NCERT Solutions for Class 10 Science Chapter 6 Control and Coordination
NCERT Solutions for Class 10 Science Chapter 6 Control and Coordination provides structured answers covering the central and peripheral nervous systems, reflex action, brain structure, plant hormones, tropic movements, and endocrine glands in human bodies.
Overview of Topics & Subtopics
Intext Questions - Page Number: 105
Q1: What is the difference between a reflex action and walking?
Reflex Action: An involuntary, rapid, and automatic response to a stimulus (e.g., pulling hand away from a hot object) mediated mainly via the spinal cord without conscious thought.
Walking: A voluntary movement controlled consciously by the hindbrain (cerebellum) and forebrain, requiring deliberate thought and learning.
Q2: What happens at the synapse between two neurons?
Answer: At a synapse (the microscopic gap between two neurons), an electrical impulse arriving at the axon terminal triggers the release of chemical substances called neurotransmitters. These chemicals diffuse across the gap and bind to receptors on the dendrite of the next neuron, creating a new electrical signal.
Q3: Which part of the brain maintains posture and equilibrium of the body?
Answer: The cerebellum, which is located in the hindbrain, is responsible for precision of voluntary movements and maintaining posture and body balance.
Intext Questions - Page Number: 108
Q1: What are plant hormones?
Answer: Plant hormones (or phytohormones) are naturally occurring chemical substances synthesized in tiny quantities in specific regions of plants. They diffuse to target areas to regulate growth, development, and environmental responses. Examples: Auxins, Gibberellins, Cytokinins, and Abscisic acid.
Q2: How do auxins promote the growth of a tendril around a support?
Answer: When a plant tendril comes in contact with a support, auxins synthesized at the shoot tip diffuse toward the side of the tendril that is away from the support. The higher concentration of auxin stimulates faster cell elongation on the shaded/opposite side, causing the tendril to bend towards and wrap tightly around the support.
Intext Questions - Page Number: 111
Q1: How does chemical coordination take place in animals?
Answer: Chemical coordination in animals is mediated by specialized organs called endocrine glands. These glands secrete chemical messengers called hormones directly into the bloodstream, which transports them to targeted organs/tissues to regulate metabolic and developmental activities.
Q2: Why is the use of iodised salt advisable?
Answer: Iodine is essential for the synthesis of thyroxin hormone by the thyroid gland. Thyroxin regulates carbohydrate, protein, and fat metabolism for optimal body growth. Deficiency of iodine in diet can cause enlargement of the thyroid gland, leading to a condition called goitre.
Textbook Chapter End Exercise Questions
Q1: Which of the following is a plant hormone?
(a) Insulin
(b) Thyroxin
(c) Oestrogen
(d) Cytokinin
Correct Answer: (d) Cytokinin (promotes cell division in plants).
Q2: The gap between two neurons is called a:
(a) dendrite
(b) synapse
(c) axon
(d) impulse
Correct Answer: (b) synapse.
Q3: The brain is responsible for:
(a) thinking
(b) regulating the heart beat
(c) balancing the body
(d) all of the above
Correct Answer: (d) all of the above.
Q4: How does our body respond when adrenaline is secreted into the blood?
Answer: Adrenaline is known as the "emergency hormone". When secreted during stressful situations:
1. Heartbeat accelerates to pump more oxygenated blood to skeletal muscles.
2. Blood flow to the digestive system and skin is reduced due to contraction of small blood vessels, redirecting blood flow to skeletal muscles.
3. Breathing rate increases rapidly due to contractions of the diaphragm and rib muscles.
