Q31. What is the primary function of the nucleolus within the cell nucleus?
a) DNA replication
b) Ribosome production
c) Protein synthesis
d) Lipid metabolism
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Correct Answer: b) Ribosome production
Explanation: The nucleolus within the cell nucleus is primarily responsible for the production and assembly of ribosome components. It synthesizes ribosomal RNA (rRNA) and combines it with proteins to form incomplete ribosomes.
Q32. The principle of ‘selective permeability’ in cellular biology refers to
a) The ability of cells to divide selectively
b) The selective transport of molecules across the cell membrane
c) The selective destruction of cellular organelles
d) The selective replication of DNA
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Correct Answer: b) The selective transport of molecules across the cell membrane
Explanation: Selective permeability refers to the cell membrane’s ability to regulate the entry and exit of substances. It allows some molecules to pass through while restricting others, maintaining the cell’s internal environment.
Q33. Which organelle is associated with the breakdown and recycling of cellular components?
a) Golgi apparatus
b) Lysosome
c) Endoplasmic reticulum
d) Nucleus
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Correct Answer: b) Lysosome
Explanation: Lysosomes are organelles that function in the breakdown and recycling of cellular components. They contain digestive enzymes that degrade worn-out organelles, food particles, and engulfed viruses or bacteria.
Q34. The primary function of vacuoles in plant cells is to
a) Synthesize proteins
b) Store nutrients and waste products
c) Produce energy
d) Conduct photosynthesis
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Correct Answer: b) Store nutrients and waste products
Explanation: Vacuoles in plant cells primarily store nutrients, waste products, and water. They play a significant role in maintaining cell turgor pressure, which helps in keeping the plant upright.
Q35. Which process involves cells engulfing solid particles?
a) Pinocytosis
b) Exocytosis
c) Phagocytosis
d) Osmosis
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Correct Answer: c) Phagocytosis
Explanation: Phagocytosis is a cellular process where cells engulf solid particles. It is a form of endocytosis and is crucial for the immune response, as it allows cells like macrophages to ingest and destroy pathogens.
Q36. What is the main purpose of cellular respiration?
a) To synthesize DNA
b) To produce proteins
c) To generate energy in the form of ATP
d) To create lipids for the cell membrane
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Correct Answer: c) To generate energy in the form of ATP
Explanation: The primary purpose of cellular respiration is to generate energy in the form of adenosine triphosphate (ATP). Through a series of metabolic processes, cells convert biochemical energy from nutrients into ATP.
Q37. Which structure in the cell is primarily responsible for maintaining cell shape and internal organization?
a) Cell wall
b) Mitochondria
c) Cytoplasm
d) Cytoskeleton
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Correct Answer: d) Cytoskeleton
Explanation: The cytoskeleton is responsible for maintaining cell shape and internal organization. It’s a network of fibers that provide support, shape, and aids in cell movement and division.
Q38. In which part of the cell does the Krebs cycle (Citric Acid Cycle) take place?
a) Cytoplasm
b) Mitochondrial matrix
c) Nucleus
d) Endoplasmic reticulum
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Correct Answer: b) Mitochondrial matrix
Explanation: The Krebs cycle, also known as the Citric Acid Cycle, takes place in the mitochondrial matrix. It is a key part of cellular respiration and is involved in the chemical conversion of carbohydrates, fats, and proteins into carbon dioxide and water.
Q39. The process by which plants convert carbon dioxide and water into glucose and oxygen using sunlight is called
a) Cellular respiration
b) Photosynthesis
c) Fermentation
d) Glycolysis
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Correct Answer: b) Photosynthesis
Explanation: Photosynthesis is the process by which plants (and some other organisms) convert light energy into chemical energy. They use sunlight to synthesize glucose from carbon dioxide and water, releasing oxygen as a by-product.
Q40. Which type of protein embedded in the cell membrane is responsible for the transport of substances across it?
a) Enzymatic proteins
b) Transport proteins
c) Receptor proteins
d) Structural proteins
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Correct Answer: b) Transport proteins
Explanation: Transport proteins embedded in the cell membrane are responsible for the movement of substances across it. They facilitate the transport of ions, molecules, and other substances, crucial for maintaining cell homeostasis.