Q1. Which of the following is an aggressive colonizer that poses a major threat to aquatic ecosystems in India?
- Lantana camara
- Water Hyacinth
- Parthenium
- Touch-me-not
Correct Option: 2. Water Hyacinth
Explanation: Water Hyacinth (Eichhornia crassipes) is a floating aquatic plant native to Tropical America. It spreads rapidly in stagnant or slow-moving water, forming thick mats that:
• Block sunlight for underwater plants
• Deplete dissolved oxygen
• Disrupt aquatic ecosystems
• Hamper fishing, irrigation, and navigation
• Hence, it is one of the most harmful invasive aquatic weeds in India and globally.
Q2. Which medicinal plant is the commercial source of Diosgenin used for synthesizing steroidal drugs?
- Sarpagandha
- Elephant’s Foot
- Kuth
- Red Vanda
Correct Option: 2. Elephant’s Foot
Explanation: Elephant’s Foot (Dioscorea species) is a wild yam found in the North-Western Himalayas. Its tubers are a commercial source of Diosgenin, a steroidal sapogenin.
• Diosgenin is used in synthesizing cortisone, progesterone, pregnenolone, and other steroid-based pharmaceuticals.
• Extracted via hydrolysis of saponins present in the tubers.
This makes it highly valuable in pharmaceutical manufacturing.
Q3. Which part of the tree is responsible for transporting water and nutrients from the roots to the leaves?
- Phloem
- Cambium
- Xylem
- Heartwood
Correct Option: 3. Xylem
Explanation: Xylem, also called sapwood, is the plant tissue that:
• Transports water and minerals from the roots to stems and leaves.
• Is made up of long, tubular vessels that enable upward conduction.
• Its inner layers die over time to become heartwood, giving structural support.
• Phloem transports food; cambium is a growth layer; heartwood is non-functional dead wood.
Q4. Which type of root allows parasitic plants to absorb nutrients from their host plants?
- Taproots
- Prop roots
- Pneumatophores
- Haustorial roots
Correct Option: 4. Haustorial roots
Explanation: Haustorial roots are specialized structures found in parasitic plants, such as:
• Mistletoe (Viscum album)
• Dodder (Cuscuta)
These roots penetrate the host’s tissues to absorb water and nutrients, allowing the parasite to survive without direct soil contact.
They are vital for nutrient theft in obligate or partial parasitic plants.
Q5. What is the term for mass flowering of bamboo followed by death?
- Etiolation
- Tapering
- Gregarious flowering
- Autumn tinting
Correct Option: 3. Gregarious flowering
Explanation: Gregarious flowering refers to the simultaneous flowering of a bamboo species across a wide area, followed by mass death of the plants.
• Occurs after long intervals (e.g., 30–120 years).
• Results in massive seed production, often followed by ecological challenges like rodent population explosions and forest fires.
This is an evolutionary survival strategy and causes serious forest management concerns.