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Samacheer Kalvi 9th Science Books English Medium Plant Physiology

Science : Chapter 19 : Plant Physiology

I. Multiple choice Questions:

1. A big tree falls in a forest but its roots are still in contact with the soil. The branches of this fallen tree straight up. This happens in response to ___________.

  1. water and light
  2. water and minerals
  3. gravity and water
  4. light and gravity

Ans : water and light

2. The tropic movement that helps the climbing vines to find a suitable support is __________.

  1. phototropism
  2. geotropism
  3. thigmotropism
  4. chemotropism

Ans : thigmotropism

3. The chemical reaction occurs during photosynthesis is _____________.

  1. CO2 is reduced and water is oxidized
  2. water is reduced and CO2 is oxidized
  3. both CO2 and water are oxidized
  4. both CO2 and water are produced

Ans : CO2 is reduced and water is oxidized

4. Transpiration is best defined as __________.

  1. loss of water by the plant
  2. evaporation of water from the aerial surfaces from the plant
  3. loss of water in the form of water vapour from the underground parts of the plant body
  4. release of water from the plant into the atmosphere

Ans : evaporation of water from the aerial surfaces from the plant

II. State whether the following statements are true or false. If false, write the correct statement

1. The response of plant to the chemical stimulus is called phototropism. ( False )

Ans : Chemotropism.

2. Shoot is positively phototropic and negatively geotropic. ( True )

3. Scientific term used to represent the bending of roots towards water is called geotropism. ( False )

Ans : Hydrotropism

4. Joseph Priestley devised an experiment to find out that water alone was the cause of the increase in the weight of the plant. ( False )

Ans : It was VanHelmont who thought that water alone was the cause of the increase in weight of the plant.

5. When the weather is hot water evaporates lesser which is duet o opening of stomata. ( False )

Ans : When the weather is hot water evaporates more which is due to opening of stomata.

III. Fill in the blanks

1. The shoot system grows upward in response to ___________

Ans : Phototropism

2. __________ is positively hydrotropic as well as positively geotropic.

Ans : Root

3. The green pigment present in the plant is __________

Ans : Chlorophy II

4. The minerals like nitrogen, potassium and phosphorus, are required in substantial quantity by the plants are called ___________

Ans : Macronutrients

IV. Match column A with column B

1. Roots growing downwards into soilPositive phototropism
2. Shoots growing towards the lightNegative geotropism
3. Shoots growing upwardnegative phototropism
4. Roots growing downwards away from lightPositive geotropism

Ans : 1 – D, 2 – A, 3 – B, 4 – C

V. Analog

1. Towards a stimulus : _____________ Away from the stimulus : Negative tropism

Ans : Positive Tropism

2. Hydrotropism : Response towards water Phototropism : ___________

Ans : Response towards light

3. Photosynthesis : ____________ Transpiration : Stomata

Ans : ChlorophyII

VII. Short Answer:

1. Give an example for a plant whose leaf shows a mesmerizing movement.

Desmodium gyrans (Indian Telegraph plant)

2. Write the scientific terms used to represent the following:

a) Growing of roots towards the gravity.

positive geotropism and positive hydrotropism – root.

b) Bending of roots towards the water.

Positive phototropism – stem

VII. Answer the following in one or two sentences

1. What is nastic movement?

Some movements in plants not directed towards stimuli is known as Nastic movement.

2. Name the plant part.

a) Which bends in the direction of gravity but away from the light?


b) Which bends towards light but away from the force of gravity?


2. Differentiate Phototropism from Photonasty

1) Unidirectional, response to the stimulus of light.Non directional response to the stimulus of light.
2) Growth dependent movementGrowth independent movement
3) Permanent and irreversible.Temporary and reversible
4) Slow action
Eg. Growth of stem towards light
4) Immediate fast action
Eg. Unfolding of Dandelion flower in the morning and closing in the evening.

6. Photosynthesis converts energy X into energy Y

a) What are X and Y

X – Solar energy; Y- Chemical energy

b) Green plants are autotrophic in their mode of nutrition, why?

Green plants have green pigment, so can prepare food directly from sunlight using CO2 and H2O as raw material. Almost all the organisms rely on plant for their food – so green plants are autotrophic.

7. Define Transpiration.

The loss of water in the form of water vapour from the aerial parts of the plant body is called Transpiration.


I. Multiple Choice Questions

1. The bending of root of a plant in response to water is called………….

  1. thigmonasty
  2. phototropism
  3. hydrotropism
  4. photonasty

Ans ; hydrotropism

2. A growing seeding is kept in the dark room. A burning candle is placed near it for a few days. The top part of the seeding bends towards the burning candle. This is an example of …….

  1. chemotropism
  2. thigmotropism
  3. phototropism
  4. geotropism

Ans ; phototropism

3. The root of the plant is ………….

i) positively phototropic but negatively geotropicii) positively geotropic but negatively phototropic.
iii) negatively phototropic but positively hydrotropic.iv) negatively hydrotropic but positively phototropic.
  1. (i) and (ii)
  2. (ii) and (iii)
  3. (iii) and (iv)
  4. (i) and (iv)

Ans ; (ii) and (iii)

4. The plant part which exhibits negative geotropism is ………….

  1. root
  2. stem
  3. branch
  4. leaves

Ans ; stem

5. The non-directional movement of a plant part in response to temperature is called …………..

  1. thermotropism
  2. thermonasty
  3. chermotropism
  4. thigmonasty

Ans ; thermonasty

6. Dandelion flowers open the petals in bright light during the day time but close the petals in dark at night. The response of Dandelion flowers is called ……………

  1. geonasty
  2. thigmonasty
  3. chemonasty
  4. photonasty

Ans ; photonasty

7. During photosynthesis plants exhale …………

  1. carbondioxide
  2. oxygen
  3. hydrogen
  4. helium

Ans ; oxygen

8. ChlorophyII in a leaf is required for ………….

  1. photosynthesis
  2. transpiration
  3. tropic movement
  4. nastic movement

Ans ; photosynthesis

9. A plant is kept in a dark room for about 24 hours before conducting any experiment on
photosynthesis in order to ……….

  1. remove chlorophyII from the leaf.
  2. remove starch from the leaves.
  3. ensure that photosynthesis occurred.
  4. to prove transpiration.

Ans ; remove starch from the leaves.

10. Transpiration takes place through ……………

  1. fruit
  2. seed
  3. flower
  4. stomata

Ans ; stomata

II. Fill in the blanks

1. The solar tracking of sunflower in accordance with the path of sun is due to ___________.

Ans ; heliotropism

2. The response of a plant part towards gravity is __________.

Ans ; geotropism

3. When the leaves of a sensitive plant are touched with a fnger, they fold up and when light fades at dusk the petals of a Dandelion fower close.  Tese two plants show ____ and_____ movements.

Ans ; thigmonastic and photonastic

4. Opening and closing of Moon flower is not a tropism because the movement in this is ______.

Ans ; Ny….nasty

5. The raw materials for photosynthesis are _________ and _______.

Ans ; CO2 and H2O

6. When iodine solution is added for testing starch, part of the leaf with _______ turn blue-black colour.

Ans ; starch

7. In leaves, the food is stored in the form of _________.

Ans ; starch

8. Plants may inhale carbon dioxide for photosynthesis but need ___________ for their living.

Ans ; oxygen

9. Plants utilize only _______% of the absorbed water for photosynthesis and the other activities.

Ans ; 1%

10. Plants inhale and exhale continuously through the __________.

Ans ; stomata

III. State whether the following statements are true or false. If false write the correct

1. When the leaves of Mimosa Pudica plant are touched with the finger, they fold up quickly. This is an example of thigmonasty. ( True )

2. The petals of moon flower open up in morning and closes in the evening. This is called photonasty. ( False )

Ans : Open in night and closes in the day. The movement is thermonasty (or) photonasty.

3. Photosynthesis produces glucose and carbondioxide. ( False )

Ans : It produces glucose and oxygen,

4. Photosynthesis is important in releasing oxygen to keep the atmosphere in balance. ( True )

5. Plants lose water when the stomata on leaves are closed. ( False )

Ans : Plant lose water when the stomata on leaves are kept open.

IV Match the following

1. PhotonastyResponse to temperatureTulipa Sp
2) ThigmonastyResponse to lightMimisa pudic
3) ThermonastyResponse to touchMoon flower

Ans : 1 – B – C, 2 – C – B, 3 – A – A

1. Name the part of plant which shows positive geotropism. Why?

Tendency of roots to grow downwards is known as positively geotropic.

2. What does a Mimosa pudica plant do in response to touch? What is phenomenon known as?

It folds up and droop and this phenomenon is known as thigmonasty or seismonasty.

3. i) What happens to the dandelion flower a) during the day time; b) at night

ii) What is the phenomenon known as?

During the day time the flower unfolds and it closes in the evening or night. This phenomenon is known as photonasty.

4. What is the difference between the movement of flower in sunflower plant and closing of the leaves in the Minosa pudica?

In Sunflower, the flower tracks and moves in response to the direction of sun. This response is known as Heliotropism.

In Mimosa pudica (touch-me-not) plant the leaves fold up and droop. This type of movement is also nown as seismonasty or thigmonasty.

Unlike tropic movement, nastic movements are independent of the stimulus direction and may or may not be growth movement.

5. Complete the following table with the different types of tropism:

StimulusGravityUnilateral lighrWater
ResponseShootNegative geotropismPositive PhototropismNo response
RootPositive geotropismNegative PhototropismPositive  ydrotropism

6. Mention the difference between Stomatal and lenticular transpiration.

1) Most dominant oneNot at all dominant
2) Most of water loss – (ie) 90- 95% of the total amountOccur through tiny openings that protrude from the barks in woody stems and twigs.
3) Occur in all plants.Only in trees with bark.

7. Give an example for the movement plant part which is very quick and can be observed easily.

The easily observable and quick movement that can be seen in a plant is the falling of leaf – in Mimosa pudica by thigmonasty.

8. To which directional stimuli do

a) roots respond;

The roots respond to geotropic and hydrotropic stimuli where as

b) shoots respond?

shoots respond to phototropic stimulus.

9. Name the cell that surround the stoma?

The cells that surround the stoma are guard cells.

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