Unit 1 AP Bio review for final

A small protein is composed of 110 amino acids linked together in a chain. As shown in Figure 1, the first and last five amino acids in the chain are hydrophobic (have nonpolar and uncharged R-groups), whereas the remaining 100 amino acids are hydrophilic (have charged or polar R-groups). The nature of the R-group determines if the amino acid is hydrophobic or hydrophilic. A mutation results in the production of a version of the small protein that is only 105 amino acids long, as shown in Figure 2. Five of the hydrophobic amino acids are missing from one end of the chain. Which of the following best depicts the tertiary structures of the two proteins in water? The diagrams in the options are not drawn to the same scale as those in Figure 1 and Figure 2.

A

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

A

Which of the following best describes the formation of the bond shown in Figure 1

A covalent bond is formed between a carbon atom and a nitrogen atom along with the formation of H2O .

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.

Humans produce sweat as a cooling mechanism to maintain a stable internal temperature. Which of the following best explains how the properties of water contribute to this physiological process?

The high heat of vaporization of water allows the body to remove excess heat through a phase change of water from liquid to gas.

Which of the following is a catabolic process?

digestion of sucrose

Which of the following best describes the structures of carbohydrates?

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

High levels of certain plant nutrients in runoff can lead to rapid growth of algae (an algal bloom) in aquatic ecosystems. These algal blooms are generally followed by algal death and decomposition, which consumes large amounts of dissolved oxygen in the water and results in oxygen levels insufficient to support aerobic respiration. This process is known as eutrophication. The amount of algae present in a body of water can be estimated from the amount of chlorophyll a in a sample of the water. A researcher studying eutrophication collected samples at different times of the year in a freshwater ecosystem. The samples were analyzed for total nitrogen and chlorophyll a concentration (Figure 1) as well as total phosphorus and chlorophyll a concentration (Figure 2). Which of the following best explains how higher concentrations of nitrogen and phosphorus contribute to eutrophication?

Algae require nitrogen and phosphorus to build macromolecules, so higher concentrations of these nutrients can result in algal blooms.

A culture of Spirogyra (an autotrophic alga) is maintained in a water solution containing dissolved carbon dioxide and a source of phosphates but lacking nitrogen compounds. A researcher determines the rates of synthesis of several organic compounds found in the Spirogyra before and after several weeks in the water solution. Which of the following graphs best illustrates a likely result of the experiment?

B

Students conducted a controlled experiment to investigate whether sawdust provides enough nutrients to support plant growth. The students separated ten nearly identical sunflower seedlings into two groups. They grew the seedlings in the first group in potting soil and the seedlings in the second group in sawdust composed mostly of cellulose. After twenty days, the students recorded observations about the seedlings in each group. The students' observations are presented in the table. The observed differences between the groups most likely resulted from differences in the ability of the seedlings to produce which of the following monomers?

C

Describe the connection between anabolic and catabolic chemical reactions in a metabolic pathway.

Catabolic reactions produce energy and simpler compounds, whereas anabolic reactions involve the use of energy to make more complex compounds.

Bacteriophages are viruses that infect bacteria. In an experiment, bacteriophages were labeled with either radioactive phosphorus or radioactive sulfur. The labeled bacteriophages were incubated with bacteria for a brief amount of time and then removed. The infected bacteria cells were found to contain significant amounts of radioactive phosphorus but not radioactive sulfur. 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

Why is it impossible for humans to digest food that contains cellulose?

Human digestive enzymes cannot break down the β -1,4 glycosidic linkage in cellulose, which requires a special enzyme that is absent in humans.

Figure 1 is a diagram of water molecules at the air-water interface at the surface of a pond. Based on Figure 1, which of the following best describes how the properties of water at an air-water interface enable an insect to walk on the water's surface?

Hydrogen bonds between molecules at the surface of the water provide surface tension, which allows the water surface to deform but not break under the insect.

In the metabolism of cell, why is hydrolysis used?

Hydrolysis breaks down polymers.

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.

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

It forms hydrogen bonds.

A typical bag of fertilizer contains high levels of nitrogen, phosphorus, and potassium but trace amounts of magnesium and calcium. Which of the following best matches the fertilizer component with the molecule in which it will be incorporated by organisms in the area?

Nitrogen will be incorporated into nucleic acids.

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.

Compare and contrast saturated and unsaturated triglycerides.

Saturated triglycerides contain single bonds and are solids at room temperature, while unsaturated triglycerides contain double bonds and are liquids at room temperature.

Which of the following best describes the hydrolysis of carbohydrates?

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

High levels of certain plant nutrients in runoff can lead to rapid growth of algae (an algal bloom) in aquatic ecosystems. These algal blooms are generally followed by algal death and decomposition, which consumes large amounts of dissolved oxygen in the water and results in oxygen levels insufficient to support aerobic respiration. This process is known as eutrophication. The amount of algae present in a body of water can be estimated from the amount of chlorophyll a in a sample of the water. A researcher studying eutrophication collected samples at different times of the year in a freshwater ecosystem. The samples were analyzed for total nitrogen and chlorophyll a concentration (Figure 1) as well as total phosphorus and chlorophyll a concentration (Figure 2). Which of the following describes the relationship between the amount of chlorophyll a in a water sample and the concentration of nitrogen in that sample?

The concentrations of nitrogen and chlorophyll are directly correlated.

Figure 1 represents a common process that occurs in organisms. Which of the following is an accurate description of the process shown in Figure 1 ?

The formation of a covalent peptide bond in a dehydration synthesis reaction

Which of the following best describes how amino acids affect the tertiary structure of a protein?

The interactions of the different R -groups with other R -groups and with their environment determine the tertiary structure of the protein.

A mutation in the gene coding for a single-polypeptide enzyme results in the substitution of the amino acid serine, which has a polar R group, by the amino acid phenylalanine, which has a nonpolar R group. When researchers test the catalysis of the normal enzyme and the mutated enzyme, they find that the mutated enzyme has much lower activity than the normal enzyme does. Choose the best explanation for the lower activity.

The substitution altered the secondary and tertiary structure of the enzyme so that the mutated enzyme folds into a different shape than the normal enzyme does.

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 polar. Water molecules have the ability to form hydrogen bonds with each other and with the walls of the xylem.

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

carbon atoms covalently bonded to each other

Dehydration synthesis leads to the formation of what?

polymers

Cellulose and starch are examples of ________.

polysaccharides

Which of the following is a function of proteins in cells?

structure

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.

what are phospholipids used for?

the plasma membrane of animal cells

The α-helix and the β-pleated sheet are part of which protein structure?

the secondary structure

Which fat serves as an animal's major form of energy storage?

triglycerides