Chapter-2-CONTROL-AND-COORDINATION

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.

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.

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).

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

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

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.

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

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

(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.

(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.

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.

(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.

(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.

(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.

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

(b) Roots respond to light and gravity.

(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.

(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.

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.

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

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

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.

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

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.

(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.

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

(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.

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.

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.

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.

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.

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.

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.

(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.

(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.

(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).

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).

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).

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.

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.

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.

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

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.

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.

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

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.

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.

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.

(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.

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.

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.

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.

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.

Ascorbic acid, also known as Vitamin C, is a vitamin found in food particularly in citrus fruits and green vegetables.

Auxin, which is present at the tip of shoot, is responsible for the phenomenon of phototropism in plants.

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

Phototropism is the movement of a plant part in response to a stimulus (light). Hence, the movement of sunflower in accordance with the path of the sun is due to phototropism.

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

The roots show positive geotropism and stem or other aerial parts of plants show negative geotropism. Its reverse, the roots show negative phototropism while other aerial parts show positive geotropism.

Closing up of leaves of a sensitive plant on touching with an object (also known as Thigmonasty) is not caused by a growth movement.

The root of plant grows in response to gravity inside the soil. Hence, it is positively geotropic but negatively phototropic.

Abscisic acid is the growth inhibitor plant hormone.

The growth of tendrils in pea plants is due to the rapid cell division and elongation in tendril cells that are away from the support.

Abscisic acid is the growth inhibitor plant hormone.

Abscisic acid, the growth inhibitor plant hormone, triggers the fall of mature leaves and fruits from the plant body.

Hydrotropism is the movement of a plant part in response to water. The water is the stimulus in this process.

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.

The process of bending of a shoot towards light is known as phototropism.

Thigmotropism is the movement of a plant part in response to touch. Touch is the stimulus in this process.

The process of bending of a shoot towards light is known as phototropism.

Hydrogen oxide (OH) acts as a stimulus in the process of hydrotropism.

Thigmotropism is the movement of a plant part in response to touch of an object. Touch is the stimulus in this process.

The process of winding of tendril around a support is known as thigmotropism.

Auxin has adverse effect on growth rate of roots hence, it decrease the growth rate of roots.

Thigmonasty is the non-directional movement of a plant part in response to the touch. The folding up of Mimosa pudica (touch me not or chui-mui) leaves when touching is an example of this process.

Photonasty 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.

Touch is a directional stimulus roots of a plant do not respond.

Thigmonasty 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.

Auxin is the hormone that causes phototropism in plants.

Abscisic acid is the growth inhibitor plant hormone.

The process of bending of a shoot towards light is known as phototropism.

Auxin is the phytohormone which is responsible for the bending of the stem of a plant towards a source of light. This hormone is present at shoot tip.

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

Folding up of leaves of sensitive plant in response to touch is known as photonasty which is not a type of tropism. Opening up of the leaves of a daisy flower in response to light is also not an example of tropism.

(a) From the given question, the chemical substance P is Auxin which is produced at the shoot tip and can diffuse to other plant parts.

(b) Auxin moves to the darker side of the plant, causing the cells there to grow large.

(c) Auxin has adverse effect on growth rate of roots hence, it decrease the growth rate of roots. Unlike roots, the auxin has positive effect on growth rate of stem hence, it increases the growth rate of stem.

(d) Process Q is positive phototropism while process E is negative phototropism. Growth towards a light source is called positive phototropism, while growth away from light is called negative phototropism.

(e) Chemical substance like P is Auxin, a Phytohormone or plant hormone. Like Auxin, Gibberellin is also an example of phytohormone.

(a) Roots show positive geotropism and grow in the direction of gravity. In soil, they grow towards dark hence, show negative phototropism.

(b) Stem or shoot shows positive phototropism and grows towards the light. They grow in opposite direction of gravity hence, show negative geotropism.

(c) The plant roots (Part X) always move towards water hence shows positive hydrotropism.

(d) Tendrils grow towards a stimulus (touch) and show directional movement and represent thigmotropism. Stem (Part Y) can have tendrils on it.

(a) (i) Plant A shows positive photonasty.

(ii) Plant B shows negative photonasty.

(b) (i) In the morning, a dandelion flower opens up its petals in bright light. This phenomenon is known is positive photonasty.

(ii) A Moonflower flower closes its petals at night. This phenomenon is known as negative photonasty.

(c) Thigmonasty is the non-directional movement of a plant part in response to the touch. The folding up of leaves of plant C when touching is an example of this process.

(d) The folding up of Mimosa pudica leaves when touching is an example of Thigmonasty process.

(e) Plant A and B exhibit the phenomenon based on growth movements.

(a) Stimulus A could be water as roots show the positive hydrotropism.

(b) Stimulus B could be gravity as roots show the positive geotropism.

(c) Stimulus C could be light as roots show the negative phototropism.

(d) The two stimuli could be B (gravity) and C (light).

(a) (i) R is a leaf tendril.

(ii) S is a stem tendril.

(b) 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.

(c) Touch (support) is the stimulus involved in this case.

(d) behaviour of organs R and S is a tropic movement. Tropic movement is always in the direction of stimulus. All parts of a plant (roots, stem and leaves etc.) exhibit tropic movements.

(e) Pea plant is like P (leaf tendrils) and bitter gourd plant is like Q (stem tendrils).

(a) (i) Inside the flower, the organ X is carpel (a female reproductive organ).

(ii) Inside the flower, the organ Y is stamen (a male reproductive organ).

(b) (i) Part A of flask shaped organ is stigma.

(ii) Part B of flask shaped organ is style.

(iii) Part C of flask shaped organ is ovary.

(c) (i) Grain D of organ Y (stamen) is pollen grain.

(ii) Part E of organ Y (stamen) is anther.

(d) Tube F is the pollen tube.

(e) 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.

P is abscisic acid (a plant growth inhibitor hormone) and is responsible for the wilting and falling of leaves. Q is auxin which is responsible for the phenomenon of phototropism in plants as it is present at shoot tip. R is gibberellin which is responsible for enlargement of shoot. S is cytokinin which is responsible for breaking the dormancy of seeds and buds.

(a) The position of plant parts A and B shows negative geotropism and positive geotropism respectively.

(b) Gravity is the stimulus which causes plant part A to grow and bend upwards, and plant part B to bend downwards.

(a) Above mentioned processes are similar i.e. both are nastic movements.

(b) In first process of folding of leaves of sensitive plant (thigmonasty), the stimulus is touch but in second process of folding of petals of dandelion flower (photonasty), stimulus is light. First process (thigmonasty) is not a growth movement but second process (photonasty) is a growth movement.

Nervous system and endocrine system are the two systems of control and coordination in higher animals like human.

Central nervous system and peripheral nervous system are the two parts of the vertebrate nervous system.

A reflex action occurs when the body responds to a stimulus without the involvement of the brain. Rapid pull out of hands from touching a hot surface and batting of eyelids are examples of reflex actions.

A neuron, also known as nerve cell, is mainly consists of three components, namely cell body or soma, dendrites and axon.

Dendrites are the short fibres of a neuron. They transmit impulses from synapses to cell body.

Axon is the long fibre of a neuron. It carries the impulse away from the cell body.

Cerebrum is the largest and uppermost portion of the human brain.

The cerebellum is the area of brain that controls motor movement coordination, balance, equilibrium and muscle tone.

Function of cerebellum: It controls motor movement coordination, balance, equilibrium and muscle tone.

Function of pons: It regulates the breathing process. It also takes part in sensations such as hearing, taste and balance.

Growth hormone (GH), also known as somatotropin, is secreted by anterior lobe of the pituitary gland.

Hormones are the chemical messengers produced by glands in the endocrine system.

Hormones are the chemical messengers produced by glands in the endocrine system.

Growth hormone (GH), also known as somatotropin, is secreted by anterior lobe of the pituitary gland.

(a) Testosterone hormone, also known as male sex hormone, is secreted by testes.

(b) Oestrogen and progesterone hormones are released by ovaries.

(a) The scientific name for light receptor is photoreceptor.

(b) The scientific name for heat receptor is thermoreceptor.

(c) The scientific name for sound receptor is phonoreceptor.

(d) The scientific name for smell receptor is olfactory receptor.

(d) The scientific name for taste receptor is gustatory receptor.

Diabetes mellitus, also known as hyperglycemia, is caused by the deficiency of insulin hormone in the body.

Goitre, an enlargement of the thyroid gland, is caused by the deficiency of thyroxine hormone in the body.

Iodine is necessary for the making of thyroxine hormone by the thyroid gland which prevents goiter formation.

Some patients of diabetes treated by giving injections of insulin because it decreases the blood sugar level in the body.

Feedback mechanism is a method of controlling the hormone production.

(a) Thyroid is large, ductless gland present in the neck. It acts as an endocrine gland.

(b) Salivary glands present in and around the mouth and neck acts as an exocrine gland.

(c) Pancreas, an organ located in the abdomen, acts both as an endocrine gland as well as an exocrine gland.

Diet provides iodine which makes keeps the thyroid gland healthy by making thyroxine hormone and also prevents goitre.

In the diabetes (hyperglycemia) disease, the sugar level gets increased in the body.

Nose contains olfactory receptor whereas tongue has gustatory receptor.

Eye retina contains cells which are sensitive to light.

Endocrine system and Nervous system are the two main communications systems in an animal's body.

(a) Thyroid, thymus, pituitary and ovary these all are ductless glands.

(b) Adrenalin, insulin, thyroxine and estrogen these all are hormones.

Spinal cord and brain form the central nervous system (CNS).

Knee jerk reflex is an example of reflex action. The other examples include coughing and sneezing.

Iodine is required to synthesize of thyroxine hormone in the body hence necessary in our diet.

Coughing is an important defensive reflex that occurs through the stimulation of a complex reflex arc.

(a) The two examples of effectors are glands and muscle.

(b) Our nervous system allows us to react to our surroundings. Information from receptors passes along sensory neurons to our brain. Our brain sends impulses along motor neurons to our muscles.

(c) A neuron which carries an impulse to the brain is called a sensory neuron.

(d) The neuron which carries a message for action to a muscle or gland is known as a motor neuron.

In human body, there are 5 sense organs present. They are eyes, ears, nose, tongue and skin.

A receptor is an organ or cell able to respond to heat, light or other external stimulus and transmit a signal to a sensory nerve. Example: Photoreceptor (a receptor which detects light) and phonoreceptor (a receptor which detects sound).

An effector is a muscle, gland or an organ capable of responding to a stimulus, especially a nerve impulse.

The cylindrical bundle of nerve fibres and associated tissue which is enclosed in the spine and connects nearly all parts of the body to the brain. It functions primarily in the transmission of neural signals between the brain and the rest of the body.

The medulla helps regulate breathing, heart and blood vessel function, digestion, sneezing and swallowing. It is a center for respiration and circulation.

Spinal nerves, cranial nerves and visceral nerves are the three types of nerves which constitute the peripheral nervous system.

A reflex action is voluntary action which is a rapid and autonomic response to stimuli while walking is a voluntary action which requires our thinking and it’s in our control.

Agarbatti produces vapors on burning and generates a characteristics a fragrance which is detected by the olfactory receptors present in the nose. The electrical impulses are generated by the action of smell of agarbatti which sets off chemical reactions. Cerebrum, a sensory area present in the fore brain, receives these electrical impulses by which we can identify the smell of burning agarbatti.

Hormones are produced by the endocrine glands. These hormones are responsible for different functions in the various organs of the body.

A receptor is an organ or cell able to respond to heat, light or other external stimulus and transmit a signal to a sensory nerve. It detects all the information from our surroundings and carries it to the nervous system.

An effector is a muscle, gland or an organ capable of responding to a stimulus, especially a nerve impulse.

(i) Thyroxine hormone is secreted by the thyroid gland.

(ii) Parathormone is secreted by the parathyroid glands.

(iii) Insulin hormone is secreted by the pancreas gland.

(iv) Adrenaline hormone is secreted by the adrenal glands.

Testosterone is the principle male sex hormone and is responsible for reproductive growth and development in male vertebrates.

Oestrogen is the principle female sex hormone and is responsible for development of female secondary sexual characteristics.

There are mainly 3 regions present in hindbrain. They are:

(i) Pons: It regulates the breathing process. It also takes part in sensations such as hearing, taste and balance.

(ii) Cerebellum: It controls motor movement coordination, balance, equilibrium and muscle tone.

(iii) Medulla: It is the controlling centre for reflex actions like coughing, sneezing and swallowing etc. It also controls various involuntary actions like blood pressure and peristaltic movements of the elementary canal.

Function of cerebrum: It is the largest part of the brain and also known as cortex. It is associated with higher brain function such as thought, memory and action.

Forebrain, midbrain and hindbrain are three regions of human brain.

Cranium is a part of the skull in which brain is located. It protects the brain from damage.

In human beings and other animals, the chemical coordination takes place through the chemical messengers, called hormones. These hormones are produced by specific organs and carry through blood stream to other body parts. They are affected only a particular place of specific organ which is known as target organ. The organs control and coordinate different functions like growth, development, behavior, metabolism and secondary sexual characteristics etc.

Iodine is required to synthesize of thyroxine hormone in the body. This hormone is secreted by the thyroid gland and is responsible for metabolism of carbohydrates, fats and proteins. Taking of iodine is advisable to prevent from goiter disease.

The insulin hormone lowers the blood sugar (glucose) level in the body. The people suffering from severe diabetes are treated by injecting insulin in the body.

Nervous system coordinates the activities of body. It is responsible for the coordination of biological activities inside the body through the network of specialised cells called neurons. It receives the information from surroundings and processes through neurons and interprets it and then responds accordingly.

Endocrine system is a discrete set of glands that secrete different types of hormones to the circulatory system in order to regulate the functions of the body. Each gland of the endocrine system is responsible for the secretion of different hormones which act as messengers between the nervous system and the organs of body.

(a) Thyroxine: Controls the metabolic rate of carbohydrates, fats and proteins in the body.

(b) Adrenaline: Regulates blood pressure, heart rate, breathing rate, and carbohydrate metabolism.

(c) Growth hormone: Controls the growth of human body.

The endocrine glands present in the human body are:

(i) Pineal gland

(ii) Hypothalamus

(iii) Pituitary

(iv) Thyroid

(v) Parathyroid

(vi) Thymus

(vii) Pancreas

(viii) Adrenal glands

(ix) Testes (in males)

(x) Ovaries (in females).

Pancreas, testes and ovaries function as exocrine glands.

The correct matching of hormones with their functions is as:

(i) – (d)

(ii) – (c)

(iii) – (e)

(iv) – (a)

(v) – (b)

This is an example of reflex action. Here, drawing pin lying on the floor is the stimulus. The receptors located in the skin sense pain which triggers and impulse in a sensory neuron and transmits the message to the spinal cord. The impulse is passed onto a relay neuron which passes it to the motor neuron which passes the impulse to a muscle in the feet. It results contraction of muscle and pulling out feet away from the drawing pin.

In human beings, puberty and adolescence are the result of sex glands. Testes in males produce testosterone, a male sex hormone, which is associated with male puberty. In boys, this stage appears an age of 13-14 years. Ovaries in females produce oesterogen, a female sex hormone, is responsible for all the changes associated with female puberty. In girls, this stage is usually attains at an age of 10-12 years.

Neurons have cell membrane, nucleus and cytoplasm similar to other cells.

(a) A receptor is an organ or cell able to respond to heat, light or other external stimulus and transmit a signal to a sensory nerve.

An effector is a muscle, gland or an organ capable of responding to a stimulus, especially a nerve impulse.

(b) Cerebrum, a part of the forebrain, is responsible for controlling our thoughts, sensations, actions and movements.

Cerebellum, a part of the hindbrain, is responsible for maintaining the body posture and balance of the brain.

Voluntary action is controlled by the brain whereas involuntary action is controlled by the spinal cord. Riding a bicycle, dancing, and eating an apple are some examples of voluntary actions while breathing, flow of blood through our veins, blinking eye lids, heart beating, feeling emotions, growing for that matter are all involuntary actions.

Digestion is a kind of involuntary action.

CNS stands for Central Nervous System.

(a) Cerebrum, a part of the forebrain, consists of two cerebral hemispheres.

(b) Spinal cord has spinal nerves attached to it.

(a) Adrenaline hormone prepares the body for action.

(b) Insulin hormone controls the amount of glucose in blood.

(c) Testosterone hormone gives boys a deep voice.

(d) Oestrogen hormone gives girls soft skin.

(a) The smell of the food is a stimulus.

(b) Olfactory receptors are the cells in your nasal passages which perceive the smell.

(c) Salivary gland (effector) is the gland which is stimulated to secrete saliva.

A neuron is the structural and functional unit of nervous system.

The below flow chart depicts the classification of nervous system into various parts.

Example: A student who is getting late for school suddenly sees his watch then starts walking fast autonomously. Here, when the eyes see the time they send the information to brain through the sensory nerves. After which the brain receives the information, analyses them and sends the instructions to walk faster to muscle of our legs through the motor nerves. Then, the muscle of the legs act simultaneously by which student walks faster.

Autonomic nervous system is self-governing nervous system which controls and regulates the functions of the internal organs of our body involuntarily.

The voluntary nervous system helps us to take voluntary actions which are under the conscious control of the brain.

Example: A student who is getting late for school suddenly sees his watch then starts walking fast autonomously. Here, when the eyes see the time they send the information to brain through the sensory nerves. After which the brain receives the information, analyses them and sends the instructions to walk faster to muscle of our legs through the motor nerves. Then, the muscle of the legs act simultaneously by which student walks faster.

A reflex action is an involuntary, rapid response in the body to a stimulus.

Example: Moving our hand away on touching a hot bowl.

Reflex arc is the pathway taken by the nerve impulses in the reflex actions.

All reflex actions are involuntary in nature but all involuntary actions are not reflexes. A reflex action is a rapid and autonomic response to a stimulus which is not under the voluntary control of the brain. Involuntary actions do not need thinking and also not performed by us knowingly. Sneezing and coughing are the examples of reflex actions whereas digestion and respiration are involuntary actions.

The nervous system consists of the brain, spinal cord, sensory organs and all of the nerves that connect these organs with the rest of the body. Its main function is to establish the communication system between the organs of our body. It receives information from the surroundings, processes it, interprets it and then responds accordingly.

Brain, spinal cord and nerves are the main organs of the nervous system.

After affecting, the sense organ in our body sends the message (in the form of electrical impulses) to brain through the sensory neurons. The brain reads the signals and decides the necessary action to be taken out. Then, brain sends out the instructions through motor nerves to the body muscles of concerned part and then this part acts accordingly.

A neuron, also known as nerve cell, is a cell that carries message between the brain and other body parts. It is the basic unit of the nervous system.

In the nervous system, the synapse is a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter. Synapse between two neurons allows electrical impulses to pass in one direction only. The process is as follows: When the receptor sends an electrical impulse, it reaches at the end of the axon of sensory neuron. Then this electrical impulse releases a chemical, known as neurotransmitter, in very small amount into the synapse between two adjacent neurons. Neurotransmitter crosses the synapse and starts a similar electrical impulse in the dendrite of the next neuron. By this way, the electrical impulse passes from one neuron to the next across the synapse.

Both nervous system and endocrine system are two systems which taken together perform the functions of control and coordination in human beings.

The Central Nervous System (CNS) is made up of brain and spinal cord. The CNS is the main control center of the body. It takes in sensory information, organizes and synthesizes this input, then provides instructions for motor output to the rest of the body. In other words, it functions as the transmitter and receiver as well as the pathway for information flow and determines how the body responds to changes in its internal and external environment.

Functions of the brain: The brain is the command centre for the nervous system. It receives input from the sensory organs and sends output to the muscles. Intelligence, creativity, emotions, and memory are a few of the many things governed by the brain. It also controls the thoughts, memory and speech, movement of the arms and legs, and the function of many organs within the body.

(i) Pituitary gland secretes growth hormone.

(ii) Thyroid gland secretes thyroxine hormone.

(iii) Pancreas secreted insulin hormone.

(iv) Adrenal gland secretes adrenaline hormone.

(v) Testes secrete testosterone hormone.

The endocrine glands are ductless glands which secrete their products as hormones. They release hormones directly into the blood stream. These hormones reach the target body part through the blood and then act on it.

Hypothalamus gland controls the secretion of hormones from the pituitary.

The adrenaline hormone is secreted by adrenal gland, a gland present on top of the kidney. During emergency situations like anger, danger and stress etc., this hormone prepares our body to function at maximum efficiency. It increases blood flow into muscles, breathing and heart rate and causes liver to put more stored glucose into our blood which causes production of high energy. Thus, if adrenaline is secreted in large amounts then it prepares our body for action.

The Goitre disease occurs in adults due to deficiency of iodine in the diet. In this disease, the neck of the person gets swollen due to the enlargement of thyroid gland.

A receptor is an organ or cell able to respond to heat, light or other external stimulus and transmit a signal to a sensory nerve. Example: Photoreceptor (a receptor which detects light) and phonoreceptor (a receptor which detects sound).

Muscle is not a receptor.

Pancreas gland acts as an endocrine gland as well as an exocrine gland.

The cerebellum is the area of the hindbrain that controls motor movement, coordination, balance, equilibrium and muscle tone.

There are total 31 pairs of nerves arise from the spinal cord.

Hindbrain consists of cerebellum, medulla and pons.

A person spits out immediately when a fly enters his mouth while talking and a person's pupil contracts at once in the presence of bright light are cerebral reflexes.

Iodine is necessary for the synthesis of thyroxin hormone which is released by the thyroid gland and prevents from goiter disease.

Adrenaline hormone is released from adrenal gland.

Insulin does not regulate growth and development of the body.

The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the medulla oblongata.

The involuntary actions in the body are controlled by medulla which is located in hindbrain.

Chewing is a voluntary action.

The adrenaline hormone is secreted by adrenal gland, a gland present on top of the kidney. During emergency situations like anger, danger and stress etc., this hormone prepares our body to function at maximum efficiency.

The involuntary actions like peristaltic movements of alimentary canal in the body are controlled by medulla which is located in hindbrain.

Testosterone hormone is secreted by testes and responsible for male puberty and other secondary sexual characters.

Pituitary gland does not occur as a pair in the human body. It has 2 lobes: anterior lobe and posterior lobe.

In the nervous system, the synapse is a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.

Nervous system and endocrine system are the two systems of control and coordination in higher animals like human.

Insulin hormone decreases the blood sugar level.

The part of the brain that controls voluntary actions is cerebrum, the largest part of the brain.

Thyroid gland requires iodine to synthesise thyroxine hormone.

Pituitary gland does not act as an endocrine gland as well as an exocrine gland.

The medulla oblongata connects the brain to the spinal cord and controls involuntary actions.

Growth hormone (GH) is responsible for growth and development in human. Less secretion of this hormone results dwarfism.

Testosterone hormone, also known as male sex hormone, is secreted by testes. Oestrogen and progesterone hormones are released by ovaries. Both testosterone and oesterogen are responsible for puberty in males and females respectively.

Gustatory receptors are present in the tongue and are responsible for detecting taste. Olfactory receptors are present in the nose and responsible for detecting smell.

Pons of the human brain takes part in regulating respiration in the human body.

The electrical impulse travels in a neuron from dendrite to cell body to axon to axon end.

In a synapse, chemical signal is transmitted from axon end of one neuron to dendrite end of adjacent neuron.

The conversion of electrical signal to a chemical signal occurs at axon end in a neuron.

The correct sequence of the components in a reflex arc is as follows:

ReceptorsSensory neuronSpinal cord Motor neuronMuscle

Both statements (i) and (iv) are true.

The gustatory receptors of our body are responsible for taste.

The olfactory receptors of our body are responsible for smell.

The contraction of pupil of the eye in the presence of bright light is an example of cerebral reflex.

The Growth hormone (GH) is secreted by pituitary gland. This hormone is responsible for controlling the growth and development in humans.

The thyroxine hormone is secreted by thyroid gland. The lack of this hormone causes goiter in humans.

Pancreas gland secretes the insulin hormone which controls the blood sugar level and prevents from diabetes disease.

Goitre disease is caused to lack of iodine in the diet.

Adrenaline hormone, a hormone is released from adrenal gland, is also known as emergency hormone. During emergency situations like anger, danger and stress etc., this hormone prepares our body to function at maximum efficiency.

(a) In above question, the P is a receptor. Eyes, ears, nose, tongue and skin contain cells like P (receptor).

(b) Nerves Q are sensory nerves.

(c) In above question, R is the effector. Muscles and glands are the examples of R (effectors).

(d) Nerves S are motor nerves.

(e) Messages travel through nerves Q (sensory nerves) and S (motor nerves) in the form of electrical impulses.

(a) In above question, cells A are neurons or nerve cells.

(b) (i) Branch B is axon and (ii) C branches are dendrites.

(c) The microscopic gap D is known as synapse.

(d) Cell A or Neurons transmit electrical signals or impulses to and from the central nervous system.

(e) Cell A or Neurons are of three types: Sensory neurons, motor neurons and relay neurons.

(a) (i) In above question, the receptor P is thermoreceptor.

(ii) The neuron Q is a sensory neuron and

(iii) The organ R is spinal cord.

(b) (i) The neuron S is a relay neuron.

(ii) The neuron T is a motor neuron.

(c) The tissue U is a muscle.

(d) Reflex action is phenomenon in which hand is pulled away quickly from the hot plate.

(e) Muscle of arm is an effector in this process.

(a) In above question, the gland X is pituitary gland.

(b) The chemical substance Y is Human growth hormone.

(c) If too little of substance Y is secreted then the person becomes a dwarf (very short) because growth hormone is responsible for growth and development in humans.

(d) If too little of substance Y is secreted then the person becomes a giant (very tall) because growth hormone is responsible for growth and development in humans.

(e) Gland X (pituitary gland) is a part of the endocrine system.

(a) In above question, the system A is endocrine system. System A (Endocrine system) consists of glands.

(b) The chemical substance C is hormones.

(c) The tissue D is endocrine glands. Pineal, thyroid, pancreas, pituitary and ovaries are five such tissues in the human body.

(d) The system B is nervous system. The system B (nervous system) consists of brain, spinal cord and nerves.

(e) The fibre E is nerve fibres.

(f) The system B (nervous system) controls the functioning of system A (Endocrine system).

(a) In above question, the structure P is spinal cord.

(b) The bony cage Q is vertebral column and membranes R is meninges.

(c) The value of X is 31.

(d) The organ S is brain.

(e) The reflexes involving structure P (Spinal cord) only are known as spinal reflexes.

(a) In above question, Part A is functioning as an endocrine gland because it secretes insulin hormone.

(b) Insulin is a hormone secreted by pancreas. It controls the blood sugar level and prevents from diabetes diseases.

(c) In diabetes, the patients are treated by injecting insulin injections.

(d) Digestive enzymes like pancreatic amylase, tryspin and lipase are present in the pancreatic juice. This pancreatic juice goes to small intestine.

(e) In digestion process, the pancreatic juice is made use of.

(a) (i) In above question, the gland A is thyroid gland

(ii) The hormone B is thyroxine hormone which is released from the gland A (thyroid gland).

(b) The element C is iodine.

(c) Sea food like fish can provide sufficient element C (iodine) in the diet of a person.

(d) (i) The disease D is goiter.

(ii) The sale E is iodised salt.

After tying a piece of thread around the animal's pancreatic duct, it gets closed. By this, the digestive enzymes present in the pancreatic juice cannot reach into small intestine. Animals feel difficulty to digest the food in the absence of pancreatic juice. However, the pancreas secretes insulin hormone directly in the blood by which the animal does not get diabetes.

Both adrenaline and insulin act on liver in the body hence, the liver is the target organ for both these hormones.

(a) (i) In above question, the gland W is Pancreas.

(ii) The hormone X is insulin, secreted by gland W (pancreas).

(b) The hormone X (insulin) controls the blood sugar level and prevents from diabetes disease.

(c) (i) The disease Y is diabetes and (ii) the person Z is known as a diabetic person.

(d) In disease Y (diabetes), the patient should reduce his weight, take balance and control diet, avoid intake of more sugar in meal, do regular physical exercise and yoga, go for routine medical checkup and take medicines regularly.

(i) In above question, the gland P is adrenal glands.

(ii) The organ Q is kidneys.

(iii) The hormone R is adrenaline hormone

(iv) The substance S is glucose.

(a) In above question, the glands A are ovaries.

(b) The hormone C is oesterogen whereas hormone D is progesterone.

(c) The glands D are Testes. The hormone E is testosterone (a male sex hormone) released from gland D (testes).

(D) (i) The gametes F are ova or eggs.

(ii) The gametes G are sperms.

(e) In both males and females, puberty is associated with the secretion of hormones C (oesterogen), D (progesterone) and E (testosterone).

(a) In above question, the organ A is brain.

(b) (i) The membrane B is cranium or skull.

(ii) The membrane C is Meninges.

(iii) The membrane D is cerebrospinal fluid.

(c) The organ E is spinal cord.

(d) The organ E (spinal cord) is directly involved in the action mentioned in the question.

(e) The organ A (brain) is directly involved in the action mentioned in the question.

(a)

(b)

(c)

(d)

Tongue has taste buds hence, it is considered as a receptor. Taste buds act as receptors (gustatory receptor) for different kinds of taste. Tongue is a muscular organ having muscles which can respond to a stimulus hence, it is also considered to be an effector.