Life processes are imp for animals to survive. These include:
- Nutrition – Getting energy from food.
- Respiration – Releasing energy using oxygen.
- Excretion – Removing waste from the body.
- Reproduction – Producing offspring.
Different animals eat different foods, and their digestion and breathing methods vary. Let’s study how these processes work!
Nutrition in Animals
Animals eat foods like grass, meat, or nectar. Food contains:
- Carbohydrates (like rice, chapati).
- Proteins (like eggs, milk).
- Fats (like butter, oil).
But food is complex, so it must be broken into simpler forms for the body to use. This happens in the alimentary canal (a long tube from mouth to anus).
Digestion in Human Beings
- Mouth
- Teeth chew food (mechanical digestion).
- Saliva mixes with food, breaking starch into sugar.
- Chewing chapati makes it taste sweet due to saliva.
- Oral hygiene tip: Brush twice daily, rinse mouth after eating.
- Food Pipe (Oesophagus)
- Pushes food to stomach using muscle contractions.
- Stomach
- Churns food into a semi-liquid.
- Releases digestive juice (breaks proteins), acid (kills bacteria), and mucus (protects stomach).
- Small Intestine (6 metres long!)
- Receives juices from liver (bile for fats) and pancreas (digests carbs, proteins, fats).
- Absorbs nutrients through finger-like projections.
- Nutrients enter blood for energy.
- Large Intestine (1.5 metres long)
- Absorbs water and salts.
- Forms stool from undigested food.
- Expelled through anus (egestion).
Fun Fact:
- Gut bacteria help digestion (eat curd for good bacteria!).
- Ancient Charaka Samhita stressed mindful eating.
Do All Animals Digest Food Like Humans?
No! Different animals have unique digestion:
- Cows (Ruminants): Chew food twice (cud chewing).
- Birds: Use a gizzard (muscular organ) to grind food (no teeth!).
Respiration in Animals
Respiration = Using oxygen to break glucose for energy.
- Breathing (inhale oxygen, exhale CO₂) is physical.
- Respiration (energy release in cells) is chemical.
Respiration in Humans
- Breathing Steps
- Inhale → Oxygen enters through nostrils (filtered by hair & mucus).
- Air moves through windpipe to lungs.
- Alveoli (tiny air sacs) exchange gases:
- Oxygen → Blood.
- CO₂ → Exhaled out.
- Exhale → Diaphragm pushes air out.
- Lung Protection
- Rib cage shields lungs.
- Diaphragm (muscle below lungs) helps breathing.
Health Tips:
- Do pranayama for strong lungs.
- Avoid smoking (harms lungs!).
Do Other Animals Breathe Like Humans?
No! Breathing depends on habitat:
| Animal | Breathing Organ | Example |
|---|---|---|
| Humans, Birds | Lungs | Eagle, Elephant |
| Fish | Gills | Goldfish, Shark |
| Frogs (Tadpoles) | Gills (in water) | Frog larvae |
| Frogs (Adults) | Lungs + Skin | Adult frog |
| Earthworms | Moist Skin | Garden earthworm |
In a Nutshell
- Digestion: Mouth → Stomach → Intestines → Anus.
- Small intestine absorbs nutrients; large intestine removes waste.
- Respiration: Oxygen → Energy + CO₂ (in cells).
- Breathing: Lungs (humans), gills (fish), skin (frogs).
Questions and Answers
- Complete the food’s journey in the alimentary canal.
- Answer: Mouth → Oesophagus → Stomach → Small Intestine → Large Intestine → Anus.
- Why does chewed chapati (Test Tube B) not turn blue-black with iodine?
- Answer: Saliva breaks starch into sugar, so no reaction with iodine.
- What is the diaphragm’s role in breathing?
- Answer: Helps inhale (moves down) and exhale (moves up).
- Match the parts:
- (i) Nostrils – (a) Air entry.
- (ii) Nasal passages – (d) Traps dust.
- (iii) Windpipe – (e) Carries air to lungs.
- (iv) Alveoli – (b) Gas exchange.
- (v) Ribcage – (c) Protects lungs.
- How is breathing different from respiration?
- Answer: Breathing = Physical (inhale/exhale); Respiration = Chemical (energy release in cells).
- Why do we sneeze in dusty air?
- Answer: To expel dust and protect lungs.
- Why did Anusha breathe faster after running?
- Answer: Ran harder or has lower fitness (needs more oxygen).
- What does Yadu’s saliva + starch experiment prove?
- Answer: Saliva digests starch into sugar (no iodine colour change).
- Why does lime water turn milky with exhaled air?
- Answer: Exhaled air has more CO₂, which reacts with lime water.
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