CBSE Class 10 Science (2026–27)
Chapter 6: Control and Coordination
20 Important Questions and Answers
Q1. What is the importance of control and coordination in living organisms?
Answer:
Control and coordination help living organisms perform various life processes in an organized manner. Different organs and organ systems work together to maintain proper functioning of the body. Control enables an organism to respond to internal and external stimuli, while coordination ensures that all body parts work harmoniously. In humans, the nervous system and endocrine system carry out these functions. For example, when we touch a hot object, the nervous system quickly sends signals to withdraw the hand. Similarly, hormones regulate growth, metabolism, and reproduction. Thus, control and coordination are essential for survival, adaptation, and maintaining balance within the body.
Q2. Explain the structure and function of a neuron.
Answer:
A neuron is the structural and functional unit of the nervous system. It consists of three main parts: dendrites, cell body (cyton), and axon. Dendrites receive nerve impulses from receptors or other neurons and carry them toward the cell body. The cell body contains the nucleus and controls cellular activities. The axon is a long extension that transmits impulses away from the cell body to muscles, glands, or other neurons. Neurons communicate through electrical and chemical signals. They play a vital role in transmitting information throughout the body, enabling responses to stimuli and coordination of various activities.
Q3. Differentiate between receptors and effectors.
Answer:
Receptors and effectors are important components involved in responding to stimuli. Receptors are specialized cells or sense organs that detect changes in the environment. Examples include eyes for light, ears for sound, and skin for touch. They receive stimuli and convert them into nerve impulses that are sent to the brain or spinal cord. Effectors, on the other hand, are muscles or glands that carry out the response instructed by the nervous system. For example, muscles contract to move the hand away from a hot object. Thus, receptors detect stimuli, while effectors perform the necessary actions in response.
Q4. What is a reflex action? Give an example.
Answer:
A reflex action is a quick, automatic, and involuntary response to a stimulus without conscious thinking. It helps protect the body from harm and occurs through a reflex arc. In a reflex action, receptors detect the stimulus and send signals to the spinal cord, which immediately sends instructions to effectors. The brain is informed later. A common example is withdrawing the hand after touching a hot object. This rapid response prevents injury. Reflex actions are essential because they provide immediate protection and help the body react quickly to potentially dangerous situations.
Q5. What is a reflex arc? Describe its components.
Answer:
A reflex arc is the pathway followed by nerve impulses during a reflex action. It consists of five main components: receptor, sensory neuron, relay neuron, motor neuron, and effector. The receptor detects a stimulus and generates an impulse. The sensory neuron carries the impulse to the spinal cord, where a relay neuron processes the information. The relay neuron then passes the signal to a motor neuron. Finally, the motor neuron carries the impulse to the effector, such as a muscle or gland, which produces the response. This pathway enables rapid and automatic reactions without involving conscious thought.
Q6. Explain the role of the brain in control and coordination.
Answer:
The brain is the main coordinating center of the nervous system. It receives information from various sense organs, processes it, and sends instructions to different parts of the body. The forebrain controls thinking, memory, intelligence, and voluntary actions. The midbrain coordinates visual and auditory reflexes. The hindbrain controls balance, posture, breathing, heartbeat, and involuntary activities. The brain helps the body respond appropriately to changes in the environment and maintains coordination among different organs. It acts as the command center, ensuring smooth functioning of all body systems and enabling intelligent responses.
Q7. Describe the functions of the cerebrum and cerebellum.
Answer:
The cerebrum and cerebellum are important parts of the brain with different functions. The cerebrum is the largest part of the forebrain and controls voluntary actions, intelligence, memory, learning, reasoning, and emotions. It interprets sensory information and helps in decision-making. The cerebellum is located in the hindbrain and is responsible for maintaining balance, posture, and coordination of muscular movements. It ensures that body movements are smooth and precise. For example, activities such as walking, cycling, and writing require the coordination provided by the cerebellum. Together, these structures help regulate body functions effectively.
Q8. What are hormones? Why are they called chemical messengers?
Answer:
Hormones are chemical substances produced by endocrine glands and released directly into the bloodstream. They travel to specific target organs where they regulate various body functions such as growth, metabolism, reproduction, and development. Hormones are called chemical messengers because they carry messages from one part of the body to another. Unlike nerve impulses, which act quickly, hormones produce slower but longer-lasting effects. For example, growth hormone regulates body growth, while insulin controls blood sugar levels. Hormones help maintain coordination among different organs and ensure proper functioning of the body.
Q9. Explain the functions of the pituitary gland.
Answer:
The pituitary gland is known as the “master gland” because it controls the activities of many other endocrine glands. It is located at the base of the brain and secretes several hormones. Growth hormone regulates the growth of bones and muscles. Other hormones stimulate glands such as the thyroid, adrenal glands, and reproductive organs. The pituitary gland also controls water balance and reproductive functions. By regulating the secretion of hormones from other glands, it plays a crucial role in maintaining overall coordination within the body. Proper functioning of the pituitary gland is essential for normal growth and development.
Q10. What is the role of insulin in the human body?
Answer:
Insulin is a hormone produced by the pancreas. Its main function is to regulate the level of glucose in the blood. After digestion, glucose enters the bloodstream and provides energy to cells. Insulin helps cells absorb glucose from the blood and use or store it for future energy needs. If insufficient insulin is produced, blood sugar levels rise, leading to diabetes. Proper insulin secretion is necessary for maintaining normal blood glucose levels and ensuring efficient energy utilization. Therefore, insulin plays a vital role in metabolism and maintaining the body’s internal balance.
Q11. Differentiate between nervous control and hormonal control.
Answer:
Nervous control and hormonal control are two systems of coordination in the body. Nervous control involves nerve impulses transmitted through neurons. It is fast, specific, and produces immediate responses. Hormonal control involves hormones carried by the bloodstream. It is slower but produces long-lasting effects. Nervous control acts on muscles and glands, while hormonal control affects target organs throughout the body. For example, withdrawing a hand from a hot object is controlled by nerves, whereas growth and development are regulated by hormones. Both systems work together to maintain coordination and proper functioning of the body.
Q12. What are endocrine glands? Give examples.
Answer:
Endocrine glands are ductless glands that secrete hormones directly into the bloodstream. These hormones travel to target organs and regulate various body functions. Unlike exocrine glands, endocrine glands do not have ducts. Major endocrine glands include the pituitary gland, thyroid gland, pancreas, adrenal glands, and reproductive glands. Each gland produces specific hormones that control processes such as growth, metabolism, stress response, and reproduction. For example, the thyroid gland secretes thyroxine, which regulates metabolism, while the pancreas produces insulin to control blood sugar levels. Endocrine glands are essential for maintaining coordination and homeostasis in the body.
Q13. What is phototropism? Explain with an example.
Answer:
Phototropism is the directional growth movement of a plant in response to light. The shoot of a plant usually bends toward the light source and shows positive phototropism. This occurs because the plant hormone auxin accumulates on the shaded side of the stem, causing cells there to elongate more than those on the illuminated side. As a result, the stem bends toward the light. This adaptation helps plants receive maximum sunlight for photosynthesis. For example, a potted plant kept near a window often bends toward the incoming sunlight, demonstrating positive phototropism.
Q14. Explain geotropism in plants.
Answer:
Geotropism, also known as gravitropism, is the growth movement of a plant in response to gravity. Roots show positive geotropism because they grow downward toward the gravitational force. Shoots show negative geotropism because they grow upward, away from gravity. This growth response helps plants establish proper orientation. Roots grow into the soil to absorb water and minerals, while shoots grow upward to receive sunlight for photosynthesis. Plant hormones such as auxins help regulate this response. Geotropism is an important adaptation that enables plants to survive and grow efficiently in their environment.
Q15. What is the role of auxin in plants?
Answer:
Auxin is a plant hormone that plays a major role in growth and development. It promotes cell elongation, especially in stems and shoots. Auxin helps regulate phototropism and geotropism by controlling differential growth on different sides of the plant. It also stimulates root formation and supports fruit development. In shoots, auxin accumulates on the shaded side, causing cells to elongate and the shoot to bend toward light. This hormone is essential for proper plant growth, coordination, and adaptation to environmental conditions. Thus, auxin is one of the most important growth-regulating hormones in plants.
Q16. Explain hydrotropism with an example.
Answer:
Hydrotropism is the directional growth movement of a plant part in response to water. Roots usually show positive hydrotropism because they grow toward areas with higher moisture content. This adaptation helps plants obtain sufficient water for survival and growth. The growth response occurs due to the action of plant hormones that regulate cell elongation. For example, if water is available only on one side of the soil, plant roots bend and grow toward that side. Hydrotropism is important because it ensures efficient water absorption and helps plants survive during conditions of limited water availability.
Q17. What are plant hormones? Name any four.
Answer:
Plant hormones are chemical substances produced in small quantities that regulate growth, development, and responses to environmental stimuli. They coordinate various physiological processes in plants. Four important plant hormones are auxins, gibberellins, cytokinins, and abscisic acid (ABA). Auxins promote cell elongation and growth, gibberellins stimulate stem elongation and seed germination, cytokinins promote cell division, and ABA inhibits growth and induces dormancy. These hormones work together to regulate plant activities such as flowering, fruit development, seed germination, and responses to environmental changes. Thus, plant hormones play a vital role in plant coordination.
Q18. What is the function of the thyroid gland?
Answer:
The thyroid gland is located in the neck and secretes the hormone thyroxine. Thyroxine regulates the body’s metabolism by controlling the rate at which food is converted into energy. It also influences growth, development, and maintenance of body temperature. The production of thyroxine requires iodine, which is obtained through diet. Deficiency of iodine may lead to enlargement of the thyroid gland, causing goitre. Proper functioning of the thyroid gland is essential for maintaining energy balance and normal body activities. Thus, the thyroid gland plays a key role in regulating metabolic processes.
Q19. Why is iodine important for the human body?
Answer:
Iodine is an essential mineral required for the production of thyroxine hormone by the thyroid gland. Thyroxine regulates metabolism, growth, and development in the body. If the diet lacks sufficient iodine, the thyroid gland enlarges in an attempt to produce enough hormone, resulting in a condition called goitre. Iodine deficiency can also affect physical and mental development, especially in children. To prevent such disorders, iodized salt is commonly used. Adequate intake of iodine ensures proper thyroid function and helps maintain normal growth, energy production, and overall health.
Q20. How do plants coordinate their activities without a nervous system?
Answer:
Plants do not possess a nervous system, yet they coordinate their activities through chemical substances called plant hormones. These hormones regulate growth, development, and responses to environmental stimuli such as light, gravity, water, and touch. Hormones like auxins, gibberellins, cytokinins, and abscisic acid control different physiological processes. Plants respond through movements called tropisms, which occur due to differential growth in plant tissues. For example, shoots bend toward light due to phototropism. Thus, plant hormones act as coordinating agents, enabling plants to adapt and respond effectively to their surroundings despite lacking nerves and muscles.