11. Which of the following is the first formed primary xylem elements?
[A] Protoxylem
[B] Xylem parenchyma
[C] Metaxylem
[D] Xylem fibres
Show Answer
Correct Answer: A [Protoxylem]
Notes:
Protoxylem is the first part of the primary xylem that matures and these cells are usually smaller than the metaxylem. Metaxylem is the part of the primary xylem that differentiates after the protoxylem and these cells are usually larger than the protoxylem.
12. Which one of the following is a fast growing tree? (UPSC Prelims 1979).
[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.
13. Which of the following gave green colour to plants? (UPSC Prelims 1980).
[A] Chlorophyll
[B] Sugar
[C] Mitochondria
[D] Xylem
Show Answer
Correct Answer: A [Chlorophyll]
Notes:
Chlorophyll is the primary pigment in plants. It absorbs yellow and blue wavelengths of light while reflecting green. It is the presence and relative abundance of chlorophyll that gives plants their green color.
14. Genetic code is made up by the four-letter alphabet forming the pairs? (UPSC Prelims 1985)
[A] A—C, C—A, T—G, G—T
[B] A—G, G—A, C—A, T—C
[C] T—G, G—T, A—C, C—A
[D] A—T, T—A, C—G, G—C
Show Answer
Correct Answer: D [A—T, T—A, C—G, G—C]
Notes:
The four letters designating these bases (A, G, C, and T) are the alphabet of the genetic code. Each rung of the DNA molecule is contains a combination of two of these letters, one jutting out from each side. In this genetic code, A always combines with T, and C with G to make what is called a base pair.
15. A person walking barefooted in a field feels a sharp sting and on examination two puncture marks are found on his leg. He is most probably bitten by which of the following ages? (UPSC Prelims 1986)
[A] Poisonous snake
[B] Non-poisonous snake
[C] Scorpion
[D] Rat
Show Answer
Correct Answer: A [Poisonous snake]
Notes:
Snakebite is an injury caused by the bite of a snake, especially a venomous snake. A common sign of a bite from a venomous snake is the presence of two puncture wounds from the animal’s fangs. Those bitten may also describe a “sharp”, “rubbery”, “minty”, or “metallic” taste if bitten.
16. Which among the following is the name given to the ductless and secretory glands in the human body? (UPSC Prelims 1997)
[A] Endocrine glands
[B] Exocrine glands
[C] Salivary glands
[D] None of the above
Show Answer
Correct Answer: A [Endocrine glands]
Notes:
Ductless glands which are also known as internally secreting glands or endocrine glands secrete their products or hormones directly into the blood stream in response to instructions from the brain.
17. A man whose blood group is not known meets with a serious accident and needs blood transfusion immediately. Which one of the blood groups mentioned below and readily available in the hospital will be safe for transfusion? (UPSC Prelims 2001)
[A] O, Rh-
[B] O, Rh+
[C] AB, Rh-
[D] AB, Rh+
Show Answer
Correct Answer: B [O, Rh+]
Notes:
There is no A and B antigen on RBC of “O– ”bloodgroup , So O, Rh– is known as universal blood donor.
18. What does H denote in the popular term HIV ?
[A] Human
[B] Higher
[C] Hybrid
[D] NOTA
Show Answer
Correct Answer: A [Human]
Notes:
The Human Immunodeficiency Virus (HIV) are two species of lentivirus. It causes life-threatening disease of AIDS in humans and infects them. HIV is a sexually transmitted infection and occurs by contact with or transfer of blood, pre-ejaculate, semen, and vaginal fluids.
19. What is an enzyme?
[A] Acid
[B] Base
[C] Salt
[D] Catalyst
Show Answer
Correct Answer: D [Catalyst]
Notes:
Enzyme is a protein. It acts as a catalyst in living organisms, and controls the rate of chemical reactions inside the body.
20. Which of the following structures is responsible for the motility of bacteria?
[A] pilli
[B] flagella
[C] sheath
[D] capsules
Show Answer
Correct Answer: B [flagella]
Notes:
Flagella is responsible for the motility of bacteria. The flagellum is primarily a motility organ. This enables movement and chemotaxis.
