which stage of mitosis is occurring when the nuclear envelope begins to disappear and the chromosomes begin to attach to the spindle that is forming a

HESI RN

Biology Test

1. During which stage of mitosis does the nuclear envelope begin to disappear and the chromosomes start attaching to the spindle forming along the cell's axis?

A. Prometaphase
B. Metaphase
C. Anaphase
D. Prophase

Correct answer: A

Rationale: The correct answer is A, Prometaphase. During prometaphase, the nuclear envelope disintegrates, and chromosomes start attaching to spindle fibers. In metaphase, chromosomes align in the middle of the cell. Anaphase is characterized by the separation of sister chromatids, and prophase involves the condensation of chromosomes and the beginning of spindle formation.

2. What are the nitrogenous bases of DNA?

A. Adenine, cytosine, guanine, and thymine
B. Adenine, guanine, and uracil
C. Adenine, guanine, and thymine
D. Adenine, cytosine, guanine, and uracil

Correct answer: A

Rationale: The correct answer is A: Adenine, cytosine, guanine, and thymine. These are the four nitrogenous bases found in DNA. Adenine pairs with thymine, and cytosine pairs with guanine, forming the complementary base pairs in the double helix structure of DNA. Choice B is incorrect because uracil is a nitrogenous base found in RNA, not DNA. Choice C is incorrect as it is missing cytosine, one of the four bases in DNA. Choice D is incorrect because uracil is not a nitrogenous base in DNA, and it also lacks thymine, which is essential for DNA structure.

3. Which of the following is a group of three RNA nucleotides?

A. A stop codon
B. A codon
C. An anticodon
D. tRNA

Correct answer: B

Rationale: The correct answer is B - A codon. A codon is a sequence of three RNA nucleotides that specifies a particular amino acid or a stop signal during protein synthesis. Choice A, a stop codon, is a sequence of three nucleotides that signals the termination of protein synthesis. Choice C, an anticodon, is a group of three nucleotides found in tRNA that pairs with the complementary codon in mRNA. Choice D, tRNA, stands for transfer RNA, which is a type of RNA that carries amino acids to the ribosome during protein synthesis.

4. During photosynthesis in green plants, light energy is captured and used to convert all except which of the following into oxygen and energy-rich organic compounds?

A. Minerals
B. Water
C. Carbon dioxide
D. Metals

Correct answer: D

Rationale: During photosynthesis in green plants, light energy is utilized to convert water and carbon dioxide into oxygen and energy-rich organic compounds like glucose. Minerals play a role in plant growth but are not directly converted during photosynthesis. Metals are not part of the photosynthesis process, making them the correct answer. Therefore, the correct choice is D. Choices A, B, and C are incorrect as minerals, water, and carbon dioxide are involved in the photosynthesis process.

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).