Descriptive Science Questions and Answers
1. What is the difference between a physical change and a chemical change?
A physical change alters the form or appearance of a substance without changing its chemical composition. A chemical change results in the formation of new substances with different properties.
2. Explain the process of photosynthesis.
Photosynthesis is the process by which green plants use sunlight, carbon dioxide, and water to produce glucose and oxygen using chlorophyll.
Equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
3. What are the main parts of a cell and their functions?
– Nucleus: Controls cell activities
– Cytoplasm: Site of cellular activities
– Cell membrane: Controls entry/exit of substances
– Mitochondria: Produces energy
– Ribosomes: Makes proteins
– Cytoplasm: Site of cellular activities
– Cell membrane: Controls entry/exit of substances
– Mitochondria: Produces energy
– Ribosomes: Makes proteins
4. Define matter and list its states.
Matter is anything that has mass and occupies space. The three main states are: Solid, Liquid, and Gas.
5. What causes seasons on Earth?
Seasons occur due to the tilt of Earth’s axis and its revolution around the Sun, causing different parts of Earth to receive varying sunlight.
6. What is combustion? Give examples.
Combustion is a chemical reaction with oxygen that releases heat and light. Examples: burning wood, candle, petrol.
7. How does the human brain function?
– Cerebrum: Controls thinking and memory
– Cerebellum: Maintains balance
– Medulla: Controls involuntary actions
– Cerebellum: Maintains balance
– Medulla: Controls involuntary actions
8. What is air pollution and its effects?
Air pollution is the presence of harmful substances in air. It causes respiratory problems, global warming, and acid rain.
9. Explain the water cycle.
The water cycle includes evaporation, condensation, precipitation, and collection. It maintains Earth’s water balance.
10. What is the greenhouse effect?
The greenhouse effect is the trapping of heat by gases like CO₂ in the atmosphere, keeping Earth warm. Excess causes global warming.
11. What is germination?
Germination is the process by which a seed grows into a plant under proper conditions like moisture, air, and temperature.
12. What is electricity? How is it generated?
Electricity is the flow of electrons. It is generated using thermal, hydro, solar, or wind energy.
13. What are microbes? Name their types.
Microbes are microscopic organisms. Types: Bacteria, Viruses, Fungi, Protozoa, and Algae.
14. What is magnetism?
Magnetism is a force by magnets attracting materials like iron. Magnets have north and south poles.
15. What is an atom?
An atom is the smallest unit of matter. It consists of protons and neutrons in the nucleus and electrons orbiting it.
16. What causes the phases of the Moon?
The Moon’s phases are due to its revolution around Earth and changing sunlight angles.
17. Define heat and temperature.
Heat is energy transfer due to temperature difference. Temperature measures how hot or cold something is.
18. What is heredity?
Heredity is the passing of traits from parents to offspring through genes.
19. What are the functions of the skeleton system?
The skeleton provides shape, protects organs, helps movement, and produces blood cells.
20. What is solar energy and its advantages?
Solar energy comes from the Sun. It is renewable, eco-friendly, and reduces fossil fuel use.
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