11. Which of the following is the hybrid between a horse and a donkey?
[A] Mule
[B] Hule
[C] Tigon
[D] Zorse
Show Answer
Correct Answer: A [Mule]
Notes:
A mule is the offspring of a male donkey (a jack) and a female horse (a mare). A horse has 64 chromosomes, and a donkey has 62. The mule ends up with 63. Mules can be either male or female, but, because of the odd number of chromosomes, they can’t reproduce
12. Which of the following is an example of Symbiotic bacteria?
[A] Rhizobium
[B] Protozoa
[C] Flat worms
[D] None of the above
Show Answer
Correct Answer: A [Rhizobium]
Notes:
Rhizobium is a kind of symbiotic bacteria. Many legumes have root nodules that provide a home for symbiotic nitrogen-fixing bacteria called rhizobia. This relationship is particularly common in nitrogen-limited conditions. The Rhizobia convert nitrogen gas from the atmosphere into ammonia.
13. Which of the following crops helps in nitrogen fixation? (UPSC Prelims 1979).
[A] Rice
[B] Wheat
[C] Maize
[D] Beans
Show Answer
Correct Answer: D [Beans]
Notes:
Any legume plants will help in nitrogen fixation. Beans contain symbiotic bacteria called Rhizobia within nodules in their root systems, producing nitrogen compounds that help the plant to grow and compete with other plants. When the plant dies, the fixed nitrogen is released, making it available to other plants and this helps to fertilize the soil.
14. How does the Hybridisation develop improved crops?
[A] Creating new and better genes
[B] Eliminating undesirable genes
[C] Producing favourable combination of genes
[D] By encouraging favourable genes and removing unfavourable ones
Show Answer
Correct Answer: C [Producing favourable combination of genes]
Notes:
Hybridization is beneficial for improvement in crop production as the Hybrid variety of crops have some special characteristics like good resistance to diseases, improved yield, etc. so they are often sought to have a high production.
15. 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.
16. Which among the following is the method of growing plants in the absence of soil?
[A] Hydrology
[B] Hydrotectonics
[C] Hydroponics
[D] Hydrochronology
Show Answer
Correct Answer: C [Hydroponics]
Notes:
The method of growing plants in the absence of soil is called as hydroponics. The required suppliments to the plants are supplied through the mineral nutrient solutions.
17. Who is known as father of soil science?
[A] Norman Ernest Borlaug
[B] V.V. Dokuchaev
[C] Liberty Hyde Bailey
[D] Eratosthenes
Show Answer
Correct Answer: B [V.V. Dokuchaev]
Notes:
Vasily Vasil’evich Dokuchaev is the father of soil science.
18. Why lysosomes are called suicidal bags?
[A] because it contains digestive enzymes
[B] because it contains endoplasmic reticulum
[C] because it contains Phospholipids
[D] None of these
Show Answer
Correct Answer: A [because it contains digestive enzymes]
Notes:
The lysosome is known as the suicide bag of the cell because it contains digestive enzymes.
19. Which of the following may be most likely to be missing from a gram-positive bacterium?
[A] Penicillin-binding protein
[B] Peptidoglycan
[C] Lipopolysaccharide
[D] Phospholipid bilayer membrane
Show Answer
Correct Answer: C [Lipopolysaccharide]
Notes:
Gram-negative bacteria are surrounded by a thin peptidoglycan cell wall. It itself is surrounded by an outer membrane containing lipopolysaccharides.
20. Which of the following is absent in the phloem of pteridophytes?
[A] Bast fibers
[B] Companion cells
[C] Phloem parenchyma
[D] sieve cells
Show Answer
Correct Answer: B [Companion cells]
Notes:
Pteridophytes are vascular, spore-forming, non-seed-forming, non-flowering plants. The phloem of pteridophytes does not have companion cells.
