Respiration and Transportation
Respiration and Transportation
Respiration and circulation together give 2 questions. The examiner separates breathing from respiration, asks the site of energy release, and tests the blood components — all three of which are places where everyday language and scientific meaning diverge.
Breathing Is Not Respiration
| Point | Breathing | Respiration |
|---|---|---|
| What it is | Physical exchange of gases | Chemical breakdown of food |
| Where | Lungs | Every cell, in the mitochondria |
| Energy | None released | Energy released |
| Type | Physical process | Biochemical process |
Breathing supplies the oxygen that respiration uses. Treating the two as synonyms is the most common misconception in the topic, and correcting it is exactly what a class 7 teacher must do.
Glucose + Oxygen → Carbon dioxide + Water + Energy
Aerobic respiration uses oxygen and releases much more energy. Anaerobic respiration happens without oxygen — yeast produces alcohol and carbon dioxide, and human muscles produce lactic acid during heavy exercise, which is what causes cramps.
✗ Breathing and respiration mean the same thing | ✓ Breathing is gas exchange in the lungs; respiration releases energy in every cell
Breathing in Different Organisms
- Humans and other mammals breathe through lungs.
- Fish use gills to take oxygen dissolved in water.
- Insects use a network of air tubes called tracheae, opening through spiracles.
- Earthworms breathe through their moist skin.
- Frogs breathe through both lungs and skin.
- Plants exchange gases through stomata in leaves and lenticels in stems.
The organism-and-organ pairing is set as a matching question, and the earthworm and frog entries are the ones candidates miss.
Transportation in Humans
Blood has four components and each is asked with its function.
| Component | Function |
|---|---|
| Plasma | Liquid part; carries cells and dissolved substances |
| Red blood cells | Carry oxygen using haemoglobin |
| White blood cells | Fight infection |
| Platelets | Help blood clot |
Haemoglobin gives blood its red colour and binds oxygen; a deficiency of iron reduces it and causes anaemia. The heart has four chambers — two atria and two ventricles — and this separation keeps oxygenated and deoxygenated blood from mixing.
- Arteries carry blood away from the heart, usually oxygenated, with thick walls.
- Veins carry blood to the heart, usually deoxygenated, and have valves.
- The pulmonary artery is the exception: it carries deoxygenated blood.
- Normal adult pulse rate is about 72 to 80 beats per minute.
The pulmonary artery exception is the classic question here, because it breaks the rule that arteries carry oxygenated blood.
Transport in Plants
Plants use two conducting tissues. Xylem carries water and minerals upward from the roots; phloem carries food made in the leaves in both directions. Transpiration from the leaves creates the pull that draws water up the xylem, which is why a plant that loses its leaves also loses much of that pull.
श्वसन हर कोशिका में होता है, सांस लेना सिर्फ फेफड़ों में।
TRE pointer: The breathing-versus-respiration distinction is the reasoning question this topic exists for. The pulmonary artery carrying deoxygenated blood is the factual trap, and the organism-and-breathing-organ matching is the third item. Note that lactic acid causing cramps connects respiration to everyday experience, which is the framing a teaching paper prefers. With five options and −1/3 negative marking, secure the blood-component table completely.
60-Second Recap
- Breathing is gas exchange in the lungs; respiration releases energy in every cell's mitochondria.
- Aerobic respiration needs oxygen; anaerobic gives alcohol in yeast and lactic acid in muscles.
- Fish use gills, insects tracheae, earthworms moist skin, frogs both lungs and skin.
- Plasma, red cells, white cells and platelets are the four blood components.
- Arteries carry blood away from the heart; the pulmonary artery carries deoxygenated blood.
- Xylem carries water upward; phloem carries food both ways.
Frequently Asked Questions
What is the difference between breathing and respiration?
Breathing is the physical taking in and giving out of air by the lungs, while respiration is the chemical breakdown of food inside every cell to release energy. Breathing simply supplies the oxygen that respiration uses, and the two are not interchangeable terms.
Why does the pulmonary artery carry deoxygenated blood?
Because arteries are defined by direction, not by the blood they carry: they carry blood away from the heart. The pulmonary artery takes deoxygenated blood from the heart to the lungs to be oxygenated, which makes it the exception to the usual pattern.
What causes muscle cramps during heavy exercise?
A build-up of lactic acid. When the muscles cannot get enough oxygen during strenuous activity, they respire anaerobically and produce lactic acid instead of carbon dioxide and water. The accumulated acid causes the pain and cramping that follows.
How do earthworms breathe?
Through their moist skin, by which oxygen dissolves and diffuses into the blood. This is why earthworms must stay damp and come out of the soil when it is waterlogged. Frogs use both their skin and lungs, and insects use tracheae opening through spiracles.