Quick Summary
Transportation is necessary for moving materials inside living organisms. In plants, xylem and phloem transport water, minerals, and food. In animals, blood and the heart circulate substances.
Key Definitions
- Xylem: Conducts water and minerals.
- Phloem: Conducts prepared food.
- Translocation: Movement of food through phloem.
- Blood: Fluid connective tissue that transports substances.
- Plasma: Liquid part of blood.
- Artery: Blood vessel carrying blood away from the heart.
- Vein: Blood vessel carrying blood towards the heart.
- Capillary: Thin blood vessel where exchange of materials occurs.
Transport in Plants
| Tissue | Material transported | Direction |
|---|---|---|
| Xylem | Water and minerals | Mostly upward |
| Phloem | Food | Both upward and downward |
Water movement in plants is supported by root pressure, transpiration pull, and cohesion of water molecules.
Blood Components
| Component | Function |
|---|---|
| Plasma | Transports dissolved substances |
| Red blood cells | Carry oxygen |
| White blood cells | Fight infection |
| Platelets | Help blood clotting |
Human Heart and Circulation
The heart pumps blood throughout the body. Deoxygenated blood reaches the heart and is sent to the lungs. Oxygenated blood returns from the lungs and is pumped to the body.
Double Circulation — path of blood
The human heart has four chambers (2 atria, 2 ventricles). Blood passes through the heart twice in one complete cycle (double circulation):
This keeps oxygenated and deoxygenated blood completely separate, giving an efficient oxygen supply.
Exception to remember: the pulmonary artery carries deoxygenated blood (heart→lungs), and the pulmonary vein carries oxygenated blood (lungs→heart) — opposite to the usual rule.
Blood Vessels
| Vessel | Feature |
|---|---|
| Artery | Thick wall, high pressure |
| Vein | Has valves, lower pressure |
| Capillary | Very thin wall for exchange |
Textbook Solution Strategy
1. Separate plant transport and animal circulation in your answer. 2. Use tables for xylem vs phloem and artery vs vein. 3. For heart questions, trace the path of blood step by step. 4. Mention components of blood with functions. 5. Practise diagrams of heart and blood vessels.
Important Questions
One Mark
- Name the tissue that transports food in plants.
- What are platelets?
- Define translocation.
Two Marks
- Differentiate between xylem and phloem.
- Differentiate between artery and vein.
- Write the functions of blood.
Five Marks
- Explain circulation in humans.
- Describe components of blood and their functions.
- Explain transport of water and food in plants.
Common Mistakes
- Writing phloem transports water.
- Saying veins always carry deoxygenated blood without noting exceptions.
- Forgetting valves in veins.
- Mixing up plasma and platelets.
Revision Checklist
- Xylem and phloem comparison revised
- Blood components memorised
- Artery, vein, capillary differences practised
- Heart blood flow revised
- Important diagrams labelled once