Q1. Who formulated the cell theory?
[A] Schleiden and Schwann
[B] Robert Hooke
[C] Rudolf Virchow
[D] Matthias Schleiden
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Correct Answer: [A] Schleiden and Schwann
Explanation: The cell theory, stating that all living organisms are composed of cells and cells are the basic units of life, was formulated by Matthias Schleiden (botanist) and Theodor Schwann (zoologist) in 1839. Rudolf Virchow later added the concept of ‘Omnis cellula e cellula’ – all cells arise from pre-existing cells. Robert Hooke discovered cells but did not formulate the cell theory.
Q2. Which of the following statements is NOT a part of the modern cell theory?
[A] All living organisms are composed of cells and cell products.
[B] Cells are the basic structural and functional units of life.
[C] All cells arise from pre-existing cells.
[D] Cells are formed de novo from non-living matter.
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Correct Answer: [D] Cells are formed de novo from non-living matter.
Explanation: The modern cell theory includes: (1) all living organisms are composed of cells and cell products, (2) cells are the basic structural and functional units of life, and (3) all cells arise from pre-existing cells (Omnis cellula e cellul[A]. The idea of spontaneous generation or ‘de novo’ cell formation from non-living matter was disproven by experiments like Pasteur’s swan neck flask experiment.
Q3. The cell organelle primarily responsible for ATP synthesis is:
[A] Golgi apparatus
[B] Lysosome
[C] Mitochondria
[D] Ribosome
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Correct Answer: [C] Mitochondria
Explanation: Mitochondria are known as the ‘powerhouses of the cell’ because they are the primary sites of cellular respiration. During cellular respiration, they oxidize carbohydrates and fats to release energy in the form of ATP (Adenosine Triphosphate). Golgi apparatus is for packaging and secretion, lysosomes for digestion, and ribosomes for protein synthesis.
Q4. Ribosomes are the sites for:
[A] Lipid synthesis
[B] Protein synthesis
[C] Carbohydrate synthesis
[D] Nucleic acid synthesis
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orrect Answer: [B] Protein synthesis
Q5. Which organelle is known as the ‘suicidal bag’ of the cell?
[A] Mitochondria
[B] Lysosome
[C] Golgi apparatus
[D] Endoplasmic reticulum
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Correct Answer: [B] Lysosome
Q6. The endomembrane system of a eukaryotic cell does NOT include:
[A] Endoplasmic reticulum
[B] Golgi apparatus
[C] Lysosomes
[D] Peroxisomes
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Correct Answer: [D] Peroxisomes
Explanation: The endomembrane system is a group of organelles in eukaryotic cells that are interconnected and coordinate cellular processes. It typically includes the endoplasmic reticulum (ER), Golgi apparatus, lysosomes, and vacuoles. Peroxisomes, while membrane-bound organelles, are not considered part of the endomembrane system as they are not derived from or directly connected to ER or Golgi.
Q7. The ‘fluid mosaic model’ is used to describe the structure of:
[A] Cell wall
[B] Nucleus
[C] Cell membrane
[D] Mitochondria
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Correct Answer: [C] Cell membrane
Explanation: The fluid mosaic model, proposed by Singer and Nicolson, describes the cell membrane as a dynamic structure composed of a lipid bilayer with proteins embedded in it. The lipids provide fluidity, while proteins offer mosaic pattern and perform various functions like transport and signaling. Cell wall is rigid, nucleus has nuclear envelope, and mitochondria have double membranes, none are described by fluid mosaic model.
Q8. The main lipid components of the cell membrane are:
[A] Triglycerides
[B] Fatty acids
[C] Phospholipids
[D] Cholesterol
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Correct Answer: [C] Phospholipids
Explanation: Phospholipids are the major lipid components of the cell membrane. They are amphipathic molecules with a hydrophilic (phosphate) head and hydrophobic (fatty acid) tails, forming a bilayer in aqueous environment. Triglycerides are storage lipids, fatty acids are components of lipids, and cholesterol is a sterol lipid present in animal cell membranes for fluidity regulation.
Q9. The cell wall of plants is primarily composed of:
[A] Chitin
[B] Cellulose
[C] Peptidoglycan
[D] Lignin
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Correct Answer: [B] Cellulose
Explanation: The cell wall of plants is mainly composed of cellulose, a polysaccharide made of β-glucose units. Cellulose microfibrils provide structural support and rigidity to the plant cell wall. Chitin is in fungal cell walls, peptidoglycan in bacterial cell walls, and lignin is a complex polymer that strengthens plant cell walls, particularly in woody tissues, but not the primary component of plant cell walls in general.
Q10. Which of the following cell organelles is NOT double membrane bound?
[A] Nucleus
[B] Mitochondria
[C] Chloroplast
[D] Ribosomes
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Correct Answer: [D] Ribosomes
Explanation: Nucleus, mitochondria, and chloroplasts are double membrane bound organelles in eukaryotic cells. Ribosomes, on the other hand, are not membrane-bound organelles; they are ribonucleoprotein structures composed of rRNA and proteins, involved in protein synthesis.