the correct answer is d heterozygous traits contain one dominant and one recessive form of the gene which of the following is true of homozygous trait

HESI A2

Biology HESI A2 Practice Test

1. Which of the following is true of homozygous traits?

A. They are haploid
B. They are denoted AA
C. They are denoted aa
D. They are denoted Aa

Correct answer: B

Rationale: Homozygous traits have two identical forms of the gene, either both dominant (AA) or both recessive (aa). Therefore, choices B and C are true for homozygous traits. Choice A is incorrect because being haploid refers to having a single set of chromosomes, not necessarily homozygous traits. Choice D is incorrect as homozygous traits have identical alleles, so they are not denoted as Aa.

2. Which is true of gametes?

A. They are diploid cells
B. They are haploid cells
C. They are somatic
D. A & C are true

Correct answer: B

Rationale: Gametes are sex cells (sperm and eggs) that are involved in sexual reproduction. They are haploid cells, meaning they have half the number of chromosomes (n) compared to diploid cells. This is necessary for the formation of a diploid zygote when two gametes unite during fertilization. Somatic cells are non-reproductive cells in the body, so they are not gametes. Choice A is incorrect because gametes are not diploid but haploid. Choice C is incorrect because gametes are not somatic cells.

3. Why does cytokinesis happen?

A. DNA can duplicate
B. Organelles can convert energy
C. Bacteria can be killed
D. Daughter cells can divide

Correct answer: D

Rationale: Cytokinesis happens at the end of mitosis to physically separate the newly formed daughter cells. This allows the cell to divide into two separate daughter cells, each containing a complete set of genetic material (DNA) and organelles. The purpose of cytokinesis is to ensure that each daughter cell receives the necessary components to function independently. Choices A, B, and C are incorrect because cytokinesis does not directly involve DNA duplication, organelles converting energy, or killing bacteria.

4. Which of the following types of hormones can diffuse through the cell membrane to bind to receptors inside the cell and stimulate a chemical response to a target cell?

A. fat-soluble hormones
B. amino acid derivatives
C. hydrophilic hormones
D. water-soluble hormones

Correct answer: A

Rationale: The correct answer is A: fat-soluble hormones. Fat-soluble hormones are able to diffuse through the cell membrane to bind to receptors inside the cell. This is because they are lipophilic, allowing them to cross the lipid bilayer easily. Once inside the cell, fat-soluble hormones can directly affect gene expression or cell function. Choice B, amino acid derivatives, and choice C, hydrophilic hormones, are not able to diffuse through the cell membrane as they are not lipophilic. Therefore, they cannot bind to receptors inside the cell. Choice D, water-soluble hormones, also cannot diffuse through the cell membrane as it is hydrophilic, making it unable to reach receptors inside the cell.

5. 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.