Page No 201: - Chapter 14 Natural Resources class 9 ncert solutions Science - SaraNextGen [2024-2025]

Updated By SaraNextGen

On April 24, 2024, 11:35 AM

Question 1:

What are the different states in which water is found during the water cycle?

Answer:

During the water cycle, water is found in solid state (snow, ice, etc.), liquid state (ground water, river water, etc.), and gaseous state (water vapours).

Question 2:

Name two biologically important compounds that contain both oxygen and nitrogen.

Answer:

Two biologically important compounds that contain both oxygen and nitrogen are:

(i) Amino acids

(ii) Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)

Question 3:

List any three human activities which would lead to an increase in the carbon dioxide content of air.

Answer:

(i) Burning of fuels in various processes like heating, cooking, transportation, and industry.

(ii) Human induced forest fires

(iii) The process of deforestation includes the cutting down of trees. This decreases the uptake of carbon dioxide for photosynthesis. Eventually, the content of carbon dioxide increases.

Question 4:

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 5:

What are the two forms of oxygen found in the atmosphere?

Answer:

The two forms of oxygen found in the atmosphere are:

(i) Diatomic molecular form with chemical formula O₂.

(ii) Triatomic molecular form with chemical formula O₃ known as ozone.

Question 1:

Why is the atmosphere essential for life?

Answer:

The atmosphere is essential for life because it maintains an appropriate climate for the sustenance of life by carrying out the following activities:

(i) Atmosphere keeps the average temperature of the Earth fairly constant during day time.

(ii) It prevents a sudden increase in temperature during day time.

(iii) It also slows down the escape of heat from the surface of the Earth into outer space during night time.

Question 2:

Why is water essential for life?

Answer:

Water is essential for life because of the following reasons:

(i) Most biological reactions occur when substances are dissolved in water. Thus, all cellular processes need water as a medium to take place.

(ii) Transportation of biological substances needs water as a medium.

Question 3:

How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource?

Answer:

Almost all living organisms are dependent on soil. Some depend directly, while some depend indirectly.

Plants need soil for getting support as well as nutrients to prepare their food.

On the other hand, organisms depend on plants for food and other substances that are essential for life. Herbivores depend directly upon plants, and carnivores depend upon animals, which in turn depend upon plants for food. This makes them depend on soil indirectly.

Organisms that live in water are not totally independent of soil as a resource. These organisms depend on aquatic plants for food and other substances. These aquatic plants in turn require minerals for their sustenance. These minerals are carried to water bodies from soil by rivers, rain water, etc. Without the supply of minerals from the soil to the water bodies, it is impossible to imagine aquatic life.

Question 4:

You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?

Answer:

The meteorological department of the government collects data on the elements of weather such as maximum and minimum temperatures, maximum and minimum humidity, rainfall, wind speed, etc. They are able to study these elements using various instruments. The maximum and minimum temperature of a day is measured by a thermometer known as the maximum−minimum thermometer. Rain fall is measured by an instrument known as the rain gauge. Wind speed is measured by anemometers. There are various instruments used to measure humidity.