Q1.
Based on the given criteria, identify and describe the interactions between biotic and abiotic components shown in Fig. 12.5. Criterion 1 — Interactions between abiotic and biotic components. These may influence life processes like nutrition, respiration, and reproduction in biotic components. Criterion 2 — Interaction between two abiotic components these may influence the physical characteristics of a habitat. Criterion 3 — Interaction among the biotic components. These may influence the availability of resources needed for life processes like nutrition, respiration, and reproduction.
Answer
Fig. 12.5 shows a pond with its bank: sunlight and hills above, water with a duck, fish, frogs on lily pads, a turtle, a dragonfly, a kingfisher on a rock, a water snake and water plants, and moist soil with an earthworm below. Sorting what happens there into the three criteria gives a completed Table 12.3:
| Criterion 1: Interactions between biotic and abiotic components | Criterion 2: Interaction between two abiotic components | Criterion 3: Interaction among the biotic components |
|---|---|---|
| Earthworms live in moist soil. | The day temperature is high due to the bright sunlight. | A frog eats insects. |
| Many microbes are present in the pond. | Water is evaporating fast due to the sunlight. | A water snake eats fish. |
| A fish lays eggs in water. | Air current is blowing slowly on the water surface creating gentle waves. | Frogs and fish may compete for small insect larvae. |
| The soil near the pond is moist. | A fish lays eggs in water near vegetation to protect them from other fish or frogs. | |
| Water plants use sunlight, water and carbon dioxide to make food. | Sunlight warms the upper layer of water more than the deeper water. | The kingfisher dives and catches a fish. |
| The fish takes in oxygen dissolved in the water. | Wind and warmth together make the pond lose water, so it becomes shallower. | The duck feeds on water plants and small animals. |
| The frog sits on a floating leaf, out of the water, to breathe air. | Air passing over the water surface helps oxygen dissolve into it. | The dragonfly hunts small flying insects above the water. |
(The first four rows of each column are the book's own examples; the orange rows are further ones you can read off Fig. 12.5.)
Why it happens: the three criteria are really three different questions. Criterion 1 asks how does a non-living thing let a living process happen? — sunlight allows photosynthesis, dissolved oxygen allows respiration, water allows the eggs to develop. Criterion 2 asks how do two non-living things change the habitat itself? — sunlight plus wind change temperature, water level and how much oxygen the water holds. Criterion 3 asks how do organisms change what is available to each other? — by eating, by competing, or by using a place for shelter. Together these three are what an ecosystem is.