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Chapter 10

Air

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Highlights
  • A. Very short answer type questions.
  • B. Short answer type questions.
  • C. Long answer type questions.
  • D. Match the following column.
  • E. Distinguish between the following.
  • F. Map skills.

EXERCISE

A. Fill in the blanks.
  • 1. The two main gases present in the air are ___________ and ___________.
  • 2. Animals need ___________ gas for breathing.
  • 3. Plants use ___________ gas to prepare their own food.
  • 4. The process, by which plants prepare their food, is called ___________.
  • 5. ___________ gas, present in the atmosphere, protects us from the harmful rays of sunlight.
  • 6. Air, containing impurities, is called ___________.
B. Match the following column:
  • Column A
  • 1. Golgi Complex
  • 2. Ribosomes
  • 3. Chromosomes
  • 4. Dead cells
  • 5. Photosynthesis
  • Column B
  • (a) genes
  • (b) cork
  • (c) chloroplasts
  • (d) packaging center
  • (e) protein synthesis
C. Tick the correct option.
  • 1. The gas, which is present the most in air, is-

Answer: vacuole

  • 2. An air pollutant, which exists in solid form, is-

Answer: a single cell

  • 3. The gas, whose amount varies with weather changes, is-

Answer: nuclear membrane

  • 4. The gas, that gets reduced, through the process of photosynthesis, is-

Answer: nuclear membrane

  • 5. When sulphur dioxide reacts with water and oxygen in air, it results in the production of-

Answer: nuclear membrane

D. Answer the following questions in brief.
  • 1. Name the main components of air.

Answer: The (main) factors that determine the shape of a cell are location and function.

  • 2. State the meaning of the term ‘Photosynthesis’.

Answer: Distinguish between unicellular and multicellular organisms are

Unicellular organisms are made up of a single cell. e.g., Euglena and Amoeba.

Multicellular organisms are made up of many cells. e.g., Humans and Birds.

  • 3. State two possible harmful effects of ultraviolet rays.

Answer: All organisms are made up of cells. A cell is capable of independent existence. Due to this, cell is called the structural and functional unit of life.

  • 4. Define the term ‘Air pollutant’.

Answer: Mitochondria is known as the Powerhouse of the cell.

Mitochondria are the site of cellular respiration. Energy is produced during this process. Due to this, mitochondria are called the Powerhouse of the cell.

  • 5. Name any two of the gaseous pollutants present in air.

Answer: Mitochondria is known as the Powerhouse of the cell.

Mitochondria are the site of cellular respiration. Energy is produced during this process. Due to this, mitochondria are called the Powerhouse of the cell.

  • 6. List any four causes of air pollution.

Answer: Mitochondria is known as the Powerhouse of the cell.

Mitochondria are the site of cellular respiration. Energy is produced during this process. Due to this, mitochondria are called the Powerhouse of the cell.

E. Answer the following questions.
  • 1. Why is air necessary for animals?

Answer: three different cell types found in human beings are:

DAV Solutions for Class 8 Science Chapter 1
Diagram

These figures clearly show that liver cell is irregular in shape, fat cell is spherical and muscle cell is spindle-shaped. This shows that all cells in an organism do not have the same shape.

  • 2. How is nitrogen important for plants?

Answer: Chromosomes are formed in the nucleus during cell division. When the cell is ready to divide, the chromatin (in nucleus) condenses to form thicker, thread-like chromosomes. Chromosomes are responsible for inheritance of characters from one generation to the next generation.

  • 3. How is the balance of oxygen and carbon dioxide in air, maintained in nature?

Answer: When the cell membrane gets damaged, it exposes the cell’s contents to external environment. This results in stoppage of all functions of the cell, and eventually to cell death.

  • 4. Why is ‘acid rain’ harmful?

Answer: When the cell membrane gets damaged, it exposes the cell’s contents to external environment. This results in stoppage of all functions of the cell, and eventually to cell death.

  • 5. Why should we feel worried about ‘global warming’?

Answer: When the cell membrane gets damaged, it exposes the cell’s contents to external environment. This results in stoppage of all functions of the cell, and eventually to cell death.

  • 6. Suggest some ways of reducing air pollution.

Answer: When the cell membrane gets damaged, it exposes the cell’s contents to external environment. This results in stoppage of all functions of the cell, and eventually to cell death.

  • 7. How does planting of trees help in making air cleaner?

Answer: When the cell membrane gets damaged, it exposes the cell’s contents to external environment. This results in stoppage of all functions of the cell, and eventually to cell death.

1. Electricity
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1. Electricity
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Related Topics
  • Chapter 1 The Cell – Its Structure and Functions
  • Chapter 2 Microorganisms: Friends or Foes
  • Chapter 3 Metals and Non-Metals
  • Chapter 4 Force and Pressure
  • Chapter 5 Friction
  • Chapter 6 Sources of Energy
  • Chapter 7 Combustion
  • Chapter 8 Conservation of Plants and Animals
  • Chapter 9 Crop Production and Its Management
  • Chapter 10 Refraction and Dispersion of Light
  • Chapter 11 The Human Eye
  • Chapter 12 Sound
  • Chapter 13 Synthetic Fibres and Plastics
  • Chapter 14 Reproduction in Animals
  • Chapter 15 Reaching the Age of Adolescence
  • Chapter 16 Electric Current and Its Chemical Effects
  • Chapter 17 Stars and Solar System
  • Chapter 18 Earthquakes
  • Chapter 19 Pollution of Air
  • Chapter 20 Pollution of Water