11. Among living organisms, which one of the following is the most responsible factor for bringing about the origin of a new species? (UPSC Prelims 2002)
[A] Isolation
[B] Mutation
[C] Natural Selection
[D] Sexual Reproduction
Show Answer
Correct Answer: A [Isolation]
Notes:
Origin of new species depends on isolation of gene flow between new species and develops significant genetic divergence.
12. Which vitamin is also called as niacin?
[A] Vitamin C
[B] Vitamin B3
[C] Vitamin B12
[D] Vitamin B9
Show Answer
Correct Answer: B [Vitamin B3]
Notes:
Vitamin B3 is also called as niacin/Nicotinic acid with chemical formula C6H5NO2. Niacin is water soluble vitamin.
13. Which of the following is the taxonomic family of humans?
[A] Hominidae
[B] Haplorhini
[C] Primates
[D] Homini
Show Answer
Correct Answer: A [Hominidae]
Notes:
The genus of the human being today is called Homo and the man today is called as Homo sapiens. From simple life forms that were unicellular to the development of multicellular organisms gave rise to the vertebrates. The family to which human beings belong is called Hominidae. It was in the Miocene age that the family Hominidae split from the Pongidae(apes) family.
14. The science of histology is related to which of the following studies?
[A] Tissues
[B] Cells
[C] Algae
[D] Fungi
Show Answer
Correct Answer: A [Tissues]
Notes:
Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissues.
15. Which of the following comprise plant decomposers?
[A] Monera and fungi
[B] Plantae and fungi
[C] Monera and Animalia
[D] Animalia and Protista
Show Answer
Correct Answer: A [Monera and fungi]
Notes:
Decomposers are a type of bacteria and fungi that break down dead and decaying organic matter into simpler things like carbon dioxide, water, simple sugars and mineral salts, and return nutrients to the soil.
16. 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.
17. 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.
18. Fungi that get their food directly from dead organic matter are called?
[A] Predators
[B] Decomposers
[C] Mutualists
[D] Parasitic fungi
Show Answer
Correct Answer: B [Decomposers]
Notes:
Fungi that get their food directly from dead organic matter are called Decomposers.
19. In which of the following groups would you place a plant that produces spores and embryos but lacks seeds and vascular tissue?
[A] Fungi
[B] Bryophytes
[C] Pteridophytes
[D] Gymnosperms
Show Answer
Correct Answer: B [Bryophytes]
Notes:
Bryophytes are small, non-vascular plants. Examples are mosses, liverworts, and hornworts. They play an important role in regulating ecosystems because they provide an important buffer system for other plants that live together. They benefit from the water and nutrients that bryophytes collect.
20. What does Prothallus represent?
[A] sporophytic phase in a fern
[B] gametophytic phase in a fern
[C] sporophytic phase in a gymnosperm
[D] gametophytic phase in a gymnosperm
Show Answer
Correct Answer: B [gametophytic phase in a fern]
Notes:
Prothallus represents the gametophytic phase in a fern. The diploid sporophyte represents a major, independent, photosynthetic, and vascular plant body.
