GSEB Class 10 Science Solutions Chapter 7 Control and Coordination

 

Question 1. What is the difference between reflex action and walking?
Answer: Reflex actions happen without any thought; they are automatic responses to stimuli. The spinal cord controls these. This is an involuntary action, meaning we do not choose to do it. Walking, however, occurs after thought, meaning it happens because we wish it to. A part of the hindbrain, called the cerebellum, controls this. This is a voluntary action.
In simple words: Reflex action is automatic and involuntary, controlled by the spinal cord. Walking is a conscious, voluntary action, controlled by the cerebellum in the brain.

Exam Tip: Remember to clearly differentiate between involuntary (reflex) and voluntary (walking) actions, highlighting the controlling brain parts for each.

 

Question 2. What happens at the synapse between two neurons?
Answer: A synapse is the small gap between the axon ending of one neuron and the dendrites of another neuron. At this synapse, the electrical impulse that forms in the dendrites of a neuron is transmitted to the next neuron through chemical signals released by the first neuron's axon ending. These chemicals cross the gap and create a similar impulse in the dendrites of the next neuron. A synapse makes sure that the nerve impulse moves only in one direction. A similar connection helps transmit impulses from neurons to other cells, such as muscle cells.
In simple words: At a synapse, a chemical signal passes from one neuron to the next. This ensures nerve impulses travel in one direction, helping neurons communicate with each other and other body cells.

Exam Tip: Describe the role of both electrical impulse and chemical signals in synaptic transmission, emphasizing the unidirectional flow of information.

 

Question 3. Which part of the brain maintains posture and equilibrium of the body?
Answer: The cerebellum, which is a part of the hindbrain, helps maintain the body's posture and balance.
In simple words: The cerebellum, located in the hindbrain, helps your body stay balanced and keep its posture.

Exam Tip: Directly state the brain part responsible for posture and equilibrium. Linking it to the hindbrain provides additional context.

 

Question 4. How do we detect the smell of an agarbatti (incense stick)?
Answer: The smell of an incense stick is picked up by special olfactory receptors. These receptors are found in the forebrain, which then processes the smell information.
In simple words: We smell an incense stick because of olfactory receptors in our forebrain that sense the smell.

Exam Tip: Mention both the type of receptor (olfactory) and its location (forebrain) for a complete answer.

 

Question 5. What is the role of brain in reflex action?
Answer: The spinal cord consists of nerves that give information for thinking. Thinking requires more complex mechanisms and neural connections. These complex connections are concentrated in the brain, which reacts to stimuli and serves as the body's main coordinating center. The brain and spinal cord form the central nervous system. They get information from all body parts and process it. Therefore, the brain plays an important part in reflex actions.
In simple words: The brain is the main coordination center that processes stimuli, even if reflex actions are primarily managed by the spinal cord. It helps integrate information from all body parts.

Exam Tip: While the spinal cord directly controls reflex actions, remember that the brain still plays a role in integrating information and overall coordination. Avoid stating that the brain has no role at all.

 

Question 6. What are plant hormones?
Answer: Plant hormones are chemicals found in plants that help to coordinate their growth, development, and responses to various stimuli and the environment. For instance, auxins, gibberellins, cytokinins, and abscisic acids are different types of plant hormones.
In simple words: Plant hormones are natural chemicals in plants that help control how they grow, develop, and react to their surroundings.

Exam Tip: Define plant hormones as chemical messengers and give a few examples to show your understanding.

 

Question 7. How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?
Answer: The movement of leaves of the sensitive plant (Mimosa pudica) is a nastic movement, meaning it is non-directional and happens quickly in response to touch. It involves changes in water pressure within specialized cells called pulvini, and is not related to growth. In contrast, the movement of a shoot towards light is a phototropic movement, which is directional and growth-related. The shoot bends slowly due to differential growth, where cells on the shaded side elongate more.
In simple words: Sensitive plant leaves move fast when touched, but not towards or away from the touch, and it doesn't involve growth. A shoot moving towards light is slow, moves in a specific direction, and involves growth.

Exam Tip: Highlight the key differences: directionality (non-directional vs. directional), speed (quick vs. slow), and underlying mechanism (turgor changes vs. differential growth).

 

Question 8. Give an example of a plant hormone that promotes growth.
Answer: Auxin is a plant hormone that helps in cell growth and elongation. Gibberellins also encourage the growth of the stem.
In simple words: Auxin is a plant hormone that helps plant cells grow longer. Gibberellins also help the stem to grow.

Exam Tip: Provide one or two clear examples of growth-promoting hormones, such as auxin or gibberellins, along with their specific function.

 

Question 9. How do auxins promote the growth of a tendril around a support?
Answer: When tendrils come into contact with a support, the part of the tendril touching the object does not grow as quickly as the part away from the object. This happens because of the action of auxin hormone. Less auxin is found on the side that touches the support compared to the free side. As a result, auxin promotes growth on the free side, causing the tendrils to coil around the support.
In simple words: When a tendril touches something, the auxin hormone makes the side not touching the object grow faster. This causes the tendril to wrap around the support.

Exam Tip: Explain the role of differential auxin concentration and its effect on cell growth, leading to the coiling action of tendrils around a support.

 

Question 10. Design an experiment to demonstrate hydrotropism.
Answer:
Aim: To demonstrate hydrotropism.
Material Required: Tray, soil, seeds, water, pipe.
Procedure:

• Take a tray filled with soil.
• Plant a seedling in the tray at one end.
• To the other end add water to the soil with the help of a pipe as shown in the figure.

Observation: The root (radicle) of the plant seedling moves towards the wet soil. This shows that roots are positively hydrotropic.
In simple words: This experiment shows that plant roots grow towards water. We put a seed in soil and water one end. We then observe the roots moving towards the watered side, proving they are attracted to water.

Exam Tip: Clearly state the aim, list all materials, describe each step of the procedure, and then explain the observation and conclusion, linking it back to hydrotropism.

 

Question 11. How does chemical coordination take place in animals?
Answer: In animals, chemical coordination is maintained by hormones that are produced by endocrine glands. These hormones act as chemical messengers. Endocrine glands release them directly into the blood without needing any special ducts. From the blood, these hormones travel to the target tissue or organ to perform their action. These organs and tissues then react, helping the body manage various situations.
In simple words: Animals use hormones from endocrine glands for chemical coordination. These hormones act as messengers, traveling through the bloodstream to specific target organs to help the body function and respond to different situations.

Exam Tip: Focus on hormones as chemical messengers, endocrine glands, direct release into the bloodstream, and their action on target organs.

 

Question 12. Why is the use of iodised salt advisable?
Answer: Iodine is essential for the thyroid gland to produce thyroxin hormone. Thyroxin helps regulate the metabolism of carbohydrates, proteins, and fats in the body, providing the best balance for proper growth. If there isn't enough iodine in our diet, there's a chance we might get goitre. The thyroid gland then swells, causing a lump in the neck. Iodized common salt contains the correct amount of iodine. Therefore, to avoid iodine deficiency, iodized salt is suggested.
In simple words: Iodized salt is recommended because iodine helps the thyroid gland make thyroxin, which is important for metabolism and growth. Without enough iodine, one can develop goitre, where the thyroid gland swells.

Exam Tip: Explain the role of iodine in thyroxin production, the function of thyroxin, the consequence of iodine deficiency (goitre), and why iodized salt prevents this.

 

Question 13. How does our body respond when adrenaline is secreted into the blood?
Answer: The adrenaline hormone is released in large amounts when a person is frightened or mentally stressed. When it reaches the heart, the heart beats quicker to deliver more oxygen to the muscles. Breathing rate also increases because of the contractions of the rib muscles and the diaphragm. It also increases blood pressure and allows more glucose to enter the blood. All these reactions together help our body handle emergency situations.
In simple words: When adrenaline is released, your heart beats faster, you breathe quicker, and blood pressure rises. More glucose enters the blood. These changes help your body react during stressful or emergency moments.

Exam Tip: List the specific physiological changes that occur when adrenaline is secreted (heart rate, breathing, blood pressure, glucose release) and explain how these prepare the body for "fight or flight."

 

Question 14. Why are some patients of diabetes treated by giving injections of insulin?
Answer: Diabetes happens because the pancreas produces little or no insulin hormone. In such a person, the blood sugar level is high. Insulin changes extra sugar in the blood into glycogen. So, patients who have diabetes are given insulin injections to help manage their blood sugar level.
In simple words: Diabetes happens when the pancreas doesn't make enough insulin. Insulin helps change blood sugar into glycogen. So, diabetics get insulin shots to keep their blood sugar levels normal.

Exam Tip: Explain the cause of diabetes (lack of insulin), the role of insulin in sugar metabolism, and how insulin injections help manage blood sugar levels.

 

In-Text Activities Solved

 

Activity 7.1
Answer:

• Put some sugar in your mouth. How does it taste?
• Block your nose and now eat sugar. Is there any difference in its taste?
• While eating lunch, block your nose in the same way and notice your observation.

Observation: We do not get the same taste of food or sugar as we did earlier.
In simple words: When you eat sugar with your nose blocked, it tastes different. This shows that our sense of smell helps us taste food properly.

Exam Tip: This activity highlights the connection between taste and smell. Emphasize that smell significantly influences our perception of taste.

 

Activity 7.2
Answer:

• Take a conical flask with water.
• Cover its neck with a wire mesh.
• Keep two or three freshly germinated beans on the wire mesh.
• Take a cardboard box which is open from one side.
• Keep the flask in the box such that the open side of the box faces light coming from a window.
• After two or three days it is seen that the shoot bends and moves towards the light.

(i) The old parts of the root and shoot will change their direction.

(ii) There will be a difference in the growth of the shoot.
(iii) From this activity we conclude that light causes the movement growth in the shoot of the plant. It is the plant's response in the direction of light.
In simple words: This experiment shows that plant shoots grow towards light. By placing a plant in a box with light from one side, we see the shoot bend towards the light. This is how plants respond to light.

Exam Tip: Describe the setup clearly, including the light source and plant's initial position. The key observation is the shoot bending towards light, demonstrating phototropism.

 

Activity 7.3
Answer:

In simple words: This table lists different endocrine glands in the body, the hormones they produce, and what each hormone does. It shows how various parts of the body are controlled by chemical messengers.

Exam Tip: When presenting information about glands and hormones, a table is an excellent way to organize the data, clearly showing each gland, its secretions, and their functions. Ensure all relevant columns are present and correctly filled.

 

Gujarat Board Class 10 Science Control and Coordination Textbook Questions and Answers

 

Question 1. Which of the following is the plant hormone?
(b) Thyroxine
(c) Oestrogen
(d) Cytokinin
Answer: (d) Cytokinin
In simple words: Out of the choices, Cytokinin is the correct plant hormone. Thyroxine and Oestrogen are animal hormones.

Exam Tip: Be careful to distinguish between plant and animal hormones, as their names can sometimes sound similar. Cytokinin is a well-known plant growth regulator.

 

Question 2. The gap between two neurons is called a -
(a) dendrite.
(b) synapse.
(c) axon.
(d) impulse.
Answer: (b) synapse.
In simple words: The tiny space where two neurons meet and communicate is called a synapse.

Exam Tip: Understand the key parts of a neuron (dendrite, axon, cell body) and the specific term for the junction where they communicate (synapse).

 

Question 3. The brain is responsible for –
(a) thinking.
(b) regulating the heart beat.
(c) balancing the body.
(d) all of the options
Answer: (d) all of the options
In simple words: The brain handles many important tasks, including thinking, controlling your heart rate, and keeping your body balanced.

Exam Tip: Remember that the brain is a complex organ with multiple vital functions, including cognitive processes, involuntary actions, and coordination.

 

Question 4. What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?
Answer: The receptors in our body gather information about changes in the surrounding environment, which are called stimuli. They are found in our sense organs, like the inner ear, nose, tongue, and eyes. These receptors then send this information as nerve impulses to the central nervous system (spinal cord and brain). The message is then understood, and instructions are sent to effectors, which carry out responses. If receptors do not work correctly, environmental stimuli cannot create nerve impulses, and the body will not respond.
In simple words: Receptors in our sense organs collect information from the environment and send it to the brain. If they don't work, we can't sense changes around us or react properly.

Exam Tip: Define receptors, list their locations, and explain their role in the stimulus-response pathway. Crucially, describe the consequences if they malfunction.

 

Question 5. Draw the structure of a neuron and explain its function.
Answer:

Functions: The information gathered at the end of a neuron's dendritic tip triggers a chemical reaction that creates an electrical impulse. This impulse travels from the dendrite to the cell body, and then moves along the axon to its end. At the axon's end, the electrical impulse causes the release of certain chemicals. These chemicals then cross the synapse and begin a similar impulse in the dendrite of the next neuron. In this way, nervous impulses move through the body. Thus, nervous tissue is made of an organized network of neurons that specialize in carrying information via electrical impulses from one part of the body to another.
In simple words: Neurons are cells that send messages using electrical signals. Information comes into the dendrites, goes through the cell body, and travels down the axon. At the end, chemicals are released to pass the message to the next neuron or other cells.

Exam Tip: When asked to draw and explain, ensure your diagram is clearly labeled, and your explanation covers how an impulse is generated, transmitted through the neuron, and then passed to the next neuron across a synapse.

 

Question 6. How does phototropism occur in plants?
Answer: Phototropism is the movement of a shoot towards light. This movement is caused by more cell growth on the shaded side of the shoot compared to the side facing the light. This increased growth happens because auxin hormone is secreted towards the shaded side. This process can be demonstrated with an experiment. A plant placed in a box with light from one side will show its shoot bending towards the light source. This occurs because the cells on the side away from the light elongate more, causing the shoot to curve towards the light.

Aim: To show phototropism.
Procedure:

• Take a conical flask filled with water.
• Cover the neck of the flask with a wire mesh.
• Keep two or three freshly germinated bean seeds on the wire mesh.
• Take a cardboard box which is open from one side.
• Keep the flask in the box in such a manner that the open side of the box faces the light coming from a window.
• Now, turn the flask so that the shoots are away from light and the roots towards light. Leave it undisturbed in this condition for a few days.

Observation:

• After two or three days, you will notice that the shoots bend towards light and roots away from light.
• The old parts of the roots and shoots change directions.
• New growth in the shoot is in the direction of sunlight.

Conclusion: The shoot shows phototropism.
In simple words: Phototropism means a plant's shoot grows towards light. This happens because the hormone auxin causes cells on the shaded side to grow faster, making the shoot curve towards the light. An experiment with a plant in a box with a side opening for light demonstrates this bending.

Exam Tip: Explain the role of auxin in differential growth on the shaded side of the shoot, leading to bending towards light. Use the experiment as evidence.

 

Question 7. Which signals will get disrupted in case of a spinal cord injury?
Answer:

1. Reflex actions
2. Impulses from various body parts will not be conducted to the brain.
3. Messages from the brain will not be conducted to various organs of the body.

In simple words: A spinal cord injury would stop important signals. Reflex actions would be affected, and messages between the body and the brain would not be able to travel properly in either direction.

Exam Tip: A spinal cord injury can severely impact both sensory (body to brain) and motor (brain to body) nerve pathways, as well as automatic reflexes. List these disruptions clearly.

 

Question 8. How does chemical coordination occur in plants?
Answer: In plants, chemical coordination happens with the help of plant hormones, also known as phytohormones. Various plant hormones help to organize growth, development, and how plants react to the environment. They are produced in specific areas far from where they act and then spread to the action area. For example, auxin encourages cell growth, gibberellins help in vegetative growth, cytokinins promote cell division, and abscisic acid stops growth and can cause leaves to wilt.
In simple words: Plants coordinate their growth and responses using special chemicals called plant hormones. These hormones are made in one part of the plant and then move to other parts to tell them what to do, like grow, develop, or react to changes.

Exam Tip: Emphasize phytohormones as chemical messengers, their synthesis in one part and action in another, and give examples with their specific roles in plant processes.

 

Question 9. What is the need for a system of control and coordination in an organism?
Answer: A multicellular organism's body is made of many parts and smaller parts, each specialized to do a particular job. Therefore, it is important for all the organism's organs to work together properly to respond to a stimulus. In humans, the nervous system and endocrine system both work together to achieve control and coordination.
In simple words: Organisms need control and coordination so all their different body parts can work together smoothly. This helps them respond correctly to things around them.

Exam Tip: Highlight the complexity of multicellular organisms and the necessity of coordinated effort among specialized parts for proper functioning and response to stimuli.

 

Question 10. How are involuntary action and reflex action different from each other?
Answer:
(a) Involuntary action – involves the autonomic nervous system.

• They occur in response to internal stimuli.
• They are connected with the functioning of internal body parts.
• It occurs without the will of the organism.
• Example – heartbeat, breathing, etc.
• These are regulated by the medulla oblongata (hindbrain).

(b) Reflex action – involves all parts of the voluntary nervous system even though they are not voluntary.

• They operate against harmful stimuli which are generally external.
• They are connected with emergency, i.e., response to stimuli.
• Some reflexes involve the brain, rather than the spinal cord.
• Reflex action is generally controlled by the spinal cord.

In simple words: Involuntary actions are internal and automatic, like breathing, controlled by the brain. Reflex actions are quick, often external responses to danger, like pulling your hand from heat, mostly controlled by the spinal cord.

Exam Tip: Clearly define each type of action, distinguishing their controlling systems (autonomic vs. voluntary nervous system involvement), nature of stimuli (internal vs. external), and primary control centers (medulla oblongata vs. spinal cord).

 

Question 11. Compare and contrast nervous and hormonal mechanism for control and coordination in animals.
Answer: Nervous coordination in human beings: In human beings, the nervous system controls various functions through small units called neurons. Neurons receive information via sensory nerves and pass it on. Hormonal coordination: Hormones coordinate body activities and growth. Important functions like blood sugar level metabolism, growth, and development are controlled by hormones produced by endocrine glands. Thus, in human beings, hormones show long-lasting responses. The actions of hormones are highly specific.
In simple words: Nervous control is fast, uses electrical signals, and is short-lived. Hormonal control is slower, uses chemical messengers in the blood, and has longer-lasting, more widespread effects.

Exam Tip: Create two distinct columns or sections for nervous and hormonal mechanisms. Compare them on speed, type of signal, duration of effect, and target specificity.

 

Question 12. What is the difference between the manner in which movement takes place in a sensitive plant and movement in our legs?
Answer: Movement in a sensitive plant:

• It happens in response to an external stimulus like touch and shock.
• Plant cells change shape by adjusting their water content.
• No nerves are involved.
• There is no specialized tissue in plants for carrying information.
• Plant cells do not have specialized proteins.

Movement in our legs:

• It happens in response to our needs and is a voluntary action.
• Movement in our legs is a voluntary action controlled by the cerebellum part of the hindbrain.
• Nerves transmit the message for leg movement.
• Animals have specialized nervous tissue for carrying information, and muscle cells help in movement.
• Animal cells have specialized proteins that help muscles to contract or relax.

In simple words: Sensitive plants move non-directionally by changing water in cells, without nerves. Our leg movements are voluntary, controlled by the brain, use nerves, and involve muscle proteins to contract.

Exam Tip: Highlight the fundamental differences: voluntary vs. involuntary, neural vs. hormonal/turgor-based, and the presence or absence of specialized tissues like nerves and muscles.

 

Gujarat Board Class 10 Science Control and Coordination Additional Important Questions and Answers

 

Very Short Answer Type Questions

 

Question 1. What is stimulus?
Answer: Something that causes a response in an organism is called a stimulus.
In simple words: A stimulus is anything that makes an organism react.

Exam Tip: Keep the definition concise and clear, focusing on the cause-and-effect relationship.

 

Question 2. What is an impulse?
Answer: Information travels through our nerves as electro-chemical signals. These signals are called impulses.
In simple words: An impulse is an electro-chemical signal that carries information along our nerves.

Exam Tip: Define impulse in the context of the nervous system, mentioning its electrochemical nature.

 

Question 3. What is synapse?
Answer: The functional junction between two neurons is called a synapse.
In simple words: A synapse is the tiny connection point where two neurons communicate.

Exam Tip: Provide a precise definition of a synapse as the junction between neurons.

 

Question 4. What is reflex action?
Answer: It is a spontaneous, involuntary, and unconscious response to a stimulus.
In simple words: A reflex action is a quick, automatic body response that happens without you thinking about it.

Exam Tip: Include the key characteristics: spontaneous, involuntary, and unconscious, as these define a reflex action.

 

Question 5. Why is reflex action important?
Answer: Reflex actions are important because they help us respond quickly in emergency situations. For example, jerking our hand away when touching a hot iron is a reflex that prevents serious injury.
In simple words: Reflex actions are important because they help us react very quickly to danger, protecting us from harm.

Exam Tip: Focus on the protective and quick response aspect of reflex actions, providing a clear example.

 

Question 6. Name the part of brain in which hypothalamus is located.
Answer: Hindbrain.
In simple words: The hypothalamus is found in the hindbrain.

Exam Tip: State the location of the hypothalamus directly. While often associated with the diencephalon, it's also considered part of the broader hindbrain region in some contexts.

 

Question 7. What part of the brain is responsible for precision of voluntary action?
Answer: Cerebellum.
In simple words: The cerebellum is the brain part that makes our voluntary movements smooth and precise.

Exam Tip: Directly name the cerebellum as the part responsible for the coordination and precision of voluntary movements.

 

Question 8. What is the impact of nervous electrical impulse upon muscle proteins?
Answer: It helps in changing the shape and arrangement of proteins in muscle cells.
In simple words: When a nerve impulse reaches muscle cells, it causes the proteins inside them to change shape and move, which makes the muscle contract.

Exam Tip: Explain that nerve impulses cause muscle proteins (actin and myosin) to change shape, leading to muscle contraction and movement.

 

Question 9. Which part of the brain is concerned with memory?
Answer: Forebrain.
In simple words: The forebrain is the part of the brain responsible for memory.

Exam Tip: State the specific region of the brain responsible for memory. The forebrain, particularly the cerebrum, handles higher cognitive functions including memory.

 

Question 10. How is brain protected from shocks and injuries?
Answer: The brain is protected by the brain box, which is called the skull. Inside the skull, there is a shock-absorbing fluid that further safeguards the brain.
In simple words: Your brain is protected by your skull, a strong bony box, and also by a special fluid inside that absorbs shocks.

Exam Tip: Mention both the bony skull and the cerebrospinal fluid as the primary protective mechanisms for the brain.

 

Question 11. Write the components of central nervous system.
Answer: Brain and spinal cord.
In simple words: The central nervous system is made up of the brain and the spinal cord.

Exam Tip: List the two main components: the brain and the spinal cord.

 

Question 12. Write the components of peripheral nervous system.
Answer: Spinal nerves and cranial nerves.
In simple words: The peripheral nervous system includes the spinal nerves and the cranial nerves.

Exam Tip: Identify the cranial and spinal nerves as the key parts of the peripheral nervous system.

 

Question 13. Name two plant hormones that help in stem growth.
Answer: Auxin and gibberellin.
In simple words: Auxin and gibberellin are two plant hormones that help the stem grow.

Exam Tip: Name auxin and gibberellin as these are the primary plant hormones involved in stem elongation and overall growth.

 

Question 14. What are cranial nerves?
Answer: Nerves that originate from the brain are called cranial nerves.
In simple words: Cranial nerves are special nerves that come directly from the brain.

Exam Tip: Provide a direct and concise definition of cranial nerves based on their origin from the brain.

 

Question 15. Which nutrient of food is associated with muscular action?
Answer: Proteins.
In simple words: Proteins are the food nutrient linked to how muscles work.

Exam Tip: Remember that proteins are essential for muscle structure and function, including contraction.

 

Question 16. Name the hormone responsible for
(a) Phototropic movement of plant.
(b) Promoting cell division in plants.
Answer:
(a) Auxin
(b) Cytokinin
In simple words: Auxin helps plants move towards light, and cytokinin helps plant cells divide and grow.

Exam Tip: Remember specific hormones for each plant function (e.g., Auxin for phototropism and elongation, Cytokinin for cell division). Different hormones control different aspects of plant life.

 

Question 17. Name the stress and fear hormones.
Answer: Adrenaline hormone.
In simple words: The hormone that makes us feel stressed or scared is adrenaline.

Exam Tip: Adrenaline is also known as the 'fight or flight' hormone due to its role in preparing the body for emergency situations.

 

Question 18. What are photoreceptors?
Answer: The receptors present in our eyes are called photoreceptors, as they are light sensitive.
In simple words: Photoreceptors are special cells in our eyes that can detect light.

Exam Tip: Understand that specific receptors are designed to detect particular types of stimuli (e.g., light, sound, taste, smell, touch).

 

Question 19. What are gustatory receptors?
Answer: The receptors present in our tongue which detect the taste are called gustatory receptors.
In simple words: Gustatory receptors are the parts of our tongue that help us taste different flavors.

Exam Tip: Relate gustatory receptors to taste and olfactory receptors to smell to avoid confusion.

 

Question 20. What are olfactory receptors?
Answer: The receptors present in our nose and helps in detecting smell are called olfactory receptors.
In simple words: Olfactory receptors are located in our nose and are responsible for our sense of smell.

Exam Tip: Keep the functions of each type of sensory receptor distinct: photoreceptors for sight, gustatory for taste, and olfactory for smell.

 

Question 21. Name the part of hind brain which takes part in regulation of respiration.
Answer: Pons.
In simple words: The pons, a part of the hindbrain, helps control breathing.

Exam Tip: Familiarize yourself with the specific functions of each part of the brain, especially those related to vital involuntary actions.

 

Question 22. Name the structural and functional unit of human nervous system.
Answer: Neuron.
In simple words: The basic building block and working unit of our nervous system is the neuron.

Exam Tip: The neuron is the fundamental unit for transmitting electrical and chemical signals throughout the body.

 

Question 23. What could be the possible disadvantage if reflex action were controlled by the brain?
Answer: The action time would be longer and the response to any stimuli would have taken more time.
In simple words: If our brain had to think about reflex actions, our reactions would be much slower, which could be dangerous in emergencies.

Exam Tip: Reflex actions bypass the brain to ensure rapid responses, which is crucial for protecting the body from harm.

 

Question 24. Why is pituitary gland called master gland?
Answer: It is because pituitary gland controls and coordinates the secretions of all the other endocrine glands.
In simple words: The pituitary gland is called the master gland because it regulates and coordinates what other hormone-producing glands in the body do.

Exam Tip: Understand that the pituitary gland's influence over other glands makes it central to the endocrine system's overall function.

 

Question 25. What are phytohormones?
Answer: The hormones present in plants which are involved in the control and coordination of plant are called phytohormone.
In simple words: Phytohormones are special hormones found in plants that help them control their growth and how they respond to things.

Exam Tip: Recognize that plants also have hormones (phytohormones) that regulate various life processes, similar to animal hormones.

 

Question 26. Name any 4 stimuli which acts on plants.
Answer: Light, water, gravity, touch and chemical substance.
In simple words: Plants react to things like light, water, gravity, touch, and various chemicals.

Exam Tip: These stimuli trigger various tropic (directional) and nastic (non-directional) movements in plants.

 

Question 27. Name one endocrine gland which performs dual function.
Answer: Pancreas – It secretes hormones and digestive enzyme.
In simple words: The pancreas is an endocrine gland that does two jobs: it makes hormones like insulin and also produces digestive enzymes.

Exam Tip: The pancreas serves both endocrine (hormone production) and exocrine (enzyme production) functions, which is unique among glands.

 

Question 28. Name the components of neuron.
Answer: Dendrite, cell body, axon and nerve ending.
In simple words: A neuron is made up of dendrites, a cell body, an axon, and nerve endings.

Exam Tip: Be able to identify and briefly describe the role of each main part of a neuron in transmitting signals.

 

Question 29. Name the hormone secreted by thyroid gland.
Answer: Thyroxine.
In simple words: The thyroid gland produces a hormone called thyroxine.

Exam Tip: Thyroxine is important for regulating metabolism and growth in the body.

 

Question 1. Give protective features of the nervous system.
Answer:
1. The brain is protected by the bony cranium. The brain is also covered by three membranes called meninges. The space between the meninges is filled with cerebrospinal fluid which protects the brain from mechanical shocks.
2. The meninges and the cerebrospinal fluid cover the spinal cord too. Besides this the spinal cord is protected by the vertebral column.
In simple words: Our brain is kept safe inside the skull and is also cushioned by three layers called meninges and a special fluid. The spinal cord, which is also part of the nervous system, is protected by the backbone.

Exam Tip: Remember the two main protective structures for the brain (cranium, meninges, CSF) and for the spinal cord (vertebral column, meninges, CSF).

 

Question 2. How do nervous tissues bring about muscular movements?
Answer: When a nerve impulse reaches the muscle, the muscle fibres move. This movement is brought about by the special proteins present in the muscle cells. These proteins change their shape and arrangement making the muscle cell shrinks. This makes the muscle cell contract.
In simple words: When nerves send a signal to a muscle, special proteins inside the muscle cells change their shape. This causes the muscle cells to shorten and contract, leading to movement.

Exam Tip: Focus on the sequence: nerve impulse → muscle (actin/myosin proteins) → change in shape → muscle contraction → movement.

 

Question 3. What are tropic movements?
Answer: Tropic movements are directional movements which are either towards the stimuli or away from it.
• Phototropism: Movement is in response to light: stem positive, root negative
• Geotropism: Movement is in response to gravity: stem negative, root positive
• Hydrotropism: Movement in response to water: stem negative, root positive
In simple words: Tropic movements are when a plant part grows either towards or away from something in its environment, like light or water.

Exam Tip: For each tropic movement, identify the stimulus and how different plant parts (stem, root) respond (positive or negative).

 

Question 4. How is the secretion of hormones regulated?
Answer: The secretion of hormones is regulated by the feedback mechanism. For e.g., the rise of sugar level in the blood stimulates the pancreas to secrete insulin. When the blood sugar level falls, insulin secretion is reduced.
In simple words: Hormone release is controlled by a feedback system. For example, if blood sugar goes up, the pancreas releases insulin; if sugar levels drop, insulin release slows down.

Exam Tip: Understand the concept of negative feedback, where the product of a process (like blood sugar level) inhibits the process (hormone secretion) that produces it, maintaining balance.

 

Question 5. How do neurons transmit information?
Answer: Information passes through neuron in the form of electro-chemical signals. These signals are called impulse. When an impulse reaches the end of the axon it sets off the release of some chemicals. These chemicals cross the gap or the synapse and start a similar electrical impulse in a dendrite of the next neuron. A similar synapse allows the delivery of impulses from the neurons to other cells, like muscle cells or glands.
In simple words: Neurons send messages using electrical signals called impulses. When an impulse reaches the end of one neuron, it releases chemicals. These chemicals travel across a tiny gap (synapse) to the next neuron, starting a new electrical signal there.

Exam Tip: Remember that nerve transmission involves both electrical signals within a neuron and chemical signals across the synapse.

 

Question 6. Give the difference between sensory and motor nerve.
Answer: Sensory nerves – It takes the information from receptors and transmit it to brain. Motor nerves – It transmits the information for action to be taken from brain to the effector organs i.e. muscles.
In simple words: Sensory nerves carry messages from our body's sensors (like skin) to the brain, while motor nerves carry instructions from the brain to our muscles to make them move.

Exam Tip: Think of sensory nerves as "input" and motor nerves as "output" for the central nervous system.

 

Question 7. What are functions regulated by fore brain?
Answer: The functions of fore brain (cerebrum and lobes) are:
Cerebrum – It has sensory area where information is received from sense organs. Motor areas are also present from where impulse are sent to effector organs. It also contains specific regions for each kind of stimulus and its response is located e.g. there are specialized regions for hearing, smell and sight.
In simple words: The forebrain, especially the cerebrum, handles things like receiving information from our senses, sending commands to our muscles, and having special areas for hearing, smelling, and seeing.

Exam Tip: The forebrain is responsible for most of our higher-level thinking and sensory processing functions.

 

Question 8. How is the movement of the leaves of the sensitive plant different from the movement of a shoot towards light?
Answer: Movement in leaves:
• It is non-directional.
• Movement is due to quick response to the stimuli.
• It is not related to growth.
Movement of Shoot:
• It is directional.
• It is due to slow response to the stimulus.
• It is related to growth.
In simple words: Sensitive plant leaves move quickly and in any direction when touched, not because they are growing. A plant shoot moving towards light is a slow, directional growth response.

Exam Tip: Distinguish between nastic movements (non-directional, often rapid, not growth-related) and tropic movements (directional, often slow, growth-related).

 

Question 9. Give the function of thyroxin hormone. Which endocrine gland secretes this hormone?
Answer: Thyroid gland secretes the thyroxin hormone. Function: It regulates the metabolism of carbohydrates, fats and proteins.
In simple words: The thyroid gland produces thyroxin, a hormone that controls how our body uses energy from carbohydrates, fats, and proteins.

Exam Tip: Thyroxin's primary role is in regulating the body's metabolic rate, impacting energy use and overall growth.

 

Question 10. Draw a neat labelled diagram of neuron.
Answer: To draw a neat labelled diagram of a neuron, you would include the cell body (cyton) with its nucleus, dendrites branching out to receive signals, an axon for transmitting signals, a myelin sheath covering the axon, and synaptic terminals at the end of the axon.
In simple words: You need to sketch a neuron, showing its main parts like the central cell body, the branching dendrites that pick up messages, the long axon that sends them, and the tiny nerve endings at the very end.

Exam Tip: Practice drawing and labelling the key parts of a neuron, understanding their roles in transmitting nerve impulses.

 

Question 11. Give the characteristics of hormones.
Answer:
• They are specific chemical messengers.
• Secreted by endocrine glands.
• Directly poured into blood.
• Act on specific tissues or organs known as target organs.
In simple words: Hormones are special chemical signals made by glands, released straight into the blood, and they only work on certain body parts.

Exam Tip: Focus on hormones as chemical communicators that travel via the bloodstream to specific target cells, distinguishing them from nerve impulses.

 

Question 12. Name the hormones released by the following:
1. Ovary
2. Testis
3. Pancreas
4. Pituitary
Answer:
1. Ovary – Progesterone and Oestrogen.
2. Testis - Testosterone
3. Pancreas - Insulin and Glucagon
4. Pituitary – Growth hormone.
In simple words: The ovary releases progesterone and oestrogen; the testis produces testosterone; the pancreas makes insulin and glucagon; and the pituitary gland secretes growth hormone.

Exam Tip: Memorize the primary hormones produced by each of these major endocrine glands and their general roles.

 

Question 13. What health disorder may occur if the following hormones are not secreted properly?
1. Insulin
2. Thyroxine
3. Testosterone
4. Growth hormone
Answer:
1. Diabetes
2. Goitre
3. Masculine characters will not develop properly in male.
4. Dwarfism if less hormone; Gigantism if secreted more.
In simple words: Not enough insulin can cause diabetes, low thyroxine can lead to goitre, insufficient testosterone hinders proper male development, and too little or too much growth hormone can result in dwarfism or gigantism.

Exam Tip: Be able to link each hormone with its associated deficiency/excess disorder and the characteristic symptoms.

 

Question 14. What are plant hormones?
Answer: Plant hormones are chemicals that bring about chemical coordination in plants. They help to coordinate growth, development and responses to the environment in plants. They are synthesized at places away from where they act and simply diffuse to the area of action. Examples: Auxin – It is synthesized at the shoot tip and helps the stem to grow longer. Gibberellins – Help in vegetative growth of the plant. Cytokinins – Promote cell divisions and are present in high concentration in fruit and seeds.
In simple words: Plant hormones are chemicals that manage how plants grow, develop, and react to their surroundings. They are made in one part of the plant but work in another, helping things like stem length, overall growth, and cell division.

Exam Tip: Define plant hormones (phytohormones) as chemical messengers and give examples like auxin, gibberellins, and cytokinins with their main functions.

 

Question 15. What are the different parts of the brain? Give functions of each part.
Answer: The brain is divided into three regions: fore brain, mid brain and hind brain.
Fore brain:
• The fore brain includes the cerebrum and the olfactory lobes.
• The cerebrum is the largest part of the brain and consists of two cerebral hemispheres.
• It has sensory areas where information is received from sense organs. Similarly there are motor areas from where impulses are sent to effector organs.
• In the cerebrum specific regions for each kind of stimulus and its response are located. Example – there are specialized regions for hearing, smell and sight.
Mid brain:
• It is made up of thalamus and hypothalamus.
• It connects the fore brain to the hind brain.
Hindbrain – consists of cerebellum, pons and medulla:
• Pons regulates respiration.
• Medulla is the centre of involuntary actions like salivation, vomiting, sneezing coughing etc.
In simple words: The brain has three main parts: the forebrain, midbrain, and hindbrain. The forebrain handles sensing, movement, and complex thoughts, with specific areas for things like hearing and sight. The midbrain connects the forebrain and hindbrain. The hindbrain manages important body functions like breathing (pons) and other automatic actions such as coughing (medulla).

Exam Tip: When describing brain parts, ensure you list the main subdivisions (forebrain, midbrain, hindbrain) and at least one key function for each major component within those subdivisions.

 

Question 16. What is the role of adrenaline hormone that is secreted and released in the blood?
Answer: Adrenaline acts on target organs and specific tissues as follows:
1. Heart beats faster increasing the oxygen supply to the muscles.
2. Muscles of ribs and diaphragm contraction increases thereby increasing the breathing rate.
3. Blood vessels of the digestive system and skin contracts resulting in diversion of blood to our skeletal muscles.
In simple words: Adrenaline makes your heart pump faster, sending more oxygen to your muscles. It also makes you breathe quicker by tightening your rib muscles and diaphragm. Plus, it moves blood away from your skin and digestive system towards your muscles, all to help your body handle emergencies.

Exam Tip: Link adrenaline's effects (increased heart rate, breathing, blood diversion) directly to its role in preparing the body for "fight or flight" situations.

 

Question 17. Name the secretions of the following glands and give their function: pituitary, testis and ovary.
Answer: Pituitary: It secretes growth hormone which regulates growth and development of the body. Excessive secretion causes gigantism and decreased secretion causes dwarfism.
Testis: Secretes testosterone which regulates male accessory sex organ and secondary sexual characters.
Ovary: Secretes oestrogen which regulates female accessory sex organs and secondary sexual characters in females.
In simple words: The pituitary gland releases growth hormone that controls body development. The testis produces testosterone, which guides male characteristics. The ovary makes oestrogen, which influences female characteristics.

Exam Tip: For each gland, identify its main hormone(s) and a key function, including consequences of imbalance if relevant.

 

Question 18. Compare and contrast nervous and hormonal mechanism for control and coordination.
Answer: Nervous coordination:
• It is brought about by a network of nerves which connect different parts of the body to the central nervous system.
• Messages are sent through nerves to different parts of the body.
• Nerves and the central nervous system control and coordinate different functions.
Hormonal coordination:
• It is brought about by hormones secreted by endocrine glands into the blood and reaching different parts of the body.
• Messages are sent through hormones to different parts of the body.
• Every function is controlled and coordinated by special hormone.
• Increase and decrease of hormone quantity affect target organs.
In simple words: Nervous coordination uses a network of nerves and electrical signals for quick communication. Hormonal coordination uses hormones released into the blood, which act more slowly but have wider, longer-lasting effects.

Exam Tip: Key differences include speed of action (nervous-fast, hormonal-slow), mode of transmission (nerves-electrical, hormones-chemical), and specificity/duration of effect.

 

Question 19. Draw a neat labelled diagram of human brain.
Answer: To draw a neat labelled diagram of the human brain, you should include the main regions: cerebrum, cerebellum, pons, medulla, thalamus, hypothalamus, and pituitary gland, along with the protective cranium and spinal cord. Label the forebrain, midbrain, and hindbrain sections clearly.
In simple words: You need to sketch the human brain and clearly label its major parts like the cerebrum, cerebellum, pons, and medulla, showing how they fit together.

Exam Tip: Practice drawing and labelling the human brain, emphasizing the three main divisions (forebrain, midbrain, hindbrain) and key structures within each.

 

Question 20. What is the difference between sensory and motor neuron? Which part of human brain is responsible for auditory reception and sensation of smell?
Answer:
1. Sensory Neuron – It carries the stimulus from receptor to the brain.
2. Motor Neuron – It carries the impulse from brain to the effect organ.
The forebrain (specifically specialized regions within the cerebrum) is responsible for auditory reception and the sensation of smell.
In simple words: Sensory neurons send messages from our senses to the brain, while motor neurons carry commands from the brain to our muscles. The front part of our brain (forebrain) handles hearing and smelling.

Exam Tip: Remember the flow of information: Sensory → Brain → Motor. The forebrain is the center for higher sensory processing like hearing and smell.

 

Question 22. Give difference between nervous system and endocrine system.
Answer: Endocrine System:
• This system does not have direct connection with the organs or tissues controlled by it.
• The information of coordination is transmitted slowly.
• The effect is long lasting.
Nervous System:
• This system has direct connection and control over the tissues or organs.
• The information is transmitted very
• The effect is short lived.
In simple words: The endocrine system uses hormones traveling through blood for slow, long-lasting effects without direct connections. The nervous system uses nerve cells and electrical signals for fast, short-lived effects with direct connections to organs.

Exam Tip: Focus on the method of communication (electrical vs. chemical), speed of response (fast vs. slow), and duration of effect (short-lived vs. long-lasting) to differentiate these systems.

 

Question 23. Differentiate between the following:
(a) Spinal nerve and cranial nerve
(b) Dendrite and axon
(c) Central nervous system and peripheral nervous system.
Answer:
(a)
1. Spinal nerve – It arises from spinal cord.
2. Cranial nerve – it arises from brain.
(b)
1. Dendrite – It arises from the cell body, short branched parts, that receive messages from the reception.
2. Axon – It is a long unbranched part that comes from the cell body. Through axon the messages passes to another nerve cell.
(c) Central nervous system:
• It consists of brain and spinal cord.
• It contain centres for controlling various activities of the body
Peripheral nervous system:
• It consists of cranial nerves, spinal nerves and visceral nerve
• No such centres present for controlling as nerves only transmit the impulse.
In simple words: (a) Spinal nerves come from the spinal cord, while cranial nerves come from the brain. (b) Dendrites are short, branched parts of a neuron that receive messages, while axons are long, unbranched parts that send messages. (c) The Central Nervous System (CNS) includes the brain and spinal cord and acts as the main control center, whereas the Peripheral Nervous System (PNS) consists of all other nerves that carry messages to and from the CNS.

Exam Tip: Clearly state the origin and general function for nerves, and the structure and role for neuron parts and nervous system divisions.

 

Question 24. Draw a diagram of human hormonal system.
Answer: To draw a diagram of the human hormonal system, you would typically illustrate the locations of major endocrine glands such as the hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid glands, thymus, adrenal glands, pancreas, ovaries (in females), and testes (in males). You would also label the key hormones associated with each gland, as shown in previous tables and text.
In simple words: You need to draw a picture showing where all the main hormone-producing glands are located in the human body.

Exam Tip: Practice identifying the anatomical locations of the major endocrine glands in both male and female diagrams, as well as the hormones they secrete.

 

Question 25. In our body what is the function of thyroxin hormone?
Answer: Thyroxin hormone regulates the metabolism of carbohydrates, proteins and fats.
In simple words: Thyroxin hormone helps control how our body uses carbohydrates, proteins, and fats to get energy.

Exam Tip: Remember thyroxin's central role in metabolic regulation, which affects energy levels and overall body function.

 

Question 26. Name the endocrine gland that secretes insulin in our bodies.
Answer: Pancreas.
In simple words: The pancreas is the gland in our body that produces insulin.

Exam Tip: The pancreas is a dual-function gland, vital for both digestion and blood sugar regulation via insulin and glucagon.

 

Question 27. Mention the functions of fore brain.
Answer: Fore brain consists of three parts and each has its own functions
1. Olfactory lobe – It is related to olfactory responses, sense of smell.
2. Cerebrum – This controls muscular movements, visual, auditory responses, responses of touch, smell, temperature and conscious association.
3. Diencephalon – It regulates water balance in the body, metabolism of carbohydrates and fats, controls feelings of anger, pleasure, fear, hunger, etc.
In simple words: The forebrain has three parts. The olfactory lobe manages smell. The cerebrum controls movement, sight, hearing, touch, and thinking. The diencephalon helps regulate water, metabolism, and emotions like anger and hunger.

Exam Tip: Remember that the forebrain is responsible for most complex functions including sensory processing, voluntary movement, and cognitive tasks.

 

Question 28. Name three different types of neurons and state the function of each.
Answer:
1. Sensory neuron – These neurons receive signals from a sense organ.
2. Motor neuron – These neurons send signals to a muscle or a gland.
3. Association neuron – These neurons relay the signals between sensory neuron and motor neuron.
In simple words: Sensory neurons take messages from our senses, motor neurons send commands to our muscles, and association neurons connect sensory and motor neurons.

Exam Tip: Understand the directional flow of information in the nervous system, where sensory neurons bring information in, motor neurons send commands out, and association neurons link them.

 

Question 29. Give the detailed description of peripheral nervous system.
Answer: The peripheral nervous system is composed of the cranial nerves and spinal nerves. There are 12 pairs of cranial nerves. The cranial nerves come out of the brain and go to the organs in the head region. There are 31 pairs of spinal nerves. The spinal nerves come out of the spinal cord and go to the organs which are below the head region.
In simple words: The peripheral nervous system (PNS) includes all the nerves outside the brain and spinal cord. It has 12 pairs of cranial nerves that go to parts of the head, and 31 pairs of spinal nerves that go to the rest of the body below the head.

Exam Tip: Remember that the PNS acts as the communication network connecting the CNS to the rest of the body, carrying both sensory and motor information.

 

Question 31. Discuss the structure of human brain.
Answer: Human brain is a highly complex organ which is mainly composed of the nervous tissue. The tissues are highly folded to accommodate a larger surface area in less space. The brain is covered by a three layered system of membranes called meninges. Cerebrospinal fluid CSF is filled between the meninges. The CSF provides cushion to the brain against mechanical shocks. For optimum protection the brain is housed inside the skull. The human brain can be divided into three regions, viz. forebrain, midbrain and hindbrain.
• Forebrain: It is composed of the cerebrum.
• Midbrain: It is composed of the hypothalamus.
• Hindbrain: It is composed of the cerebellum, pons and medulla oblongata.
In simple words: The human brain is a very complex organ made of nerve tissue, folded to fit more area in a small space. It's protected by three layers of membranes called meninges, and a fluid (CSF) cushions it against bumps. The entire brain sits inside the skull and is divided into three main parts: forebrain (cerebrum), midbrain (hypothalamus), and hindbrain (cerebellum, pons, medulla).

Exam Tip: Emphasize the protective structures (skull, meninges, CSF) and the three main anatomical divisions (forebrain, midbrain, hindbrain), along with their primary components.

 

Question 32. Discuss the functioning of muscles under the nervous control.
Answer: Muscle tissues have special filaments called actin and myosin. When a muscle receives a nerve impulse, an electrical signal is triggered in the muscle. Calcium ions enter the muscle cells. It results in actin and myosin filaments sliding towards each other and that is how a muscle contracts. Contraction in a muscle brings movement in the related organ.
In simple words: Muscles work when nerves send a signal. This signal causes tiny parts inside the muscle cells, called actin and myosin filaments, to slide past each other, making the muscle shorten or contract. This contraction is what creates movement in our body parts.

Exam Tip: Focus on the "sliding filament theory" for muscle contraction: nerve impulse → calcium release → actin and myosin slide → muscle contracts, leading to movement.

 

Question 33. Why is the release of hormone important in our body?
Answer: Hormones are produced in the endocrine glands. Hormone is mainly composed of protein. Hormones assist the nervous system in control and coordination. Nerves do not reach to every nook and corner of the body and hence hormones are needed to affect control and coordination in those parts. Although the nervous control is very fast, hormonal control is somewhat slower.
In simple words: Hormones are important because they help our body control and coordinate many functions, especially in places where nerves can't reach. While nerves act fast, hormones work slower but can affect more parts of the body, helping keep everything balanced.

Exam Tip: Highlight that hormones provide widespread, longer-term control and coordination, complementing the nervous system's rapid, localized actions, especially for processes like growth, metabolism, and reproduction.

 

Question 34. Plants show tropic movement for their survival. Describe and discuss these movements in plants.
Answer: The following tropic movements are seen in plants:
(a) Geotropic Movement: The growth in a plant part in response to the gravity is called geotropic movement. Roots usually show positive geotropic movement, i. e. they grow in the direction of the gravity. Stems usually show negative geotropic movement.
(b) Phototropic Movement: The growth in a plant part in response to light is called phototropic movement. Stems usually show positive phototropic movement, while roots usually show negative phototropic movement. If a plant is kept in a container in which no sunlight reaches and a hole in the container allows some sunlight; the stem finally grows in the direction of the sunlight moving out through the hole. This happens because of a higher rate of cell division in the part of stem which is away from the sunlight. As a result, the stem bends towards the light. The increased rate of cell division is attained by increased secretion of the plant hormone auxin in the part which is away from sunlight.
(c) Hydrotropic Movement: When roots grow in the soil, they usually grow towards the nearest source of water. This shows a positive hydrotropic movement.
In simple words: Plants move in specific ways to survive. Geotropism is how they react to gravity (roots grow down, stems grow up). Phototropism is their response to light (stems grow towards it, roots away). Hydrotropism is when roots grow towards water. These movements help plants get what they need.

Exam Tip: For each tropic movement, clearly define the stimulus and how different plant parts (roots, stems) respond to it, linking these responses to plant survival.

 

Question 35. In the tabular form list all the hormones released by our body with the location, function and the glands involved in the making of it.
Answer: The description is provided in the following tabular form:

In simple words: Our body makes different hormones from various glands located in specific places. Each hormone, like growth hormone or thyroxine, has a special job to do, like helping us grow or managing our energy levels.

Exam Tip: Remember the primary hormones, their glands, and a key function for each, especially those involved in growth, metabolism, and emergency responses.

 

Question 36. Explain homeostasis.
Answer: Homeostasis refers to keeping a constant internal environment, which is vital for an organism's health. Small changes in body temperature, water levels, and nutrient amounts could be very harmful. Thus, homeostasis helps control and regulate our body temperature. Mammals and birds are warm-blooded, meaning they maintain a steady body temperature even when the outside environment changes. Humans keep their body temperature at 37 degrees Celsius; we have ways to lose heat when we get too warm and ways to retain heat when we get too cold.
In simple words: Homeostasis is how our body keeps everything inside steady and balanced, like our temperature, even when things outside change. This helps us stay healthy.

Exam Tip: Define homeostasis clearly and provide examples of what it regulates (temperature, water, nutrients) and why it is important for survival.

 

Question 37. State the functions of plant hormones. Name four different types of plant hormones.
Answer: Phytohormones assist in the control and coordination within plants. These plant hormones also help in growth, vegetative development, fruit ripening, and promoting stem cell division. Four types of plant hormones include auxins, gibberellins, cytokinins, and abscisic acid.
In simple words: Plant hormones control how plants grow and react to things. They help plants get bigger, ripen fruits, and make new cells. Auxin, gibberellin, cytokinin, and abscisic acid are examples.

Exam Tip: List a minimum of four plant hormones and state a primary function for each. Emphasize their role in coordinating plant processes.

Long Answer Type Questions

 

Question 1. (a) Label the parts of the nerve cell and give one function each.
(b) What are two limitations of electrical impulse?
Answer:
(a) Refer to the diagram of a nerve cell (neuron) in your textbook for a visual representation. The main parts and their functions are:
• Nucleus prominent: The central part of the cell, managing its activities.
• Dendrite projections: Branched extensions that receive signals from other neurons.
• Myelin sheath: A fatty layer that insulates the axon and helps speed up electrical signals.
• Cell body (Cyton): Contains the nucleus and connects dendrites to the axon.
• Large dendrite (i.e., Axon): The long projection that transmits signals away from the cell body.
• Synaptic terminal: The end of the axon where neurotransmitters are released to communicate with other cells.
(b) Limitations of electrical impulse:
• Impulse reaches only those cells that have nerve connections.
• It cannot continue to create the electrical impulse indefinitely.
In simple words: (a) A nerve cell has dendrites to get messages, an axon to send them, and nerve endings to pass them on. (b) Electrical signals only go to cells connected by nerves and can't keep firing forever.

Exam Tip: For diagram questions, ensure you can accurately draw and label the neuron, and clearly state the function of each labeled part. Also, understand why electrical impulses are not universally effective for long-distance signaling in animals.

 

Question 2. (a) Draw a well labelled diagram of neuromuscular junction.
(b) Describe the feedback mechanism.
Answer:
(a) Refer to a well-labeled diagram of a neuromuscular junction in your textbook. Key parts to label include:
• Axon: The nerve fiber transmitting the signal.
• Neuromuscular junction: The point where the nerve meets the muscle.
• Muscle fibre: The individual muscle cell.
• Capillary: Blood vessel supplying nutrients.
• Mitochondrion: Organelle providing energy for muscle contraction.
(b) Feedback mechanism: This system helps regulate the secretion of hormones, including the timing and the amount of hormone to be released. For example, if blood sugar levels rise, the pancreas immediately releases insulin in the necessary amount into the blood to keep the sugar level stable.
In simple words: (a) Look at a picture of a neuromuscular junction to see how nerves connect to muscles. (b) The feedback system checks hormone levels and adjusts them. If blood sugar goes up, the pancreas releases insulin to bring it back down.

Exam Tip: When describing feedback mechanisms, use a clear example like insulin and blood sugar regulation to illustrate how the body maintains balance. For diagrams, focus on clear labels and understanding the connections.

 

Question 3. Define reflex arc and draw its labelled diagram.
Answer: Reflex arc: It is the nerve pathway involved in a reflex action, enabling quick responses. A message from the receptor is sent by sensory nerves to the spinal cord, which then sends information for a response to a motor nerve that reaches the effector. An example is quickly withdrawing your hand when you touch a hot object.
Refer to a well-labeled diagram of a reflex arc in your textbook. Key parts to label include:
• Spinal cord (CNS): The central nervous system component.
• Message to brain: The pathway for conscious awareness, though the reflex bypasses immediate brain control.
• Sensory neuron: Carries impulses from the receptor to the spinal cord.
• Motor neuron: Carries impulses from the spinal cord to the effector.
• Receptors = Heat/Pain Receptors in skin: Detects the stimulus.
• Relay neuron: Connects sensory and motor neurons in the spinal cord.
• Effector = Muscle in arm: Performs the response.
In simple words: A reflex arc is a fast nerve path that helps your body react quickly without thinking, like pulling your hand away from something hot. Messages go from sensors to the spinal cord and then to muscles.

Exam Tip: Understand the sequence of a reflex arc (receptor → sensory neuron → relay neuron → motor neuron → effector). Practice drawing the diagram and labeling all key components accurately, including the direction of nerve impulses.

 

Question 4. (a) Name five different types of movements with one example for each.
(b) Name five different hormones secreted by plants with one function for each.
Answer:
(a) Movements in plants:
• Phototropism: The stem tip grows towards light. Example: A plant bending towards a window.
• Geotropism: Response towards gravity. Example: Roots grow downwards with gravity's pull.
• Chemotropism: Response to chemicals. Example: Pollen tubes grow towards the ovule during fertilization.
• Thigmotropism: Response to touch on tendrils and other climbing parts, which are positively thigmotropic. Example: A tendril coiling around a support.
• Nastic movement: It is neither towards nor away from a stimulus. Example: The leaves of a "touch-me-not" plant (Mimosa pudica) bend and droop when touched.
(b) Hormones secreted by plants:
• Auxin: They are produced at the shoot tip and help in the growth of the stem.
• Gibberellin: Helps in the vegetative growth of the plant.
• Cytokinin: Promotes cell division.
• Abscisic acid: Inhibits growth and causes the wilting of leaves.
• Ethylene: Helps in the ripening of fruit.
In simple words: (a) Plants move in different ways: toward light (phototropism), toward gravity (geotropism), toward chemicals (chemotropism), by touch (thigmotropism), or just by reacting without direction (nastic movement). (b) Plant hormones like auxin help stems grow, gibberellin helps general growth, cytokinin promotes cell division, abscisic acid stops growth and makes leaves wilt, and ethylene helps fruit ripen.

Exam Tip: For plant movements, ensure you can name each type, define it, and provide a clear example. For plant hormones, know at least three hormones and one specific function for each.

 

Question 5. Name any 5 hormones secreted by human beings with its glands and functions.
Answer: Here are five hormones secreted by human beings, along with their glands and functions:
(i) Growth hormone: Secreted by the pituitary gland. Function: It encourages the growth of long bones and muscles. Too much secretion leads to gigantism, while not enough causes dwarfism.
(ii) Thyroxin: Secreted by the thyroid gland. Function: It controls the metabolism of carbohydrates, proteins, and fats, speeds up energy production, and boosts glucose absorption.
(iii) Insulin: Secreted by the pancreas. Function: It controls the rate at which glucose is oxidized. If insulin is absent, blood glucose levels will continue to rise.
(iv) Adrenaline: Secreted by the adrenal gland. Function: It is released during stress and emotional disturbance. Excitement stimulates adrenaline secretion, which increases heart rate, blood pressure, and breathing rate. It is known as the emergency hormone or fight or flight hormone.
(v) Testosterone: Secreted by the testis. Function: It aids in the development of male secondary sexual characteristics, such as moustache and beard growth.
In simple words: Our bodies make many hormones. Growth hormone from the pituitary helps us grow. Thyroxin from the thyroid manages our energy and food use. Insulin from the pancreas keeps blood sugar balanced. Adrenaline from the adrenal glands prepares us for stress. Testosterone from the testes helps male development.

Exam Tip: Select five distinct hormones from different glands. Clearly state the gland, hormone, and its main function. For growth hormone and insulin, also mention the effects of under- or over-secretion.

 

Question 6. What is meant by reflex-action? With the help of a labelled diagram trace the sequence of events which occur when we touch a hot object.
Answer: Reflex action happens when a receptor is stimulated, sending a signal to the central nervous system, where the brain coordinates the response. However, for very quick responses, the message might go through the spinal cord without brain involvement. This is a reflex action. Reflex actions are fast and happen without the brain's involvement, so no conscious thought occurs. For example, you would quickly pull your hand away from a hot flame without thinking about it.
Refer to a well-labeled diagram of a reflex arc in your textbook. Key parts to label and the sequence of events include:
• Receptors (Heat/Pain Receptors in skin): These detect the hot object.
• Sensory neuron: Carries the signal from the receptor to the spinal cord.
• Relay neuron: In the spinal cord, it passes the signal from the sensory neuron to the motor neuron.
• Motor neuron: Carries the signal from the spinal cord to the effector.
• Effector (Muscle in arm): The muscle contracts, causing the hand to withdraw.
• Spinal cord (CNS): Processes the reflex.
• Message to brain: A message is eventually sent to the brain, but the reflex occurs before conscious perception.
In simple words: A reflex action is a super-fast body reaction that doesn't need your brain to think first, like pulling your hand off a hot stove. The signal goes from your skin to your spinal cord and then straight to your muscles to move.

Exam Tip: Clearly define reflex action and then systematically trace the path of the nerve impulse through the reflex arc, naming each component and its role. Use the hot object example for clarity.

Questions On Higher Order Thinking Skills (Hots)

 

Question 1. Give the names of hormones responsible for the physical changes in a boy and girl.
Answer: For physical changes in a boy, the hormone responsible is Testosterone. For physical changes in a girl, the hormone responsible is Oestrogen.
In simple words: Testosterone causes physical changes in boys, while oestrogen causes physical changes in girls.

Exam Tip: Directly state the hormone and the gender for which it is responsible, ensuring correct spelling.

 

Question 2. Name the element of halogen family required for the proper functioning of thyroid gland.
Answer: The element from the halogen family required for the proper functioning of the thyroid gland is Iodine.
In simple words: The thyroid gland needs iodine to work correctly.

Exam Tip: Recall the specific mineral essential for thyroid health; it's a common knowledge fact.

 

Question 3. A doctor advised a patient to take less sugar in her diet. Which disease is she suffering from?
Answer: The patient is suffering from Diabetes, which is caused by a deficiency of insulin.
In simple words: If a doctor tells you to eat less sugar, you likely have diabetes because your body isn't making enough insulin.

Exam Tip: Link dietary advice about sugar directly to diabetes and its hormonal cause (insulin deficiency).

 

Question 4. Name the stress and fear hormone.
Answer: The stress and fear hormone is Adrenaline.
In simple words: Adrenaline is the hormone that makes you feel stress and fear.

Exam Tip: Identify adrenaline as the key hormone involved in the "fight or flight" response.

 

Question 5. Name the receptors of light, sound, smell and taste.
Answer: The receptors are:
• Light: Photoreceptors (e.g., in eyes)
• Sound: Phonoreceptors (e.g., in ear)
• Smell: Olfactory receptors (e.g., in nose)
• Taste: Gustatory receptors (e.g., in tongue)
In simple words: Our eyes have photoreceptors for light, ears have phonoreceptors for sound, noses have olfactory receptors for smell, and tongues have gustatory receptors for taste.

Exam Tip: Memorize the specific names of sensory receptors and their corresponding stimuli and sense organs.

 

Question 6. A patient is not able to balance his body and cannot walk properly by keeping the balance and cannot coordinate it. Name the part of brain which is affected.
Answer: The part of the brain affected is the Hindbrain, specifically the cerebellum, which helps with balance and coordination.
In simple words: If someone can't balance or walk straight, it means the hindbrain, especially the cerebellum, is not working correctly.

Exam Tip: Connect symptoms like loss of balance and coordination directly to the function of the hindbrain (cerebellum).

 

Question 7. Name the hormone that controls the rate of respiration, also name the part of brain responsible for controlling respiration.
Answer: The hormone that controls the rate of respiration is Adrenaline. The part of the brain responsible for controlling respiration is the Pons.
In simple words: Adrenaline is the hormone that changes how fast you breathe, and the pons in your brain controls breathing.

Exam Tip: Distinguish between hormonal and nervous control; adrenaline affects respiration rate, while the pons regulates the respiratory rhythm.

 

Question 8. Doctor advised a patient to take iodised salt. Explain why?
Answer: Iodine present in iodized salt helps the thyroid gland secrete thyroxine, which manages the metabolism of carbohydrates, fats, and proteins. Therefore, the doctor advised iodized salt to prevent iodine deficiency, which can cause thyroid problems.
In simple words: Iodized salt has iodine, which helps your thyroid gland make a hormone called thyroxine. This hormone controls how your body uses food for energy. So, taking iodized salt helps keep your thyroid healthy.

Exam Tip: Explain the direct link between iodine, thyroxine production, metabolism, and the prevention of thyroid disorders like goitre.

 

Question 9. What are the limitations of electrical impulse?
Answer: The limitations of electrical impulses are:
• It reaches only to target organs that have nerve connections.
• It cannot recreate the signal again once it has passed.
In simple words: Electrical signals only work where there are nerves, and they can't send the same message over and over immediately after it's sent.

Exam Tip: Remember that electrical impulses are fast but localized and transient, unlike hormonal signals which are slower but widespread and longer-lasting.

 

Question 10. If there is no neuron in an organ, how will the message reach in other way?
Answer: If there are no neurons or nerves in an organ, messages can still be sent by hormones. The endocrine system uses hormones, which travel through the bloodstream, to reach target organs and coordinate functions in areas not directly innervated by nerves.
In simple words: If an organ doesn't have nerves, hormones can carry messages to it through the blood, allowing the body to still control it.

Exam Tip: Highlight the complementary nature of the nervous and endocrine systems, especially how hormones provide control where neural connections are absent.