Available Answers

1. 1.

   Check Yourself

   1. All living organisms need air for __________________.
   2. The moving air is called __________________.
   3. __________________ is a mixture of gases.
   4. Nitrogen makes up around __________________% of the atmosphere.
   5. Oxygen is essential for __________________ of fuels.
2. 2.

   Check Yourself

   1. The smoke and dust particles are found in _______________ and _______________ area.
   2. Plants have small openings called _______________ on the undersides of leaves.
   3. Fish use their _______________ to respire.
   4. Human beings have  _______________ for respiration.
   5. _______________ need carbon dioxide for photosynthesis.
3. 3.

   Tick (√) the correct answer:

   1. Which one of the following parts help in breathing?
      1. Stem
      2. Root
      3. Stomata
      4. Chlorophyll
   2. Which of the following uses gills to breathe?
      1. Fish
      2. Plants
      3. Amoeba
      4. Humans
   3. The major constituent of air is
      1. nitrogen
      2. oxygen
      3. carbon dioxide
      4. water vapour
   4. Which one of the following gases is released by animals during respiration?
      1. Carbon dioxide
      2. Oxygen
      3. Nitrogen
      4. None of these
   5. Which one of the following gases is used by plants to make their food from air ?
      1. Argon
      2. Oxygen
      3. Nitrogen
      4. Carbon dioxide
4. 4.

   Fill in the blanks:

   1. ________________ gas helps in burning.
   2. The blanket of air surrounding the earth is called ________________.
   3. In fish, respiration of air is done through ________________.
   4. Plants require ________________, ________________ and ________________ for photosynthesis.
   5. ________________ makes up the largest percentage of the atmosphere by volume and does not help in burning.
5. 5.

   Write 'T' for true and 'F' for false:

   1. Atmosphere is essential for the life on earth.
   2. Nitrogen gas is essential for respiration and combustion.
   3. Nitrogen is the major constituent of air.
   4. Air is a mixture of two gases.
   5. Plants produce carbon dioxide during photosynthesis.
6. 6.

   Match the following:

   Column I	Column II
   1. Atmosphere	a. Mixture of gases
   2. Ultraviolet rays	b. Get dissolved oxygen in water
   3. Air	c. Varies from animal to animal
   4. Aquatic animals	d. Detrimental rays of the sun
   5. Respiration	e. Blanket of air surrounding earth