All Free Biology MCQs with Answers
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19844 questions · page 629 of 1985
6281. Which of the following statements is incorrect about Glyoxysomes?
- A. They contain enzymes which help in conversion of fatty acids into carbohydrate.
- B. They are abundant in soybeans but absent in pea.
- C. They are single membranous organelles.
- D. They are present throughout life of a plant and provide them with energy through Glyoxylate cycle.
Explanation: The statement that glyoxysomes can provide with energy is wrong. They do not have an energy-coupled electron transport system like mitochondria, but instead contain flavine oxidases, which catalyze the substrate-dependent reduction of oxygen to H2O2.
Correct answer: They are present throughout life of a plant and provide them with energy through Glyoxylate cycle.6282. Distribution of intrinsic proteins in the plasma membrane is?
- A. Random
- B. Symmetrical
- C. Asymmetrical
- D. None of these
Explanation: The cell membrane is described by the fluid mosaic model, the mosaic part refers to the asymmetrical random distribution of proteins.
Correct answer: Asymmetrical6283. The cellular structure of a plant cell consists of which non-living component?
- A. Nucleus
- B. Cell wall
- C. Cell membrane
- D. All of these
Explanation: Option B is correct since, in a plant cell, the 'cell wall' is the only part that is non-living because it is an extracellular product and exists outside the living boundary of the cell i.e. the plasma membrane, and protects the cell besides providing it a definite shape.
Correct answer: Cell wall6284. Enzymes in 'Calvin cycle' are found in which cell organelles?
- A. Smooth endoplasmic reticulum
- B. Chloroplasts
- C. Mitochondrion
- D. Golgi complex
Explanation: Option B is correct since enzymes in the 'Calvin cycle' are found in the 'chloroplast stroma' as the Calvin cycle takes place in the stroma (the inner space of chloroplasts).
Correct answer: Chloroplasts6285. Where are the phosphatidylserine residues in the plasma membrane are located?
- A. The outer leaflet of the plasma membrane
- B. Inner leaflet of the plasma membrane
- C. Evenly distributed in the inner and outer leaflet
- D. None of these
Explanation: Option B is correct since in normal cells, 'phosphatidylserine residues' are found exclusively on the inner side of the cellular membrane. During 'apoptosis', phosphatidylserine is transported to the outer cell surface.
Correct answer: Inner leaflet of the plasma membrane6286. The mobility of integral proteins can be measured by physical state of which of the following?
- A. Amino acids
- B. External phospholipids
- C. Membrane phospholipids
- D. Membrane appendages
Explanation: Option C is correct since integral proteins are embedded in the 'phospholipid bilayer' of the membrane, the mobility of the integral proteins is determined largely by the physical state of membrane phospholipids.
Correct answer: Membrane phospholipids6287. Protein constitutes what percentage of the total dry weight found in cells?
- A. 50
- B. 55
- C. 40
- D. 65
Explanation: Option A is correct since proteins constitute 50% percent of the total dry weight of cells and are the most abundant organic compounds found in cells.
Correct answer: 506288. Secondary cell wall is absent in _.
- A. Xylem
- B. Phloem
- C. Meristems
- D. All of these possess secondary cell walls
Explanation: Option C is correct since the cell wall of the meristematic cell is made up of cellulose, the cell wall is thin and flexible while the secondary wall is absent. Whereas secondary cell walls are present in the xylem and phloem.
Correct answer: Meristems6289. Which of the following cytoskeletal fibers contain tubulin protein?
- A. One which forms the assembly of spindles during mitosis
- B. One involved in internal cell motion
- C. One involved in maintenance of cell shape
- D. All of the above options are correct
Explanation: Microtubules are long, unbranched, sender tubulin protein structures. One very important function of microtubules is their role in the assembly and disassembly of the spindle structure during mitosis. Thus only A is correct.
Correct answer: One which forms the assembly of spindles during mitosis6290. The rigidity of leaves and younger parts of the plants is contributed by _.
- A. Microtubules
- B. Plant vacuole
- C. Actin
- D. Glyoxysomes
Explanation: The plant vacuole is the major contributor to the turgor that provides support for the individual plant cell and contributes to the rigidity of the leaves and younger parts of the plants.
Correct answer: Plant vacuole