Respiration in Organisms
Overview
Breathe in, breathe out — with every breath, oxygen comes in and CO2 goes out — and energy is produced in the cells. This is respiration. Every living thing does it — trees, fish, earthworms too — each in their own way.
Typed Notes
Fire inside the cell — respiration
Glucose obtained from food + oxygen (from breathing) → CO2 + water + energy — this happens in every cell — this is cellular respiration. Just like an engine burns fuel, a cell burns glucose — slowly, without any flame. That is why: (1) we can survive only for seconds without breathing; (2) when we eat more and grow, we need more oxygen; (3) both food and breathing are necessary for energy.
Aerobic vs Anaerobic
(1) Aerobic — with oxygen: more energy is produced, waste products are CO2 and water — this is our normal method. (2) Anaerobic — without oxygen: less energy is produced, different waste products: yeast (khameer) → alcohol + CO2 — this is why dough rises (baking) and alcohol is made from it; in our muscles when we are very tired (running hard) — oxygen becomes less — lactic acid is produced — causing fatigue and cramps (massage and rest bring oxygen back — and it gets better). Yeast works anaerobically — that is why it is used in fermentation.
Human breathing — the system
Nose (nostrils) → nasal passage (hairs and mucus filter dust and germs, air is warmed and moistened) → trachea (windpipe — cartilage rings keep it from collapsing) → two bronchi → lungs (right has 3 lobes, left has 2 — to make space for the heart) → bronchioles → alveoli (millions of tiny air sacs — this is where oxygen and blood exchange takes place) — ribs (move up and down) and diaphragm (a muscular sheet) help: they contract and expand — air comes in. Adult breathing rate: 15–18 times per minute; higher in children; increases during exercise (muscles need more oxygen).
Plants and other living things
Fish — gills: water is taken in through the mouth, oxygen is absorbed from it through the thin gill membranes, CO2 is released back into the water; earthworm — moist skin (if it dries out, it is in trouble); insects — spiracles (small holes on the body); frog — not through the tongue — through skin (in water) and lungs (on land). Plants — they also breathe through stomata (24 hours) — but photosynthesis happens only during the day: during the day — net oxygen is released; at night — only respiration — CO2 is released — that is why sleeping under a large tree at night is not advisable (CO2 can become concentrated).
Key Concepts
Revision ke liye ek nazar — exam se pehle yahi padhna hai.
- 01Cellular respiration: in every cell, glucose + oxygen → CO2 + water + ENERGY. This is the body's fuel.
- 02Aerobic respiration: with oxygen (more energy). Anaerobic: without oxygen — yeast → alcohol + CO2 (used in baking and brewing); in muscles it produces lactic acid — causing cramps (fatigue).
- 03Breathing vs Respiration: breathing — only air moving in and out (nose to lungs); respiration — happens at the cellular level (energy is produced). Breathing rate: 15–18 times per minute in a resting adult; increases during exercise.
- 04Human respiratory system: nostrils → nasal passage (filters dust) → trachea/windpipe (cartilage rings — keeps it from collapsing) → 2 bronchi → lungs (bronchioles → alveoli — where the real work of breathing happens) — ribs and diaphragm help in the process.
- 05Other living things: fish — gills (take oxygen from water); earthworm — moist skin; insects — spiracles; plants — stomata (at night, only respiration happens — CO2 is released — that is why you should not sleep under a large tree at night).
Questions & Solutions
Pehle khud try karo — phir solution kholo. Yahi tariqa topper banata hai.
What is the difference between breathing and respiration?
What is the difference between aerobic and anaerobic respiration?
Why do we get cramps in our legs after running?
How does a fish breathe in water?
Why are there cartilage rings in the trachea?
Why is it not advisable to sleep under a large tree at night?
Cellular respiration: glucose + O2 → CO2 + water + energy (in every cell). Aerobic (with O2, more energy) vs anaerobic (yeast → alcohol; muscles → lactic acid and cramps). Breathing: nose → trachea → lungs (alveoli); rate 15–18 per minute. Fish use gills, earthworm uses skin, plants use stomata (release CO2 at night).
Chapter-end quiz
4 MCQsOption tap karo — turant pata chalega sahi ya galat, explanation ke saath.
Q1.What is the main useful product of cellular respiration?
Q2.What type of respiration does yeast carry out?
Q3.What substance builds up and causes muscle cramps?
Q4.Which organ does a fish use to breathe?
Mark karo — dashboard par progress dikhega.