11. The young chicks come out of eggs within how many days after being hatched by the hen? (UPSC Prelims 1979).
[A] One week
[B] Two weeks
[C] Three weeks
[D] Four weeks
Show Answer
Correct Answer: C [Three weeks]
Notes:
A hen that is committed to hatching chicks is known as a broody. The state of being broody is controlled by instinct, hormones and lighting conditions. Chicken come out of the eggs within the 21 days after being hatched by the hen. Some breeds take a little less and some a little longer. If the egg has not hatched after 25 days, it should be removed from the broody hen or incubator. Eggs need constant heat during the full incubation period for the embryo to develop into a chick.
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 is not a parasite? (UPSC Prelims 1984)
[A] Tick
[B] Housefly
[C] Bed bug
[D] Louse
Show Answer
Correct Answer: B [Housefly]
Notes:
Tick, beg bug and louse are parasitic insects that live on the skin of mammals or birds.
Housefly is not a parasite.
14. Which of the following microorganisms causes Ring worm? (UPSC Prelims 1990)
[A] Bacterium
[B] Fungus
[C] Virus
[D] Worm
Show Answer
Correct Answer: B [Fungus]
Notes:
Ringworm isn’t a worm. It’s a skin infection that’s caused by moldlike fungi that live on the dead tissues of your skin, hair, and nails. It can occur at any place and on your scalp. When one gets it between the toes, it’s what people call athlete’s foot.
15. Haemophilia is a genetic disorder that leads to which of the following conditions? (UPSC Prelims 1998)
[A] Decrease in haemoglobin level
[B] rheumatic heart disease
[C] decrease in WBC
[D] non-clotting of blood
Show Answer
Correct Answer: D [non-clotting of blood]
Notes:
Hemophilia is a mostly inherited genetic disorder that impairs the body’s ability to make blood clots, a process needed to stop bleeding. Rarely a new mutation may occur during early development or haemophilia may develop later in life due to antibodies forming against a clotting factor.
16. Which one of the following statements is not correct? (UPSC Prelims 2003)
[A] Milk contains none of the B-vitamins
[B] Vitamin-A (retinal) deficiency leads to dry and scaly skin
[C] One of the symptoms of scurvy is pain in the joints
[D] Vitamin B1 (thiamine) deficiency can lead to heart failure
Show Answer
Correct Answer: A [Milk contains none of the B-vitamins]
Notes:
Milk contains the water soluble vitamins thiamin (vitamin B1), riboflavin (vitamin B2), niacin (vitamin B3), pantothenic acid (vitamin B5), vitamin B6 (pyridoxine), vitamin B12 (cobalamin), vitamin C, and folate. Milk is a good source of thiamin, riboflavin and vitamin B12.
17. Which of the following classes belongs to an Octopus? (UPSC Prelims 2003)
[A] an arthropod
[B] an echinoderm
[C] a heimchordate
[D] a mollusc
Show Answer
Correct Answer: D [a mollusc]
Notes:
The octopus is a soft-bodied, eight-limbed mollusc of the order Octopoda. Around 300 species are recognised, and the order is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids.
18. What term is used for a gene that exhibits multiple effects?
[A] Pleiotropism
[B] Multitropism
[C] Complementary
[D] Allele
Show Answer
Correct Answer: A [Pleiotropism]
Notes:
Pleiotropism describes the genetic effect of a single gene on multiple phenotypic traits. A classic example of pleiotropy is phenylketonuria, a human disease that affects multiple systems but is caused by one gene defect. The underlying mechanism is that the gene codes for a product that is, for example, used by various cells, or has a signaling function on various targets.
19. Which vitamin is also called as riboflavin?
[A] Vitamin B1
[B] Vitamin B2
[C] Vitamin B3
[D] Vitamin B6
Show Answer
Correct Answer: B [Vitamin B2]
Notes:
Vitamin B2 is also called as riboflavin. Chemical formula of vitamin B2 is C17H20N4O6.
20. In the branch of biology, what is the transmission of paternal traits to progeny called?
[A] Genetics
[B] Heredity
[C] Gerontology
[D] Genetic Engineering
Show Answer
Correct Answer: B [Heredity]
Notes:
The transmission of characteristics from parent to offspring is called heredity, and can be inferred from inherited characteristics.
