Science Class 10 - Control And-Coordination Notes

Control and Coordination

Welcome to the chapter on Control and Coordination for Class 10. In this chapter, you will learn how living organisms control and coordinate their activities. You will understand the role of the nervous system, hormones, and sense organs in animals, and how plants respond to stimuli. By the end of this chapter, you will be able to explain the mechanisms of control and coordination in both plants and animals.

Introduction

All living organisms need to control and coordinate their body functions to survive. Control and coordination help organisms respond to changes in their environment and maintain balance in their bodies.

Control and Coordination in Animals

• Nervous System: The system that helps animals sense changes and respond quickly. It includes the brain, spinal cord, and nerves.
• Reflex Action: A quick, automatic response to a stimulus (e.g., pulling your hand away from something hot).
• Sense Organs: Eyes, ears, nose, tongue, and skin help us sense the world around us.
• Coordination: The working together of different parts of the body, controlled by the nervous system and hormones.

The Human Nervous System

• Brain: The control center of the body. It receives messages from sense organs and sends instructions to muscles and glands.
• Spinal Cord: Connects the brain to the rest of the body and helps in reflex actions.
• Nerves: Carry messages between the brain, spinal cord, and other parts of the body.

Coordination by Hormones

• Endocrine System: Glands that make hormones, which are chemical messengers.
• Hormones: Control growth, development, metabolism, and other functions (e.g., insulin, adrenaline, growth hormone).
• Examples: The pituitary gland is called the "master gland" because it controls other glands. The pancreas makes insulin to control blood sugar.

Control and Coordination in Plants

• Plants do not have a nervous system.
• Movements in Plants: Plants respond to stimuli like light, gravity, touch, and chemicals.
• Tropism: The growth of a plant in response to a stimulus. Types include phototropism (light), geotropism (gravity), and thigmotropism (touch).
• Plant Hormones: Chemicals like auxins, gibberellins, cytokinins, and abscisic acid help control growth and responses.

Practice Questions

1. What is the function of the nervous system in animals?
2. Name two hormones and their functions.
3. What is a reflex action? Give one example.
4. What is phototropism? How does it help plants?
5. How do plants respond to touch?

Challenge Yourself

• Draw and label the human nervous system.
• Observe a plant near a window for a week. What changes do you see?

Did You Know?

• The human brain has about 100 billion nerve cells!
• The "touch-me-not" plant closes its leaves when touched because of rapid movement of water in its cells.

Glossary

• Stimulus: A change in the environment that causes a response.
• Neuron: A nerve cell that carries messages.
• Hormone: A chemical messenger made by glands.
• Tropism: Growth movement of a plant toward or away from a stimulus.

Answers to Practice Questions

1. It helps animals sense changes and respond to them.
2. Insulin (controls blood sugar), adrenaline (prepares body for action).
3. A quick, automatic response to a stimulus. Example: Pulling your hand away from something hot.
4. Phototropism is the growth of a plant toward light. It helps plants get more sunlight for making food.
5. Plants like the "touch-me-not" close their leaves when touched (thigmotropism).

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Understanding control and coordination helps us know how living things survive and respond to their environment!