Q1. Consider the following statements regarding energy flow in ecosystems:
- Grazing food chains can be found in both terrestrial and aquatic ecosystems.
- The major conduit of energy flow in aquatic ecosystems is through the grazing food chain.
- A much larger fraction of energy flows through the detritus food chain in terrestrial ecosystems compared to the grazing food chain.
How many of the statements are incorrect?
(a) Only one
(b) Only two
(c) All three
(d) None
Answer: (a) Only one
Explanation:
- Statement 1 → Correct, grazing food chains exist in both ecosystem types.
- Statement 2 → Incorrect. In aquatic ecosystems, the detritus food chain contributes more energy than the grazing chain.
- Statement 3 → Correct. Terrestrial ecosystems rely heavily on detritus pathways.
Q2. Consider the following statements regarding ecological succession:
- Autogenic succession → driven by biotic factors.
- Hydrarch succession → succession starting in aquatic habitats.
- Xerarch succession → succession starting in dry habitats.
- Allogenic succession → driven by abiotic factors like soil or climate changes.
How many statements are correct?
(a) Only one
(b) Only two
(c) All three
(d) All four
Answer: (d) All four
Explanation:
- Autogenic → changes due to organisms (e.g., plant growth altering soil).
- Hydrarch → succession in water bodies.
- Xerarch → dry land succession.
- Allogenic → external abiotic factors drive change.
Q3. Which of the following statements best defines Homeostasis in ecosystems?
(a) Tendency of a biological system to resist change, allowing an ecosystem to maintain stability.
(b) Equal proportion of species richness in an ecosystem at a particular time.
(c) Water carrying capacity of the ecosystem in a xerarch community.
(d) None of the above.
Answer: (a) Tendency of a biological system to resist change, allowing an ecosystem to maintain stability.
Explanation:
- Homeostasis refers to self-regulation mechanisms that maintain equilibrium in ecosystems despite external changes.
Q4. Match the types of succession with their characteristics:
Succession Type
- Autogenic
- Hydrarch
- Xerarch
- Allogenic
Description/Characteristics
A. Succession by abiotic components
B. Succession in aquatic ecosystems
C. Succession by biotic components
D. Succession in dry land
(a) 1-A, 2-B, 3-C, 4-D
(b) 1-C, 2-B, 3-D, 4-A
(c) 1-B, 2-C, 3-D, 4-A
(d) 1-D, 2-C, 3-B, 4-A
Answer: (b) 1-C, 2-B, 3-D, 4-A
Explanation:
- Autogenic → biotic-driven
- Hydrarch → aquatic start
- Xerarch → dry land start
- Allogenic → abiotic-driven
Q5. Consider the following statements regarding energy flow:
- Ecological efficiency → efficiency of energy transfer between trophic levels.
- Bioaccumulation → progressive concentration of toxins within a single organism.
- Biomagnification → increase of pollutant concentration across trophic levels.
How many statements are correct?
(a) Only one
(b) Only two
(c) All three
(d) None
Answer: (b) Only two
Explanation:
- Statement 1 → Correct, ecological efficiency = % energy transfer.
- Statement 2 → Partially incorrect; bioaccumulation is accumulation within an organism, not across levels.
- Statement 3 → Correct; biomagnification occurs across trophic levels.
