All Free Biology MCQs with Answers
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19844 questions · page 685 of 1985
6841. Animal cells, and cells of some microorganisms and lower plants contain _ located near the exterior surface of the nucleus.
- A. One centriole
- B. Two centrioles
- C. Two pairs of centrioles
- D. Two mitochondria
Explanation: Centrioles are located on the outer surface of nucleus making right angle with each other in a non-dividing cell.
Correct answer: Two centrioles6842. Just before the cell divides:
- A. Chromosomes duplicate
- B. Centrioles duplicate
- C. Ribosomes duplicate
- D. Nucleoli duplicate
Explanation: Duplication of centrioles is the first indication of initiation of cell division in animal cells.
Correct answer: Centrioles duplicate6843. Centrioles play important role in the:
- A. Cytokinesis of plant cell
- B. Karyokinesis of plant cell
- C. Furrowing during cell division
- D. Formation of mitotic apparatus in plants
Explanation: In animal cells cytokinesis occurs through furrowing and it starts at the central point between centriole pairs positioned on opposite poles of the dividing cell.
Correct answer: Furrowing during cell division6844. Cell contains many tiny granular structures known as:
- A. Ribosomes
- B. Nuclei
- C. Mitochondria
- D. Golgi Apparatus
Explanation: Ribosomes are tiny membraneless granular structures of both prokaryotic and eukaryotic cells.
Correct answer: Ribosomes6845. Ribonucleoprotein particles discovered by Palade in cell are:
- A. Ribosomes
- B. Lysosomes
- C. Nucleosomes
- D. Golgi vesicles
Explanation: Ribosomes are made up of RNA and proteins. Palade discovered the ribosomes
Correct answer: Ribosomes6846. Ribosomes exist in two forms in eukaryotic cells, i.e.:
- A. Freely scattered in cytoplasm and attached with SER
- B. Freely scattered in cytoplasm and attached with RER
- C. Freely scattered in nucleoplasm and attached with RER
- D. Freely scattered in nucleoplasm and attatched with SER
Explanation: Ribosomes are of two types with respect to their spatial distribution in cell i.e., free and attached with membrane of endoplasmic reticulum. Such endoplasmic reticulum become roughsurfaced (RER).
Correct answer: Freely scattered in cytoplasm and attached with RER6847. Pick up the choice which is true about subunits of eukaryotic ribosomes:
- A. The larger subunits sediments at 60S while smaller subunits sediments at 40S.
- B. The larger subunit sediments at 50S, while smaller subunit sediments at 30S.
- C. The larger subunit sediments at 60S, while smaller subunit sediments at 30S.
- D. The larger subunit sediments at 50S, while smaller subunit sediments at 40S.
Explanation: The larger subunit (60S) have higher rate of sedimentation as compared to smaller one (40S), for eukaryotes
Correct answer: The larger subunits sediments at 60S while smaller subunits sediments at 40S.6848. Ribosomal subunits are attached to the mRNA string from:
- A. 3- end
- B. 2- end
- C. 4- end
- D. 5- end
Explanation: The genetic message, transcribed on mRNA is translated in 5' to 3' direction.
Correct answer: 5- end6849. New ribosomes are assembled in the:
- A. Nucleus
- B. Nucleolus
- C. Mitochondria
- D. Golgi apparatus
Explanation: As nucleolus is the factory of ribosome synthesis.
Correct answer: Nucleolus6850. The factory of ribosomes is the,..............while that of protein synthesis is the ..........
- A. Nucleolus, ribosomes
- B. Nucleus, ribosomes
- C. Ribosomes, nucleolus
- D. Nucleolus, mitochondria
Explanation: Nucleoli synthesize the ribosomes and in turn ribosomes synthesize the proteins.
Correct answer: Nucleolus, ribosomes