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Chapter 8

Respiration in Plants

Class 7 - Living Science Biology Ratna Sagar


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Question 1

............... is the process in which glucose is oxidized in the presence of oxygen to release energy.

Answer

Respiration is the process in which glucose is oxidized in the presence of oxygen to release energy.

Question 2

The glucose combines with oxygen to produce carbon dioxide, water and ............... ATP molecules.

Answer

The glucose combines with oxygen to produce carbon dioxide, water and 38 ATP molecules.

Question 3

In ............... respiration, glucose is not completely oxidized.

Answer

In anaerobic respiration, glucose is not completely oxidized.

Question 4

In anaerobic respiration, glucose is oxidized to form carbon dioxide, ............... and 2 ATP energy molecules.

Answer

In anaerobic respiration, glucose is oxidized to form carbon dioxide, ethyl alcohol and 2 ATP energy molecules.

Question 5

In ..............., energy is released in the form of heat and light and not stored for future use.

Answer

In combustion, energy is released in the form of heat and light and not stored for future use.

Think and answer

Question 1

Forests are called the lungs of the earth. Why?

Answer

As the lungs purify (oxygenate) the air we breathe, the plants purify the air of atmosphere by releasing oxygen and absorbing carbon dioxide. Thus, forests serve as lungs of the earth, cleaning and oxygenating the air.

Tick the most appropriate answer

Question 1

The by-products of photosynthesis are

  1. carbon dioxide, water and 38 ATP molecules.
  2. carbon dioxide, ethyl alcohol and 2 ATP molecules.
  3. oxygen and glucose.
  4. carbon dioxide and glucose.

Answer

oxygen and glucose.

Reason — Photosynthesis is the process by which plants form food (glucose) and release oxygen.

Question 2

How many ATP molecules are produced by the oxidation of 2 molecules of glucose?

  1. 38
  2. 76
  3. 2
  4. 40

Answer

76

Reason — Oxidation of one molecule of glucose produces 38 ATP molecules. So, two molecule of glucoses on oxidation will produce 38 x 2 = 76 ATP molecules.

Question 3

In aerobic respiration, the by-products are

  1. carbon dioxide, water and 2 ATP molecules.
  2. carbon dioxide, ethyl alcohol and 2 ATP molecules.
  3. carbon dioxide, water and 38 ATP molecules.
  4. oxygen, water and 38 ATP molecules.

Answer

carbon dioxide, water and 38 ATP molecules

Reason — Glucose + Oxygen ⟶ Carbon dioxide + Water + Energy (38 ATP)

Question 4

Cellular respiration in plants takes place in the

  1. chloroplast.
  2. endoplasmic reticulum.
  3. golgi bodies.
  4. mitochondria.

Answer

mitochondria

Reason — Cellular respiration in plants takes place in the mitochondria (power house of the cell)

Question 5

Plants that grow in salty water have specialized roots called

  1. pneumatophores.
  2. pseudopodia.
  3. lenticels.
  4. root hairs.

Answer

pneumatophores

Reason — They are aerial roots that help in respiration.

Fill in the blanks

Question 1

The energy released during respiration is stored in energy-rich chemical substances called ............... .

Answer

The energy released during respiration is stored in energy-rich chemical substances called ATP (Adenosine Triphosphate).

Question 2

The entire process of respiration takes place partially in cytoplasm and partially in ............... .

Answer

The entire process of respiration takes place partially in cytoplasm and partially in mitochondria.

Question 3

In aerobic respiration, glucose is completely oxidized to form ............... and water.

Answer

In aerobic respiration, glucose is completely oxidized to form carbon dioxide and water.

Question 4

Only ............... ATP molecules are released by the oxidation of 1 glucose molecule during anaerobic respiration.

Answer

Only two ATP molecules are released by the oxidation of 1 glucose molecule during anaerobic respiration.

Question 5

When the guard cells lose water, they lose their turgidity and the stomata ............... .

Answer

When the guard cells lose water, they lose their turgidity and the stomata closes.

Match the following

Question 1

Sl.
No.
Column AColumn B
1.aerobic respirationfound in the old and mature roots and hard woody stems
2.anaerobic respirationroots that grow out of the surface of water
3.stomatareleases carbon dioxide, ethyl alcohol and 2 ATP molecules
4.lenticelsfound in green leaves and stems
5.pneumatophoresreleases carbon dioxide, water and 38 ATP molecules

Answer

Sl.
No.
Column AColumn B
1.aerobic respirationreleases carbon dioxide, water and 38 ATP molecules
2.anaerobic respirationreleases carbon dioxide, ethyl alcohol and 2 ATP molecules
3.stomatafound in green leaves and stems
4.lenticelsfound in the old and mature roots and hard woody stems
5.pneumatophoresroots that grow out of the surface of water

Write true or false. Correct the false statements

Question 1

During anaerobic respiration, complete oxidation of glucose takes place.

Answer

False

Corrected statement — During anaerobic respiration, incomplete oxidation of glucose takes place.

Question 2

Respiration takes place only in the leaves of a plant.

Answer

False

Corrected statement — Respiration takes place in all parts of plant plant like leaves, stem, roots, etc.

Question 3

When the guard cells are full of water, they swell and bulge outwards opening the stomata.

Answer

True

Question 4

The exchange of gases takes place in the leaves by the process of diffusion.

Answer

True

Question 5

In photosynthesis, no energy is released.

Answer

True

Differentiate between

Question 1

aerobic and anaerobic respiration

Answer

Sl.
No.
Aerobic RespirationAnaerobic Respiration
1.It takes place in the presence of oxygen.It takes place in the absence or shortage of oxygen.
2.Complete oxidation of food takes place.Incomplete oxidation of food takes place.
3.38 ATP molecules are produced by the oxidation of one glucose molecule.2 ATP molecules are produced by the oxidation of one glucose molecule.
4.Its end products are carbon dioxide and water.Its end products are ethyl alcohol and carbon dioxide.

Question 2

respiration and combustion

Answer

Sl.
No.
RespirationCombustion
1.It occurs in the living cells.It does not occur in the living cells.
2.It takes place at room temperature.It takes place at high temperature.
3.It is a slow process.It is a fast process.
4.Energy is released in several steps and stored as ATP.Energy is released in the form of heat and light.
5.Enzymes are involved.No enzyme is involved.
6.Conversion of carbohydrates to carbon dioxide and water occurs in many steps.Carbon dioxide and water are produced in one step.

Question 3

stomata and lenticels

Answer

Sl.
No.
StomataLenticels
1.Stomata are present in leaves and green stems.Lenticels are present in mature stems, roots and fruits.
2.Stomata are active only during day time.Lenticels are active both during day and night.
3.Stomata have guard cells and they can be opened and closed.Lenticels do not have guard cells, they are always open.

Question 4

photosynthesis and respiration

Sl.
No.
PhotosynthesisRespiration
1.Food is synthesized by plants using carbon dioxide and water.Food is oxidized using oxygen to release energy.
2.It takes place only in autotrophs.It takes place in both autotrophs and heterotrophs.
3.It takes place only in the cells of green plants that have chloroplast.It takes place in the mitochondria of all living cells of a plant.
4.It takes place only during the day time.It takes place during day and night.
5.It requires carbon dioxide and water.It requires glucose and oxygen.
6.Oxygen is released as a by-product.Carbon dioxide and water are released as by-product.
7.It captures energy and stores it in sugars.It releases the energy stored in sugars.

Fill in the blanks

Question 1

............... is a process that takes place in plants throughout the day. It is of ............... types. They are ............... respiration and ...............respiration. In ............... respiration, complete ............... of glucose takes place in the presence of ............... to release ..............., ............... and ............... ATP molecules. In ............... respiration, incomplete ............... takes place in the ............... of oxygen to release ..............., ............... and ...............ATP molecules.

Answer

Respiration is a process that takes place in plants throughout the day. It is of two types. They are aerobic respiration and anaerobic respiration. In aerobic respiration, complete oxidation of glucose takes place in the presence of oxygen to release carbon dioxide, water and 38 ATP molecules. In anaerobic respiration, incomplete oxidation takes place in the absence of oxygen to release ethyl alcohol, carbon dioxide and two ATP molecules.

Answer the following in short

Question 1

How many ATP molecules are produced during aerobic respiration?

Answer

38 ATP molecules are produced during aerobic respiration.

Question 2

What is absent during anaerobic respiration?

Answer

Oxygen is absent during anaerobic respiration.

Question 3

What are the by-products of anaerobic respiration?

Answer

The by-products of anaerobic respiration are ethyl alcohol and carbon dioxide with 2 molecules of ATP.

Question 4

What are guard cells?

Answer

Each stoma has two bean-shaped cells called guard cells. The opening and closing of stomata is regulated by change in turgidity of the guard cells.

Question 5

What are pneumatophores?

Answer

Pneumatophores are the specialized roots of plants growing in salty and marshy area, that grow out of the surface of water. They have many pores on their surface to respire.

Answer the following in detail

Question 1

Describe the different types of respiration that takes place in plants.

Answer

Depending upon the presence or absence of oxygen, respiration is of two types — aerobic respiration and anaerobic respiration.

Aerobic respiration — When the oxidation of food (glucose) takes place in the presence of oxygen, it is called aerobic respiration. In this process, glucose is completely oxidized to form carbon dioxide and water. It takes place in mostly higher animals and plants. In aerobic respiration, 38 ATP molecules are released from oxidation of one glucose molecule.

Glucose + Oxygen ⟶ Carbon dioxide + Water + Energy (38 ATP)

Anaerobic respiration — When the oxidation of food (glucose) takes place in the absence of oxygen, it is called anaerobic respiration. In this process, glucose is not completely oxidized to form carbon dioxide and water. Rather, it is oxidized to produce ethyl alcohol or lactic acid and 2 ATP molecules.

Glucose (in absence of oxygen) ⟶ Carbon dioxide + Ethyl alcohol + Energy (2 ATP)

Question 2

How does exchange of gases take place through the stomata?

Answer

Each stoma has two bean-shaped cells called guard cells. The inner walls of the guard cells are thicker than the outer walls. When the guard cells are full of water, they swell and bulge outwards, opening the stomata. When the stomata is open, the exchange of gases takes place by the process of diffusion. Oxygen and water vapour leave the plant through the stomata while carbon dioxide enters through them.
When the guard cells lose water, they lose their turgidity closing the stomata. When the stomata is closed, no exchange of gases takes place through it.

How does exchange of gases take place through the stomata? Respiration in Plants, Living Science Biology Ratna Sagar Solutions ICSE Class 7.

Question 3

How does respiration occur in the stems and roots?

Answer

The old and mature roots and hard woody stems of certain trees are covered by bark. The bark contains very tiny openings called lenticels. The lenticels enable the oxygen to reach the intercellular spaces of interior tissues and carbon dioxide to be released into the atmosphere. At the base of the lenticels are loosely arranged cells that allow the diffuse gases to pass through them.
Respiration also takes place through the roots of plants. Air is present in the spaces between the soil particles. The oxygen in this air is absorbed by root hairs present on the roots. From root hairs, it is supplied to all the parts of the roots. Carbon dioxide released during respiration is diffused out of the roots through the same root hairs.

Question 4

Write the differences between respiration in plants and animals.

Answer

Sl.
No.
Respiration in AnimalsRespiration in Plants.
1.Animals take in oxygen through lungs.Plants take in oxygen through stomata, lenticels and the general surface of the roots.
2.Carbon dioxide is released as by-product in the process and is not taken back.Carbon dioxide is released as a by-product in the process and is reabsorbed for photosynthesis.
3.The food and oxygen used for respiration are taken from outside.The food and oxygen used for respiration are produced by the plants themselves.
4.The rate of respiration is very fast.The rate of respiration is slow.

Look at the pictures

Question 1

Look at the pictures given below and answer the following questions:

Identify this structure. In which part of the plant is it found? What is its function? Name the parts labelled as A and B. How is Figure 1 different from Figure 2? Respiration in Plants, Living Science Biology Ratna Sagar Solutions ICSE Class 7.
  1. Identify this structure.
  2. In which part of the plant is it found?
  3. What is its function?
  4. Name the parts labelled as A and B.
  5. How is Figure 1 different from Figure 2?

Answer

  1. The given structure is of Stomata.
  2. It is found in leaves and green young stems.
  3. The function of stomata is exchange of gases and regulation of rate of transpiration.
  4. The parts labelled as A and B are:
    A → Guard Cells
    B → Stomatal Opening
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