Q 1. Answer the following questions.
(i) What is an ecosystem?
Answer: The system formed by the interaction of all living organisms with each other and with the physical and chemical factors of the environment in which they live, all linked by the transfer of energy and material, is called an ecosystem.
NCERT Solutions for Class 7 Science Chapter 13 – Wastewater Story
(ii) What do you mean by natural environment?
Answer: The basic components and organisms that are naturally present in the environment without any human involvement, like the land, water, air, plants and animals, comprise the natural environment.
(iii) Which are the major components of the environment?
Answer: It includes
- Natural Components (Air, Water, Land and Living things)
- Human-made Components (Components created by human beings)
- Human Components (Human populations)
(iv) Give four examples of a human-made environment.
Answer: Four examples are buildings, parks, industries and bridges.
(v) What is lithosphere?
Answer: The solid crust or the hard top layer of the earth is called the lithosphere. It is made up of rocks and minerals and is covered by a thin layer of soil. It is an irregular surface with various landforms like mountains, plateaus, plains, etc.
(vi) Which are the two major components of the biotic environment?
Answer: Plants and animals are the two major components.
THE NATURE CONSERVANCY: NURTURING A SUSTAINABLE FUTURE
(vii) What is a biosphere?
Answer: The biosphere or the living world is the narrow zone of earth where land, water and air interact with each other to support life. The plant and animal kingdoms together form the biosphere.
Q 2. Tick the correct answer.
(i) Which is not a natural ecosystem?
(a) Desert
(b) Aquarium
(c) Forest
Answer: b
(ii) Which is not a component of the human environment?
(a) Land
(b) Religion
(c) Community
Answer: a
(iii) Which is a human-made environment?
(a) Mountain
(b) Sea
(c) Road
Answer: c
(iv) Which is a threat to the environment?
(a) Growing plant
(b) Growing population
(c) Growing crops
Answer: b
Q 3. Match the following.
| (i) Biosphere | (a) blanket of air which surrounds the earth |
| (ii) Atmosphere | (b) domain of water |
| (iii) Hydrosphere | (e) the narrow zone where the land water and the air interacts |
| (iv) Environment | (d) our surroundings |
| (e) narrow zone where the land water and the air interacts | |
| (f) relation between the organisms and their surroundings |
Answer 3:
| (i) Biosphere | (e) narrow zone where the land water and the air interacts |
| (ii) Atmosphere | (a) blanket of air which surrounds the earth |
| (iii) Hydrosphere | (b) domain of water |
| (iv) Environment | (d) our surroundings |
Q 4. Give reasons.
(i) Man modifies his environment.
Answer: Man modifies his environment to fulfil his basic needs, as it is the basic life support system. He builds houses to live in and industries to work in, which modifies the environment and also its mineral wealth. Humans have used the fossils for their own development, disturbing the ecological system and animal habitats.
(ii) Plants and animals depend on each other.
Answer: Plants and animals are interdependent on each other because plants are the producers, and animals are the consumers. Plants release oxygen in the atmosphere, which is inhaled by human beings and humans exhale carbon dioxide, which helps plants in producing their own food.