at the beginning of meiosis how many chromosomes does the diploid parent cell have

HESI RN

Biology Test

1. At the beginning of meiosis, how many chromosomes does the diploid parent cell have?

A. 23
B. 24
C. 46
D. 54

Correct answer: C

Rationale: The correct answer is C: 46. At the start of meiosis, the diploid parent cell contains 46 chromosomes. During meiosis, the number of chromosomes is halved, resulting in each gamete having 23 chromosomes. Choice A (23) is incorrect because that is the number of chromosomes in a human gamete, not the parent cell. Choice B (24) and Choice D (54) are also incorrect as they do not reflect the correct number of chromosomes in a diploid parent cell at the beginning of meiosis.

2. Which of the following correctly identifies the two types of cells?

A. Mitosis and meiosis
B. Mitochondrion and chloroplast
C. Genotype and phenotype
D. Prokaryotic and eukaryotic

Correct answer: D

Rationale: The correct answer is D: Prokaryotic and eukaryotic. Cells are classified into two major types: prokaryotic, which lack a nucleus, and eukaryotic, which have a defined nucleus and other membrane-bound organelles. Choice A, mitosis and meiosis, refers to cell division processes. Choice B, mitochondrion and chloroplast, are cell organelles involved in energy production and photosynthesis, respectively. Choice C, genotype and phenotype, relate to genetic characteristics and physical traits, not cell types.

3. Water is a polar molecule that can be:

A. cohesive and corrosive
B. cohesive and adhesive
C. electrostatic and ionic
D. repellent and attractive

Correct answer: B

Rationale: Water is a polar molecule due to an uneven distribution of electrons, allowing it to form hydrogen bonds. This property makes water both cohesive (attracted to itself) and adhesive (attracted to other substances). Choice A is incorrect because water is not corrosive; rather, it is a solvent. Choices C and D are incorrect as they do not describe the cohesive and adhesive properties of water.

4. During which stage of photosynthesis is solar energy converted to chemical energy?

A. During phosphate synthesis
B. During light reactions
C. During the Krebs cycle
D. During the Calvin cycle

Correct answer: B

Rationale: The correct answer is B, during the light reactions. During the light reactions of photosynthesis, solar energy is absorbed by chlorophyll and converted into chemical energy in the form of ATP and NADPH. Choice A is incorrect as phosphate synthesis does not involve the conversion of solar energy. Choice C, the Krebs cycle, is a part of cellular respiration, not photosynthesis. Choice D, the Calvin cycle, is responsible for fixing carbon dioxide into carbohydrates and does not involve the direct conversion of solar energy to chemical energy.

5. Which of the following is not one of the four nitrogenous bases that make up the DNA structure?

A. Adenine
B. Guanine
C. Uracil
D. Thymine

Correct answer: C

Rationale: The correct answer is C: Uracil. Uracil is found in RNA, not DNA. The four nitrogenous bases in DNA are adenine, thymine, cytosine, and guanine. Choice A, Adenine, is a nitrogenous base in DNA. Choice B, Guanine, is another nitrogenous base in DNA. Choice D, Thymine, is also one of the four nitrogenous bases in DNA. Therefore, the correct answer is Uracil (Choice C).