All Free Biology MCQs with Answers
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19844 questions · page 676 of 1985
6751. Krebs cycle occurs in the_of mitochondria.
- A. Matrix
- B. Stroma
- C. F1 particles
- D. Cristae
Explanation: The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions that take place in the matrix of mitochondria. The mitochondrial matrix contains all enzymes and coenzymes that are required for Kreb's cycle.
Correct answer: Matrix6752. The inner membrane of mitochondria forms extensive infoldings called:
- A. Cristae
- B. Lamella
- C. Cisternae
- D. Matrix
Explanation: The infoldings in the inner membrane of mitochondria are specifically called cristae.
Correct answer: Cristae6753. Which organelle is required for aerobic respiration?
- A. Plastids
- B. Mitochondria
- C. ER
- D. Nucleus
Explanation: Mitochondria is the powerhouse of the cell. Aerobic cellular respiration occurs in mitochondria in eukaryotic cells.
Correct answer: Mitochondria6754. The structure in double-membrane bound organelle, primarily involved in ATP generation through cellular respiration is:
- A. F1-particles
- B. Mitoplast
- C. Mitochondria
- D. Ergastoplasm
Explanation: F1-particles are actually ATP synthase enzymes. It is responsible for the generation of ATP through chemiosmosis in mitochondria during cellular respiration.
Correct answer: F1-particles6755. F0-F1 particles is another name for:
- A. ATP synthetase
- B. ATP synthase
- C. Cytochrome complex
- D. None of these
Explanation: The inner surface of cristae has granular structures called F0-F1 particles. These particles are actually ATP synthase enzymes.
Correct answer: ATP synthase6756. Which of the following organelle has a continuous connection with nuclear membrane?
- A. Golgi apparatus
- B. RER
- C. Lysosomes
- D. SER
Explanation: Fact: The rough endoplasmic reticulum(RER) is continuous with the nuclear membrane.
Correct answer: RER6757. How many nuclear pores are present in a typical differentiated cell, such as RBCs?
- A. About 3,000 per nucleus
- B. About 1-2 per nucleus
- C. About 30,000 per nucleus
- D. About 3-4 per nucleus
Explanation: The number of nuclear pores is more in undifferentiated cells as compared to differentiated cells. Since RBCs are fully differentiated cells, they have 3-4 nuclear pores, but the number of nuclear pores in egg cells is about 30,000.
Correct answer: About 3-4 per nucleus6758. The structure present in a eukaryotic cells but absent in prokaryotic cells is:
- A. Nucleus
- B. Ribosomes
- C. DNA
- D. Cell surface membrane
Explanation: The term 'prokaryotes' is derived from the Greek word 'pro meaning before' and 'karyon meaning nucleus'. Prokaryotic cells are those cells that do not have a definite nucleus and membrane-bound organelles. On the other hand, a definite nucleus is present in eukaryotic cells.
Correct answer: Nucleus6759. It makes nucleoli during interphase:
- A. Primary constriction
- B. Secondary constriction
- C. Centromere
- D. Telomere
Explanation: Some chromosomes may have a point of union, other than primary constriction, along the length of chromatids. This is called secondary constriction, also known as nucleolar organizer. It gives rise to nucleoli during interphase.
Correct answer: Secondary constriction6760. Prokaryotic and eukaryotic cells generally have which of the following feature in common?
- A. A membrane-bounded nucleus
- B. A cell wall made up cellulose
- C. Presence of ribosomes
- D. Linear genome
Explanation: Both prokaryotic and eukaryotic cells have ribosomes while membrane-bound nucleus, cellulosic cell wall, and linear chromosomes are found only in eukaryotic cells.
Correct answer: Presence of ribosomes