which of the following is often referred to as the powerhouse of the cell

HESI RN

Biology Practice Test

1. Which of the following is often referred to as the powerhouse of the cell?

A. Nucleus
B. Chromatin
C. Mitochondria
D. Ribosomes

Correct answer: C

Rationale: Mitochondria are known as the powerhouse of the cell because they generate most of the cell's supply of ATP, which is the energy currency used for various cellular processes. The nucleus (Choice A) is the control center of the cell, housing genetic material. Chromatin (Choice B) is a complex of DNA and proteins within the nucleus. Ribosomes (Choice D) are responsible for protein synthesis and not the primary energy production in the cell.

2. What is the difference between DNA and RNA?

A. RNA has an extra Phosphate group
B. DNA has one less oxygen than RNA
C. RNA has one less oxygen than DNA
D. DNA has an extra sugar molecule

Correct answer: B

Rationale: The correct answer is B. DNA has one less oxygen atom in its sugar molecule (deoxyribose) compared to RNA, which has a ribose sugar. Choice A is incorrect because RNA does not have an extra phosphate group. Choice C is incorrect as RNA actually has one more oxygen atom than DNA. Choice D is incorrect as DNA and RNA have different sugar molecules, with DNA having deoxyribose and RNA having ribose.

3. What is the liquid found inside the cell?

A. Plasma membrane
B. Cilia
C. Cytoplasm
D. Cytosol

Correct answer: D

Rationale: The correct answer is D, Cytosol. Cytosol is the liquid component of the cytoplasm where various cellular processes occur. Choices A, B, and C are incorrect because the plasma membrane is the outer boundary of the cell, cilia are hair-like structures on the cell surface, and cytoplasm is the jelly-like substance that contains organelles within the cell, not the liquid inside the cell.

4. The term pleiotropy is best defined as which of the following?

A. A situation in which one gene remains unexpressed
B. One gene influencing multiple, seemingly unrelated phenotypic traits
C. Two genes affected by a single allele
D. A condition in which multiple genes are missing

Correct answer: B

Rationale: Pleiotropy is best defined as one gene influencing multiple, seemingly unrelated phenotypic traits. This phenomenon showcases the multifunctionality of genes, where a single gene can have effects on various aspects of an organism's phenotype. Choices A, C, and D do not accurately capture the concept of pleiotropy. Option A refers to gene expression, not pleiotropy. Option C describes genetic interactions but not in the context of pleiotropy. Option D talks about missing genes, which is unrelated to the definition of pleiotropy.

5. Binary fission is a type of asexual reproduction. Which of the following occurs during the binary fission process?

A. The chromosomes bind to the plasma membrane
B. The chromosomes attach to the spindle formed along the axis
C. The chromosomes gather in the center of the cell
D. The chromosomes begin to separate

Correct answer: A

Rationale: The correct answer is A. In binary fission, the chromosomes bind to the plasma membrane before the cell splits into two. This initial step ensures that each daughter cell receives a complete set of genetic material. Choice B is incorrect because the spindle apparatus is characteristic of eukaryotic cell division (mitosis), not prokaryotic binary fission. Choice C is incorrect as chromosomes do not necessarily gather in the center of the cell during binary fission. Choice D is incorrect because the chromosomes do not begin to separate in binary fission; they replicate and then move to opposite ends of the cell before division.