11. 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.
12. ‘Lathyrism’ is a crippling disease caused by eating which of the following? (UPSC Prelims 1989)
[A] Tinned fish
[B] Chick pea and pulses
[C] Meat
[D] Adulterated oil
Show Answer
Correct Answer: B [Chick pea and pulses]
Notes:
The lathyrism resulting from the ingestion of Lathyrus odoratus seeds (Chick pea and pulses) is often referred to as odoratism or osteolathyrism, which is caused by a different toxin (beta-aminopropionitrile) that affects the linking of collagen, a protein of connective tissues.
13. What does the stones formed in human kidney consist of? (UPSC Prelims 2000)
[A] calcium oxalate
[B] sodium acetate
[C] magnesium sulphate
[D] calcium
Show Answer
Correct Answer: A [calcium oxalate]
Notes:
Stones are typically classified by their location: nephrolithiasis (in the kidney), ureterolithiasis (in the ureter), cystolithiasis (in the bladder), or by what they are made of (calcium oxalate, uric acid, struvite, cystine).
14. Which one of the following organisms can serve as a biofertiliser for rice crop? (UPSC Prelims 2000)
[A] Blue-green algae
[B] Rhizobium sp
[C] Mycorrhizal fungi
[D] Azotobacter sp
Show Answer
Correct Answer: A [Blue-green algae]
Notes:
Blue green algae is used as a biofertilizer in rice crop. Blue green algae has the nitrogen fixing ability which enhances the production of rice. Blue–green algae are not algae at all, but types of bacteria called cyanobacteria that are normally present in many lakes.
15. Which of the following is a sexual spore?
[A] Ascospore
[B] Sporangiospore
[C] Conidia
[D] Zoospore
Show Answer
Correct Answer: A [Ascospore]
Notes:
The ascospore is a spore contained in an ascus; this type of spore is typical of fungi classified as ascomycetes.
16. What are the inclusion bodies of the measles virus?
[A] intracytoplasmic
[B] intranuclear
[C] both (a) and (b)
[D] none of these
Show Answer
Correct Answer: C [both (a) and (b)]
Notes:
The inclusion bodies of the measles virus are intracytoplasmic and intranuclear.
17. Which of the following is not an auxiliary pigment?
[A] Chlorophyll ‘a’
[B] Chlorophyll ‘e’
[C] Phycocyanin
[D] Xanthophyll
Show Answer
Correct Answer: A [Chlorophyll ‘a’]
Notes:
Chlorophyll ‘a’ is an essential pigment, it is not helpful.
18. Algae cell wall is made up of which of the following?
[A] Chitin
[B] Cutin
[C] Cellulose
[D] Suberin
Show Answer
Correct Answer: C [Cellulose]
Notes:
The Algae cell wall is made up of Cellulose.
19. Which of the following statements regarding algae is incorrect.
[A] Most algae are photosynthetic
[B] Algae can be classified according to their pigments
[C] All algae are filamentous
[D] Spirogyra does not produce zoospores
Show Answer
Correct Answer: C [All algae are filamentous]
Notes:
Most algae are photosynthetic, Algae can be classified according to their pigments and Spirogyra does not produce zoospores.
20. How do bryophytes differ from pteridophytes?
[A] Swimming antherozoids
[B] An independent gametophyte
[C] Archegonia
[D] Lack of vascular tissue
Show Answer
Correct Answer: D [Lack of vascular tissue]
Notes:
Vascular tissue is completely absent in bryophytes. Water and nutrients enter the cells by diffusion. And vascular tissue in rhodophytes consists of xylem and phloem.
