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101.

Which molecule forms the backbone of the DNA double helix?

Glucose

Amino acids

Nucleotides

Fatty acids

Explanation Comments

Answer: Nucleotides

Explanation:

DNA is composed of nucleotides, each consisting of a phosphate group, a sugar molecule (deoxyribose), and a nitrogenous base, forming the backbone of the double helix.

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102.

Which organelle is primarily involved in the synthesis of ATP in plant cells?

Ribosome

Chloroplast

Mitochondrion

Lysosome

Explanation Comments

Answer: Chloroplast

Explanation:

Chloroplasts in plant cells capture light energy and convert it into chemical energy in the form of ATP and glucose through the process of photosynthesis.

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103.

What is the role of lysosomes in the cell?

Digestion and waste removal

Protein synthesis

Cell division

Energy production

Explanation Comments

Answer: Digestion and waste removal

Explanation:

Lysosomes contain hydrolytic enzymes that break down waste materials and cellular debris, aiding in digestion and waste removal.

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104.

What is the main purpose of the sodium-potassium pump in cellular membranes?

To maintain cell membrane potential

To synthesize proteins

To facilitate diffusion of sodium and potassium

To generate ATP

Explanation Comments

Answer: To maintain cell membrane potential

Explanation:

The sodium-potassium pump actively transports sodium ions out of the cell and potassium ions into the cell, maintaining the electrochemical gradient and membrane potential.

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105.

Which phase of the cell cycle is characterized by the cell growing and carrying out normal functions?

S phase

G2 phase

M phase

G1 phase

Explanation Comments

Answer: G1 phase

Explanation:

The G1 phase is the first stage of interphase, during which the cell grows and performs its normal metabolic functions.

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106.

What type of bond holds the two strands of DNA together?

Covalent bonds

Peptide bonds

Hydrogen bonds

Ionic bonds

Explanation Comments

Answer: Hydrogen bonds

Explanation:

Hydrogen bonds between complementary nitrogenous bases (adenine-thymine and cytosine-guanine) hold the two strands of the DNA double helix together.

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107.

Which organelle is responsible for photosynthesis in plant cells?

Chloroplast

Ribosome

Mitochondrion

Endoplasmic reticulum

Explanation Comments

Answer: Chloroplast

Explanation:

Chloroplasts contain chlorophyll and are the sites of photosynthesis, where light energy is converted into chemical energy in the form of glucose.

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108.

Which molecule is primarily involved in transporting oxygen in the blood of vertebrates?

Collagen

Albumin

Hemoglobin

Myoglobin

Explanation Comments

Answer: Hemoglobin

Explanation:

Hemoglobin is a protein in red blood cells that binds to oxygen and transports it from the lungs to the tissues and cells throughout the body.

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109.

Which of the following is the basic unit of heredity?

Lipid

Gene

Protein

Carbohydrate

Explanation Comments

Answer: Gene

Explanation:

A gene is a segment of DNA that contains the instructions for building a specific protein or set of proteins, making it the basic unit of heredity.

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110.

What is the sugar component of DNA?

Ribose

Glucose

Deoxyribose

Fructose

Explanation Comments

Answer: Deoxyribose

Explanation:

The sugar in the backbone of DNA is deoxyribose, a five-carbon sugar that lacks one oxygen atom compared to ribose, which is found in RNA.

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