Chapter 1 (a) – Sensitivity And Response In Plants | Life Science Solution Class 10

1. Locomotion
2. Movement
3. Spontaneous movement
4. Movement and locomotion.

1. Tropic movement
2. Nastic movement
3. Amoeboid movement
4. None of these.

Very Short Answer (VS) type questions

Question 1

What is the name of the movement involved in the opening of the Tulip flower?

Answer

The movement involved in the opening of a tulip flower is called heliotropism.

Question 2

Name tropic movement of stem tip under the influence of direction of sunlight. 

Answer

The tropic movement of the stem tip under the influence of the direction of sunlight is called phototropism.

Question 3

Cite an example of nastic movement.

Answer

The mimosa plant’s closing and opening of leaves in response to touch or disturbance is an example of nastic movement.

Question 4

Name the type of movement which depends on the intensity of stimulus.

Answer

Nastic movement.

Question 5

In Sundew when an insect comes in contact with leat, the hairs move towards the insect. Name the movement.

Answer

Question 6

“The leaflets of a sensitive plant become folded when touched”-What type of movement is this?

Answer

The movement described in the statement is an example of nastic movement, specifically thigmonasty or seismonasty, which is the response of plants to mechanical stimuli such as touch.

Question 7

Which kind of movement is seen in the trap door or in the tentacles of an insectivorous plant when it comes in contact with the body of an insect? 

Answer

The kind of movement seen in the trap door or in the tentacles of an insectivorous plant when it comes in contact with the body of an insect is a rapid movement known as rapid movement or rapid plant movement.

Question 8

Which hormone is responsible for tropic movement? 

Answer

The hormone responsible for tropic movement in plants is auxin.

Question 9

Give an example of a plant which shows tactic movement. 

Answer

An example of a plant that shows tactic movement is the Venus flytrap (Dionaea muscipula).

Question 10

What type of movement is exhibited by the stem when it moves towards light ?

Answer

The type of movement exhibited by the stem when it moves towards light is a tropic movement, specifically phototropism.

Fill in the blanks 

1. The movement of an organism in response to the intensity of the stimulus is called ____. 
2. The movement of a plant’s stem towards the source of light is called ____. 
3. The name of the movement found in Mimosa pudica is ____.
4. In movement, the pollen tube moves toward the ovum which is called ____.

Answer

1. The movement of an organism in response to the intensity of stimuli is called taxis.
2. The movement of a plant’s stem towards the source of light is called phototropism.
3. The name of the movement found in Mimosa pudica is seismonasty or thigmonasty.
4. In the movement, the pollen tube moves toward the ovum, which is called chemotaxis.

Short answer type questions

Question 1

What is movement? 

Answer

Movement is the ability of an organism or a part of an organism to change its position or location in response to various internal or external stimuli.

Question 2

Define tactic movement.

Answer

Tactic movement is a type of movement exhibited by organisms, in which the movement is directed towards or away from a stimulus. The stimulus could be chemical, thermal, light, gravity, or any other external factor.

Question 3

What is tropic movement?

Answer

Tropic movement is a type of movement exhibited by plants in response to external stimuli, such as light or gravity, which causes the plant to grow towards or away from the stimulus. Tropic movements are typically slower and involve the growth and curvature of plant organs, such as stems, roots, and leaves.

Question 4

What do you mean by nastic movement?

Answer

Nastic movement is a type of movement exhibited by plants that is not dependent on the direction of the stimulus, but rather on the magnitude or intensity of the stimulus. Nastic movements are typically rapid and reversible, and involve changes in turgor pressure or the opening and closing of specialized plant organs, such as petals, leaves, and traps.

Question 5

What is the difference between tropic and tactic movements? 

Answer

The three brief points on the difference between tropic and tactic movements:

1. Tropic movements are directional responses to external stimuli, whereas tactic movements are responses directed towards or away from a stimulus.
2. Tropic movements are dependent on the direction of the stimulus, while tactic movements are dependent on the intensity or presence of a stimulus.
3. Tropic movements are primarily observed in plants, while tactic movements are observed in a wide range of organisms, including bacteria, protozoa, and animals.

Question 6

How many types of tropic movements are there?

Answer

There are three main types of tropic movements in plants:

1. Phototropism: The growth or movement of a plant in response to light.
2. Geotropism or Geotropism: The growth or movement of a plant in response to gravity.
3. Thigmotropism: The growth or movement of a plant in response to touch or mechanical stimuli.

Question 7

Mention the difference between a tactic and nastic movements.

Answer

Question 8

What is chemonasty?

Answer

Chemonasty is a type of nastic movement in plants that is triggered by the presence or concentration of a chemical stimulus. It is a non-directional response, meaning the direction of the movement is not dependent on the direction of the stimulus.

Question 9

Write two differences between tactic and nastic movements with example.

Answer

Question 10

What are the differences between movement and locomotion? 

Answer

Question 11

What is tactic movement? What are the different types of tactic movements? 

Answer

Tactic movement is a type of movement in which an organism moves in response to a stimulus, such as light, gravity, chemicals, or touch. The direction of the movement is dependent on the direction of the stimulus.

There are many different types of tactic movements. Some common examples include:

1. Phototaxis: This is the movement of an organism towards or away from light. Positive phototaxis is the movement towards light, while negative phototaxis is the movement away from light.
2. Chemotaxis: This is the movement of an organism towards or away from a chemical stimulus. Positive chemotaxis is the movement towards a chemical, while negative chemotaxis is the movement away from a chemical.
3. Geotaxis: This is the movement of an organism towards or away from gravity. Positive geotaxis is the movement towards the ground, while negative geotaxis is the movement away from the ground.
4. Thigmotaxis: This is the movement of an organism towards or away from a solid surface. Positive thigmotaxis is the movement towards a surface, while negative thigmotaxis is the movement away from a surface.
5. Thermotaxis: This is the movement of an organism towards or away from heat. Positive thermotaxis is the movement towards heat, while negative thermotaxis is the movement away from heat.

Question 12

Explain Phototropic movements.

Answer

Phototropic movements are a type of tropic movement in which an organism or its body part moves in response to a unidirectional source of light. The direction of the movement is dependent on the direction of the light source.

Question 13

How will you prove the positive hydrotropic and negative hydrotropic movements in plant body ?

Answer

To prove positive hydrotropic and negative hydrotropic movements in plant bodies, you can conduct the following experiments:

1. Positive hydrotropism experiment:
   a) Take a seedling with a straight root and remove all the lateral roots.
   b) Place the seedling on a moist substrate with a concentration gradient of water (i.e., one end with high water concentration and the other end with low water concentration).
   c) After some time, observe that the roots of the seedling bend towards the side with higher water concentration, indicating positive hydrotropic movement.
2. Negative hydrotropism experiment:
   a) Take a seedling with a straight root and remove all the lateral roots.
   b) Place the seedling on a moist substrate with a concentration gradient of water (i.e., one end with high water concentration and the other end with low water concentration).
   c) After some time, observe that the roots of the seedling bend away from the side with higher water concentration, indicating negative hydrotropic movement.

Question 14

Explain Geotropic movement.

Answer

Geotropism, also known as Geotropism, is the growth or movement of plants in response to gravity. In geotropic movement, the plant’s roots grow downwards, towards the centre of the earth, while the stem or shoot grows upwards, away from the earth’s centre.

Question 15

What are the differences between tactic and tropic movements?

Answer

Long Answer (LA) type questions

Question 1

(a) Define locomotion. (b) Name a plant in which locomotion is observed and an animal in which locomotion is not observed. 

Answer

(a) Locomotion is the ability of an organism to move from one place to another using its own muscular or non-muscular structures.

(b) Locomotion in plants is mainly exhibited by the sensitive plant or mimosa pudica, which can move its leaves and stem in response to touch or other stimuli, but they are not able to move from one place to another like animals. An example of an animal that does not exhibit locomotion is a coral, which is a stationary organism that attaches itself to a surface and remains in that location for its entire life.

Question 2

Describe with examples the different types of movements which are observed in plants. 

Answer

Describe with examples the different types of movements which are observed in plants. 

Answer

Movement: The process by which the living organism remains fixed in a place but its parts or organs show a change of position due to the influence of stimuli, is known as movement.

Types of plant movement: Plant movements are classified into three categories: Tactic, Tropic and Nastic.

1. Tactic movement: The movement of locomotion induced by external stimuli like temperature, light, chemicals etc., is called tactic movement. Example – Chlamydomonas
2. Tropic movement: When the direction of growth movement of curvature of a plant organ bears a definite relation to the direction of stimulus (either towards or away from the stimulus), then the movement is termed as a tropic movement. Example – Root and shoot of the plant.
3. Nastlc movement: The movement of curvature of a plant organ that bears no relation to the direction of the stimulus but Is responsive to the intensity of the stimulus, Is called nastic movement. Example – Photonastic movement in Sunflower.

Question 3

Describe different types of nastic movements with one example from each.

Answer

Nastic movements are non-directional movements in plants that occur in response to a stimulus, and their direction is independent of the direction of the stimulus. There are different types of nastic movements, which are described below along with one example from each:

1. Seismonastic Movements: These are rapid movements that occur in response to mechanical stimuli, such as touch or vibrations. Example: The closing of leaves of the sensitive plant (Mimosa pudica) in response to touch or disturbance.
2. Thermonastic Movements: These are movements that occur in response to temperature changes. Example: The opening of the flowers of certain plants, such as the evening primrose (Oenothera biennis), in response to a drop in temperature.
3. Photonastic Movements: These are movements that occur in response to changes in light intensity. Example: The opening and closing of petals in response to changes in light intensity, as seen in the flowers of the tulip (Tulipa spp.).
4. Nyctinastic Movements: These are movements that occur in response to changes in the day-night cycle. Example: The opening and closing of flowers and leaves of certain plants, such as the morning glory (Ipomoea spp.), in response to changes in light and dark periods.

Question 4

What are the differences between tropic and nastic movements in plants? 

Answer

Question 5

What is tropic movement? Explain two types of tropic (phototropic and geotropic) movements in plants ?

Answer

Tropic movement: Tropic movement is a type of plant movement that occurs in response to a directional stimulus, such as light or gravity.

1. Phototropism: Phototropism is a tropic movement that occurs in response to light.
   There are two types of phototropism :
   a) Positive phototropism – In positive phototropism, the plant grows towards the source of light.
   Example – Movement of the shoot.
   b) Negative phototropism – in negative phototropism, the plant grows away from the source of light.
   Example – Movement of the root.
2. Geotropism: Geotropism is a tropic movement that occurs in response to gravity.
   a) Positive phototropism – In positive geotropism, the plant grows downwards, towards the centre of gravity.
   Example – Movement of the root.
   b) Negative phototropism – In negative geotropism, the plant grows downwards, away from the centre of gravity.
   Example – Movement of the root.

Question 6

Discuss with examples three types of tropic movements in plants.

Answer

Plants exhibit various tropic movements or directional growth responses in response to external stimuli such as light, gravity, touch, or moisture.

Here are three types of tropic movements in plants:

1. Phototropism: Phototropism is the directional growth response of plants towards or away from a light source. Most plants exhibit positive phototropism, where the shoot grows towards the light, while the roots exhibit negative phototropism, growing away from the light. An example of a plant exhibiting phototropism is sunflowers. They move their heads to track the sun’s movement, to maximize their exposure to sunlight.
2. Geotropism: Geotropism is the directional growth response of plants in response to gravity. Roots exhibit positive Geotropism, growing towards the direction of gravity, while shoots exhibit negative Geotropism, growing in the opposite direction. An example of a plant exhibiting Geotropism is the bean plant. When the plant is placed on its side, the roots curve and grow downwards while the stem curve and grows upwards, towards the direction of gravity.
3. Thigmotropism: Thigmotropism is the directional growth response of plants in response to touch or mechanical stimuli. This movement can either be towards the stimulus or away from it, depending on the plant species. An example of a plant exhibiting thigmotropism is the Venus Flytrap. The leaves of the Venus Flytrap are lined with sensitive hairs, and when an insect lands on them and triggers the hairs, the leaves close around the insect, capturing it for digestion.

Question 7

Briefly describe the different types of tropic movements in plants.

Answer

Plants exhibit different types of tropic movements, which are directional growth responses in response to external stimuli. The three main types of tropic movements in plants are:

1. Phototropism: This is the directional growth response of plants towards or away from a light source. Shoots exhibit positive phototropism, growing towards the light, while roots exhibit negative phototropism, growing away from the light. The movement is caused by the hormone auxin, which accumulates on the shaded side of the plant, causing the cells to elongate and grow towards the light.
2. Geotropism: This is the directional growth response of plants in response to gravity. Roots exhibit positive Geotropism, growing towards the direction of gravity, while shoots exhibit negative Geotropism, growing in the opposite direction. The movement is caused by the hormone auxin, which accumulates at the bottom of the root, causing it to elongate and grow downwards.
3. Thigmotropism: This is the directional growth response of plants in response to touch or mechanical stimuli. The movement can either be towards the stimulus or away from it, depending on the plant species. The movement is caused by the differential growth of cells on either side of the plant, causing it to bend or grow in response to the touch.

Question 8

What is nastic movement in plants? Mention three types of nastic movement in plants.

Answer

Nastic movement is a type of plant movement that is independent of the direction of the stimulus. In other words, the direction of the response is not dependent on the direction of the stimulus, unlike tropic movements. Instead, nastic movements occur due to changes in turgor pressure, which cause the plant to change its shape or position.

Here are three types of nastic movements in plants:

1. Thermonasty: Thermonasty is the nastic movement of plants in response to changes in temperature. The movement is typically in response to a decrease in temperature, and the plant’s leaves or flowers close up to protect themselves from the cold. An example of a plant that exhibits thermonasty is the tulip flower.
2. Nyctinasty: Nyctinasty is the nastic movement of plants in response to changes in light-dark cycles. The movement is usually in response to darkness, and the plant’s leaves or flowers close up. An example of a plant that exhibits nyctinasty is the mimosa pudica or “sensitive plant,” which folds its leaves in response to touch or darkness.
3. Seismonasty: Seismonasty is the nastic movement of plants in response to mechanical stimuli such as touch or vibration. The movement is not directional, and the plant’s leaves or branches move in response to the stimulus. An example of a plant that exhibits seismonasty is the Venus Flytrap, which closes its leaves around insects when they trigger the plant’s sensitive hairs.

Question 9

Describe an experiment to show that plant organs move towards light.

Answer

Describe an experiment to show that plant organs move towards light.

Answer

1. Materials required – Potted seedling, table.
2. Procedure – The potted seedling is kept near the open window through which adequate sunlight falls on the seedling.
3. Observation – After some days we notice that the stem moves towards the source of light i.e., towards the open window.
4. Inference – We can thus say that the stem, moving towards the direction of the external stimulus i.e., light, is positively phototropic or in other words, positively heliotropic. The leaves being in a transverse position towards the external stimulus is transversely phototropic.

Question 10

Discuss briefly the hydrotropic movement in plants. 

Answer

Hydrotropism is a type of tropism in which the roots of a plant grow towards a source of water. It is an important adaptive mechanism that allows plants to find and obtain water in their environment, which is essential for their survival and growth.

There are two main types of hydrotropic movements: positive hydrotropism, in which roots grow towards a source of water, and negative hydrotropism, in which roots grow away from water. Positive hydrotropism is the most common type of hydrotropism and is exhibited by most plants.

An example of positive hydrotropism can be seen in the roots of maize plants, which grow towards a source of water in the soil.

Question 11

Distinguish between Tactic and Nastic movements.

Answer

Question 12

What is tropic movements? Describe any two types of tropic movements in plants.

Answer

Tropic movements are directional plant movements in response to external stimuli such as light, gravity, touch, or chemicals.

Two types of tropic movements in plants are:

1. Phototropism: Phototropism is a plant’s growth response to light. If the light source is coming from one direction, the plant will grow towards it (positive phototropism) or away from it (negative phototropism). The photoreceptor molecule responsible for detecting light is called phytochrome, which is found in the plant’s leaves and stem tips.
   An example of phototropism is a sunflower, which follows the sun’s movement throughout the day to maximize exposure to sunlight.
2. Geotropism: Geotropism is a plant’s growth response to gravity. The roots grow downwards, towards the direction of the gravitational pull (positive Geotropism), while the stem grows upwards, away from the direction of the gravitational pull (negative Geotropism).
   An example of Geotropism is a potted plant that has been placed on its side – the stem will bend upwards towards the sky, while the roots will bend downwards towards the soil.

Drawing based questions

Question 1

Draw the experimental set-up of geotropic movement and label it. 

Answer

Experiment geotropism

1. Materials required: Few germinating seeds, a moist substance (sawdust).
2. Procedure:
   • Place the germinating seeds in a horizontal position over the moist substance (wet sawdust).
   • Keep the setup in a dark chamber to avoid the influence of light.
3. Observation:

• • After some days, the tip of the radicle (the embryonic root) will bend downwards, showing positive geotropism of the root.
  • The plumule (the embryonic shoot) moves in a direction vertically upwards, showing negative geotropism of the stem.

Inference:

• • Stem bending away from the gravitational pull shows negative geotropism, whereas, the root shows positive geotropism by moving towards the external stimulus.
  • The movement of roots and stems in response to gravity is essential for plants to grow upright and absorb nutrients and water from the soil.

Question 2

Draw the experiment of seismonasty and label It.

Answer

Seismonasty is a type of nastic movement in plants that occurs in response to mechanical stimulation, such as touch or vibration. It is commonly observed in sensitive plants such as the Mimosa pudica (also known as the “touch-me-not” plant).

During seismonasty, the plant’s leaves and petioles (the stalk that attaches the leaf to the stem) fold inwards and droop downwards in response to a stimulus. This is achieved through changes in turgor pressure within specialized motor cells located in the plants.