Q21. What is the primary role of the smooth endoplasmic reticulum (SER) in cells?
a) Protein synthesis
b) Lipid synthesis and detoxification
c) Energy production
d) DNA replication
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Correct Answer: b) Lipid synthesis and detoxification
Explanation: The smooth endoplasmic reticulum (SER) is primarily involved in lipid synthesis, metabolism of carbohydrates, and detoxification of drugs and poisons. Unlike the rough ER, it lacks ribosomes on its surface.
Q22. The fluid mosaic model describes the structure of
a) The cell wall
b) The cell membrane
c) Cytoplasm
d) Mitochondrial membrane
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Correct Answer: b) The cell membrane
Explanation: The fluid mosaic model is a widely accepted model that describes the structure of the cell membrane. It depicts the membrane as a fluid combination of lipids and proteins, with the components able to move freely within the lipid bilayer.
Q23. During which phase of mitosis do the chromosomes align at the cell’s equator?
a) Prophase
b) Metaphase
c) Anaphase
d) Telophase
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Correct Answer: b) Metaphase
Explanation: During metaphase, the chromosomes align at the equator (middle) of the cell. This is a crucial step in mitosis, ensuring that each new cell will receive an identical set of chromosomes.
Q24. Autophagy in a cell refers to
a) Cell division
b) Cell death
c) The process of consuming and recycling cellular components
d) The absorption of external particles
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Correct Answer: c) The process of consuming and recycling cellular components
Explanation: Autophagy is the process by which cells consume and recycle their own components. It plays a role in cell maintenance, survival during nutrient starvation, and the disposal of damaged organelles.
Q25. Which part of the cell is responsible for assembling ribosomes?
a) Nucleolus
b) Golgi apparatus
c) Endoplasmic reticulum
d) Mitochondria
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Correct Answer: a) Nucleolus
Explanation: The nucleolus, found within the nucleus, is responsible for assembling ribosomes. It is involved in the production and maturation of ribosomal RNA (rRNA), a critical component of ribosomes.
Q26. Plasmolysis in plant cells occurs due to
a) Watering the plant
b) Exposure to a hypertonic solution
c) Exposure to a hypotonic solution
d) High temperatures
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Correct Answer: b) Exposure to a hypertonic solution
Explanation: Plasmolysis in plant cells occurs when cells lose water after being placed in a hypertonic solution, leading to the cell membrane pulling away from the cell wall. This is a process of cellular dehydration.
Q27. Which part of a cell contains hereditary information?
a) Mitochondria
b) Ribosome
c) Nucleus
d) Endoplasmic reticulum
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Correct Answer: c) Nucleus
Explanation: The nucleus of a cell contains most of the cell’s hereditary information, or DNA. The DNA within the nucleus carries the instructions necessary for all the cell’s functions and characteristics.
Q28. Cilia and flagella in eukaryotic cells are primarily used for
a) Photosynthesis
b) Movement
c) Protein synthesis
d) Digestion
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Correct Answer: b) Movement
Explanation: Cilia and flagella are hair-like structures that protrude from the cell surface and are primarily used for locomotion. Cilia move in a coordinated waving or beating motion, while flagella whip to propel the cell.
Q29. Which process converts glucose to pyruvate, generating ATP and NADH?
a) Glycolysis
b) Krebs cycle
c) Electron transport chain
d) Fermentation
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Correct Answer: a) Glycolysis
Explanation: Glycolysis is the process of breaking down glucose into pyruvate, resulting in the production of ATP (energy) and NADH (an electron carrier). It is the first step in cellular respiration and occurs in the cytoplasm of cells.
Q30. Pinocytosis is a type of
a) Cell division
b) Cell death
c) Endocytosis
d) Exocytosis
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Correct Answer: c) Endocytosis
Explanation: Pinocytosis is a form of endocytosis where the cell ingests extracellular fluid and its dissolved solutes. It is often referred to as “cellular drinking” and is a mechanism for the intake of fluid and nutrients.