select the strand of dna that would match this segment acttgca

HESI A2

Biology HESI A2 Practice Test

1. Select the strand of DNA that would match this segment: ACTTGCA

A. TGAACGT
B. GACCATG
C. ACTTGCA
D. None of the above

Correct answer: A

Rationale: The correct match for the DNA segment ACTTGCA is TGAACGT. In DNA, adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G). Therefore, the complementary strand to ACTTGCA should be TGAACGT, making choice A the correct answer. Choice B (GACCATG) does not follow the base pairing rules; hence, it is incorrect. Choice C (ACTTGCA) is the original segment, not its complementary strand. Choice D is incorrect as well because a matching strand does exist.

2. Why is DNA important for metabolic activities of the cell?

A. It controls the synthesis of enzymes.
B. It stabilizes the cell wall.
C. It initiates cell division.
D. It prevents diffusion of nutrients.

Correct answer: A

Rationale: The correct answer is A. DNA plays a crucial role in metabolic activities by controlling the synthesis of enzymes. Enzymes are the biological catalysts that regulate and facilitate metabolic reactions within the cell. Choice B is incorrect because DNA is not involved in stabilizing the cell wall; that role is usually associated with other components like the cell membrane. Choice C is incorrect as cell division is primarily regulated by different processes and molecules, not directly by DNA. Choice D is incorrect because DNA is not related to preventing the diffusion of nutrients; instead, it is involved in coding for proteins that aid in various cellular functions.

3. Which of the following is true of the Krebs cycle?

A. It is a redox reaction involving proteins produced during glycolysis
B. It is a redox reaction involving sugars produced during glycolysis
C. Protons are passed along a gradient to produce ATP
D. It is also known as the glycolic acid cycle

Correct answer: B

Rationale: The Krebs cycle, also known as the citric acid cycle, involves a series of redox reactions that occur in the mitochondria. The cycle begins with the oxidation of acetyl CoA, which is derived from the breakdown of sugars produced during glycolysis. These sugars are broken down further in the Krebs cycle to produce ATP and reduce electron carriers such as NADH and FADH2. The cycle does not involve proteins produced during glycolysis. Protons are not passed along a gradient to produce ATP directly in the Krebs cycle; rather, they are used in the electron transport chain to generate ATP. The Krebs cycle is not known as the glycolic acid cycle; glycolysis is the metabolic pathway that produces pyruvate from glucose.

4. Which word or phrase fits best in the following sentence? Cathy asked many questions the first time she ___________ at the hospital.

A. volunteered
B. volunteering
C. was volunteered
D. volunteer

Correct answer: A

Rationale: The correct word to use in this sentence is 'volunteered' as it indicates an action that Cathy did in the past. The sentence suggests that Cathy was engaging in volunteering at the hospital for the first time, so the past tense form 'volunteered' is the most appropriate choice. Choice B ('volunteering') is incorrect because it is the present participle form and does not fit the past tense context of the sentence. Choice C ('was volunteered') is passive voice and implies that someone else made Cathy volunteer, which is not the intended meaning. Choice D ('volunteer') is incorrect as it is the base form of the verb and does not match the past tense requirement of the sentence.

5. Which, if any, of the following statements are true?

A. Water boils at approximately 100°C (212°F) at standard atmospheric pressure
B. The boiling point is the temperature at which the vapor pressure is higher than the atmospheric pressure around the water
C. Water boils at a lower temperature in areas of lower pressure
D. A and C are true

Correct answer: D

Rationale: Both statements A and C are true. Water indeed boils at approximately 100°C (212°F) at standard atmospheric pressure. However, water boils at a lower temperature in areas of lower pressure due to the decreased atmospheric pressure, which affects the vapor pressure and boiling point of water. Statement B is incorrect because the boiling point is the temperature at which the vapor pressure equals the external pressure (atmospheric pressure in this case), not when it is higher.