CBSE Class 9 Science Natural Resource Worksheet Set D

Question : Name two biologically important compounds that contain both oxygen and nitrogen.
Answer : The biologically important compounds that contain both oxygen and nitrogen are nitrates (NO₂) and nitrates (NO₃).

Short / Long Answer

Question : What is the greenhouse effect?
Answer : Some gases like carbon dioxide, methane, nitrous oxide prevent the escape of heat from the Earth's surface by trapping it. This increases the average temperature of the Earth.
This is called the green house effect. An increase in the content of such gases would lead to a situation of global warming.

Question : Why is water essential for life?
Answer : Water is essential for life because of these reasons:
It provides medium to carry out all the cellular processes.
All the reactions that occur in our body and within cells occur between substances that are dissolved in water.
It is required for the transportation of materials from one part of the body to the other.
lt helps to maintain body temperature.
Water makes up about 7o % of body weight of all the living organisms.

Question : You have seen weather reports on television and in newspapers. How, do you think we are able to predict the weather?
Answer : Meteorologists collect information regarding the pattern of temperature, speed of wind, air presser and all other features which influence weather. All these information are collected by remote sensing and weather forecast satellites. This information is then compiled in meterological departments which prepare a weather report that is
displayed on the maps. This information is further transmitted through radio, television and newspaper.

Question : Write a note on how forests influence the quality of our air, soil and water resources.
Answer : Forests influence the quality of air, soil and water resources in the ways as below:
A. Influence of forests on air :
Forests help to maintain oxygen and carbon dioxide balance in the air, They reduce the level of CO₂ in the air and to prevent greenhouse effect.
These maintain temperature of the environment,
Forests increase the rate of photosynthesis in surrounding region.
B.Influence of forests in quality of soil:
Trees spread their roots deep inside the Earth and bind the soil particles firmly. This reduces soil erosion.
Forests help to maintain nutrient cycles (biogeochemical cycles) in the atmosphere.
C. Influence of forests in quality of water:
Water cycle will be maintained by the help of trees
Forests conserve water and make them available on the surface of Earth as water sources.