which of the following is a logical conclusion?

The pores of the bag are larger than the glucose molecules but smaller than the starch molecules.

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.

The diagram shows how water can adhere to the xylem in the stems of plants, which contributes to water movement in the plant. Which of the following best explains how water is able to move upward from the roots of a plant, through its xylem in the stem, and out to the leaves?

Water and the xylem are both nonpolar. Water molecules have the ability to form hydrogen bonds with one another but not with the xylem walls.