which cell structure is responsible for efficiently packaging dna into a small volume to fit into the nucleus of a cell and protect the dna structure

HESI RN

Biology Test

1. Which cell structure is responsible for efficiently packaging DNA into a small volume to fit into the nucleus of a cell and protect the DNA structure and sequence?

A. Golgi apparatus
B. Chromatin
C. Smooth endoplasmic reticulum
D. Mitochondria

Correct answer: B

Rationale: The correct answer is B: Chromatin. Chromatin is responsible for packaging DNA into a more compact, dense shape to fit into the nucleus of a cell. This compact packaging helps protect the DNA structure and regulate gene expression. The Golgi apparatus is involved in modifying, sorting, and packaging proteins. The smooth endoplasmic reticulum is involved in lipid metabolism and detoxification. Mitochondria are known as the powerhouse of the cell, producing energy in the form of ATP.

2. A water molecule contains two types of atoms that are covalently bonded. Which of the following makes up a water molecule?

A. One hydrogen atom and one oxygen atom
B. One hydrogen atom and two oxygen atoms
C. Two hydrogen atoms and two oxygen atoms
D. Two hydrogen atoms and one oxygen atom

Correct answer: D

Rationale: The correct answer is D: Two hydrogen atoms and one oxygen atom. A water molecule consists of two hydrogen atoms covalently bonded to one oxygen atom. This forms a stable structure known as H2O. Choice A is incorrect as water molecule contains two hydrogen atoms. Choices B and C are incorrect as they do not reflect the correct composition of a water molecule.

3. What is the composition of the cellular membrane?

A. A bilayer of phospholipid molecules
B. A single layer of phospholipid molecules
C. Proteins that act as transport highways
D. Carbohydrates

Correct answer: A

Rationale: The cellular membrane is primarily composed of a phospholipid bilayer, which consists of two layers of phospholipid molecules. These molecules have a hydrophilic (water-attracting) head and hydrophobic (water-repelling) tail, creating a barrier that separates the internal cellular environment from the external surroundings. While proteins are embedded within this bilayer and act as transport channels, receptors, and structural support, carbohydrates are found on the outer surface of the membrane for cell recognition and signaling purposes. Therefore, the correct answer is a bilayer of phospholipid molecules.

4. Which of the following is not found in a prokaryotic cell?

A. Plasma membrane
B. Cytoplasm
C. Nucleus
D. Ribosomes

Correct answer: C

Rationale: The correct answer is C, 'Nucleus.' Prokaryotic cells do not have a defined nucleus, unlike eukaryotic cells. The plasma membrane, cytoplasm, and ribosomes are all components found in prokaryotic cells. The plasma membrane surrounds the cell and regulates what enters and exits, the cytoplasm is the gel-like substance that fills the cell, and ribosomes are responsible for protein synthesis.

5. Prophase is the first stage of mitosis. Which of the following best describes chromosomes during this stage?

A. They are gathered on either side of the separating cell
B. They are all aligned along the metaphase plate
C. They are attached to the spindle
D. They are visibly separate

Correct answer: D

Rationale: The correct answer is D. During prophase, the chromosomes condense and become visible as distinct structures under a microscope. Choice A is incorrect as chromosomes are not gathered on either side of the separating cell during prophase. Choice B is incorrect because chromosomes align along the metaphase plate during the subsequent stage, metaphase. Choice C is incorrect as chromosomes become attached to the spindle fibers during prometaphase, the stage following prophase.