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Page No 57:

Question 1:

Which of the following statements is correct about receptors?
(a) Gustatory receptors detect taste while olfactory receptors detect smell
(b) Both gustatory and olfactory receptors detect smell
(c) Auditory receptors detect smell and olfactory receptors detect taste
(d) Olfactory receptors detect taste and gustatory receptors smell

Answer:

Gustatory receptors are present on the tongue and it detects taste. Olfactory receptors are located in the mucosa of the nasal cavity which detects the smell.

Hence, the correct answer is option A.

 

Page No 57:

Question 2:

Electrical impulse travels in a neuron from
(a) Dendrite → axon → axonal end → cell body
(b) Cell body → dendrite → axon → axonal end
(c) Dendrite → cell body → axon → axonal end
(d) Axonal end → axon → cell body → dendrite

Answer:

 Dendrites of one neuron receive an electrical impulse from axonal end of another neuron. After that, the impulse travels through the cell body to axon to axonal end.

Hence, the correct answer is option C.

 

Page No 57:

Question 3:

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

Answer:

Chemical signals (neurotransmitter) are transmitted from axonal end of one neuron to dendrite of another neuron through a gap called synapse.

Hence, the correct answer is option D.

 

Page No 57:

Question 4:

In a neuron, conversion of electrical signal to a chemical signal occurs at/in
(a) cell body
(b) axonal end
(c) dendritic end
(d) axon

Answer:

Electrical impulse release some chemical called neurotransmitters at the axonal end. This chemical excites the dendrite of another neuron to transmit the signal.

Hence, the correct answer is option B.

 

Page No 57:

Question 5:

Which is the correct sequence of the components of a reflex arc?
(a) Receptors → Muscles → Sensory neuron → Motor neuron → Spinal cord
(b) Receptors → Motor neuron → Spinal cord → Sensory neuron → Muscle
(c) Receptors → Spinal cord → Sensory neuron → Motor neuron → Muscle
(d) Receptors → Sensory neuron → Spinal cord → Motor neuron → Muscle

Answer:

Sensory neuron collect signal from the receptor in a reflex arc. This signal moves forward to spinal cord and then through the motor neuron, it reaches to muscles.

 Hence, the correct answer is option D.



Page No 58:

Question 6:

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 signals from spinal cord to muscles
(iii) Motor neurons carry signals from receptors to spinal cord
(iv) The path through which signals are transmitted from a receptor to a muscle or a gland is called reflex arc
(a) (i) and (ii)
(b) (i) and (iii)
(c) (i) and (iv)
(d) (i) , (ii) and (iii)

Answer:

Reflex action is involuntary and immediate movement in response to stimulus and the path followed by a reflex action is called reflex arc.

 Hence, the correct answer is option C.

Page No 58:

Question 7:

Which of the following statements are true about the brain?
(i) The main thinking part of brain is hind brain
(ii) Centres of hearing, smell, memory, sight etc are located in fore brain.
(iii) Involuntary actions like salivation, vomiting, blood pressure are controlled by the medulla in the hind brain
(iv) Cerebellum does not control posture and balance of the body
(a) (i) and (ii)
(b) (i), (ii) and (iii)
(c) (ii) and (iii)
(d) (iii) and (iv)

Answer:

 The forebrain is the main thinking part of the brain. Separate areas for hearing, smell, sight are located in the forebrain. Many of the involuntary action including salivation, vomiting, blood pressure is controlled by medulla in the hindbrain.

Hence, the correct answer is option C.

Page No 58:

Question 8:

Posture and balance of the body is controlled by
(a) cerebrum
(b) cerebellum
(c) medulla
(d) pons

Answer:

The cerebellum is a part of hindbrain which coordinates the voluntary movements of skeletal muscles such as posture, balance and equilibrium.
 
Hence, the correct answer is option B.

Page No 58:

Question 9:

Spinal cord originates from
(a) cerebrum
(b) medulla
(c) pons
(d) cerebellum
 

Answer:

Spinal cord originates from the medulla. It is the pathway for messages sent by the brain to the body and from the body to the brain.

 Hence, the correct answer is option B.

Page No 58:

Question 10:

The movement of shoot towards light is
(a) geotropism
(b) hydrotropism
(c) chemotropism
(d) phototropism

Answer:

 The term "Photo" means light and "tropism" means directional movement. Shoot responds to light by growing towards the direction of the source of light.

Hence, the correct answer is option D.

Page No 58:

Question 11:

The main function of abscisic acid in plants is to
(a) increase the length of cells
(b) promote cell division
(c) inhibit growth
(d) promote growth of stem

Answer:

Abscisic acid is a growth-inhibiting hormone. It promotes dormancy in seed and bud, wilting of leaves and closing of stomata.

 Hence, the correct answer is option C.



Page No 59:

Question 12:

Which of the following is not associated with growth of plant?
(a) Auxin
(b) Gibberellins
(c) Cytokinins
(d) Abscisic acid

Answer:

Abscisic acid is a growth-inhibiting hormone. It promotes dormancy in seed and bud, wilting of leaves and closing of stomata.

 Hence, the correct answer  is option D

Page No 59:

Question 13:

Iodine is necessary for the synthesis of which hormone?
(a) Adrenaline
(b) Thyroxin
(c) Auxin
(d) Insulin

Answer:

Iodine is necessary for the thyroid gland to make "Thyroxine". Thyroxine promotes metabolism in all the cells and tissue in the body. Excessive secretion of thyroxine result in the body is called as hyperthyroidism, and less secretion is called hypothyroidism.

Hence, the correct answer is option B.

Page No 59:

Question 14:

Choose the incorrect statement about insulin
(a) It is produced from pancreas
(b) It regulates growth and development of the body
(c) It regulates blood sugar level
(d) Insufficient secretion of insulin will cause diabetes

Answer:

Insulin has no role in the growth and development of the body. It is a hormone produced by the pancreas. It allows other cells to transform glucose into energy in the body.

 Hence, the correct answer is option B.

Page No 59:

Question 15:

Select the mis-matched pair
(a) Adrenaline : Pituitary gland
(b) Testosterone: Testes
(c) Estrogen : Ovary
(d) Thyroxin : Thyroid gland

Answer:

 Growth hormone is one of the hormones secreted by the pituitary. The pituitary gland is  referred to as "master gland" since it affects many activities of other glands.

Hence, the correct answer is option A.

Page No 59:

Question 16:

The shape of guard cells changes due to change in the
(a) protein composition of cells
(b) temperature of cells
(c) amount of water in cells
(d) position of nucleus in the cells

Answer:

 Excess water makes the guard cell turgid and lack of water makes the guard cell flaccid.

Hence, the correct answer is option C.

 

Page No 59:

Question 17:

The growth of tendril in pea plants is due to
(a) effect of light
(b) effect of gravity
(c) rapid cell divisions in tendrillar cells that are away from the support
(d) rapid cell divisions in tendrillar cells in contact with the support

Answer:

Due to cell division, there is more growth in areas away from support. This results in tendril getting twined around the support.

Hence, the correct answer is option C.

 


 

Page No 59:

Question 18:

The growth of pollen tubes towards ovules is due to
(a) hydrotropism
(b) chemotropism
(c) geotropism
(d) phototropism

Answer:

Ovule release a certain chemical that stimulates the growth of pollen tube towards ovules.

Hence, the correct answer is option B.

 



Page No 60:

Question 19:

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

Answer:

A tropism is the growth of a plant as a response to a stimulus, and phototropism occurs when a plant responds to light by bending in the direction of the light. So the movement of sunflower in accordance with the path of the sun is due to phototropism.

Hence, the correct answer is option A.

 

Page No 60:

Question 20:

The substance that triggers the fall of mature leaves and fruits from plants is due to
(a) auxin
(b) gibberellin
(c) abscisic acid
(d) cytokinin

Answer:

Abscisic acid is a growth-inhibiting hormone and its effect include wilting of leaves.

Hence, the correct answer is option C.

 

Page No 60:

Question 21:

Which of the following statements about transmission of nerve impulse is incorrect?
(a) Nerve impulse travels from dendritic end towards axonal end
(b) At the dendritic end electrical impulses bring about the release of some chemicals which generate an electrical impulse at the axonal end of another neuron
(c) The chemicals released from the axonal end of one neuron cross the synapse and generate a similar electrical impulse in a dendrite of another neuron
(d) A neuron transmits electrical impulses not only to another neuron but also to muscle and gland cells

Answer:

Axonal end contains vesicle filled with a chemical called "neurotransmitter" which cross the gap or synapse and generate electrical impulse at the dendrite of another neuron.

Hence, the correct answer is option B.

 

Page No 60:

Question 22:

Involuntary actions in the body are controlled by
(a) medulla in fore brain
(b) medulla in mid brain
(c) medulla in hind brain
(d) medulla in spinal cord

Answer:

Medulla in hindbrain contains centres for respiration, cardiovascular-reflex and gastric secretions. Many of the involuntary action including salivation, vomiting, blood pressure is controlled by it. 

Hence, the correct answer is option C.

 

Page No 60:

Question 23:

Which of the following is not an involuntary action?
(a) Vomiting
(b) Salivation
(c) Heart beat
(d) Chewing

Answer:

Involuntary action is the actions which are happening "without" the conscious choice of the organism. So chewing which is under conscious control is a voluntary action.

Hence, the correct answer is option D.

 

Page No 60:

Question 24:

When a person is suffering from severe cold, he or she cannot
(a) differentiate the taste of an apple from that of an ice cream
(b) differentiate the smell of a perfume from that of an agarbatti
(c) differentiate red light from green light
(d) differentiate a hot object from a cold object

Answer:

Olfactory receptors are located in the mucosa of the nasal cavity which detects the smell. Severe cold block olfactory receptor due to this sense of smell is reduced.

Hence, the correct answer is option B.

 



Page No 61:

Question 25:

What is the correct direction of flow of electrical impulses?

Answer:

The impulse travels from dendrites to the cell body and then axon to the axon terminal. Electrical impulse release some chemical called neurotransmitters at the axonal terminal. This chemical excites the dendrite of another neuron to transmit the signal.

Hence, the correct answer is option C.

 

Page No 61:

Question 26:

Which statement is not true about thyroxin?
(a) Iron is essential for the synthesis of thyroxin
(b) It regulates carbohydrates, protein and fat metabolism in the body
(c) Thyroid gland requires iodine to synthesize thyroxin
(d) Thyroxin is also called thyroid hormone

Answer:

Thyroxine is a hormone secreted by the thyroid gland. It is carried around the body in the bloodstream. Iodine is necessary for the production of Tand T(thyroid hormones). It also regulates the rate of metabolism.  
 
Hence, the correct answer is option A.
 

Page No 61:

Question 27:

Dwarfism results due to
(a) Excess secretion of thyroxin
(b) Less secretion of growth hormone
(c) Less secretion of adrenaline
(d) Excess secretion of growth hormone

Answer:

The growth hormone is secreted by the pituitary gland and it regulates the growth and development of the body. If there is a deficiency of this hormone in childhood, it leads to dwarfism.

Hence, the correct answer is option B.

 

Page No 61:

Question 28:

Dramatic changes of body features associated with puberty are mainly because of secretion of
(a) oestrogen 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

Answer:

The dramatic changes in the body features associated with puberty are mainly due to the secretion of testosterone from the testes (in male) and estrogen from the ovary (in female).

Hence, the correct answer is option C.

 

Page No 61:

Question 29:

A doctor advised a person to take an injection of insulin because
(a) his blood pressure was low
(b) his heart was beating slowly
(c) he was suffering from goitre
(d) his sugar level in blood was high

Answer:

Insulin is produced by the pancreas. Insulin controls the sugar level in the bloodstream. Hence, the doctor advised him to take an injection of insulin to bring his sugar level to normal.

Hence, the correct answer is option D.

 



Page No 62:

Question 30:

The hormone which increases the fertility in males is called
(a) oestrogen
(b) testosterone
(c) insulin
(d) growth hormone

Answer:

The male sex hormone is testosterone. It is produced by the testes on the onset of puberty. It plays an important role in the development of the male sex organ and also in secondary sexual character in male.

Hence, the correct answer is option B.

 

Page No 62:

Question 31:

Which of the following endocrine glands is unpaired?
(a) Adrenal
(b) Testes
(c) Pituitary
(d) Ovary

Answer:

The pituitary gland is a small, unpaired endocrine gland that is present on the floor of the cranium of the brain. It controls the secretion of several important hormones.

Hence, the correct answer is option C.

 


 

Page No 62:

Question 32:

Junction between two neurons is called
(a) cell junction
(b) neuro muscular junction
(c) neural joint
(d) synapse

Answer:

Synapse is a small gap between the axon of one neuron and the dendrite of the next neuron. The signals from one neuron are transmitted through chemicals(neurotransmitters) through this synapse. 

Hence, the correct answer is option D.

 

Page No 62:

Question 33:

In humans, the life processes 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

Answer:

In human beings, the control and coordination of all the life processes are brought about by both nervous system and endocrine system. Nervous system works by generation and transmission of electrical impulse while the endocrine system works by secreting chemical messengers called hormones. 

Hence, the correct answer is option D.
 

Page No 62:

Question 34:


Label the parts (a), (b), (c) and (d) and show the direction of flow of electrical signals in Figure 7.2.

Answer:

a) Sensory neuron
b) Spinal cord  
c) Motor neuron
d) Muscle
The direction of the flow of electrical signals: Receptor in handSensory neuronSpinal cordMotor neuronEffectorMuscles in arm 



Page No 63:

Question 35:

Name the plant hormones responsible for the following
(a) elongation of cells
(b) growth of stem
(c) promotion of cell division
(d) falling of senescent leaves.

Answer:

(a) elongation of cells: Auxin
(b) growth of stem: Gibberellins
(c) promotion of cell division: Cytokinin
(d) falling of senescent leaves: Abscisic acid



 

Page No 63:

Question 36:


Label the endocrine glands in Figure 7.3.

Answer:

(a) Pineal gland
(b) Pituitary gland
(c) Thyroid gland
(d) Thymus

Page No 63:

Question 37:


In Figure 7.4 (a), (b) and (c), which appears more accurate and why?

Answer:

Figure (a) appears more accurate as roots are showing positive geotropism while the shoot is showing negative geotropism and positive phototropism.

Page No 63:

Question 38:

Label the parts of a neuron in Figure 7.5.

Answer:

(a) Dendrite
(b) Cell-body
(c) Axon
(d) Axon-terminal

Page No 63:

Question 39:

Match the terms of Column (A) with those of Column (B)
 

Column (A)
Column (B)
(a)
Olfactory receptors
(i)
Tongue
(b)
Thermo receptors (temperature receptors)
(ii)
Eye
(c)
Gustatoreceptors
(iii)
 Nose
(d)
Photoreceptors
(iv)
 Skin

Answer:

 

Column (A)
Column (B)
(a)
Olfactory receptors
(iii)Nose
 
(b)
Thermo receptors (temperature receptors)
(iv) Skin
 
(c)
Gustatoreceptors
(i)Tongue
 
(d)
Photoreceptors
(ii) Eye   
 

Page No 63:

Question 40:

What is a tropic movement? Explain with an example.

Answer:

Tropic movement is the response to stimuli that comes from one direction. It is a directional movement. If the movement of the plant part is towards the stimulus, then it is known as positive tropism. If the movement of the plant part is away from the stimulus, then it is known as negative tropism. For example phototropism, chemotropism, geotropism, hydrotropism etc

 

Page No 63:

Question 41:

What will happen if intake of iodine in our diet is low?

Answer:

The thyroid gland secretes the hormone thyroxine which controls the rate of metabolism of carbohydrates, fats, and proteins in the body. Iodine is required for the release of thyroxin from the thyroid gland. If iodine is deficient, thyroxine hormone will be deficient in the body and will cause goitre. The neck appears to be swollen due to enlargement of the thyroid gland.
 

Page No 63:

Question 42:

What happens at the synapse between two neurons?

Answer:


The information flows from one neuron to another neuron through the synapse. Presynaptic neuron and the postsynaptic neuron are separated by a small gap — the synaptic cleft. The synaptic cleft is filled with extracellular fluid.
  • Membranes of neurons are separated by fluid-filled spaces called the synaptic cleft.
  • Axon terminals have vesicles filled with chemicals (neurotransmitters).
  • Impulse stimulates the movement of synaptic vesicles towards the membrane.
  • Here, they fuse with the plasma membrane and release their neurotransmitters at the synaptic cleft where they bind with their specific receptors.
  • In this way, the impulse is conducted or transmitted from one neuron to another.

 



Page No 64:

Question 43:

Answer the following :
(a) Which hormone is responsible for the changes noticed in females at puberty?
(b) Dwarfism results due to deficiency of which hormone?
(c) Blood sugar level rises due to deficiency of which hormone?
(d) Iodine is necessary for the synthesis of which hormone?

Answer:

(a) Oestrogen
(b) Growth hormone
(c) Insulin
(d) Thyroxin

Page No 64:

Question 44:

Answer the following :
(a) Name the endocrine gland associated with brain?
(b) Which gland secretes digestive enzymes as well as hormones?
(c) Name the endocrine gland associated with kidneys?
(d) Which endocrine gland is present in males but not in females?

Answer:

(a) Pituitary
(b) Pancreas
(c) Adrenal gland
(d) Testis

Page No 64:

Question 45:

Draw the structure of a neuron and explain its function.

Answer:

Structure of neuron-



The main function of neurons is to transmit signals from the brain to all parts of the body. 
Neurons are arranged end to end, forming a chain. This helps in the continuous transmission of impulses. Each neuron receives an impulse through its dendrite and transmits it to the next neuron in a sequence through its axon. 
 

Page No 64:

Question 46:

What are the major parts of the brain? Mention the functions of different parts.

Answer:

The human brain is the main coordinating center of the body. It is a part of the central nervous system and receives information from the other parts of the body and interprets them. The human brain can be divided into three distinct regions.

(i) Forebrain: It consists of the cerebrum, thalamus, and hypothalamus. The forebrain is the main site of learning, intelligence, and thinking. It also has sensory and motor sites which control all the voluntary movements. Hypothalamus is concerned with things like body temperature, urge to eat, drink, etc.

(ii) Midbrain: It consists of regions concerned with the sense of sight, hearing, etc. It also transmits motor impulses to the limbs.

(iii) Hindbrain: It consists of the cerebellum, pons, and medulla oblongata. It controls most of the involuntary actions like heartbeat, blood pressure, etc. Cerebellum maintains the posture and equilibrium of the body.

Page No 64:

Question 47:

What constitutes the central and peripheral nervous systems? How are the components of central nervous system protected?

Answer:

The central nervous system consists of the brain and spinal cord while the peripheral nervous system consists of all the nerves that branch out from the brain and the spinal cord. 
The brain sits inside a bony box called a skull (or cranium). Inside the skull, there is a fluid-filled called cerebrospinal fluid that acts as a shock absorber. The spinal cord is well protected by the vertebral column or backbone.
 

Page No 64:

Question 48:

Mention one function for each of these hormones :
(a) Thyroxin
(b) Insulin
(c) Adrenaline
(d) Growth hormone
(e) Testosterone.

Answer:

(a) Thyroxin- It regulates carbohydrate, fat, and protein metabolism in our body. It indirectly affects the growth of the body by promoting the growth and differentiation of tissues.

(b) Insulin- ​It regulates the blood sugar level in the human body. It increases the permeability of the cell membrane for glucose and accelerates the passage of glucose into the cells from the bloodstream.

(c) Adrenaline- In case of danger, emergency, or stress, adrenaline is secreted in large quantities to prepare the body to face the situation. For this reason, it is also known as the ‘emergency hormone’. This hormone is secreted even in normal situations but in small quantities. 

(d) Growth hormone- It is involved in the growth and development of the human body. 

(e) Testosterone- It is responsible for the growth and development of male secondary sexual characters.
 

Page No 64:

Question 49:

Name various plant hormones. Also give their physiological effects on plant growth and development.

Answer:

There are five major types of plant hormones: auxins, gibberellins, cytokinins, abscisic acid, and ethylene. 

Auxins- When the growing parts of a phototropic plant detect sunlight, auxins (synthesized at the shoot tips) help the cells grow longer. When light falls on one side of the plant, the auxins generally diffuse towards the shaded side of the shoot. They also helps in root formation, apical dominance, inhibition of abscission and fruit growth.

Gibberellins-They are produced in the roots of a plant. They promote stem elongation by promoting cell division in the inter-nodal region.

Cytokinins-They promotes cell division. Therefore, they are present in greater concentration in those areas of the plants where rapid cell division occurs. For example, the tip of the shoot.

Abscisic acid- It promotes seed dormancy by inhibiting cell growth. It is involved in the opening and closing of stomata. It is also responsible for the shedding of leaves.

Ethylene- It regulates fruit ripening. It is produced during the ripening of fruits.

Page No 64:

Question 50:

What are reflex actions? Give two examples. Explain a reflex arc.

Answer:

Reflex action is a sudden, spontaneous, automatic, involuntary response to the stimulus. It is an involuntary response as it is carried out without any conscious effort by the brain. The path along which the action is carried out is called the reflex arc.
Examples- (1) Sudden withdrawal of hand while it comes in contact with a hot object. 
(2) Narrowing of the pupil on exposure to bright light. 

Reflex arc- The pathway of the nerve impulses involved during a reflex action constitutes the reflex arc. When there is a stimulus, it is first perceived by receptors present on the skin that send the stimulus in the form of an impulse, from the sensory neuron to the spinal cord. The spinal cord interprets the stimulus and sends the impulse to the motor neurons. The motor neurons in turn stimulate the effectors or muscles to respond to the stimulus.



 

Page No 64:

Question 51:

“Nervous and hormonal systems together perform the function of control and coordination in human beings.” Justify the statement.

Answer:

In human beings, control and coordination is brought about by both nervous system and endocrine system. The nervous system works by generation and transmission of electrical impulses while the endocrine system works by secreting chemical messengers called hormones. These systems complement the action of each other to control and coordinate different functions in our body. For example, when an emergency stimulus is detected by the nervous system, the stimulus is received and analysed by CNS that sends messages to effectors to provide a proper response. At the same time, the sympathetic nervous system activates the adrenal gland to release adrenaline that prepares the body by increasing heart rate, blood pressure, respiration and dilates the pupil, etc. Thus, both these systems interact and work together to produce an effective response.  

Page No 64:

Question 52:

How does chemical coordination take place in animals?

Answer:

In animals, chemical coordination is coordinated by hormones. The organ system responsible for the synthesis and regulation of these hormones is known as the endocrine system. Both the nervous system and the endocrine system are responsible for control and coordination in our body. For example, when an emergency stimulus is detected by the nervous system, the stimulus is received and analyzed by CNS that sends messages to effectors to provide a proper response. 

Page No 64:

Question 53:

Why is the flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron but not the reverse?

Answer:

The dendrites contain the receptors for the neurotransmitters while the axon terminals have synaptic vesicles that are filled with the neurotransmitters. So, when the impulse is generated, the synaptic vesicles fuse with the membranes of the synaptic knobs of axon terminal and the neurotransmitters are released in the synaptic cleft. These are then sensed by the receptors present on the dendrites of the postsynaptic neuron. As dendrites do not release the neurotransmitters, the impulse cannot travel from the dendrites of one neuron to the axonal end of the other neuron. It is always uni-directional, that is, from the axonal end of the pre-synaptic neuron to the dendrites of the post-synaptic neurons.



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