Q1. The two branches of a plant give two different fruits : tomatoes and brinjals. This can be explained
(a) By hybridisation
(b) By grafting one with the other
(c) By nature’s freak
(d) By (a) or (c) mentioned above
(UPSC Prelims 1979)
Answer: (b) By grafting one with the other
Explanation:
Grafting is a horticultural technique where two different plant parts are joined to grow as one. If tomato and brinjal plants are grafted, each branch retains its genetic identity, producing distinct fruits. This is a controlled and intentional method, not a freak occurrence.
Q2. Age of a tree can be determined
(a) By counting the number of rings
(b) By thickness of the bark
(c) By bulk of the tree
(d) By number of leaves
Answer: (a) By counting the number of rings
Explanation: Each year, a tree adds a growth ring to its trunk. By counting these rings, one can estimate the age of the tree. These rings reflect seasonal growth patterns, with distinct bands formed due to variations in climate and nutrient availability.
Q3. The growth of seedling plants after transplantation will not always be proper because
(a) New soil may not contain the required minerals
(b) During transplantation root hairs get damaged
(c) Roots cannot penetrate deep into the soil
(d) Of all factors stated above
Answer: (b) During transplantation root hairs get damaged
Explanation: Root hairs are vital for absorbing water and nutrients. During transplantation, these delicate structures often get damaged, leading to poor growth or wilting. While soil conditions matter, root hair damage is the primary cause of transplant shock.
Q4. Honey bees are called social insects because
(a) They visit all flowers to collect nectar
(b) They live among men
(c) They depend for their food upon other insects
(d) They move socially with other insects
(UPSC Prelims 1982)
Answer: (a)
Explanation: Honey bees are termed social insects due to their organized colony structure, division of labor, and cooperative behavior. Their nectar collection and communication through dances reflect complex social interactions.
Q5. Age of tree can be estimated by
(a) Counting the number of concentric rings
(b) Counting the nodes and internodes of the trunk
(c) Measuring the girth of the tree trunk
(d) Counting the number of branches
(UPSC Prelims 1983)
Answer: (a) Counting the number of concentric rings
Explanation: The age of a tree is determined by counting its annual growth rings, visible in a cross-section of the trunk. Each ring represents one year of growth, making it a reliable method for age estimation.
Q6. Turmeric is obtained from which part of the plant?
(a) Fruit
(b) Stem
(c) Root
(d) Flower
(UPSC Prelims 1983)
Answer: (c) Root
Explanation: Turmeric is derived from the rhizome, a type of underground root. After harvesting, the rhizomes are boiled, dried, and ground into the familiar yellow spice, widely used in cooking and medicine.
Q7. Radio carbon dating process is used to know the age of
(a) Fossils
(b) Plants
(c) Rocks
(d) All of these
Answer: (a) Fossils
Explanation: Radiocarbon dating is used to determine the age of organic materials, such as fossils and ancient plant remains, by measuring the decay of carbon-14 isotopes. It is not suitable for rocks, which require other dating methods.
Q8. In which State of India is coconut grown extensively?
(a) Karnataka
(b) Andhra Pradesh
(c) Kerala
(d) Assam
Answer: (c) Kerala
Explanation: Kerala is the leading producer of coconuts in India due to its humid climate, fertile soil, and coastal geography. Coconut cultivation is deeply embedded in the state’s agriculture and economy.
Q9. Sir J. C. Bose was a great scientist because he showed the
(a) Sensitivity in plants
(b) Pigments in plants
(c) Growth in plants
(d) Relations between plants and animals
(UPSC Prelims 1984)
Answer: (a) Sensitivity in plants
Explanation: Jagadish Chandra Bose demonstrated that plants respond to stimuli, proving their sensitivity through experiments using the Crescograph. His work bridged botany and physics, showing that plants have life-like responses.
Q10. Which of the following is correct for tea ?
(a) Alkaline and nicotine
(b) Alkaline and caffeine
(c) Acidic and nicotine
(d) Acidic and caffeine
(UPSC Prelims 1985)
Answer: (d) Acidic and caffeine
Explanation: Tea contains caffeine, a natural stimulant, and is generally acidic in nature due to its tannins and other compounds. It does not contain nicotine, which is found in tobacco.
Q11. ‘Khaira’ is a plant disease caused due to the deficiency of
(a) Iron
(b) Carbon
(c) Zinc
(d) None of the above
(UPSC Prelims 1987)
Answer: (c) Zinc
Explanation: Khaira disease affects rice plants and is caused by zinc deficiency. Symptoms include bronzing and browning of leaves, leading to reduced yield if not corrected with zinc supplementation.