the fur color in a population of dogs is controlled by two alleles black b and tan b the black allele exhibits complete dominance if the phenotype of

HESI A2

Biology HESI A2 Practice Test

1. The fur color in a population of dogs is controlled by two alleles: black (B) and tan (b). The black allele exhibits complete dominance. If the phenotype of the dog is tan fur, what is its genotype?

A. BB
B. Bb
C. bb
D. Not enough information

Correct answer: C

Rationale: The correct answer is C: "bb." Since tan fur is the recessive trait controlled by the allele 'b,' the only possible genotype for a dog with tan fur is 'bb.' If a dog had the genotype 'BB' or 'Bb,' the dominant trait (black fur) would be expressed, not tan fur. Choice D, 'Not enough information,' is incorrect because based on the information provided, we can deduce the genotype of a dog with tan fur.

2. How are lipids different from other organic molecules?

A. They are indivisible.
B. They are not water soluble.
C. They contain zinc.
D. They form long proteins.

Correct answer: B

Rationale: The correct answer is B: 'They are not water soluble.' Lipids are not water-soluble, which distinguishes them from other organic molecules. Choice A is incorrect because lipids are not indivisible; they can be broken down into fatty acids and glycerol. Choice C is incorrect as lipids do not necessarily contain zinc; they are a diverse group of molecules. Choice D is incorrect because lipids do not form long proteins; proteins are made up of amino acids, not lipids.

3. What are the two catabolic pathways that lead to cellular energy production?

A. Fermentation and internal respiration
B. Fermentation and external respiration
C. Fermentation and cellular respiration
D. Fermentation and anaerobic respiration

Correct answer: C

Rationale: The correct answer is 'Fermentation and cellular respiration.' Fermentation is an anaerobic catabolic process that occurs in the absence of oxygen, producing limited amounts of ATP. Cellular respiration, on the other hand, is the aerobic catabolic pathway that occurs in the presence of oxygen and is the most efficient way of producing ATP. Choices A, B, and D are incorrect because internal respiration, external respiration, and anaerobic respiration are not the correct pathways leading to cellular energy production.

4. 72 chromosomes undergo meiosis. How many chromosomes will be in each gamete?

A. 18
B. 36
C. 72
D. 144

Correct answer: A

Rationale: During meiosis, the number of chromosomes is halved in each gamete. Since 72 chromosomes undergo meiosis, each gamete will contain half of that number, which is 36 chromosomes. Therefore, the correct answer is 18 chromosomes in each gamete. Choice B (36 chromosomes) is incorrect because it represents the total number of chromosomes that undergo meiosis, not the number in each gamete. Choice C (72 chromosomes) is incorrect as it represents the initial number of chromosomes, not the number in each gamete after meiosis. Choice D (144 chromosomes) is incorrect as it doubles the initial number of chromosomes, which is not the outcome of meiosis.

5. Which of the following is the structure of the male reproductive system that stores spermatozoa during the maturation process?

A. vas deferens
B. scrotum
C. epididymis
D. testicular artery

Correct answer: C

Rationale: The epididymis is the structure of the male reproductive system that stores spermatozoa during the maturation process. Sperm cells produced in the testes move to the epididymis, where they mature and become motile before being ejaculated. The vas deferens is responsible for transporting mature sperm to the urethra during ejaculation, the scrotum holds the testes and helps regulate their temperature for sperm production, and the testicular artery supplies blood to the testes. Therefore, choices A, B, and D are incorrect as they do not play a direct role in storing spermatozoa during the maturation process.