11. RBCs are formed in which of the following in the adults?
[A] black bone marrow
[B] white bone marrow
[C] red bone marrow
[D] blue bone marrow
Show Answer
Correct Answer: C [red bone marrow]
Notes:
There are two types of bone marrow: red marrow (also known as myeloid tissue) and yellow marrow. Red blood cells, platelets and most white blood cells arise in red marrow; some white blood cells develop in yellow marrow.
12. Which one of the following is secreted by Pancreas and regulates the amount of sugar in the body? (UPSC Prelims 1980).
[A] Renin
[B] Creatin
[C] Vitamin
[D] Insulin
Show Answer
Correct Answer: D [Insulin]
Notes:
Insulin and glucagon are hormones secreted by islet cells within the pancreas. They are both secreted in response to blood sugar levels, but in opposite fashion. Insulin is normally secreted by the beta cells of the pancreas. Glucagon raises blood glucose levels by stimulating the liver to metabolize glycogen into glucose molecules and to release glucose into the blood. Insulin is a hormone that regulates blood sugar levels.
13. 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.
14. The highest fat content is found in the milk of which of the following animals? (UPSC Prelims 1991)
[A] Buffalo
[B] Cow
[C] Camel
[D] Reindeer
Show Answer
Correct Answer: A [Buffalo]
Notes:
Buffalo milk has the highest fat content, which is on average twice as high as that of cow milk. The fat-to-protein ratio in buffalo milk is about 2:1.
15. Which of the following was discovered by Alexander Fleming?
[A] DNA
[B] Vaccination
[C] penicillin
[D] blood circulation
Show Answer
Correct Answer: C [penicillin]
Notes:
Alexander Fleming discovered penicillin, whose use as an antibiotic has saved millions of lives.
16. Which of the following statements are correct about Golgi bodies?
[A] Camillo Golgi discovered the Golgi apparatus.
[B] found in the eukaryotic cells
[C] It is a sac-like organelle
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Camillo Golgi discovered Golgi bodies in 1898. Golgi bodies are found in eukaryotic cells and are involved in the packaging of protein and lipid molecules.
17. What is a jelly-like substance found floating inside the plasma membrane called?
[A] Cell sap
[B] Cytoplasm
[C] Karyoplasm
[D] Mitochondria
Show Answer
Correct Answer: B [Cytoplasm]
Notes:
The jelly-like substance inside the plasma membrane in which all the organelles float is called cytoplasm.
18. Which of the following are blue-green algae?
[A] Prokaryotes
[B] Eukaryotes
[C] Both 1 and 2
[D] Neither 1 nor 2
Show Answer
Correct Answer: A [Prokaryotes]
Notes:
Blue-green algae or cyanobacteria are prokaryotes. They lack membrane bound organelles and a nucleus.
19. In cell culture, the measles virus can lead to which of the following?
[A] nuclear pyknosis
[B] transformation of cells
[C] syncytium formation
[D] rounding and aggregation of cells
Show Answer
Correct Answer: C [syncytium formation]
Notes:
In cell culture, the measles virus can lead to syncytium formation.
20. Chromatophores participate in which of the following processes?
[A] Photosynthesis
[B] respiration
[C] Development
[D] Speed
Show Answer
Correct Answer: A [Photosynthesis]
Notes:
Chromatophores are one of the members of phototrophic bacteria. They contain bacteriochlorophyll pigments and carotenoids and participate in photosynthesis.
