NCERT Class-9 Science Solutions: Chapter 14-Natural Resources Part 6

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Question 36:

Following are a few organisms (A) Lichen (B) Mosses (C) Mango tree (D) Cactus. Which among the above can grow on stones; and also help in formation of soil? Write the mode of their action for making soil.

Answer:

Out of the above given organisms lichens can grow on rocks. During growth, they release certain substances that cause the rock surface 10 powders down and form a thin layer of soil. Lichens grow on the rock surface, extract minerals from them. This creates small crevices at places where a thin layer of soil builds up. Mosses grow over these crevices and cause deepening of the crevices and result in build sup of more soil inside them. Deeper crevices form cracks and cracks become wider and deeper when the roots of short lived herbs pass into them. With the passage of time, the roots of bigger plants, (e.g., peepal, banyan tree) pass into the cracks. Cracks gradually widen and cause slow fragmentation and eventually pulverization of rocks.

Question 37:

Soil formation is done by both abiotic and biotic factors. List the names of these factors by classifying them as abiotic and biotic?

Answer:

Abiotic factors involved in soil formation are

  • Rocks

  • Water

  • Sun

  • Wind

Biotic factors involved in soil formation are

  • Lichens

  • Bryophytes

  • Bacteria

  • Fungi

  • Nematodes

  • Earthworm

  • Arthropods

Question 38:

All the living organisms are basically made up of . How do they enter the living forms? Discuss.

Answer:

The elements like C, N, S, P, H and O enter into living forms through plants. Most of these elements first enter plants either by photosynthesis or active absorption and form the structural components of organic materials. From plants, these elements pass on to other organisms through the food chain

Image organisms are basically made up of C,N,S,P,H and O

Image Organisms Are Basically Made up of C,N,S,P,H and O

Image organisms are basically made up of C,N,S,P,H and O

Question 39:

Why does the percentage of gases like oxygen, nitrogen and carbon dioxide remain almost the same in the atmosphere?

Answer:

The percentage of gases like oxygen, nitrogen and carbon dioxide remains almost the same in the atmosphere because the cycling process of all these gases maintains their percentage in the atmosphere at constant level. Constant recycling replenishes the lost gas in the atmosphere and balance is maintained

Question 40:

Why does moon have very cold and very hot temperature variations e.g., even though it is at the same distance from the sun as the earth is?

Answer:

It is because the moon lacks the atmosphere that the earth has. The atmosphere plays a vital role in protecting the earth from these large variation of temperature that can be seen on the moon.

The extreme is present because of the sun ray hitting the moon surface without meeting any resistance and its occur in place of the moon which face the sun

The extreme cold occurs because there is no atmosphere to trap the suns heat on the moon and its occur on the areas which do not face the sun

Question 41:

Why do people love to fly kites near the seashore?

Answer:

The movement of air from one region to another region is called wind. On Earth, wind consists of bulk movement of air. It plays major role in recreational activity like kite flying. Sea shores are major windy areas where wind power can be used for kite flying because during day the air above land gets heated faster and starts rising. So the air above the sea moves into this area rapidly.