All Free Biology MCQs with Answers
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19844 questions · page 633 of 1985
6321. Which of the following structures is not found in a prokaryotic cell?
- A. Mesosome
- B. Plasma membrane
- C. Nuclear envelope
- D. Ribosome
Explanation: Prokaryotic cells lack a nuclear envelope; their genetic material is located in a region called the nucleoid, not enclosed by a membrane.
Correct answer: Nuclear envelope6322. Cellular organelles with membranes are
- A. Endoplasmic reticulum, ribosomes, and nuclei
- B. Lysosomes, Golgi apparatus, and mitochondria
- C. Nuclei, ribosomes, and mitochondria
- D. Chromosomes, ribosomes, and endoplasmic reticulum
Explanation: These organelles are membrane-bound: lysosomes and the Golgi apparatus have single membranes, while mitochondria have double membranes.
Correct answer: Lysosomes, Golgi apparatus, and mitochondria6323. Which of the following are not membrane-bound?
- A. Lysosomes
- B. Mesosomes
- C. Vacuoles
- D. Ribosomes
Explanation: Ribosomes are made of rRNA and proteins and have no membrane. All the other listed organelles (lysosomes, mesosome, vacuoles) are membrane-bound.
Correct answer: Ribosomes6324. DNA is not present in:
- A. Nucleus
- B. Mitochondria
- C. Chloroplast
- D. Ribosomes
Explanation: Ribosomes are the sites of protein synthesis and are composed of ribosomal RNA and proteins. They do not contain DNA.
Correct answer: Ribosomes6325. The nuclear envelope is a derivative of:
- A. Microtubules
- B. Rough endoplasmic reticulum
- C. Smooth endoplasmic reticulum
- D. Membrane of Golgi complex
Explanation: The rough endoplasmic reticulum (RER) is directly involved in the formation of the nuclear envelope. During cell division, the nuclear envelope disintegrates, and its components are absorbed into the RER. After division, the RER helps in reassembling the nuclear envelope, making it a derivative of the RER.
Correct answer: Rough endoplasmic reticulum6326. The structures that are formed by stacking of organised flattened membranous sacs in the chloroplasts are:
- A. Cisternae
- B. Stroma
- C. Cristae
- D. Grana
Explanation: Grana are stacks of thylakoids within the chloroplasts, where light-dependent reactions of photosynthesis occur. These are the correct structures formed by stacking of flattened membranous sacs.
Correct answer: Grana6327. Select the correct matching in the following pairs.
- A. Rough ER - Synthesis of glycogen
- B. Rough ER - Oxidation of fatty acids
- C. Smooth ER - Oxidation of phospholipids
- D. Smooth ER - Synthesis of lipids
Explanation: Smooth endoplasmic reticulum (SER) is crucial for the synthesis of lipids, including phospholipids and fatty acids, and is involved in various metabolic processes.
Correct answer: Smooth ER - Synthesis of lipids6328. Which one of the following is not an inclusion body found in prokaryotes?
- A. Glycogen granule
- B. Polysome
- C. Phosphate granule
- D. Cyanophycean granule
Explanation: Polysomes, or polyribosomes, are clusters of ribosomes translating mRNA into proteins and are not considered inclusion bodies. Therefore, they are not typical of prokaryotic inclusion bodies.
Correct answer: Polysome6329. The solid linear cytoskeletal elements having a diameter of 6 nm and made up of a single type of monomer are known as?
- A. Microtubules
- B. Microfilaments
- C. Intermediate filaments
- D. Cilia
Explanation: Microfilaments are fine, thread-like protein fibers, 3-6 nm in diameter. They are composed predominantly of a contractile protein called actin.
Correct answer: Microfilaments6330. The osmotic expansion of a cell kept in water is chiefly regulated by
- A. Mitochondria
- B. Vacuoles
- C. Plastids
- D. Ribosomes
Explanation: Vacuoles are membrane-bound organelles that store nutrients and waste products, helping maintain osmotic balance and cell turgor by controlling water uptake.
Correct answer: Vacuoles