11. What is plant cell wall mainly composed of?
[A] Vitamin
[B] Lipids
[C] Cellulose
[D] Protein
Show Answer
Correct Answer: C [Cellulose]
Notes:
A plant cell wall is arranged in layers and contains cellulose microfibrils, hemicellulose, pectin, lignin, and soluble protein. Plant cell walls are primarily made of cellulose, which is the most abundant macromolecule on Earth.
12. Why do the tropical deciduous trees shed their leaves in summer? (UPSC Prelims 1983)
[A] Leaves get dried up due to the excessive heat
[B] To prevent excessive loss of water through transpiration
[C] Because rainfall is inadequate
[D] Days are longer
Show Answer
Correct Answer: B [To prevent excessive loss of water through transpiration]
Notes:
Tropical deciduous forests shed their leaves for about six to eight weeks in summer. As this is a hot-dry season, the leaves get dry due to high temperature and deficiency of moisture causing these trees to shed their leaves.
13. Which of the following diseases is hereditary? (UPSC Prelims 1987)
[A] Haemophilia
[B] Tuberculosis
[C] Cancer
[D] Dysentery
Show Answer
Correct Answer: A [Haemophilia]
Notes:
Haemophilia is a mostly inherited genetic disorder that impairs the body’s ability to make blood clots, a process needed to stop bleeding. This results in people bleeding longer after an injury, easy bruising, and an increased risk of bleeding inside joints or the brain.
14. The sensation of fatigue in the muscles after prolonged strenuous physical work is caused by? (UPSC Prelims 2000)
[A] a decrease in the supply of oxygen
[B] minor wear and tear of muscle fibres
[C] the depletion of glucose
[D] the accumulation of lactic acid
Show Answer
Correct Answer: D [the accumulation of lactic acid]
Notes:
The sensation of fatigue which the muscles feel after a prolonged and a strenuous physical workout is caused by the accumulation of lactic acid.
This is so because lactic acid buildup tends to cause fatigue and soreness in the muscles.
There is a burning sensation felt up in the muscles when buildup of acid happens in muscles during exercise. This is also known as acidosis.
15. Which branch of biology is known for the study of tissues on artificial mediums?
[A] Pisciculture
[B] Silviculture
[C] Tissue Culture
[D] Horticulture
Show Answer
Correct Answer: C [Tissue Culture]
Notes:
Tissue culture is the growth of tissues or cells in an artificial medium isolated from the parent organism. This technique is also called micropropagation.
16. Which of the following biomolecules is more widely distributed in the cell?
[A] Chloroplast
[B] RNA
[C] DNA
[D] Spaherosomes
Show Answer
Correct Answer: B [RNA]
Notes:
DNA and RNA are two types of nucleic acids. DNA is converted into RNA by the process of transcription. The three types of RNA are m-RNA, t-RNA and r-RNA.
17. Which of the following is a characteristic of Kingdom Plantae?
[A] They are non-motile
[B] They make their own food hence are called autotrophs
[C] It contain photosynthetic pigments called chlorophyll present in the plastids
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
The Plant Kingdom has the following distinctive features:They are motionless, they make their own food, hence they are called autotrophs, they reproduce asexually by vegetative propagation or sexually, these are multicellular eukaryotes, the plant cell has an outer cell wall and a large central vacuole, Plastids in plants contain photosynthetic pigments called chlorophyll, they have separate organs for anchoring, reproduction, support and photosynthesis.
18. Which of the following is a characteristic of angiosperms?
[A] Seed-bearing plants
[B] Seeds are enclosed within fruits
[C] Both 1 & 2
[D] Neither 1 nor 2
Show Answer
Correct Answer: C [Both 1 & 2]
Notes:
Characteristics of angiosperms: Seed plants, seeds are sealed inside the fruit, presence of well differentiated plant body, produce flowers during their lifetime, presence of two subtypes – monocotyledonous and dicotyledonous
19. Which of the following happens in Gram-positive cells?
[A] second outer membrane that helps to retain the crystal violet stain
[B] multiple layer of peptidoglycan that helps to retain the crystal violet stain
[C] thick capsule that traps the crystal violet stain
[D] periplasmic space that traps the crystal violet
Show Answer
Correct Answer: B [multiple layer of peptidoglycan that helps to retain the crystal violet stain]
Notes:
Multiple layer of peptidoglycan that helps to retain the crystal violet stain is happens in Gram-positive cells. Gram-positive organisms have a thicker peptidoglycan cell wall than Gram-negative bacteria.
20. The cytoplasmic membrane of which of the following organisms contains sterols?
[A] Clostridum
[B] Proteus
[C] Mycoplasma
[D] Bacillius
Show Answer
Correct Answer: C [Mycoplasma]
Notes:
Mycoplasma is a genus of bacteria that do not have a cell wall surrounding the cell membrane.
