Chapter 6 - Control and Coordination Class 10 Notes (Science)
Chapter 6 Control and Coordination Class 10 Notes (Science)
Updated Solution 2024-2025 Updated Solution 2024-2025
NCERT Solutions for Science, Chapter 6 Control and Coordination Class 10 Notes, Question/Answers, Activity & Projects
Chapter 6 Control and Coordination Class 10 Notes (Science)
Activity 6.1
- Put some sugar in your mouth. How does it taste?
Ans: The sugar tastes sweet, as it stimulates the taste buds on the tongue that are responsible for detecting sweetness.
- Block your nose by pressing it between your thumb and index finger. Now eat sugar again. Is there any difference in its taste?
Ans: Yes, there is a noticeable difference. Blocking the nose reduces the ability to taste sweetness fully, as the sense of smell plays a crucial role in detecting flavors. The taste becomes less intense and is more limited to the basic sweetness, with less complexity in flavor.
- While eating lunch, block your nose in the same way and notice if you can fully appreciate the taste of the food you are eating.
Ans: Blocking the nose while eating lunch diminishes the ability to fully appreciate the taste of the food. Smell contributes significantly to the flavor profile of food, and without it, the experience feels much less flavorful and often flat. You may still perceive basic tastes like salty, sweet, sour, or bitter, but the overall taste is less rich and more one-dimensional.
Questions
Q 1. What is the difference between a reflex action and walking?
Ans 1: The main difference between a reflex action and walking lies in their nature, control, and complexity:
1. Reflex Action:
- Definition: A reflex action is an automatic, involuntary response to a stimulus that does not require conscious thought. It is a simple, quick reaction that typically involves only a few neurons in the spinal cord or brainstem.
- Control: Reflex actions are controlled by the spinal cord and do not involve the brain (though they can be processed in the brain after the action occurs).
- Example: A knee-jerk reaction when a doctor taps your knee with a hammer.
- Complexity: Reflex actions are generally simple and immediate, requiring little coordination or conscious thought.
2. Walking:
- Definition: Walking is a voluntary, complex, and coordinated action involving the movement of limbs and the entire body. It requires conscious thought and is controlled by higher centers in the brain, such as the motor cortex.
- Control: Walking involves the brain and spinal cord working together to control muscle movements. The brain sends signals to the muscles, and sensory feedback from the muscles helps adjust the movement.
- Example: The deliberate act of walking from one place to another.
- Complexity: Walking is a complex action that involves multiple muscles, joints, and sensory feedback, requiring conscious coordination and planning.
In summary, reflex actions are involuntary and simpler, while walking is a voluntary and more complex activity requiring coordination from the brain and body.
Q 2. What happens at the synapse between two neurons?
Ans 2: At the synapse between two neurons, a message is passed from one neuron to the next. The neuron sending the message releases chemicals called neurotransmitters into a small gap called the synaptic cleft. These neurotransmitters travel across the gap and bind to receptors on the receiving neuron. When this happens, it triggers a response in the receiving neuron, either continuing the message or stopping it. This process allows communication between neurons, helping to send signals throughout the brain and body.
Q 3. Which part of the brain maintains posture and equilibrium of the body?
Ans 3: The part of the brain that helps maintain posture and balance is called the cerebellum. It’s located at the back of the brain and plays a key role in coordinating movements, ensuring that we can stand, walk, and move without losing our balance.
Q 4. How do we detect the smell of an agarbatti (incense stick)?
Ans 4: To detect the smell of an agarbatti (incense stick), we rely on our sense of smell. When an agarbatti is lit, it releases tiny particles called scent molecules into the air. These molecules travel through the air and enter our nose when we breathe in. Inside the nose, special cells called olfactory receptors detect these molecules. Once detected, the brain processes the information and helps us recognize the specific scent, like sandalwood or jasmine. So, the smell of an agarbatti is detected when these scent molecules reach our nose and are processed by our brain.
Q 5. What is the role of the brain in reflex action?
Ans 5: The brain plays a limited role in reflex actions. Reflex actions are quick, automatic responses to stimuli that usually don’t involve the brain directly. Instead, they are controlled by the spinal cord. For example, if you touch something hot, your body quickly pulls away without waiting for the brain to process the pain. However, the brain is informed about the action afterward, so you become aware of it. In summary, the brain is not involved in the quick reflex itself, but it helps you understand the situation once it happens.
Activity 6.2
- Fill a conical flask 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 light coming from a window (Fig. 6.5).
- After two or three days, you will notice that the shoots bend towards light and roots away from light.
- 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.
- Have the old parts of the shoot and root changed direction?
- Are there differences in the direction of the new growth?
- What can we conclude from this activity?
Ans: activity 6.2
Q 1. Have the old parts of the shoot and root changed direction?
Ans 1: Yes, the old parts of the shoot and root will change direction. The shoots, which were initially bending towards the light, will now bend away from the light, and the roots, which were initially bending away from the light, will now bend towards it.
Q 2. Are there differences in the direction of the new growth?
Ans 2: Yes, the new growth will show different behavior. The new part of the shoot will continue to grow towards the light (phototropism), while the new root growth will move away from the light (gravitropism).
Q 3. What can we conclude from this activity?
Ans 3: We can conclude that light influences the direction of plant growth. This is called phototropism for the shoots, where the plant grows towards the light, and gravitropism for the roots, where they grow away from the light. The change in direction when the flask is rotated demonstrates the plant’s ability to respond to its environment and adjust its growth accordingly.
Questions
Q 1. What are plant hormones?
Ans 1: Plant hormones are natural chemicals that help control and regulate various growth and development processes in plants. They act like messengers, guiding how plants grow, respond to light, water, and stress, and how they reproduce. Some common plant hormones include auxins, gibberellins, cytokinin’s, ethylene, and abscisic acid. Each hormone has a specific role, like promoting root growth, helping flowers bloom, or signaling when to shed leaves.
Q 2. How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?
Ans 2: The movement of leaves in a sensitive plant (Mimosa pudica) is a rapid response to touch or other stimuli. When the leaves are touched, they fold or droop as a defense mechanism. This movement is called nastic movement and is triggered by changes in water pressure within the plant cells.
In contrast, the movement of a shoot towards light, known as phototropism, is a slower, directional growth response. The shoot grows towards light because cells on the darker side of the shoot elongate, helping the plant to maximize its exposure to light for photosynthesis.
So, while the sensitive plant’s leaves move quickly in reaction to touch, the shoot moves gradually toward light in a controlled growth process.
Q 3. Give an example of a plant hormone that promotes growth.
Ans 3: An example of a plant hormone that promotes growth is auxin. Auxins help plants grow taller by encouraging the cells to elongate. They are mainly found in the tips of roots and shoots and play a key role in processes like stem elongation, root development, and fruit growth.
Q 4. How do auxins promote the growth of a tendril around a support?
Ans 4: Auxins promote the growth of a tendril around a support by causing cells on one side of the tendril to grow faster than those on the other side. This uneven growth makes the tendril bend toward the support, allowing it to wrap around it. The tendril continuously adjusts its growth as it touches different surfaces, helping the plant to climb and secure itself.
Q 5. Design an experiment to demonstrate hydrotropism.
Ans 5: Experiment to Demonstrate Hydrotropism:
Objective: To observe how plant roots grow towards water (hydrotropism).
Materials Needed:
- A potted plant or seedlings
- A transparent container or box
- Filter paper or moist cotton
- Water
- A ruler
Procedure:
- Place the plant in a transparent container.
- Arrange filter paper or moist cotton on one side of the container, and leave the other side dry.
- Add water only to the side with the filter paper or cotton.
- Cover the container to prevent evaporation and place it in a well-lit area.
- Observe the plant’s root growth over several days.
Expected Result: The roots will grow towards the side with water, showing hydrotropism, which is the plant’s response to water by directing root growth toward moisture.
Conclusion: This experiment demonstrates that plant roots are sensitive to water and grow towards it for better access to moisture.
Fig 7.2 Experiment showing hydrotropism of roots
Activity 6.3
- Look at Fig. 6.7.
- Identify the endocrine glands mentioned in the figure.
- Some of these glands have been listed in Table 6.1 and discussed in the text. Consult books in the library and discuss with your teachers to find out about other glands.
Ans: Activity 6.3
Q 1. Look at Fig. 6.7. Identify the endocrine glands mentioned in the figure.
Ans 1: Figure 6.7 Endocrine glands in human beings (a) male, (b) female
Common glands typically illustrated in such figures include:
- Pituitary gland
- Hypothalamus
- Thyroid gland
- Parathyroid glands
- Adrenal glands
- Pancreas (endocrine portion)
- Gonads (testes in males and ovaries in females)
Q 2. Some of these glands have been listed in Table 6.1 and discussed in the text. Consult books in the library and discuss with your teachers to find out about other glands
Ans 2: The other glands not listed in Table 6.1, here is an expanded overview of additional endocrine glands and their functions:
- Pineal Gland
- Location: Brain, between the two hemispheres, in a groove where the two halves of the thalamus join.
- Hormone: Melatonin
- Function: Regulates sleep-wake cycles and biological rhythms.
- Parathyroid Glands
- Location: Behind the thyroid gland in the neck.
- Hormone: Parathyroid Hormone (PTH)
- Function: Regulates calcium and phosphate levels in the blood, essential for bone health.
- Thymus Gland
- Location: Upper chest, behind the sternum.
- Hormone: Thymosin’s
- Function: Promotes development and differentiation of T-lymphocytes, critical for the immune system.
- Pancreas (Islets of Langerhans)
- Location: Abdomen, behind the stomach.
- Hormones: Insulin and Glucagon
- Function:
- Insulin: Lowers blood glucose levels.
- Glucagon: Raises blood glucose levels.
- Hypothalamus
- Location: Base of the brain, above the pituitary gland.
- Hormones: Releasing and Inhibiting Hormones
- Function: Regulates the pituitary gland and maintains homeostasis by controlling hunger, thirst, temperature, and circadian rhythms.
- Placenta (Temporary in Pregnancy)
- Location: In the uterus during pregnancy.
- Hormones: Human Chorionic Gonadotropin (hCG), Progesterone, Estrogen
- Function: Supports pregnancy by maintaining the uterine lining and regulating fetal development.
Research Suggestions
You can consult NCERT Biology textbooks, Human Anatomy and Physiology books by authors like Guyton and Hall, or reference materials such as “Endocrinology” by Hadley for in-depth knowledge. Discussing with teachers or utilizing online resources like PubMed or Google Scholar will provide further insights.
Chapter 6 – Control and Coordination Class 10 Notes, Question/Answer, Activity & Projects
Updated Solution 2024-2025
Activity 6.4
- Hormones are secreted by endocrine glands and have specific functions. Complete Table 6.1 based on the hormone, the endocrine gland or the functions provided.
Table 6.1: Some important hormones and their functions
S.No. | Hormone | Endocrine Gland | Functions |
1 | Growth hormone | Pituitary gland | Stimulates growth in all organs |
2 | Thyroid gland | Regulates metabolism for body growth | |
3 | Insulin | Regulates blood sugar levels | |
4 | Testosterone | Testes | |
5 | Ovaries | Development of female sex organs and regulates menstrual cycle | |
6 | Adrenaline (Epinephrine) | Adrenal gland | |
7 | Releasing hormones | Stimulates pituitary gland to release hormones |
Ans: Activity 6.4: Here’s the completed table with all missing values filled:
S.No. | Hormone | Endocrine Gland | Functions |
1 | Growth hormone | Pituitary gland | Stimulates growth in all organs |
2 | Thyroxine (T4) | Thyroid gland | Regulates metabolism for body growth |
3 | Insulin | Pancreas | Regulates blood sugar levels |
4 | Testosterone | Testes | Development of male sex organs and secondary traits |
5 | Estrogen | Ovaries | Development of female sex organs and regulates menstrual cycle |
6 | Adrenaline (Epinephrine) | Adrenal gland | Prepares body for stress response (“fight or flight”) |
7 | Releasing hormones | Hypothalamus | Stimulates pituitary gland to release hormones |
Questions
Q 1. How does chemical coordination take place in animals?
Ans 1: Chemical coordination in animals happens through hormones. Hormones are chemical messengers secreted by glands, such as the thyroid, adrenal, and pancreas, directly into the bloodstream. They travel to specific target organs and regulate various functions like growth, metabolism, and reproduction. This process ensures that the body works in a coordinated and balanced way.
Q 2. Why is the use of iodised salt advisable?
Ans 2: The use of iodised salt is recommended because it provides iodine, an essential nutrient for our body. Iodine helps maintain healthy thyroid function, which controls metabolism and growth. A lack of iodine can lead to health problems like goiter (swelling of the neck) and developmental issues in children. Using iodised salt ensures we get enough iodine in our diet to prevent these problems.
Q 3. How does our body respond when adrenaline is secreted into the blood?
Ans 3: When adrenaline is released into the bloodstream, our body prepares for “fight or flight.” This hormone increases heart rate, boosts energy, and sharpens focus. It also dilates airways to help with breathing and redirects blood to muscles, making us stronger and more alert. These changes help us react quickly in stressful or dangerous situations.
Q 4. Why are some patients of diabetes treated by giving injections of insulin?
Ans 4: Some people with diabetes can’t produce enough insulin, a hormone that helps control blood sugar levels. In such cases, insulin injections are given to help regulate blood sugar and prevent complications. The injection helps their body maintain the right amount of insulin, which is needed for proper metabolism and energy use.
Exercise
Q 1. Which of the following is a plant hormone?
(a). Insulin
(b). Thyroxin
(c). Oestrogen
(d). Cytokinin
Ans 1: (d) Cytokinin: Cytokinin’s are plant hormones that promote cell division, growth, and differentiation. They play a key role in the regulation of plant development, including influencing the growth of roots, shoots, and leaves.
Insulin, thyroxin, and Oestrogen are hormones found in animals, not plants.
Q 2. The gap between two neurons is called a:
(a). Dendrite
(b). Synapse
(c). Axon
(d). Impulse
Ans 2: (b) Synapse: The synapse is the gap between two neurons where information is transmitted from one neuron to another.
Q 3. The brain is responsible for:
(a). Thinking
(b). Regulating the heartbeat
(c). Balancing the body
(d). All of the above
Ans 3: (d). All of the above: The brain is responsible for thinking, regulating the heartbeat, and balancing the body, among many other functions.
Q 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?
Ans 4: Receptors in our body are like sensors that detect changes in the environment, both inside and outside our body. They send signals to the brain, helping us respond to things like light, sound, temperature, and pain. For example, skin receptors detect touch or heat, and eyes detect light for vision.
If receptors don’t work properly, problems can arise. For instance, if pain receptors malfunction, a person may not feel injuries, leading to undetected harm. If vision receptors in the eyes are damaged, it can cause blindness or difficulty seeing. Similarly, malfunctioning taste receptors can affect a person’s ability to taste food, making eating less enjoyable or even unsafe.
Q 5. Draw the structure of a neuron and explain its function.
Ans 5: The main functions of neurons are:
- Transmit Electrical Signals: Neurons carry electrical impulses, called action potentials, to transmit information throughout the body.
- Communication Between Brain and Body: Neurons allow the brain to send messages to muscles, organs, and other parts of the body for coordination and response.
- Sensory Processing: Sensory neurons receive stimuli from the environment (e.g., light, sound, touch) and send signals to the brain for interpretation.
- Motor Control: Motor neurons transmit signals from the brain and spinal cord to muscles, enabling movement.
- Cognitive Functions: Neurons in the brain support thinking, memory, learning, and decision-making.
- Synaptic Transmission: Neurons communicate with each other at synapses through the release of neurotransmitters, facilitating signal transmission.
(STRUCTURE OF NUERON)
Q 6. How does phototropism occur in plants?
Ans 6: Phototropism is the way plants grow in response to light. When a plant receives light from one direction, the cells on the darker side grow longer than the ones on the lighter side. This uneven growth causes the plant to bend toward the light. The process is controlled by a hormone called auxin, which helps the plant cells stretch and grow in the right direction, allowing the plant to get more sunlight for photosynthesis.
Q 7. Which signals will get disrupted in case of a spinal cord injury?
Ans 7: In the case of a spinal cord injury, several signals are disrupted:
- Motor Signals: Movement commands from the brain to muscles are interrupted, affecting voluntary muscle control (e.g., walking, arm movement).
- Sensory Signals: Sensory information (pain, temperature, touch) from the body to the brain is blocked, leading to loss of sensation.
- Autonomic Functions: Functions like heart rate, blood pressure, digestion, and bladder control can be affected due to disruption in automatic bodily functions.
- Reflexes: Reflex actions (e.g., pulling away from a hot object) may be diminished or lost below the injury site.
- Communication Between Brain and Body: General communication between the brain and different body parts becomes impaired, causing loss of coordination or control.
These disruptions depend on the location and severity of the spinal cord injury.
Q 8. How does chemical coordination occur in plants?
Ans 8: Chemical coordination in plants happens through plant hormones, also called phytohormones. These hormones are chemicals produced in small amounts that help regulate growth, development, and responses to the environment. They are produced in one part of the plant and travel to other parts to trigger specific changes.
For example, auxins help in cell growth and elongation, especially in roots and shoots. Cytokinin’s promote cell division and help plants grow new tissues. Gibberellins are involved in stem elongation and seed germination. Ethylene regulates fruit ripening, and abscisic acid helps the plant respond to stress, like drought.
These hormones work together to control various processes, ensuring that the plant adapts to its surroundings and grows properly.
Q 9. What is the need for a system of control and coordination in an organism?
Ans 9: A system of control and coordination in an organism is essential because it helps different parts of the body work together smoothly. This system ensures that the body responds correctly to changes in the environment, maintains balance (homeostasis), and carries out necessary functions like moving, breathing, or digesting food. Without control and coordination, the body would not be able to function properly or respond to stimuli, which could lead to serious health issues.
Q 10. How are involuntary actions and reflex actions different from each other?
Ans 10: Involuntary actions and reflex actions are both automatic and happen without conscious thought, but they differ in how they are controlled:
- Involuntary actions are controlled by the brain and occur automatically, like breathing or digestion. These actions happen without us thinking about them but involve complex brain processes.
- Reflex actions are much quicker responses to stimuli, usually controlled by the spinal cord. They don’t involve the brain and happen instantly, like pulling your hand away from something hot.
In short, reflex actions are faster and don’t involve the brain, while involuntary actions are slower and controlled by the brain.
Q 11. Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
Ans 11: Nervous and hormonal mechanisms are both ways animals’ control and coordinate their body functions, but they work differently:
1. Nervous Mechanism:
- Fast: Nerve impulses travel quickly through neurons (nerve cells).
- Short-lived: Effects are immediate but last for a short time.
- Targeted: Acts on specific areas, like muscles or glands.
- Example: Moving your hand away from something hot.
2. Hormonal Mechanism:
- Slower: Hormones travel through the bloodstream to target organs.
- Long-lasting: Effects take longer to start but can last for a long time.
- Wide-reaching: Can affect many parts of the body at once.
- Example: Growth or metabolism regulation through thyroid hormones.
In summary, the nervous system is quick and specific, while the hormonal system is slower but has a more widespread, longer-lasting effect.
Q 12. What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?
Ans 12: Difference between movement in a sensitive plant and in human legs:
- Sensitive Plant (Mimosa pudica):
- Movement is rapid and automatic, responding to touch.
- The leaves fold or droop when touched, as a defense mechanism.
- Movement happens due to changes in turgor pressure within plant cells.
- It’s a nervous reaction, triggered by electrical impulses within the plant.
- Human Legs:
- Movement is voluntary and controlled by the brain.
- Muscles contract and relax in response to signals from the nervous system.
- Movement occurs through muscle action and joint coordination.
- It requires energy from the body (ATP) to function.
In short, plant movement is involuntary and based on turgor pressure, while leg movement is voluntary and powered by muscle contractions.
Chapter 6 – Control and Coordination Class 10 Notes, Question/Answer, Activity & Projects
Updated Solution 2024-2025
This complete solution is prepared as per the latest syllabus of 2024-25. If you have any further queries, feel free to ask! 