Biology HESI A2 Practice Test

Correct Answer: C

Rationale: The correct answer is C (bb) because tan fur is the recessive phenotype controlled by the tan allele (b). Since the black allele (B) exhibits complete dominance, a dog must have two copies of the tan allele (bb) to have a tan fur phenotype. Choice A (BB) and B (Bb) would result in black fur, not tan. Choice D (Not enough information) is incorrect as the question provides enough information to determine the correct genotype based on the phenotype given.

Correct Answer: A

Rationale: The correct answer is A: Atmosphere. The atmosphere is the layer of gases that surrounds a planet. It consists of different layers, including the stratosphere and troposphere mentioned in the other choices. The biosphere refers to the regions on Earth where living organisms exist, not the gases surrounding the planet. Therefore, the correct term for the mixture of gases surrounding a planet is the atmosphere.

Correct Answer: A

Rationale: Tonicity refers to the movement of water across a semipermeable membrane based on the concentration of solutes. Water moves from an area of low solute concentration to high solute concentration to achieve balance. Therefore, the correct answer is A: Water. Solute (choice B) is incorrect as tonicity is not about the movement of solute particles. Cells (choice C) is incorrect as tonicity affects the movement of water, not cells themselves. "None of the above" (choice D) is incorrect as tonicity specifically involves the movement of water molecules.

Correct Answer: B

Rationale: The scientist needs 12mL, which is equivalent to 0.012L. Since the bottle holds 12L, it contains more than enough solution. Therefore, choice B is correct. Choice A is incorrect because the scientist needs less than the total amount in the bottle. Choice C is incorrect because the scientist actually has more than enough. Choice D is also incorrect as the scientist does have more than required.

Correct Answer: B

Rationale: The correct answer is B: heterozygous. In a heterozygous situation, an individual carries two different alleles for a particular gene, resulting in different forms of the allele. This creates genetic diversity and can lead to varying phenotypic expressions. The term phenotype (A) refers to the physical characteristics of an organism, not specifically related to different forms of alleles. Homolog (C) refers to chromosomes that are similar in structure and function but not necessarily different forms of alleles. Homozygous (D) describes a situation where an individual carries two identical alleles for a gene, which does not involve different forms of alleles.