Science — Food, Living World, Motion & Measurement
1. Food — Where Does It Come From?
Sources of Food
- PLANTS: Fruits. Vegetables. Grains (rice, wheat). Pulses. Oilseeds.
- ANIMALS: Milk. Eggs. Meat. Fish. Honey.
Food Variety Across India
'Different regions eat DIFFERENT foods — rice in the South, wheat in the North, fish on the coasts.' AP food: RICE is the STAPLE. Accompanied by: dal, sambar, pickles, curd. 'Our food depends on what GROWS where we live.'
Herbivores, Carnivores, Omnivores
- Herbivores: Eat only plants (cow, deer, rabbit).
- Carnivores: Eat other animals (lion, tiger, eagle).
- Omnivores: Eat BOTH (human, bear, crow).
2. Components of Food — What Does Our Body NEED?
| Nutrient | Function | Sources |
|---|---|---|
| Carbohydrates | ENERGY | Rice, wheat, potato, sugar |
| Proteins | GROWTH and REPAIR | Pulses, milk, eggs, meat |
| Fats | Stored energy | Oil, butter, nuts |
| Vitamins & Minerals | Body protection and regulation | Fruits, vegetables |
| Water | Essential for ALL body functions | Water, fruits, milk |
Deficiency Diseases
- Lack of Vitamin A → NIGHT BLINDNESS. Lack of Vitamin C → SCURVY (bleeding gums). Lack of Vitamin D → RICKETS (weak bones). Lack of Iron → ANAEMIA. Lack of Iodine → GOITRE.
3. Living World — Adaptations
Habitats and Adaptations
| Habitat | Example | Key Adaptation |
|---|---|---|
| Desert | Camel | Hump (fat store). Long eyelashes. Wide feet. |
| Aquatic | Fish | Gills. Streamlined body. Fins. |
| Polar | Polar bear | Thick fur. Layer of FAT (blubber). White colour (camouflage). |
| Forest | Tiger | Stripes (camouflage). Sharp claws. Strong legs. |
4. Motion and Measurement
Types of Motion
Rectilinear (straight line). Circular. Periodic (repeating — pendulum). 'Motion is a CHANGE in position over time.'
Measuring Length
SI unit: METRE (m). 1 m = 100 cm = 1000 mm. 1 km = 1000 m. Use ruler, measuring tape.
Measuring Time
SI unit: SECOND (s). Stopwatch. Clock. 'Ancient methods: sundial (shadow of the sun). Sand clock. Water clock.'
5. Light, Shadows and Reflections
Light Travels in a STRAIGHT LINE (Rectilinear Propagation).
Evidence: Shadows. Pinhole camera.
Shadows — Three Conditions
Source of light. OPAQUE object. Screen (wall, ground).
Reflection — Bouncing of Light
Smooth, polished surfaces (MIRROR). 'Angle of incidence = Angle of reflection.'
