Chapter 6: Control and Coordination

Q1. What is the difference between a reflex action and thinking?

Solution

Reflex action:
• Involuntary and automatic
• Does not involve the brain
• Very fast response
• Controlled by spinal cord

Thinking:
• Voluntary and conscious
• Involves the cerebral cortex
• Slow process
• Involves memory, analysis, and decision-making

Q2. What are the parts of the brain? What are their functions?

Solution

Parts of the brain:
• Cerebrum: Controls thinking, memory, reasoning, voluntary actions
• Cerebellum: Controls balance, posture, and coordination of movements
• Medulla oblongata: Controls involuntary actions — breathing, heartbeat, blood pressure
• Hypothalamus: Controls hunger, thirst, sleep, body temperature
• Pons: Relays messages between parts of the brain

Q3. What is a neuron? Describe its structure.

Solution

A neuron (nerve cell) is the structural and functional unit of the nervous system.

Structure:
• Cell body: Contains nucleus and cytoplasm
• Dendrites: Short, branched extensions that receive signals
• Axon: Long extension that carries impulses away from cell body
• Myelin sheath: Insulating layer around axon for faster signal transmission
• Synapse: Gap between two neurons where neurotransmitters are released

Q4. What are hormones? How do they differ from nervous control?

Solution

Hormones: Chemical messengers secreted by endocrine glands that regulate body functions.

Differences:
• Nervous control: Fast, short-lived, through electrical impulses, specific target
• Hormonal control: Slow, long-lasting, through blood, widespread effects

Hormones control growth, metabolism, reproduction, mood, and development.

Q5. What are the endocrine glands in the human body?

Solution

Major endocrine glands:
• Pituitary gland: "Master gland" — controls other glands
• Thyroid gland: Produces thyroxine (metabolism)
• Adrenal glands: Produce adrenaline (emergency hormone)
• Pancreas: Produces insulin (blood sugar regulation)
• Testes: Produce testosterone (male hormones)
• Ovaries: Produce estrogen and progesterone (female hormones)

Q6. What happens when the person is frightened?

Solution

When frightened:
• Adrenaline is secreted by adrenal glands
• Heart rate increases
• Blood pressure rises
• Blood is directed to muscles
• Pupils dilate to see more
• Breathing rate increases
• This prepares the body for "fight or flight" response

Q7. How does the human eye work?

Solution

The human eye works by:
• Light enters through the cornea
• Iris controls the size of the pupil
• Lens focuses light on the retina
• Retina has rod and cone cells — rods for dim light, cones for colour
• Image is formed inverted on retina
• Optic nerve sends signals to brain
• Brain interprets the image as erect

Q8. What is the difference between a plant hormone and an animal hormone?

Solution

Plant hormones:
• Called phytohormones
• Produced in growing regions
• No specific glands
• Examples: Auxin, Gibberellin, Cytokinin, Abscisic acid, Ethylene

Animal hormones:
• Produced by endocrine glands
• Transported through blood
• Have specific target organs
• Examples: Insulin, Adrenaline, Thyroxine

← Chapter 5: Life Processes Chapter 7: How do Organisms Reproduce? →

← All Class 10 Biology Chapters