Q21. What structure in eukaryotic cells contains the genetic material?
a) Mitochondria
b) Nucleus
c) Golgi apparatus
d) Ribosome
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Correct Answer: b) Nucleus
Explanation: The nucleus in eukaryotic cells contains most of the cell’s genetic material, organized as multiple long linear DNA molecules in complex with various proteins to form chromosomes. It is the command center of the cell, directing protein synthesis and cell growth.
Q22. Active transport across a cell membrane requires
a) No energy
b) Water
c) ATP
d) Light
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Correct Answer: c) ATP
Explanation: Active transport is a process by which substances are moved across the cell membrane against their concentration gradient, requiring energy in the form of ATP. This is necessary for transporting certain molecules and ions that cannot passively diffuse across the membrane.
Q23. The rough endoplasmic reticulum (RER) is characterized by
a) A lack of ribosomes on its surface
b) The presence of ribosomes on its surface
c) The synthesis of lipids
d) Storing genetic material
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Correct Answer: b) The presence of ribosomes on its surface
Explanation: The rough endoplasmic reticulum is characterized by the presence of ribosomes on its surface. These ribosomes are sites for protein synthesis, giving the RER its “rough” appearance under a microscope.
Q24. Which process in the cell involves dividing the cytoplasm to form two separate daughter cells?
a) Mitosis
b) Cytokinesis
c) Apoptosis
d) Interphase
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Correct Answer: b) Cytokinesis
Explanation: Cytokinesis is the process in cell division where the cytoplasm of a single eukaryotic cell is divided to form two separate daughter cells. It usually occurs after mitosis, the division of the nucleus.
Q25. Peroxisomes in cells are involved in
a) The synthesis of proteins
b) The breakdown of fatty acids and detoxification processes
c) Storing genetic material
d) Modifying and packaging proteins
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Correct Answer: b) The breakdown of fatty acids and detoxification processes
Explanation: Peroxisomes are involved in the breakdown of fatty acids and in detoxification processes. They contain enzymes that transfer hydrogen from various substrates to oxygen, producing hydrogen peroxide, which is then broken down into water.
Q26. Cellular structures responsible for maintaining cell shape, securing organelles in specific positions, and moving substances within the cell are collectively known as
a) The cytoskeleton
b) The cell membrane
c) Endoplasmic reticulum
d) Golgi apparatus
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Correct Answer: a) The cytoskeleton
Explanation: The cytoskeleton is a network of fibers that not only helps to maintain the cell’s shape but also secures organelles in specific positions, aids in intracellular transport, and is involved in cell signaling.
Q27. In the context of cell signaling, what role do receptor proteins in the cell membrane play?
a) They synthesize signaling molecules.
b) They transport substances across the cell membrane.
c) They receive and transmit signals from outside the cell.
d) They provide structural support to the cell membrane.
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Correct Answer: c) They receive and transmit signals from outside the cell.
Explanation: Receptor proteins in the cell membrane are integral for cell signaling. They bind to signaling molecules outside the cell and transmit these signals to the cell’s interior, initiating various cellular responses.
Q28. Which organelle is primarily involved in the synthesis of lipids and metabolism of carbohydrates?
a) Lysosome
b) Golgi apparatus
c) Smooth endoplasmic reticulum
d) Mitochondria
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Correct Answer: c) Smooth endoplasmic reticulum
Explanation: The smooth endoplasmic reticulum (SER) plays a significant role in lipid synthesis and carbohydrate metabolism. It lacks ribosomes on its surface, distinguishing it from the rough ER, and is also involved in detoxification.
Q29. Microfilaments, an element of the cytoskeleton, are primarily composed of
a) Tubulin
b) Actin
c) Keratin
d) Collagen
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Correct Answer: b) Actin
Explanation: Microfilaments are fine, thread-like protein fibers, predominantly composed of actin, a protein. They play a role in cell movement, shape, and division, and are a key component of the cytoskeleton.
Q30. Which cellular process is vital for the regeneration of ATP from ADP and inorganic phosphate?
a) Photosynthesis
b) Cellular respiration
c) Protein synthesis
d) DNA replication
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Correct Answer: b) Cellular respiration
Explanation: Cellular respiration is a critical process for the regeneration of ATP from ADP and inorganic phosphate. This biochemical process converts the chemical energy stored in nutrients into ATP, providing energy for cellular functions.