Lakhmir Singh solutions for Biology (Science) [English] Class 10 chapter 2 - Control and Coordination [Latest edition]

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

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

What does a tendril do in response to the touch of a support? What is this phenomenon known as?

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

Where is the auxin hormone made in a plant stem?

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

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

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

What is the stimulus in phototropism?

What is the stimulus in geotropism?

What is the stimulus in chemotropism?

What is the stimulus in hydrotropism?

What is the stimulus in thigmotropism?

Give the scientific terms used to represent the  Bending of a shoot towards light.

Give the scientific terms used to represent the Growing of roots towards the earth.

Give the scientific terms used to represent the Growth of a pollen tube towards ovule.

Give the scientific terms used to represent the Bending of roots towards water.

Give the scientific terms used to represent the Winding of tendril around a support.

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

Give one example of a plant part which is positively hydrotropic as well as positively geotropic.

Give one example of a plant part which is positively phototropic but negatively geotropic.

Which of the following is a growth movement and which is not?

1. Folding up of leaves of sensitive plant on touching with hand.
2. Folding up of petals of dandelion flower when light fades.

Name the plant part which bends in the direction of gravity but away from light.

Name the plant part which bends towards light but away from the force of gravity.

To which directional stimuli do roots respond?

To which directional stimuli do shoots respond?

A plant's response to light is called ______.

A plant's response to gravity is called ______.

Plant shoot grows upward in response to ______.

Plant roots grow downward in response to ______.

Tendrils wind around a support in response to ______.

Plant roots grow ______ and in the direction of force of ______.

The root of a plant grows downward. This is known as ______.

Fill in the following blank :

 ...... is the hormone that causes phototropism in plants

The response of leaves to the sunlight is called ______.

Plant parts show two types of movements, one dependent on growth and other independent of growth Give one example  which depends on growth

Plant parts show two types of movements, one dependent on growth and other independent of growth. Give one example  which does not depend on growth

What is a plant hormone? Name four plant hormones. State one function of each.

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

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

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

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

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

What happens to the dandelion flower

1. during the daytime, and
2. at night?

What is this phenomenon known as?

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

What happens to the moonflower

1. during the daytime, and
2. at night?

What is this phenomenon known as?

What is a tendril?

Name the two types of tendrils.

Name the five types of tropisms.

How are tropic movements helpful to plants? Explain with an example.

Define chemotropism.

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

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

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

What is the difference between photonasty and thigmonasty?

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:

1. Which figure shows the correct position taken by the parts A and B of the plant?
2. What type of phenomenon is exhibited by the figure chosen in (a) above?

Name the plant hormone which is responsible for the following effect:

Falling of leaves

Name the plant hormone which is responsible for the following effect:

Opening of stomata

Name the plant hormone which is responsible for the following effect:

Bending of the stem towards light

Name the plant hormone which is responsible for the following effect:

Closing of stomata

Name the plant organ which is positively phototropic.

Name the plant organ which is positively geotropic

Name the plant organ which is negatively geotropic.

Name the plant organ which is positively hydrotropic.

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

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

What is meant by 'tropisms' (or tropic movements)? Explain with an example.

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

Define phototropism. Give one example of phototropism.

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

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

Define geotropism.

Give one example of geotropism.

What is meant by ‘positive geotropism’ and ‘negative geotropism’? Give one example of each type. Draw a labelled diagram to illustrate your answer, indicating the plant part, which shows positive geotropism, and the plant part, which shows negative geotropism.

Name one plant part which exhibits positive thigmotropism.

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

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

 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 labelled diagram.

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

Define thigmotropism. Give one example of thigmotropism.

 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?

Which of the following is not a plant hormone?

One of the following plant hormones is responsible for the phenomenon of phototropism in plants. This is :
(a) gibberellin
(b) eltroxin
(c) cytokinin
(d) auxin

The movement of a plant part in response to the force of attraction exerted by the earth is called :
(a) hydrotropism
(b) geotropism
(c) chemotropism
(d) phototropism

The movement of sunflower in accordance with the path of the sun is due to :
(a) photonasty
(b) phototropism
(c) hydrotropism
(d) chemotropism

The plant part which exhibits negative geotropism is :
(a) root
(b) stem
(c) branch
(d) leaves

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

Which of the following is not caused by a growth movement?

The root of a plant is :
(i) positively phototropic but negatively geotropic
(ii) positively geotropic but negatively phototropic
(iii) negatively phototropic but positively hydrotropic
(iv) negatively hydrotropic but positively phototropic
(a) (i) and (ii)  (b) (ii) and (iii)  (c) (iii) and (iv)  (d) (i) and (

The main function of the plant hormone called abscisic acid is to ______.

The growth of tendrils in pea plants is due to the :

(a) effect of sunlight on the tendril cells facing the sun
(b) effect of gravity on the part of tendril hanging down towards the earth
(c) rapid cell division and elongation in tendril cells that are away from the support
(d) rapid cell division and elongation in tendril cells in contact with the support

Which of the following phytohormone is not associated with the promotion of growth in plants?

The plant hormone which triggers the fall of mature leaves and fruits from the plant body is:

Which of the following terms denotes the movement of the root of a plant towards moisture in the soil?
(a) thigmotropism
(b) chemotropism
(c) hydrotropism
(d) geotropism

The growth of a pollen tube towards the ovule caused by a sugary substance as stimulus is an example of :
(a) phototropism
(b) chlorotropism
(c) gravitropism
(d) chemotropism

The bending of the shoot of a plant in response to light is called :
(a) geotropism
(b) phototropism
(c) thigmotropism
(d) photonasty

The stimulus in the process of thigmotropism is ______.

A growing seedling is kept in a dark room. A burning candle is placed near it for a few days. The top part of seedling bends towards the burning candle. This is an example of :
(a) chemotropism
(b) hydrotropism
(c) phototropism
(d) geotropism

Which of the following acts as a stimulus in the process of hydrotropism?
(a) hydrocarbon
(b) hydrogen oxide
(c) hydrogen chloride
(d) hydrogen peroxide

The growth movement of a plant part in response to the touch of an object is called :
(a) thigmonasty
(b) hydrotropism
(c) thigmotropism
(d) geotropism

The climbing organs of plants like tendrils grow towards any support which they happen to touch and wind around the support. This is an example of :
(a) chemotropism
(b) nastic movement
(c) thigmotropism
(d) geotropism

The rate of growth in roots is decreased by one of the following plant hormones. This plant hormone is ______.

When the leaves of a Mimosa pudica plant are touched with a finger, they fold up quickly. This is an example of ______.

Dandelion flowers open the petals in bright light during the daytime but close the petals in dark at night. This response of dandelion flowers to light is called:

To which of the following directional stimulus roots of a plant do not respond?

One of the following is not caused by the growth related movement of the concerned plant part. This is:

The bending of the root of a plant away from a source of light is caused by a plant hormone called :
(a) cytokinin
(b) gibberellin
(c) abscisic acid
(d) auxin

Most of the plant hormones promote plant growth. A plant hormone which inhibits growth is ______.

The movement of a shoot towards light is:

The bending of the stem of a plant towards a source of light is caused by the action of a phytohormone known as :
(a) abscisic acid
(b) auxin
(c) gibberellins
(d) cytokinin

Which of the following plant part exhibits negative phototropism?
(a) root
(b) branch
(c) leaves
(d) stem

Which of the following are not tropisms?
(i) growing of pollen tube in response to a sugary substance
(ii) folding up of leaves of sensitive plant in response to touch
(iii) winding of tendril around a support in response to touch
(iv) opening up of the leaves of a daisy flower in response to light
(a) (i) and (ii)  (b) (ii) and (iii)  (c) (i) and (iv)  (d) (ii) and (iv)

The chemical substance P is made and secreted by the meristematic tissue at the tip of stem (or shoot) of a plant. The chemical substance P is responsible for a phenomenon Q in plants in which the stem bends towards a source of light. The same chemical substance P has an opposite effect on the root of a plant. It causes the root of a plant to bend away from the source of light in a process called R.
(a) What is the chemical substance P?
(b) State whether P prefers to remains in the sunlit side of a stem or in shade.
(c) What is the effect of substance P on the rate of growth of (i) a root, and (ii) a stem?
(d) What is the name of process (i) Q, and (ii) R?
(e) What is the general name of chemical substances like P? Name another substance which belongs to this class of chemical substances.

A potted plant is growing in a transparent glass jar. In this plant, X and Y are the two growing parts having a lot of meristematic tissue. It is observed that the part X of this plant exhibits positive geotropism but negative phototropism. On the other hand, part Y of this plant exhibits negative geotropism but positive phototropism.
(a) Name the part X of plant.
(b) Name the part Y of plant.
(c) Which part of the plant, X or Y, will exhibit positive hydrotropism?
(d) Which part of the plant, X or Y, can have tendrils on it?
(e) Which phytohormone causes the part X to exhibit negative phototropism?

There are three plants A, B and C. The flowers of plant A open their petals in bright light during the day but close them when it gets dark at night. On the other hand, the flowers of plant B open their petals at night but close them during the day when there is bright light. The leaves of plant C fold up and droop when touched with fingers or any other solid object.

1. Name the phenomenon shown by the flowers of (i) plant A and (ii) plant B.
2. Name one flower each which behaves like the flower of (i) plant A and (ii) plant B.
3. Name the phenomenon exhibited by the leaves of plant C.
4. Name a plant whose leaves behave like those of plant C.
5. Which plant/plants exhibit the phenomenon based on growth movements?

While conducting experiments to study the effect of various stimuli on the plants, it was observed that the roots of a plant X grow and bend towards two stimuli A and B but bend away from a third stimulus C. The stem of the plant X, however, bends away from stimuli A and B but bends towards the stimulus C. The stimulus B is known to act on the roots due to too much weight of the earth. Keeping these points in mind, answer the following question:

1. What could stimulus A be?
2. Name the stimulus B.
3. What could stimulus C be?
4. The branches of a fallen tree in a forest grow straight up in response to two stimuli. What could be these two stimuli out of A, B and C? Also name these two stimuli.

P and Q are two types of plants having weak stems which cannot stand upright on their own. The plants P and Q have organs R and S respectively which can grow towards any support which they happen to touch and wind around that support. It is observed that organ R originates from the leaves of the plant whereas organ S originates directly from the stem of the plant.
(a) What is (i) R, and (ii) S?
(b) What is the name of growth movement exhibited by the organs R and S?
(c) Name the stimulus involved in this case.
(d) State whether the behaviour of organs R and S is a tropic movement or a nastic movement.
(e) Name one plant like P and another plant like Q.

The top part A of the flask-shaped reproductive organ X in the flower of a plant secrets a surgery substance into its lower part B which goes towards the bottom part C of the flask-shaped organ. When a tiny grain D coming from the top part E of another reproductive organ Y i the flower falls on part A, it grows a long tube F through the organ X i response to the sugary substance and reaches the bottom part C of flask-shaped organ to carry out fertilisation.
(a) Name parts (i) organ X, and (ii) organ Y, inside the flower?
(b) Name parts (i) A (ii) B, and (iii) C, of flask-shaped organ.
(c) Name (i) grain D, and (ii) part E of organ Y.
(d) Name the tube F.
(e) What is the phenomenon of growing a long tube in response to sugary substance in the process of fertilisation in a flower known as?

P, Q, R and S are four major types of phytohormones. P is a phytohormone which functions mainly as a growth inhibitor. It promotes the wilting and falling of leaves. Q, R and S are phytohormones which all promote growth of plants in various ways. Q is responsible for the phenomenon of phototropism in plants. R is involved mainly in shoot extensions. The phytohormone S helps in breaking the dormancy of seeds and buds. What are P, Q, R and S? Give one reason each for your choice.

A potted plant having straight parts A and B was placed horizontally on its side as shown in Figure (i). After a few days, it was observed that parts A and B of the plant acquired new positions as shown in Figure (ii).

1. Name the phenomenon exhibited by the position of plant parts A and B in Figure (ii).
2. Name the stimulus (other than sunlight) which causes plant part A to grow and bend upwards, and plant part B to bend downwards.

When the leaves of a sensitive plant are touched with a finger, they fold up and when light fades at dusk, the petals of a dandelion flower close.

State one way in which the above two processes are similar.

When the leaves of a sensitive plant are touched with a finger, they fold up and when light fades at dusk, the petals of a dandelion flower close.

state two ways in which the above two processes differ.

Name the two systems of control and coordination in higher animals.

What are the two parts of the vertebrate nervous system?

If we happen to touch a hot object unknowingly, we immediately pull back our hand. What is this type of action known as?

Name the three components of a neuron (or nerve cell).

 What are the short fibres of a neuron known as?

What is the long fibre of a neuron known as?

Name the most important part of the human brain.

Which part of the brain maintains posture and equilibrium of the body?

State one function each of cerebellum and pons.

 Name one hormone secreted by the pituitary gland

Where are hormones made in the human body?

What is the name of the system of glands which produces hormones?

Which gland secretes the growth hormone?

Name the hormones secreted by testes.

Name and describe hormones secreted by ovaries.

What are the scientific names for the receptors in animals?

receptors for light

What are the scientific names for the receptors in animals?

 receptors for heat

What are the scientific names for the receptors in animals?

receptors for sound

What are the scientific names for the receptors in animals?

 receptors for smell

What are the scientific names for the receptors in animals?

 receptors for taste

Name the disease caused by the deficiency of insulin hormone in the body.

Name the disease caused by the deficiency of thyroxine hormone in the body.

Which halogen element is necessary for the making of thyroxine hormone by the thyroid gland?

Why are some patients of diabetes treated by giving injections of insulin?

What is the name of in-built 'arrangement' in our body which controls the timing and amount of hormones released by various endocrine glands in the body?

Name one gland  which acts only as an endocrine gland.

Name one gland which acts only as an exocrine gland.

Name one gland which acts both as an endocrine gland as well as an exocrine gland.

What part does the diet play in helping us to have a healthy thyroid gland?

If sugar is detected in the urine of a person, name the disease he is suffering from.

Name two parts of the body which contain receptors of chemical stimuli.

Which part of the eye contains cells which are sensitive to light?

What are the two main communications systems in an animal's body?

Which one term of the following includes the other three?
 thyroid, ductless gland, thymus, pituitary, ovary

Which one term of the following includes the other three?
adrenalin, insulin, hormone, thyroxine, estrogen

Which parts of the body form the central nervous system?

Give three examples of reflex actions.

Why do you need iodine in your diet?

State whether coughing is a voluntary action or reflex action.

Fill in the following blanks with suitable words :

The two examples of effectors are .........and ...........

Fill in the following blanks with suitable words :

Our.............system allows us to react to our surroundings. Information from receptors passes along...........neurons to our brain. Our brain sends impulses along..........neurons to our muscles.

Fill in the following blank with suitable word :

A neuron which carries an impulse to the brain is called a ........... neuron.

Fill in the following blank with suitable word :

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

What are the various sense organs in our body?

What is meant by receptors and effectors? Give two examples of each.

What is spinal cord? What is its main function?

Give the functions of medulla.

Name the three types of nerves which constitute the peripheral nervous system.

What is the difference between a reflex action and walking?

How do we detect the smell of an agarbatti (incense stick)?

What substances are made by endocrine glands?

What is the function of receptors and effectors in our body?

 Name the hormones secreted by given endocrine glands :

 Thyroid gland

Name the hormones secreted by given endocrine glands :

Parathyroid glands

Name the hormones secreted by given endocrine glands :

Pancreas

Name the hormones secreted by given endocrine glands:

Adrenal glands

Write the functions of testosterone and oestrogen hormones.

 Write the names of the regions in hindbrain. Give one function of each region.

Name the function of cerebrum.

The human brain can be broadly divided into three regions. name these three regions.

What is cranium? What is its function?

How does chemical coordination take place in human beings?

Why is the use of iodised salt advisable?

What is the function of insulin hormone? What type of patients are given insulin injections?

Compare the nervous system and endocrine system (hormonal system) for control and coordination in humans.

State the functions of  Thyroxine hormones.

State the functions of Adrenaline hormones. 

State the functions of Growth hormone.

Write the names of all the major endocrine glands present in the human body. Which of these glands also function as exocrine glands?

Match the hormones given in column I with their functions given in column II :

A person walks across a room in barefeet and puts his foot on a drawing pin lying on the floor. He lets out a cry. Explain what happens in his nervous system in bringing about this response.

In what ways are puberty and adolescence result of the activity of some glands in the human body?

List three ways in which neurons are similar to other cells.

Explain the difference between of the following pair of terms :
receptor and effector

Explain the difference between of the following pair of terms :

cerebrum and cerebellum

What is the difference between a voluntary and an involuntary action? Which kind of action is digestion? Explain your choice.

What does CNS stand for? Which part of CNS : (a) consists of two cerebral hemispheres, and (b) has spinal nerves attached to it?

Which hormone prepares the body for action?

Which hormone controls the amount of glucose in blood?

Which hormone gives boys a deep voice?

Which hormone gives girls soft skin?

When you smell a favourite food your mouth begins to water (that is, you secrete saliva). Write down what is the example of the smell of the food?

When you smell a favourite food your mouth begins to water (that is, you secrete saliva). Write down what is the example of the cells in your nasal passages which perceive the smell?

When you smell a favourite food your mouth begins to water (that is, you secrete saliva). Write down what is the example of the gland which is stimulated to secrete saliva.

Name the structural and functional unit of the nervous system.

Draw a flow chart to show the classification of the nervous system into various parts.

What is autonomic nervous system? What is its function?

 What is voluntary nervous system? Explain the working of the voluntary nervous system with an example.

What is a reflex action? Explain with the help of an example.

Define reflex arc. Give the flow chart of a spinal reflex arc.

How are involuntary actions and reflex actions different from each other?

What is the function of our nervous system?

What are the main organs of the human nervous system? Draw a labelled diagram to show the main organs of the human nervous system.

How does the human nervous system work? Explain.

What is a neuron?

Draw a labelled diagram of a neuron.

What is a synapse?

What happens at the synapse between two neurons?

 How are the messages carried across a synapse? Explain with the help of a labelled diagram.

Name two systems which taken together perform the functions of control and coordination in human beings.

What does the central nervous system in humans consist of? What is the job of the central nervous system?

Give the various functions of brain.

 Write the names of five endocrine glands found in the human body. Name the hormones secreted by each gland.

How do hormones reach the organs they control?

Name the gland which controls the secretion of hormones from the pituitary.

How does our body respond when adrenaline is secreted into the blood?

Name the disease which occurs in adults due to the deficiency of iodine in the diet. What is the main symptom of this disease?

A cell (or group of cells) in a sense organ which is sensitive to a particular type of stimulus is called :

(a) interceptor
(b) effector
(c) receptor
(d) acceptor

Which of the following cannot be considered a receptor?

(a) ear
(b) nose
(c) muscle
(d) eye

One of the following acts as an endocrine gland as well as an exocrine gland. This one is :

(a) salivary gland
(b) pancreas
(c) pituitary
(d) parathyroid

Which of the following helps in maintaining posture and balance of the human body?

The number of pairs of nerves which arises from the spinal cord is:

Cerbellum, medulla and pons are the parts of :
(a) mid-brain
(b) hind-brain
(c) forebrain
(d) spinal cord

Which of the following are cerebral reflexes?
(i) a person pulls away his hand on touching a hot object
(ii) a person spits out immediately when a fly enters his mouth while talking
(iii) A person walking bare foot lifts his foot at once on stepping on to a nail
(iv) A person's pupil contracts at once in the presence of bright light
(a) (i) and (ii)  (b) (ii) and (iii)  (c) (iii) and (iv)  (d) (ii) and (iv)

odine is necessary for the synthesis of which of the following hormone?
(a) adrenaline
(b) auxin
(c) thyroxine
(d) insulin

Which of the following is a mis-matched pair?

One of the following is an incorrect statement about insulin. This is:

The spinal cord originates from:

The involuntary actions in the body are controlled by :

(a) medulla in forebrain
(b)medulla in hindbrain
(c) medulla in spinal cord
(d) medulla in midbrain

Which of the following is not an involuntary action?
(a) vomiting
(b) chewing
(c) heart beat
(d) salivation

Which of the following hormone prepares our body for action in emergency situations?

(a) testosterone
(b) growth hormone
(c) adrenaline
(d) insulin

One of the following controls the peristaltic movements of alimentary canal. This one is :

(a) cerebrum
(b) cerebellum
(c) pons
(d) medulla

The hormone which is associated with male puberty is called :
(a) oestrogen
(b) adrenaline
(c) testosterone
(d) progesterone

Which of the following endocrine gland does not occur as a pair in the human body?

The junction between two adjacent neurons is called :
(a) nerve junction
(b) sensory junction
(c) synapse
(d) neuro-muscular joint

The life processes in humans are controlled and regulated by :
(a) reproductive and endocrine systems
(b) respiratory and nervous systems
(c) endocrine and digestive systems
(d) nervous and endocrine systems

A doctor advised a person to take injection of insulin because :
(a) his blood pressure was high
(b) his heart beat was high
(c) his blood sugar was high
(d) his thyroxine level in blood was high

All the voluntary actions of our body are controlled by :
(a) cerebrum
(b) cerebellum
(c) pons
(d) medulla

One of the following statements is not true about thyroxine. This is :
(a) Thyroid gland requires iron to synthesise thyroxine
(b) It regulates carbohydrate, protein and fat metabolism
(c) Iodine is essential for the synthesis of thyroxine
(d) Thyroid gland can enlarge due to lack of thyroxine

Which of the following does not act as an endocrine gland as well as an exocrine gland?
(a) testis
(b) ovary
(c) pituitary
(d) pancreas

The part of brain which controls the involuntary action such as heart beat, breathing, blood pressure, etc. is :
(a) pons
(b) medulla
(c) cerebrum
(d) cerebellum

Dwarfism results due to:

The dramatic changes in body features associated with puberty are mainly because of the secretions of :
(a) estrogen from testes and testosterone from ovary
(b) estrogen from adrenal gland and testosterone from pituitary gland
(c) testosterone from testes and estrogen from ovary
(d) testosterone from thyroid gland and estrogen from pituitary gland

Which of the following statements is correct about receptors?

The part of brain which takes part in regulating respiration in the human body is :
(a) medulla
(b) pons
(c) cerebellum
(d) cerebrum

Electrical impulse travels in a neuron from:

In a synapse, chemical signal is transmitted from :
(a) axon to cell body of the same neuron
(b) cell body to axon end of the same neuron
(c) dendrite end of one neuron to axon end of adjacent neuron
(d) axon end of one neuron to dendrite end of adjacent neuron

In a neuron, the conversion of electrical signal to a chemical signal occurs at/in:

One of the following gives the correct sequence of the components in a reflex arc. This is:

Which of the following statements are true?

(i) sudden action in response to something in the environment is called reflex action

(ii) sensory neurons carry electrical signals from spinal cord to muscles in a reflex action

(iii) motor neurons carry signals from receptors to spinal cord in a reflex action

(iv) the pathway of transmitting signals from a receptor to a muscle is a reflex action

The gustatory receptors of our body are in one of the following organs. This organ is :

a) ear
(b) nose
(c) tongue
(d) skin

The olfactory receptors in humans are located in :
(a) eyes
(b) tongue
(c) ears
(d) nose

The contraction of pupil of the eye in the presence of bright light is an example of :
(a) Voluntary reflex
(b) Spinal reflex
(c) Cerebral reflex
(d) Adrenal reflex

The faulty functioning of an endocrine gland can make a person very short or very tall. This gland is :
(a) thyroid
(b) pineal
(c) adrenal
(d) pituitary

The underactive endocrine gland which causes goitre is :
(a) pancreas
(b) thyroid
(c) adrenal
(d) pituitary

The endocrine gland whose malfunctioning causes diabetes disease is :
(a) pituitary
(b) pineal
(c) parathyroid
(d) pancreas

The use of iodised salt is recommended to prevent :
(a) diabetes
(b) gonorrhoea
(c) dysentery
(d) goitre

Which of the following are often called glands of emergency?
(a) thyroid
(b) pituitary
(c) adrenal
(d) pancreas

P is a cell (or group of cells) in the human body which is sensitive to a particular type of stimulus and conveys the messages to CNS through nerves Q. On the other hand, R is a part of the human body which can respond to a stimulus according to the instructions sent from the CNS through nerves S.
(a) What is P? Name five organs which contain cells (or group of cells) like P.
(b) Name the nerves Q.
(c) What is R? Give two examples of R.
(d) Name nerves S.
(e) How do messages travel through the nerves Q and S?

The human body contains a large number of cells A which are very long and branched, and look like electric wires. The longest branch of this cell is B whereas there are many small branches C. Any two A cells do not join to one another completely in the human body. There is a microscopic gap D between every pair of adjacent A cells through which electric impulses can pass by the release of a chemical substance.
(a) What are cells A?
(b) What is the name of (i) branch B, and (ii) branches C?
(c) What is the microscopic gap D known as?
(d) What is the function of cells like A in the human body?
(e) The cells A are of three types. name the three types.

When we touch a hot plate unknowingly, then this heat is sensed by a receptor P present in our fingers. The receptor triggers and impulse in neuron Q which transmits the message to an organ R which is a part of the central nervous system. Here the impulse is passed on to a neuron S which in turn passes it to a yet another neuron T. The neuron T passes the impulse to a tissue U in our arm. The tissue U then contracts and pulls our hand away from the hot plate.
(a) What is the name of (i) receptor P (ii) neuron Q, and (iii) organ R?
(b) What is (i) neuron S, and (ii) neuron T?
(c) Name the tissue U.
(d) What name is given to the phenomenon in which hand is pulled away quickly from the hot plate?
(e) Name the effector in this whole process.

The gland X which is located just below the brain in the human head secretes a chemical substance Y which controls the development of ones and muscles in the body of a person. Secretion of too little of substance Y as well as the secretion of too much of substance Y by the gland X leads to abnormal development of the body of a person.
(a) Name the gland X.
(b) What is the chemical substance Y?
(c) What happens if too little of substance Y is secreted?
(d) What happens if too much of substance Y is secreted?
(e) Name the system of glands in the human body of which gland X is a part.

A and B are the two systems of control and coordination in the human body. The messages in system A are transmitted in the form of chemical substances C which travel comparatively slowly through the blood stream. The substances C are made in tissues D present in the head and trunk of human body. The messages in system b are transmitted very quickly in the form of electrical impulses through fibres E. The effect of messages transmitted by system b usually lasts for a much shorter time as compared to those transmitted by system A.
(a) Name the system A. What does system A consist of?
(b) Name the chemical substance C.
(c) What is tissue D? Name any five such tissues in the human body.
(d) Name the system B. What does system B consist of?
(e) Name the fibres E.
(f) State whether system A controls the working of system B or system B controls the working of system A.

A cylindrical structure P in our body begins in continuation with medulla and extends downwards. It is enclosed in a bony cage Q and surrounded by membranes R. As many as x pairs of nerves arise from the structure P. The structure P is involved in the reflex actions of our body and conduction of nerve impulses to and from another organ S of our body with which it forms CNS.
(a) Name the structure P.
(b) Name (i) bony cage Q, and (ii) membranes R.
(c) How much is x?
(d) Name the organs S.
(e) What are the reflexes involving structure P only known as?

The pancreas is made up of two parts A and B. The part A secretes insulin whereas part B secretes pancreatic juice.
(a) Which part is functioning as an endocrine gland? Why?
(b) What is insulin and what effect does it have in the body?
(c) Name the disease which can be treated by giving insulin injection.
(d) What does pancreatic juice contain? Where does pancreatic juice go?
(e) Name the life process in which pancreatic juice is made use of.

The gland A is attached to the wind pipe in the human body. The gland A makes and secretes a hormone B which controls the metabolism of carbohydrates, fats and proteins in the body. The non-metal element C is necessary for the formation of hormone B. The deficiency of C in the diet can cause a deficiency of hormone B in the body leading to a disease D in which the neck of a person appears to be swollen. People are advised to use salt E in cooking food so as to avoid disease D.
(a) Name (i) gland A, and (ii) hormone B.
(b) What is the element C?
(c) Name one type of food which can provide sufficient C in the diet of a person.
(d) Name (i) disease D, and (ii) salt E.

   A piece of thread was tied tightly around an animal's pancreatic duct. The animal subsequently had difficulty in digesting food but did not get diabetes. Explain.

Which is the target organ of both adrenaline and insulin?
(a) heart
(b) kidney
(c) liver
(d) pancreas

A gland W is located just below the stomach in the human body. The gland W secretes a hormone X. The deficiency of hormone X in the body causes a disease Y in which the blood sugar level of a person rises too much. The person having high blood sugar is called Z.
(a) Name (i) gland W, and (ii) hormone X.
(b) What is the function of hormone X?
(c) Name (i) disease Y, and (ii) person Z.
(d) What advice would you like to give to a person who is suffering from disease Y due to faulty life-style?

There are two similar glands P which are located on top of two similar organs Q in the human body. P are often called the emergency glands and they secrete a hormone R into the blood stream. R is secreted in large amounts when a person is frightened. It brings about temporary changes in the body which allow a lot of substance S from the liver to go into the blood to provide a lot of energy in a very short time. This helps a person to fight back or run away from the frightening situation.

What are P, Q, R and S?

A and B are two pairs of glands that are present in the human endocrine system. The pair A is found only in females, whereas B is present only in males. Glands A make and secrete two hormones C and D, whereas glands B make and secrete only one hormone E. In addition to hormones, Glands A make gametes F, whereas glands B make gametes G.
(a) What are the glands A?
(b) What are the hormones C and D?
(c) What are the glands B? Name the hormone E.
(d) What are the gametes F and G?
(e) Which event in the life of males and females is associated with the secretion of the hormones C, D and E?

The organ A which is located inside the skull of our body is protected by a bony shell B. It is surrounded by three layers membranes C. The spaces between these layers are filled with a liquid D which protects organ A from mechanical shocks. Organ A in combination with another organ E makes up the central nervous system.

(a) What is organ A?
(b) What are B, C and D?
(c) Name the organ E.
(d) While walking barefoot, if we happen to step on a sharp piece of stone, we immediately lift our foot up. Which of the two organs: A or E, is directly involved in this action?
(e) If we step out from a darkened room into bright sunlight, we close our eyes for a moment. Which of the two organs: A or E, is directly involved in this action?

Write down the following activities in the correct order for a simple reflex arc:
(a) impulse travels in the motor fibre
(b) impulse travels in the sensory fibre
(c) effector organ stimulated
(d) impulse crosses the synapse

Explain why the tongue may be considered as both a receptor and an effector organ.