11. Which of the following features of the human immunodeficiency virus (HIV) makes it a living entity? (UPSC Prelims 1990)
[A] Excrete in human serum
[B] Disturb host cell respiration
[C] Undergo auto-reproduction
[D] Move from one cell to another
Show Answer
Correct Answer: C [Undergo auto-reproduction]
Notes:
The human immunodeficiency virus is a type of virus called a retrovirus. Like all viruses, human immunodeficiency virus reproduces using the genetic machinery of the cell it infects. With the help of an enzyme called integrase (also produced by HIV), the viral DNA becomes integrated with the cell’s DNA.
12. Most of the desert plants bloom during night time due to which of the following reasons? (UPSC Prelims 1995)
[A] their blooming is controlled by low temperature
[B] they are sensitive to the phases of the moon
[C] the desert insects eat away flowers during day time
[D] the desert insects are active during night time
Show Answer
Correct Answer: D [the desert insects are active during night time]
Notes:
In desert conditions, most of the activity of the plants and animals happens during the night because of very high temperature in the day time. The desert insects make themselves active and pollinate the flowers at night. To attract the insects, most of the desert plants bloom during the night.
13. Which of the following cell organelles play the most significant role in protein synthesis? (UPSC Prelims 2001)
[A] Lysosome and Centrosome
[B] Endoplasmic reticulum and Ribosome
[C] Golgi apparatus and Mitochondria
[D] Lysosome and Mitochondria
Show Answer
Correct Answer: B [Endoplasmic reticulum and Ribosome]
Notes:
Ribosome and Endoplasmic reticulum are main site for protein synthesis. Ribosome, which serve as staging area where some RNA helps in protein synthesis. Endoplasmic reticulum is an irregular, double membrane network scattered in cytoplasm, also helps in protein synthesis.
14. Which gas is released during the process of photosynthesis in plants?
[A] Carbon dioxide
[B] Methane
[C] Oxygen
[D] Nitrogen
Show Answer
Correct Answer: C [Oxygen]
Notes:
Inputs of photosynthesis are carbon dioxide and water and outputs are glucose and oxygen. Photosynthesis occurs in the presence of sunlight.
15. Study of Porifera (sponges) is known as __?
[A] Parazoology
[B] Palaeozoology
[C] Zoophytology
[D] None of these
Show Answer
Correct Answer: A [Parazoology]
Notes:
Parazoology is the branch of zoology that deals with the study of parazoa, primitive multicellular animals that lack true tissues and organs. It encompasses the study of Porifera (sponges), one of the most primitive animal phyla that date back to the Precambian era over 600 million years ago.
16. Which bacteria are used in production of biogas/gobar gas plants?
[A] Methanogens
[B] Ethanogens
[C] Propanogens
[D] N-butane
Show Answer
Correct Answer: A [Methanogens]
Notes:
Methanogens belong to the Euryarchaeota of the Archaebacteria. They convert inorganic organic compounds into methane and carbon dioxide.
17. Which of the following occurs in Bryophytes?
[A] Great economic value
[B] No value at all
[C] Great ecological importance
[D] A lot of aesthetic value
Show Answer
Correct Answer: C [Great ecological importance]
Notes:
They are called pollution indicators. These prevent soil erosion by running water.
18. Dicotyledonous branches are found in which of the following?
[A] Fern
[B] Funaria
[C] Liverworts
[D] Marchantia
Show Answer
Correct Answer: C [Liverworts]
Notes:
Dicotyledonous branches are found in Liverworts. Liverworts are also moss-like land plants that do not have a vascular system.
19. Which is used as Weedicide?
[A] Indole-3-butyric acid
[B] 2,4-dichlorophenoxyacetic acid
[C] Indole-3-Acetic Acid
[D] None of these
Show Answer
Correct Answer: B [2,4-dichlorophenoxyacetic acid]
Notes:
2,4-dichlorophenoxyacetic acid is used as Weedicide. It is this auxin that is produced synthetically. It mostly affects the foliage of the plant and is widely used in the treatment of weeds.
20. Flowers having both androecium and gynoecium are called?
[A] Bisexual flowers
[B] Anther
[C] Stamens
[D] Unisexual flowers
Show Answer
Correct Answer: A [Bisexual flowers]
Notes:
Flowers having both androecium and gynoecium are called Bisexual flowers. Flowers are the reproductive part of the plant. They are not only involved in reproduction but are also a source of food for other living organisms.
