CBSE 10th Science: Chapter 6 – Control and Coordination

Control and coordination are essential biological processes that help organisms respond to changes in their environment. In the CBSE Class 10 Science curriculum, the chapter on “Control and Coordination” covers how these processes occur in both plants and animals. This detailed article will explore the key concepts, mechanisms, and importance of control and coordination in living organisms.

Introduction to Control and Coordination

Control and coordination are fundamental to the survival of organisms. These processes ensure that an organism can perceive changes in its internal and external environment and respond appropriately. In animals, this involves the nervous system and the endocrine system, while in plants, it involves hormonal control and responses to stimuli.

Nervous System in Animals

Structure and Function

The nervous system in animals is a complex network of neurons that transmit signals between different parts of the body. It consists of two main parts:

1. Central Nervous System (CNS): Comprises the brain and spinal cord. The CNS processes information and controls most functions of the body and mind.
2. Peripheral Nervous System (PNS): Consists of nerves and ganglia outside the CNS. It connects the CNS to limbs and organs.

Neurons are the functional units of the nervous system. A neuron consists of a cell body, dendrites, and an axon. The dendrites receive signals, the cell body processes them, and the axon transmits the signals to other neurons or muscles.

Reflex Action

Reflex action is an involuntary and nearly instantaneous movement in response to a stimulus. It is a protective mechanism that allows the body to respond quickly to harmful stimuli without conscious thought. The pathway followed by the nerve impulses in a reflex action is called a reflex arc. It typically involves:

1. Receptor: Senses the stimulus.
2. Sensory Neuron: Transmits the signal to the spinal cord.
3. Interneuron: Processes the signal within the spinal cord.
4. Motor Neuron: Sends the response signal to the effector.
5. Effector: Performs the response action.

Human Brain

The human brain is the control center of the nervous system. It is divided into three main parts:

1. Forebrain: Includes the cerebrum, thalamus, and hypothalamus. The cerebrum controls voluntary actions, sensory perception, and higher-order functions like reasoning and memory. The thalamus relays sensory information, and the hypothalamus regulates bodily functions like temperature and hunger.
2. Midbrain: Acts as a relay station for auditory and visual information.
3. Hindbrain: Includes the cerebellum, pons, and medulla oblongata. The cerebellum coordinates muscle movements and maintains posture, the pons relays information between the cerebrum and the cerebellum, and the medulla oblongata controls involuntary functions like heartbeat and breathing.

Coordination in Plants

Unlike animals, plants do not have a nervous system. Instead, they rely on hormones and responses to stimuli for control and coordination.

Plant Hormones

Plant hormones, also known as phytohormones, are chemicals that regulate plant growth and development. The main plant hormones are:

1. Auxins: Promote cell elongation, root formation, and growth.
2. Gibberellins: Stimulate stem elongation, seed germination, and flowering.
3. Cytokinins: Promote cell division and growth of lateral buds.
4. Ethylene: Regulates fruit ripening and leaf abscission.
5. Abscisic Acid: Inhibits growth and promotes seed dormancy.

Tropic Movements

Tropic movements are directional responses to external stimuli. The main types of tropic movements in plants are:

1. Phototropism: Growth in response to light. Shoots usually exhibit positive phototropism (towards light), while roots show negative phototropism (away from light).
2. Geotropism: Growth in response to gravity. Roots exhibit positive geotropism (towards gravity), and shoots show negative geotropism (away from gravity).
3. Hydrotropism: Growth in response to water. Roots often exhibit positive hydrotropism (towards water).
4. Thigmotropism: Growth in response to touch. Climbing plants exhibit positive thigmotropism as they wrap around objects for support.

Endocrine System in Animals

The endocrine system in animals consists of glands that secrete hormones directly into the bloodstream. These hormones regulate various bodily functions and help maintain homeostasis.

Hormones and Their Functions

1. Pituitary Gland: Often called the “master gland,” it controls other endocrine glands and regulates growth, metabolism, and reproductive functions.
2. Thyroid Gland: Produces thyroxine, which regulates metabolism.
3. Adrenal Glands: Produce adrenaline and cortisol, which help the body respond to stress.
4. Pancreas: Produces insulin and glucagon, which regulate blood sugar levels.
5. Ovaries: Produce estrogen and progesterone, which regulate female reproductive functions.
6. Testes: Produce testosterone, which regulates male reproductive functions.

Coordination between Nervous and Endocrine Systems

The nervous and endocrine systems work together to maintain homeostasis and respond to changes in the environment. The hypothalamus in the brain plays a crucial role in this coordination. It receives information from the nervous system and triggers the release of hormones from the pituitary gland, which in turn regulates other endocrine glands.

Importance of Control and Coordination

Control and coordination are vital for the survival and proper functioning of organisms. They allow organisms to:

1. Respond to Stimuli: React appropriately to changes in their environment, ensuring survival.
2. Maintain Homeostasis: Keep internal conditions stable despite external fluctuations.
3. Perform Complex Functions: Carry out complex processes like movement, growth, and reproduction efficiently.

Conclusion

Control and coordination are essential processes in both animals and plants. The nervous system and endocrine system in animals, along with hormones and tropic movements in plants, ensure that organisms can respond to their environment and maintain homeostasis. Understanding these processes is crucial for comprehending how living organisms function and interact with their surroundings. This knowledge forms a fundamental part of the CBSE Class 10 Science curriculum, providing students with insights into the intricate mechanisms that sustain life.

Questions and Answers

1. What is the main function of the nervous system in animals?
   • The main function of the nervous system is to control and coordinate the activities of the body by transmitting signals between different parts of the body.
2. What are the two main parts of the nervous system?
   • The two main parts are the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
3. What is a neuron?
   • A neuron is a specialized cell that transmits nerve impulses. It consists of a cell body, dendrites, and an axon.
4. Define reflex action.
   • Reflex action is an involuntary and nearly instantaneous movement in response to a stimulus, mediated by the spinal cord.
5. What is a reflex arc?
   • A reflex arc is the neural pathway that controls a reflex action. It typically involves a receptor, sensory neuron, interneuron, motor neuron, and an effector.
6. Name the three main parts of the human brain.
   • The three main parts are the forebrain, midbrain, and hindbrain.
7. What is the role of the cerebrum?
   • The cerebrum controls voluntary actions, sensory perception, and higher-order functions like reasoning, memory, and intelligence.
8. What are plant hormones?
   • Plant hormones, or phytohormones, are chemicals that regulate various functions such as growth, development, and responses to stimuli.
9. Name two plant hormones and their functions.
   • Auxins: Promote cell elongation and root formation.
   • Gibberellins: Stimulate stem elongation, seed germination, and flowering.
10. What is phototropism?
    • Phototropism is the growth of a plant in response to light. Shoots usually exhibit positive phototropism (towards light), while roots exhibit negative phototropism (away from light).
11. Explain geotropism.
    • Geotropism is the growth of a plant in response to gravity. Roots exhibit positive geotropism (towards gravity), and shoots exhibit negative geotropism (away from gravity).
12. What is the endocrine system?
    • The endocrine system is a collection of glands that produce hormones, which are secreted directly into the bloodstream to regulate various bodily functions.
13. Name the hormone produced by the thyroid gland and its function.
    • The thyroid gland produces thyroxine, which regulates metabolism.
14. What is the role of insulin?
    • Insulin, produced by the pancreas, regulates blood sugar levels by facilitating the uptake of glucose into cells.
15. How do the nervous and endocrine systems work together?
    • The nervous and endocrine systems work together to maintain homeostasis. The hypothalamus receives information from the nervous system and triggers the release of hormones from the pituitary gland, which regulates other endocrine glands.
16. What is the role of the adrenal glands?
    • The adrenal glands produce hormones such as adrenaline and cortisol, which help the body respond to stress.
17. What is thigmotropism?
    • Thigmotropism is the growth of a plant in response to touch, often seen in climbing plants that wrap around objects for support.
18. What is a synapse?
    • A synapse is the junction between two neurons where nerve impulses are transmitted from one neuron to another.
19. What hormone is produced by the pituitary gland and what is its function?
    • The pituitary gland produces several hormones, including growth hormone, which regulates growth and development, and antidiuretic hormone (ADH), which regulates water balance in the body.
20. Describe the role of the hypothalamus in the endocrine system.
    • The hypothalamus controls the pituitary gland and thus regulates many body functions. It plays a crucial role in maintaining homeostasis by linking the nervous and endocrine systems.

These questions and answers cover key concepts from the chapter on “Control and Coordination” and should help reinforce understanding of the topic.