Welcome to our Class 10 Science NCERT Solutions! Here, you’ll find easy-to-understand solutions for Physics, Chemistry, and Biology. Clear explanations, step-by-step answers, and chapter-wise guidance will help you learn faster, solve exercises confidently, and score better in exams.
Q1. Which of the following is a plant hormone?
Answer: (d) Cytokinin
Explanation: Cytokinins are plant hormones that promote cell division, growth, and differentiation.
- Insulin – animal hormone regulating blood sugar.
- Thyroxin – animal hormone from thyroid gland.
- Oestrogen – female sex hormone.
Q2. The gap between two neurons is called a
Answer: (b) Synapse
Explanation: A synapse is the tiny gap between the axon tip of one neuron and the dendrite of another neuron where nerve impulses are transmitted chemically via neurotransmitters.
Q3. The brain is responsible for
Answer: (d) All of the above
Explanation: The brain performs multiple functions:
- Thinking and reasoning.
- Regulating involuntary actions like heartbeat and respiration.
- Maintaining balance and coordination.
Q4. What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?
Answer:
- Function: Receptors detect changes (stimuli) in the environment like light, sound, touch, temperature, and chemical signals. They send signals to the brain for response.
- If receptors don’t work properly:
- Blindness if eyes fail to detect light.
- Deafness if ears fail to detect sound.
- Loss of touch sensation or inability to detect pain.
Q5. Draw the structure of a neuron and explain its function.
Answer:
Structure of a Neuron:
- Cell body (Soma): Contains nucleus and cytoplasm.
- Dendrites: Short extensions that receive signals.
- Axon: Long fiber transmitting impulses to other neurons or muscles.
- Axon terminal: Sends signals to next neuron across the synapse.
Function: Neurons transmit messages in the form of electrical impulses from the brain/spinal cord to different parts of the body.
Q6. How does phototropism occur in plants?
Answer:
- Phototropism is the growth of plant parts in response to light.
- Mechanism:
- Cells on the shaded side of the stem elongate due to the hormone auxin.
- This causes the plant to bend towards light, maximizing photosynthesis.
Q7. Which signals will get disrupted in case of a spinal cord injury?
Answer:
- Spinal cord transmits nerve impulses between brain and body.
- Injury can disrupt:
- Motor signals – affecting voluntary movement.
- Sensory signals – affecting sensation of touch, pain, or temperature.
- May lead to paralysis below the injury site.
Q8. How does chemical coordination occur in plants?
Answer:
- Plants coordinate using plant hormones (chemical messengers).
- Examples:
- Auxins – stimulate cell elongation.
- Cytokinins – promote cell division.
- Gibberellins – promote seed germination.
- Abscisic acid – inhibits growth and promotes dormancy.
Q9. What is the need for a system of control and coordination in an organism?
Answer:
- To respond to internal and external stimuli.
- To maintain homeostasis (stable internal environment).
- To ensure growth, survival, and reproduction.
Q10. How are involuntary actions and reflex actions different from each other?
| Feature | Involuntary Action | Reflex Action |
|---|---|---|
| Definition | Actions done automatically without conscious thought | Rapid automatic response to a stimulus |
| Control | Controlled by brain (autonomic nervous system) | Controlled by spinal cord |
| Example | Heartbeat, breathing | Pulling hand from hot object |
Q11. Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
| Feature | Nervous System | Hormonal System |
|---|---|---|
| Messenger | Nerve impulses | Hormones |
| Speed | Fast | Slow |
| Duration | Short-lived | Long-lasting |
| Transmission | Through neurons | Through blood |
| Example | Muscle movement | Growth, metabolism |
Q12. What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?
| Feature | Sensitive Plant | Human Legs |
|---|---|---|
| Type of Movement | Tropic or nastic movement | Muscular movement |
| Stimulus | Light, touch | Voluntary control by brain |
| Mechanism | Change in turgor pressure | Muscle contraction |
- Chemical Reactions and Equations
- Acids, Bases and Salts
- Metals and Non‑Metals
- Carbon and Its Compounds
- Life Processes
- Control and Coordination
- How Do Organisms Reproduce?
- Heredity and Evolution
- Light – Reflection and Refraction
- The Human Eye and the Colourful World
- Electricity
- Magnetic Effects of Electric Current
- Our Environment
Conclusion
By using our Class 10 Science NCERT Solutions, students can strengthen their understanding of important concepts and excel in exams. These solutions are carefully prepared as per the latest NCERT syllabus and are easy to read, understand, and apply. Whether you need help with Physics numericals, Chemistry reactions, or Biology diagrams and exercises, this guide is your one-stop solution for scoring excellent marks in Class 10 Science.
