Q1. Which cell organelle is responsible for producing ribosomal RNA (rRNA)?
a) Endoplasmic reticulum
b) Golgi apparatus
c) Nucleolus
d) Mitochondria
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Correct Answer: c) Nucleolus
Explanation: The nucleolus, a prominent structure within the cell nucleus, is primarily responsible for synthesizing ribosomal RNA (rRNA). It plays a crucial role in the formation of ribosomes, which are essential for protein synthesis in the cell.
Q2. What is the primary function of mitochondria in a cell?
a) Protein synthesis
b) Photosynthesis
c) ATP production through cellular respiration
d) Lipid storage
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Correct Answer: c) ATP production through cellular respiration
Explanation: Mitochondria are often referred to as the powerhouses of the cell. Their primary function is to produce ATP (adenosine triphosphate) through the process of cellular respiration, a vital energy source for many cellular processes.
Q3. Which of the following is a feature unique to plant cells?
a) Mitochondria
b) Cell wall
c) Lysosomes
d) Centrioles
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Correct Answer: b) Cell wall
Explanation: The cell wall is a unique feature of plant cells, absent in animal cells. It provides additional support and protection and is primarily composed of cellulose. The cell wall gives plant cells their rigid structure, helping to maintain plant shape.
Q4. The smooth endoplasmic reticulum (SER) is primarily involved in
a) Protein synthesis
b) Detoxification and lipid synthesis
c) DNA replication
d) Energy production
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Correct Answer: b) Detoxification and lipid synthesis
Explanation: The smooth endoplasmic reticulum (SER) is involved in several metabolic processes, including detoxification and lipid synthesis. It plays a role in the metabolism of carbohydrates, lipid synthesis for membranes, and detoxification of drugs and poisons.
Q5. What type of cells lacks a defined nucleus?
a) Eukaryotic cells
b) Prokaryotic cells
c) Plant cells
d) Animal cells
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Correct Answer: b) Prokaryotic cells
Explanation: Prokaryotic cells, such as bacteria, lack a defined nucleus. Their genetic material is not enclosed within a nuclear membrane. This is the key distinction between prokaryotic and eukaryotic cells, the latter having a well-defined nucleus.
Q6. Ribosomes in a cell are the sites of
a) Lipid synthesis
b) ATP production
c) Protein synthesis
d) Nucleic acid replication
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Correct Answer: c) Protein synthesis
Explanation: Ribosomes are the sites of protein synthesis in a cell. They translate genetic information in the form of messenger RNA (mRNA) into proteins by linking amino acids in the order specified by the mRNA.
Q7. The process of programmed cell death is known as
a) Necrosis
b) Apoptosis
c) Autophagy
d) Metastasis
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Correct Answer: b) Apoptosis
Explanation: Apoptosis is the process of programmed cell death, an essential component of various processes including normal cell turnover, proper development and functioning of the immune system. Unlike necrosis, which is a form of traumatic cell death, apoptosis is a regulated and controlled process.
Q8. Which structure acts as a selective barrier, regulating the traffic of materials in and out of the cell?
a) Cell wall
b) Mitochondrial membrane
c) Plasma membrane
d) Nuclear envelope
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Correct Answer: c) Plasma membrane
Explanation: The plasma membrane acts as a selective barrier for cells, regulating the movement of substances in and out of the cell. It is composed of a lipid bilayer with embedded proteins, allowing it to control the cell’s internal environment efficiently.
Q9. The cytoskeleton of a cell is composed of
a) Nucleic acids
b) Phospholipids
c) Structural proteins
d) Enzymes
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Correct Answer: c) Structural proteins
Explanation: The cytoskeleton is made up of various types of structural proteins, such as actin filaments, intermediate filaments, and microtubules. These proteins provide structural support to the cell, aid in cellular movement, and are involved in intracellular transport.
Q10. What is the primary function of lysosomes?
a) Protein synthesis
b) Photosynthesis
c) Breaking down cellular waste
d) ATP synthesis
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Correct Answer: c) Breaking down cellular waste
Explanation: Lysosomes are membrane-bound organelles containing enzymes that break down various types of cellular waste, including damaged organelles, proteins, and lipids. They are crucial for cellular housekeeping and recycling processes.