Control and Coordination - Lakhmir Singh Manjit Kaur Solutions Pg No. 92 Class 10 Biology

Solutions of Control and Coordination Lakhmir Singh Manjit Kaur VSAQ, SAQ and LAQ Pg No. 92 Class 10 Biology

Solutions of Control and Coordination Lakhmir Singh Manjit Kaur VSAQ, SAQ and LAQ Pg No. 92 Class 10 Biology

Very Short Answer Type Questions-Pg-92

1. What is the general name of chemical substances which bring about control and coordination in plants?

Answer

→ Phytohormones or plant hormones are the organic substances produced naturally in plants which control growth and other physiological activities at a site away from their synthesis.

2. Which plant hormone is responsible for the wilting and falling of leaves?

Answer

→ Abscisic acid, produced in the roots and terminal buds of the plant, is involved in many developmental plant processes, including leaf abscission, responding to environmental stress, and inhibiting fruit ripening.

3. Which plant hormone makes a stem (or shoot) bend towards light?

Answer

→ Auxin, a phytohormone produced in the stem and bud tips, promotes cell elongation. Auxins promote cell stem elongation and inhibit growth of lateral buds. They promote bending of stems or shoot towards light (also known as phototropism).

4. Where is the auxin hormone made in a plant stem?

Answer

→ Auxin phytohormone is produced in the stem, buds, and root tips.

5. What is the scientific name of sensitive plant?

Answer

→ Touch me not (also known is Chui-mui) is a touch sensitive plant. The scientific name of this plant is Mimosa pudica.

6. Name one plant hormone that promotes growth and another plant hormone which inhibits growth.

Answer

Gibberellins are growth hormones that stimulate cell elongation and cause plants to grow taller.
Abscisic acid involves in many developmental plant processes, including leaf abscission, inhibiting plant growth and fruit ripening.

7. Name one example of the movement of a plant part which is very quick and can be observed easily.

Answer

→ When we touch the leaves of Mimosa pudica (touch me not) then they get folded. It is a rapid process.

8. Name the type of chemical substances that control the growth in plants.

Answer

→ Phytohormones or plant hormones are the organic substances produced naturally in plants which control growth and other physiological activities.

9. What is the stimulus in:
(a) phototropism?
(b) geotropism?
(c) chemotropism?
(d) hydrotropism?
(e) thigmotropism?

Answer

→ (a) Light is the stimulus in phototropism.
(b) Gravity is the stimulus in geotropism.
(c) Chemical is the stimulus in chemotropism.
(d) Water is the stimulus in hydrotropism.
(e) Touch is the stimulus in thigmotropism.

10. Give the scientific terms used to represent the following:
(a) Bending of a shoot towards light.
(b) Growing of roots towards the earth.
(c) Growth of a pollen tube towards ovule.
(d) Bending of roots towards water.
(e) Winding of tendril around a support.

Answer

→ (a) The process of bending of a shoot towards light is known as phototropism.
(b) The process of growing of roots towards the earth is known as geotropism.
(c) The process of growth of a pollen tube towards ovule is known as chemotropism.
(d) The process of bending of roots towards water is known as hydrotropism.
(e) The process of winding of tendril around a support is known as thigmotropism.

11. Give one example of the movement of a plant part which is caused by the loss of water (or migration of water).

Answer

→ When we touch the leaves of a sensitive plant like touch-me not (chui-mui) then they get folded up. It shows an example of the movement of leaves which is caused by the loss of water.

12. Give one example each of a plant part:
(a) which is positively hydrotropic as well as positively geotropic.
(b) which is positively phototropic but negatively geotropic.

Answer

→ (a) Root of a plant bends towards the water in soil hence shows positive hydrotropic with positive geotropic.
(b) Stem of a plant bend towards the light above the soil hence shows positive phototropic but negative geotropic.

13. Which of the following is a growth movement and which is not?
(a) folding up of leaves of sensitive plant on touching with hand.
(b) folding up of petals of dandelion flower when light fades.

Answer

→ (a) Folding up of leaves of sensitive plant on touching with hand is not a growth movement.
(b) Folding up of petals of dandelion flower when light fades is a growth movement.

14. Name the plant part:
(a) which bends in the direction of gravity but away from light
(b) which bends towards light but away from the force of gravity

Answer

→ (a) Root of a plant bends in the direction of gravity but away from light.
(b) Shoot or stem of a plant bends towards light but away from the force of gravity.

15. To which directional stimuli do:
(a) roots respond?
(b) shoots respond?

Answer

→ (a) Roots respond to light, gravity and water stimuli.
(b) Roots respond to light and gravity.

16. Fill in the following blanks:
(a) A plant's response to light is called………………
(b) A plant's response to gravity is called………………
(c) Plant shoot grows upward in response to………………
(d) Plant roots grow downward in response to………………
(e) Tendrils wind around a support in response to ………………
(j) Plant roots grow towards ………. and in the direction of force of………………
(g) A root of a plant grows downward. This is known as………………
(h) ……..is the hormone that causes phototropism in plants
(i) The response of leaves to the sunlight is called...............

Answer

→ (a) A plant's response to light is called phototropism.
(b) A plant's response to gravity is called geotropism.
(c) Plant shoot grows upward in response to sunlight.
(d) Plant roots grow downward in response to gravity.
(e) Tendrils wind around a support in response to touch.
(j) Plant roots grow towards water and in the direction of force of gravity.
(g) A root of a plant grows downward. This is known as positive geotropism.
(h) Auxin is the hormone that causes phototropism in plants.
(i) The response of leaves to the sunlight is called phototropism.

Short Answer Type Questions-Pg-93

17. Plant parts show two types of movements, one dependent on growth and the other independent of growth.
Give one example of the movement in plant parts:
(a) which depends on growth
(b) which does not depend on growth

Answer

→ (a) Phototropism is the growth of plant parts in the direction of its light source. The bending of stem or shoot towards light shows this process.
(b) Touch me not (also known is Chui-mui) is a touch sensitive plant. When we touch the leaves of this plant then they get folded.

18. What is a plant hormone? Name four plant hormones. State one function of each. (CBSE 2015)

Answer

→ Plant hormones (also known as phytohormones) are chemicals that regulate plant growth.
4 Plant hormones:
(a) Auxins: Influence cell enlargement, bud formation and root initiation. Also promotes apical dominance.
(b) Cytokinins: Influence cell division and shoot formation.
(c) Gibberellins: Stimulate cell elongation and initiate mobilization of storage materials in seeds during germination.
(d) Ethylene: Stimulates the ripening of fruit and initiates abscission of fruits and leaves.

19A. What does a root do in response to gravity? What is this phenomenon known as?

Answer

→ Positive geotropism is the process in which the roots of plants bend downwards in the direction of gravity.

19B. What does a stem (or shoot) do in response to light? What is this phenomenon known as?

Answer

→ Positive phototropism is the process in which stem or shoot of plants bends towards the light.

20A. What does a stem (or shoot) do in response to gravity? What is this phenomenon known as?

Answer

→ Negative geotropism is the process in which stem or shoot of plants grows upward against the direction of gravity.
(b) Negative phototropism is the process in which roots of plants bend away from light.

20B. What does a root do in response to light? What is this phenomenon known as?

Answer

→ Negative phototropism is the process in which roots of plants bend away from light.

21A. What does a Mimosa pudica plant do in response to touch? What is this phenomenon known as?

Answer

→ When we touch the leaves of Mimosa pudica (also known as touch-me not or chui-mui plant), they get folded up. This phenomenon of folding up of leaves is known as thigmonasty.

21B. What happens to the dandelion flower (i) during daytime and (ii) at night? What is this phenomenon known as?

Answer

→ (i) In the morning, a dandelion flower opens up in bright light. This phenomenon is known is positive photonasty.
(ii) A dandelion flower closes at night. This phenomenon is known as negative photonasty.

22A. What does a plant root do in response to water? What is this phenomenon known as?

Answer

→ The roots of a plant grow towards the water. This phenomenon is known as hydrotropism.

22B. What happens to the moonflower (i) during daytime, and (ii) at night? What is this phenomenon known as?

Answer

→ (i) The petals of moon flower get closed during the daytime because of bright light.
(ii) The petals of moon flower get opened at night because of dark. This phenomenon is known as photonasty.

23. What is a tendril? Name the two types of tendrils. What does a tendril do in response to the touch of a support? What is this phenomenon known as?

Answer

→ A tendril is a specialized leaf, petiole or stem with a threadlike shape. It is used by climbing plants for support and attachment. The tendrils grow towards the things they happen to touch and the phenomenon is known as thigmotropism.

24. Name the five types of tropisms. How are tropic movements helpful to plants? Explain with an example.

Answer

→ The five types of tropisms are:
(a) Phototropism
(b) Chemotropism
(c) Geotropism
(d) Thigmotropism
(e) Hydrotropism
The different types of tropic movements help the plant to grow and survive. Roots grow in soil towards gravity show the geotropism.

25. Define chemotropism. Give one example of chemotropism. State whether this example is of positive chemotropism or negative chemotropism.

Answer

→ Due to chemical stimulus, the growth of a plant part is known as chemotropism. For example, a sugary substance can induce to the growth of pollen tube towards the ovule. Here, sugary substance works as a stimulus and this process represents the positive chemotropism.

26. Distinguish between tropic movements and nastic movements in plants. Give examples to illustrate your answer.

Answer

→ Tropic movements are very slow and always in the direction of stimulus. All parts of a plant (roots, stem and leaves etc.) exhibit these movements. Movement of shoot towards the light and not towards gravity is an example of this kind of movement.
Nastic movements are rapid and neither away nor towards the stimulus. Leaves and petals of flower exhibit these movements. The bending and drooping of leaves in 'Touch-me-not' plant is an example of this kind of movement.

27A. What is meant by nastic movements in plants? Give one example of nastic movements in plants.

Answer

→ Nastic movement is the movement of a plant part in response to an external stimulus. In this type of movement, the direction of response is not determined by the direction of stimulus. Leaves and petals of flower exhibit these movements. The bending and drooping of leaves in 'Touch-me-not' plant is an example of this kind of movement.

27B. What is the difference between photonasty and thigmonasty?

Answer

→ Photonasty: It is the non-directional movement of a plant part (e.g. petals of flowers) in response to light. The opening and closing of petals of dandelion flowers in response to light intensity is an example of this process.
Thigmonasty: It is the non-directional movement of a plant part in response to the touch. The folding up of Mimosa pudica leaves when touching is an example of this process.

28. A potted plant is kept horizontally for a considerable time. The three positions of the parts A and B of the potted plant are shown in the following figures:
(a) Which figure shows the correct position taken by the parts A and B of the plant?
(b) What type of phenomenon is exhibited by the figure chosen in (a) above?

Answer

→ (a) Figure (ii) shows the correct position taken by the parts A and B of the plant. As the aerial parts of the plants show positive phototropism while roots show positive geotropism.
(b) Geotropism is exhibited by the figure chosen in (A) above.

29. Name the plant hormones which are responsible for the following effects:
(a) falling of leaves
(b) opening of stomata
(c) bending of stem towards light
(d) closing of stomata

Answer

→ (a) Abscisic acid is responsible for abscission of falling of leaves.
(b) Cytokinin is responsible for opening of stomata.
(c) Auxin is responsible for bending of stem towards light.
(d) Abscisic acid is responsible for closing of stomata.

30. Name the plant organs which are:
(a) positively phototropic
(b) positively geotropic
(c) negatively geotropic 
(d) positively hydrotropic

Answer

→ (a) Stem or shoot is positive phototropic (bends towards the light).
(b) Roots are positive geotropic (grow in the soil in the direction of gravity).
(c) Stem or shoot is negative geotropic (grows above the soil against the gravity).
(d) Root are positive hydrotropic (grow in the soil for water).

31. Why is the folding up of the leaves of a sensitive plant on touching with a finger not a tropism?

Answer

→ When we touch the leaves of a sensitive plant (like Mimosa pudica), they get folded. It is not a case of tropism because there is no dependency of direction of leaves movement on the direction of stimulus (touch).

32. Why is the closing of a dandelion flower at dusk (when it gets dark) not a tropism?

Answer

→ The closing of a dandelion flower at dusk (when it gets dark) is not an example of a tropism because there is no dependency of the direction of movement of petals of dandelion flower on the direction of stimulus (light).

Long Answer Type Questions-Pg-94

33A. What is meant by ‘tropisms’ (or tropic movements)? Explain with an example.

Answer

→ Tropism is the turning or bending movement of a plant in a particular direction in response to an external stimulus such as gravity or light.
Example – The process that represents the bending of plant stem towards light is known as positive phototropism.

33B. What are the different types of tropisms? Define each type of tropism. Write the name of stimulus in each case.

Answer

→ Different types of tropisms are as follows:
(i) Phototropism – It is the movement of a plant part towards light. The light is the stimulus in this process.
(ii) Geotropism – It is the movement of a plant part towards gravity. The gravity is the stimulus in this process.
(iii) Chemotropism – It is the movement of a plant part in response to a chemical. A chemical is the stimulus in this process.
(iv) Hydrotropism – It is the movement of a plant part in response to water. The water is the stimulus in this process.
(v) Thigmotropism – It is the movement of a plant part in response to touch. Touch is the stimulus in this process.

33C. How do tropisms differ from nasties (or nastic movements)?

Answer

→ Tropisms: These kinds of movements are very slow and always in the direction of stimulus. All parts of a plant (roots, stem and leaves etc.) exhibit these movements.
Nasties: These kinds of movements are rapid and neither away nor towards the stimulus. Leaves and petals of flower exhibit these movements.

34A. Define phototropism. Give one example of phototropism.

Answer

→ Phototropism is the movement of a plant part in response to a stimulus (light).

34B. How does phototropism occur in a plant stem (or shoot)? Explain with the help of labelled diagrams.

Answer

→ Phototropism in a plant stem or shoot. The bending of a plant stem towards light represents the phototropism process. Due to the action of auxin, a growth hormone, the plants stem bends towards the light. This hormone is present at shoot tip of the growing plant. It usually prefers to stay in shade or away from sunlight so when the sunlight falls on the stem directly from one side then it gets concentrated on the other side. Due to presence of more auxin, the shady side of the stem or shoot grows longer in comparison to the side of stem which is facing direct sunlight hence, makes the stem bend towards light.



34C. What is meant by positive phototropism and negative phototropism? Give one example of each type.

Answer

→ Positive phototropism is the movement of a plant part in response to a stimulus (light). If the movement of a plant part away from light then it is known as negative phototropism. The stem of a plant grows and bends towards light represents the positive phototropism while movement of root away from light inside the soil is an example of negative phototropism.

35A. Define geotropism. Give one example of geotropism.

Answer

→ Geotropism is the movement of a plant part in response to a stimulus (gravity).

35B. What is meant by 'positive geotropism' and 'negative geotropism? Give one example of each type. Draw a labeled diagram to illustrate your answer indicating the plant part which shows positive geotropism and the plant part which shows negative geotropism.

Answer

→ Positive geotropism is movement of a plant part towards the direction of gravity. For example, roots grow in the soil.
Negative geotropism is the movement of a plant part against the direction of gravity. For example, Stem or shoot grow outside the soil.

35C. Name one plant part which exhibits positive thigmotropism.

Answer

→ A tendril is a specialized leaf, petiole or stem with a threadlike shape. It is used by climbing plants for support and attachment. The tendrils grow towards the things they happen to touch and the phenomenon is known as thigmotropism.

36A. How does control and coordination take place in plants? How does it differ from that in animals?

Answer

→ Like humans and other animals, plants do not have a well-defined nervous system but they can sense things in their surroundings in the presence of various stimuli like light, gravity, water, touch etc. and respond them by different hormonal actions. The plants coordinate their behavior against environmental behavior by these hormones. This process is called coordination. These hormones are organic chemicals and play a vital role in different plant parts that results the movement of plant part in response to a stimulus. In animals, the control and coordination takes place in coordination of both nervous system and hormones.

36B. Name five stimuli which act on plants. Name the type of tropism produced by each one of these stimuli.

Answer

→ (i) Light is the stimulus in phototropism.
(ii) Gravity is the stimulus in geotropism.
(iii) Touch is the stimulus in thigmotropism.
(iv) Water is the stimulus in hydrotropism.
(v) Chemical is the stimulus in chemotropism.

36C. Define hydrotropism. Give one example of hydrotropism. State whether this example is of positive hydrotropism or negative hydrotropism. Illustrate your answer with the help of labeled diagram.

Answer

→ Hydrotropism is the movement of a plant part in response to a stimulus (water).
Example: The plant roots always move towards water hence shows positive hydrotropism.

37A. What is meant by positive tropism and negative tropism? Explain with examples.

Answer

→ Positive tropism is the growth of a plant part in response to a stimulus while negative tropism is the growth of a plant part is away from the stimulus.
Example: The roots of a plant grow towards gravity in soil represent the positive geotropism whereas stem of same plant grows against the gravity and represent the negative geotropism.

37B. Define thigmotropism. Give one example of thigmotropism.

Answer

→ Thigmotropism is the directional growth movement of a plant part in response to the stimuli (touch). Example: A tendril is a specialized leaf, petiole or stem with a threadlike shape. It is used by climbing plants for support and attachment. The tendrils grow towards the things they happen to touch.

37C. What is the difference between thigmotropism and thigmonasty? Name one plant which exhibits thigmotropism and one plant which exhibits thigmonasty. What behaviour (or responses) of these plants make you think that they exhibit thigmotropism and thigmonasty respectively?

Answer

→ Thigmotropism is the directional growth movement of a plant part in response to the stimuli (touch). Example - Tendrils
Thigmonasty is non-directional movement of a plant part in response to the stimuli (touch). Example – Mimosa pudica (Touch me not or Chui-mui plant)
Tendrils grow towards a stimulus (touch) and show directional movement and represent thigmotropism. In case of thigmonasty, the folding of leaves in Mimosa pudica (Touch me not or Chui-mui plant) is not depend on the direction of stimulus.

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