CLASS 6 SCIENCE – ANSWER KEY

SECTION A – MCQs

Q1.

1. (a) Sun
2. (b) Leaves
3. (a) Proteins
4. (b) Evaporation
5. (c) Iron
6. (b) Gravity
7. (b) Lungs
8. (a) Soluble
9. (c) Sunlight
10. (c) Cell

Q2.

1. Photosynthesis
2. Condensation
3. Oxygen
4. Poles
5. Sun
6. Metre
7. Herbivores
8. Plasma
9. Blocked
10. Moon

SECTION B – VERY SHORT ANSWERS

Q3.

1. A balanced diet contains all essential nutrients in the right amounts.
2. Plants need sunlight to prepare food by photosynthesis.
3. Evaporation is the change of liquid water into water vapour.
4. Salt and sugar.
5. A magnet is an object that attracts magnetic materials such as iron.
6. Bones support our body, protect organs and help in movement.
7. Friction is a force that opposes motion between two surfaces.
8. Solar energy and wind energy.
9. A habitat is the natural home or environment of an organism.
10. Air provides oxygen for breathing and other gases needed by living things.

SECTION C – SHORT ANSWERS

Q4.

1. Transparent: allows light to pass through, e.g. clear glass. Opaque: does not allow light to pass through, e.g. wood.
2. Water exists as solid (ice), liquid (water) and gas (water vapour).
3. Roots anchor the plant, absorb water and minerals, and may store food.
4. Nutrients are substances needed for growth and health. Examples: carbohydrates, proteins and fats.
5. A shadow forms when an opaque object blocks light falling on a surface.

Q5.

1. A reversible change can be undone, e.g. melting ice. An irreversible change cannot easily be undone, e.g. burning paper.
2. Conductors allow heat/electricity to pass easily, e.g. copper and iron. Insulators do not, e.g. wood and plastic.
3. Unlike poles attract; like poles repel.
4. Water conservation prevents wastage and ensures enough water for people, animals and plants.
5. Roots absorb water; the stem supports the plant; leaves prepare food; flowers help in reproduction; fruits protect seeds.

SECTION D – CASE-BASED QUESTIONS

Q6.

1. Steel spoon and iron nail.
2. Wooden pencil and plastic ruler.
3. Iron is a magnetic material.
4. North pole and South pole.
5. Similar poles repel each other.

Q7.

1. Solid → liquid; this is melting.
2. Evaporation.
3. Condensation.
4. Solid, liquid and gas.
5. Melting is a reversible change.

SECTION E – LONG ANSWERS

Q8(1). Photosynthesis

Green plants prepare their food through photosynthesis. Roots absorb water and minerals from the soil. Leaves take in carbon dioxide from the air. Chlorophyll in the leaves traps sunlight. Using sunlight, plants convert water and carbon dioxide into food and release oxygen.

Q8(2). Water Cycle

The Sun heats water and causes evaporation. Water vapour rises and cools to form clouds through condensation. Water then falls to Earth as rain, snow or hail through precipitation. It collects in rivers, lakes, oceans and underground sources. This continuous movement is called the water cycle.

Flow:
Water → Evaporation → Water Vapour → Condensation → Clouds → Precipitation → Collection → Water