Multiple Choice Questions.................................
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
Solution 1: (a) Gustatory receptors detect taste while olfactory receptors detect smell
A receptor is a cell that responds to an external stimulus like light, taste, or smell. Photoreceptors, for example, sense light. Taste is detected by gustatory receptors. Smell is detected by olfactory receptors.
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
Solution 2: (c) Dendrite → cell body → axon → axonal end
Dendrites absorb the stimulus, which is then transmitted to the cyton through the axon. Stimulus enters the axonal end of the terminal branches, from which it is transferred to another neuron.
Question 3: In a synapse, a chemical signal is transmitted from
(a) dendritic end of one neuron to axonal end of another neuron
(b) axon to the 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
Solution 3: (d) axonal end of one neuron to dendritic end of another neuron
Via a synaptic distance, which is made up of SYNAPSE, an electric impulse flows from one neuron's axon to the dendrite of another.
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
Solution 4: (b) axonal end
The release of neurotransmitter is triggered by an electric impulse at the axonal end. To relay the signal, these chemicals join the dendrite of another neuron.
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
Solution 5: (d) Receptors → Sensory neuron → Spinal cord → Motor neuron → Muscle
Receptors send signals to sensory neurons. These signals are transmitted to the spinal cord, which then travels to the muscles through motor neurons.
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 the spinal cord to muscles
(iii) Motor neurons carry signals from receptors to the spinal cord
(iv) The path through which signals are transmitted from a receptor to a muscle or a gland is called the reflex arc
(a) (i) and (ii)
(b) (i) and (iii)
(c) (i) and (iv)
(d) (i) , (ii) and (iii)
Solution 6: (c) (i) and (iv)
Statements ii) and iv) are incorrect since sensory nerves bring signals from muscles to the spinal cord.
Question 7: Which of the following statements are true about the brain?
(i) The main thinking part of the brain is the hindbrain
(ii) Centres of hearing, smell, memory, sight etc are located in forebrain.
(iii) Involuntary actions like salivation, vomiting, blood pressure are controlled by the medulla in the hindbrain
(iv) Cerebellum does not control the posture and balance of the body
(a) (i) and (ii)
(b) (i), (ii) and (iii)
(c) (ii) and (iii)
(d) (iii) and (iv)
Solution 7: (c) (ii) and (iii)
Since the forebrain is the part of the brain that thinks, statement I is incorrect. Since the cerebellum is in control of the body's posture and equilibrium, statement iv) is incorrect.
Question 8: Posture and balance of the body is controlled by
(a) cerebrum
(b) cerebellum
(c) medulla
(d) pons
Solution 8: (b) cerebellum
Sensory processing is handled by the cerebrum. The medulla is in control of involuntary functions. Pons monitors involuntary acts such as touch and pain and regulates respiration.
Question 9: Spinal cord originates from
(a) cerebrum
(b) medulla
(c) pons
(d) cerebellum
Solution 9: (b) medulla
Spinal cord originates from medulla.
Question 10: The movement of shoot towards light is
(a) geotropism
(b) hydrotropism
(c) chemotropism
(d) phototropism
Solution 10: (d) phototropism
Hydrotropism is the movement of plant roots toward or away from moisture. Geotropism is the term for plant growth in response to gravitational force. Chemotropism is the growth of a plant in response to a chemical stimulus.
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 the growth of stem
Solution 11: (c) inhibit growth
Auxins extend the life of cells. Cytokinins help cells divide. Gibberellins encourage stem development.
Question 12: Which of the following is not associated with the growth of a plant?
(a) Auxin
(b) Gibberellins
(c) Cytokinins
(d) Abscisic acid
Solution 12: (d) Abscisic acid
Abscisic acid inhibits plant development, so it is not linked to plant growth.
Question 13: Iodine is necessary for the synthesis of which hormone?
(a) Adrenaline
(b) Thyroxin
(c) Auxin
(d) Insulin
Solution 13: (b) Thyroxin
To synthesis thyroxin hormone iodine is necessary.
Question 14: Choose the incorrect statement about insulin
(a) It is produced from pancreas
(b) It regulates the growth and development of the body
(c) It regulates blood sugar level
(d) Insufficient secretion of insulin will cause diabetes
Solution 14: (b) It regulates growth and development of the body
Insulin doesn’t regulate growth and development of the body.
Question 15: Select the mismatched pair
(a) Adrenaline: Pituitary gland
(b) Testosterone: Testes
(c) Estrogen : Ovary
(d) Thyroxin: Thyroid gland
Solution 15: (a) Adrenaline: Pituitary gland
Adrenaline is produced by the adrenal gland, and TSH, FSH, and GSH hormones are produced by the pituitary gland.
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 the nucleus in the cells
Solution 16: (c) amount of water in cells
Excess water causes guard cells to become turgid, while a lack of water causes guard cells to become flaccid.
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
Solution 17: (c) rapid cell divisions in tendrillar cells that are away from the support
Rapid cell divisions in tendrillar cells away from the help are responsible for tendril growth in pea plants.
Question 18: The growth of pollen tubes towards ovules is due to
(a) hydrotropism
(b) chemotropism
(c) geotropism
(d) phototropism
Solution 18: (b) chemotropism
Pollen tubes expand towards ovules as a result of chemicals released by ovules.
Question 19: The movement of sunflower in accordance with the path of the sun is due to
(a) phototropism
(b) geotropism
(c) chemotropism
(d) hydrotropism
Solution 19: (a) phototropism
Phototropism is the movement of a shoot towards light.
Geotropism is the term for plant growth in response to gravitational force.
Chemotropism is the growth of a plant in response to a chemical stimulus.
Hydrotropism is the movement of plant roots toward or away from moisture.
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
Solution 20: (c) abscisic acid
Abscisic acid forms an abscission layer. This layer separates the leaf's living tissue from the rest of the structure.
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
Solution 21: (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
Chemicals and neurotransmitters are released at the axonal end of the axon, not at the dendritic end. As a result, statement b) is false.
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
Solution 22: (c) medulla in hind brain
The medulla is only found in the back of the brain.
Question 23: Which of the following is not an involuntary action?
(a) Vomiting
(b) Salivation
(c) Heartbeat
(d) Chewing
Solution 23: (d) Chewing
Chewing is not an involuntary action.
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
Solution 24: (b) differentiate the smell of a perfume from that of an agarbatti
Since olfactory receptors are blocked in the cold, we are unable to distinguish between smells.
Question 25: What is the correct direction of flow of electrical impulses?
Solution 25: (c) A neuron's dendrites transmit electrical impulses from another neuron's axonal end. The electrical impulse then passes to the axonal end via the cell body and axon.
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) The thyroid gland requires iodine to synthesise thyroxin
(d) Thyroxin is also called thyroid hormone
Solution 26: (a) Iron is essential for the synthesis of thyroxin
Since iodine is needed for the synthesis of thyroxin but not iron, statement a) is incorrect.
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
Solution 27: (b) Less secretion of growth hormone
Growth hormones are responsible for an organism's overall growth. Dwarfism occurs when the body's growth hormones aren't secreted.
Question 28: Dramatic changes of body features associated with puberty are mainly because of the 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
Solution 28: (c) testosterone from testes and estrogen from ovary
These are the sex hormones that emerge after puberty and are responsible for the secondary character. Males produce testosterone, while females produce estrogen.
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
Solution 29: (d) his sugar level in blood was high
Diabetes patients may have elevated blood glucose levels due to the non-functioning or absence of the insulin hormone. Insulin injections are given to such patients in order to control their blood glucose levels.
Question 30: The hormone which increases the fertility in males is called
(a) oestrogen
(b) testosterone
(c) insulin
(d) growth hormone
Solution 30: (b) testosterone
The hormone which increases the fertility in males is called testosterone.
Question 31: Which of the following endocrine glands is unpaired?
(a) Adrenal
(b) Testes
(c) Pituitary
(d) Ovary
Solution 31: (c) Pituitary
Each kidney has two adrenal glands, one on top of the other. In males, the testes is a paired gland that releases male sex hormones. In females, the ovary is a paired gland that releases female sex hormones. The pituitary gland is a separate gland located under the brain. It is known as the master gland because it secretes the majority of hormones.
Question 32: The junction between two neurons is called
(a) cell junction
(b) neuromuscular junction
(c) neural joint
(d) synapse
Solution 32: (d) synapse
A synapse is a mechanism that enables a neuron to send an electric signal to a neighbouring neuron or effector cell. As a result, it is a neuronal junction.
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
Solution 33: (d) nervous and endocrine systems
In the control and regulation of life cycles, the reproductive, respiratory, and digestive systems play no part. All processes, including the reproductive, respiratory, and digestive systems, are controlled and regulated by the nervous and endocrine systems.
Short Answer Questions.........................
Question 34: Label the parts (a), (b), (c) and (d) and show the direction of flow of electrical signals in the given figure.
Solution 34:
(a) Sensory neuron
(b) Spinal cord
(c) Motor neuron
(d) Muscle
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.
Solution 35:
(a) Auxin is responsible for elongation of cells.
(b) Gibberellin is responsible for growth of stem.
(c) Cytokinin is responsible for promotion of cell division.
(d) Abscisic acid is responsible for falling of senescent leaves.
Question 36: Label the endocrine glands in given figure.
Solution 36:
(a) Pineal Gland
(b) Pituitary gland
(c) Thyroid gland
(d) Thymus
Question 37: In given figure (a), (b) and (c), which appears more accurate and why?
Solution 37: Figure (a) is more reliable since it indicates positive geotrophism and positive phototrophism in a plant root.
Question 38: Label the parts of a neuron in the given figure.
Solution 38:
(a) Dendrite
(b) Cell body
(c) Axon
(d) Axon terminal
Question 40: What is a tropic movement? Explain with an example.
Solution 40: A tropic movement is a directional growth movement of a plant caused by an external stimulus. Movement can be either in the direction of the stimulus or away from it. Roots, for example, have a positive geotropic movement and develop in the same direction as gravity, while shoots have a negative geotropic movement.
Question 41: What will happen if the intake of iodine in our diet is low?
Solution 41: Iodine is required for the production of the hormone thyroxin. When we consume a low-iodine diet, we develop hypothyroidism, which contributes to goitre.
Question 42: What happens at the synapse between two neurons?
Solution 42: A nerve cell's nerve impulse is converted to neurotransmitters at the synapse, which migrate to the dendrites of the next neuron, resulting in an electric impulse.
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?
Solution 43:
(a) The hormone oestrogen is responsible for the changes that occur in females during puberty.
(b) Dwarfism is caused by a lack of Growth Hormones.
(c) A lack of Insulin Hormone causes blood sugar levels to increase.
(d) Iodine is needed for the production of the thyroid hormone thyroxine.
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?
Solution 44:
(a) The pituitary gland is linked to the brain.
(b) The pancreas secretes digestive enzymes as well as hormones.
(c) The adrenal gland is linked to the kidneys.
(d) Males have testicles, but females do not.
Long Answer Questions...........................
Question 45: Draw the structure of a neuron and explain its function.
Solution 45:
The transmission of nerve impulses is carried out by neurons, which are highly specialised cells.
The soma, also known as the cell body, is a star-shaped hair-like structure. Dendrites are a form of hair-like structure. Nerve impulses are received by dendrites.
The axon is the nucleus' tail, and it ends in hair-like structures that form nerve endings. Nerve endings are the conduits for nerve impulses.
Around the axon, the myelin sheath serves as an insulator. It protects axons from electrical impulses in the environment.
A neuron's job is to process and send information from the brain to the rest of the body.
Question 46: What are the major parts of the brain? Mention the functions of different parts.
Solution 46:
Functions of different parts of brain:
Forebrain:
The primary thought part of the brain is the forebrain. It has areas that receive sensory signals from a variety of receptors. Hearing, smell, sight, and other senses are handled by separate regions of the forebrain.
Mid brain and Hind brain:
The mid-brain and hind-brain are in control of involuntary acts.
Cerebellum:
Responsible for voluntary behaviour, as well as maintaining body posture and balance.
Cerebrum:
Sensory processing is handled by the cerebrum.
Medulla:
The medulla is in control of involuntary functions.
Pons:
Pons monitors involuntary acts such as touch and pain and regulates respiration.
Hypothalamus:
Sleep and wake cycles are controlled by the hypothalamus.
Question 47: What constitutes the central and peripheral nervous systems? How are the components of the central nervous system protected?
Solution 47: The brain and spinal cord make up the central nervous system. The peripheral nervous system is made up of nerves that are not connected to the spinal cord.
The central nervous system has a well-developed defence system. The brain is protected by the skull, which is a hard shell. For defence, the spinal cord is enclosed in the vertebral column. A cerebrospinal fluid protects the brain from mechanical shocks in addition to these.
Question 48: Mention one function for each of these hormones :
(a) Thyroxin
(b) Insulin
(c) Adrenaline
(d) Growth hormone
(e) Testosterone.
Solution 48:
(a) Thyroxin:
Thyroxin is a hormone that controls carbohydrate, protein, and fat metabolism in the body to ensure the best possible balance for development.
(b) Insulin:
Insulin is a hormone that controls blood glucose levels. If insulin is not secreted at the proper amount, blood glucose levels increase, causing a variety of negative effects on life processes.
(c) Adrenaline:
Adrenaline is a hormone that helps our bodies prepare for emergency situations. The hormone adrenaline is also known as the "fight or flight" hormone.
(d) Growth Hormone:
Growth hormone is in charge of both growth and growth control.
Testosterone:
Testosterone is in control of the body's expression of secondary sexual characteristics.
Question 49: Name various plant hormones. Also give their physiological effects on plant growth and development.
Solution 49:
(a) Auxin is responsible for cell lengthening.
(b) Gibberellin is responsible for stem development, which results in increased stem girth.
(c) In plants, cytokinin stimulates cell division.
(d) Abscisic acid inhibits plant growth and causes leaves and fruits to fall from the plant.
Question 50: What are reflex actions? Give two examples. Explain a reflex arc.
Solution 50: Reflex activity is a sudden spontaneous movement in a voluntary organ in response to a stimulus.
Reflex actions include:
(a) moving your hand away from a hot iron plate.
(b) blinking your eyes.
During a reflex action, a reflex arc is a direction of electrical impulse. Sensory neuron, spinal cord, motor neuron, and muscle make up this structure.
The reflex arc's steps include:
• The sensory neuron detects and transmits signals from the stimulus to the spinal cord.
• The signals are processed by the spinal cord, which then sends a message to the motor neuron.
• The motor neuron sends the signals to the effector muscle, allowing the muscle to react quickly.
Question 51: “Nervous and hormonal systems together perform the function of control and coordination in human beings.” Justify the statement.
Solution 51: Humans' nervous systems affect their ability to control and coordinate their movements. Both organelles and organ systems are regulated by the brain. The control is obtained by a network of neurons that transmit signals to and from the brain via neurotransmitters in the form of electric impulses.
The hormonal system is made up of a variety of hormones that are secreted by different glands in our bodies. The nervous system's activity is coordinated by the hormonal system. Hormones regulate life processes indirectly through a feedback system. When hormones are needed, they can produce them, and when they aren't, they can stop producing them.
Question 52: How does chemical coordination take place in animals?
Solution 52: Animals use hormones formed by glands in their bodies to coordinate chemical reactions. To enter the target site, hormones are released directly into the bloodstream. Hormones regulate how the target tissue behaves.
Example:
Adrenalin is released by the adrenal gland and travels to the heart, lungs, and gastrointestinal tract. The heart quickens its pumping operation in order to supply more blood to the limbs and facial muscles. The GI tract, on the other hand, is slowed to ensure better blood flow to the limbs. As a result, adrenaline helps the body prepare for a fight or flight scenario.
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?
Solution 53: A neuron transmits an electrical impulse. However, it must be transferred in the form of neurotransmitters to be transmitted to another neuron. Neurotransmitters are a form of chemical that has a specific function. Only specialised channels enable them to reach a neuron. Dendrites have such pathways, but axons do not. A neurotransmitter, on the other hand, may invade a dendrite. As a result, signals in a synapse flow from one neuron's axonal end to another neuron's dendritic end, but not the other way around.
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