biology midterm unit 1

Used to carry the genetic code

nucleic acids

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.

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

Which of the following statements best describes how molecules released by the fish become nutrients for the plants?

The ammonia molecules released by the fish are converted by the bacteria to nitrates, which are used by the plants to make proteins and nucleic acids.

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

The identity of each nitrogenous base

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 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.

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.

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

carbon atoms covalently bonded to each other

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

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

H (Left) OH (middle) OH (right)

The observed differences between the groups most likely resulted from differences in the ability of the seedlings to produce which of the following monomers?

HRO and HOP

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.

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

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.

Which of the following statements about glucose, galactose, and fructose is most likely true?

The carbohydrates have different properties because they have different arrangements of carbon, hydrogen, and oxygen atoms.

Which of the following best describes the effect of a greater number of cysteine amino acids on the stability of the proteins?

The change leads to increased protein stability because of an increased number of S-S bonds in the tertiary structure of the proteins.

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 the structures of carbohydrates?

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

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

water