EXERCISES
A. Answer in Detail
1 Describe the circulatory system in humans.
2. What are the components of blood?
3. Draw a neat labelled diagram of the human excretory system.
4. How does transport of water and minerals take place in plants?
5. Write a note on transpiration.
Answers
1.The circulatory system is made up of blood vessels that carry blood away from and towards the heart. Arteries carry blood away from the heart and veins carry blood back to the heart. The circulatory system carries oxygen, nutrients, and hormones to cells, and removes waste products, like carbon dioxide.
2.Blood is a specialized body fluid. It has four main components: plasma, red blood cells, white blood cells, and platelets. Blood has many different functions, including: transporting oxygen and nutrients to the lungs and tissues.
4.Plants must transport water from the roots to the leaves where it is needed for the process of photosynthesis. Nutrients produced in the leaves by photosynthesis are transported to all the parts of the plant. The phloem carries nutrients up and down the plant. The xylem only carries water up the plant.
5.The process by which plants lose water from the leaves and aerial parts in the form of water vapour is called transpiration. The device that is used to measure the rate of transpiration is called potometer. Transpiration is essential in bringing rain because when plants transpire they increase the amount of water molecules in the air which results in rainfall. It also provides a cooling effect to the plants. It also creates a transpirational pull which results in the absorption of water and minerals from the soil.