11. Which one of the following is a fast growing tree?
[A] Teak
[B] Eucalyptus
[C] Banyan
[D] Coconut
Show Answer
Correct Answer: B [Eucalyptus]
Notes:
Eucalyptus is the fast growing tree. Most eucalyptus species have a root depth of 1.5-2.0 metre and its root system is more specifically adapted to using rain-fed soil moisture from the upper soil profile, rather than from the groundwater table at considerable depth. The plant is significant for wood availability, livelihood generation and carbon sequestration that address the challenges of global warming and climate change.
12. In which of the following situations the Identical twins are born?
[A] Two sperms fertilise one ovum
[B] Two sperms fertilise two ovums simultaneously
[C] One sperm fertilises the ovum and zygote divides into two separate cells developing independently
[D] One sperm fertilises two ovums
Show Answer
Correct Answer: C [One sperm fertilises the ovum and zygote divides into two separate cells developing independently]
Notes:
Identical twins form when one egg has been fertilised by one sperm and the zygote splits into two. This happens at the very earliest stage of development, when the zygote is no more than a cluster of a few cells. If this egg then splits into two, an identical twin pregnancy can result.
13. The sequencing of the entire genome (the totality of all genes) of an organism was completed in 1996. Which one of the following was that organism? (UPSC Prelims 1997)
[A] Albino mouse
[B] yeast
[C] human being
[D] Plasmodium vivax
Show Answer
Correct Answer: D [Plasmodium vivax]
Notes:
Plasmodium vivax is a protozoal parasite and a human pathogen. This parasite is the most frequent and widely distributed cause of recurring malaria.
14. Which pigment is responsible for the colour of healthy skin in human beings?
[A] Bilirubin
[B] Haemoglobin
[C] Melanin
[D] Progesterone
Show Answer
Correct Answer: C [Melanin]
Notes:
The single most factor responsible for the cpolour of the skin is the pigment melanin. It is secreted by the melanocytes within the skin.
15. Who was the father of DNA Fingerprinting?
[A] James Watson
[B] Hargobind Khurana
[C] Alec Jeffereys
[D] Nirenberg
Show Answer
Correct Answer: C [Alec Jeffereys]
Notes:
In 1984, Alec Jeffreys developed the technique of DNA fingerprinting. These techniques have revolutionised the way that the police solve crimes.
16. Where does reduction division take place in pteridophytes?
[A] Prothallus is formed
[B] Gametes are formed
[C] spores are formed
[D] sex organs are formed
Show Answer
Correct Answer: C [spores are formed]
Notes:
In ferns, the main plant body is sporophytic. Its leaves, known as sporophylls, have sporangia on them. Reduction division takes place in these spores, producing many spores from them. Spores are the initials of the gametophyte stage.
17. In ferns, the leaves during young conditions are called__?
[A] Scale leaf
[B] Sporophyll
[C] Circinate Ptyxis
[D] None of these
Show Answer
Correct Answer: C [Circinate Ptyxis ]
Notes:
In ferns, the leaves during young conditions are called Circinate Ptyxis.
18. A condition in which the stamens are attached to the petals of a flower instead of directly attached to the thalamus is called__?
[A] Epipetalous
[B] Monadelphous
[C] Staminode
[D] Epiphyllous
Show Answer
Correct Answer: A [Epipetalous]
Notes:
A condition in which the stamens are attached to the petals of a flower instead of directly attached to the thalamus is called Epipetalous. Solanum is an example of Epipetalous.
19. What is the main mode of nutrition in plants?
[A] autotrophic mode
[B] heterotrophic mode
[C] Parasitic mode
[D] Saprophytic mode
Show Answer
Correct Answer: A [autotrophic mode]
Notes:
The main mode of nutrition in plants is the autotrophic mode of nutrition and leaves of plants contain chlorophyll which helps them to make their own food.
20. The presence of pores in Porifera is called__.
[A] cnidoblasts
[B] Ostia
[C] Medusa
[D] None of these
Show Answer
Correct Answer: B [Ostia]
Notes:
The presence of pores in Porifera’s body wall is called Ostia. Porifera are commonly called sponges.
