Transportation Excretion and Circulation in Plants and Animals

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Notes by Ankur upaadhyay gujarat board/combined science igcse.9998791839 india.
Q.1 Explain transportation of water in plants.
A.1 (1) Higher plants possess xylem which is associated with the transport of water. (2) Water absorbed by the root from the soil is transported to stem, branches, leaves and flowers. (3) The main structural components of the xylem responsible for the transport of water are tracheids and vessels. (4) As the root cells are directly in contact with soil,they take up ions.due to this, a difference is created between concentration of these ions between the root and the soil. (5) Water moves into the root from the soil to elimlnate this difference.This water movement creates a column of water that is steadily pushed upwards. (6) Plants use another strategy to move water in the xylem upwards to the highest points of the plant body. (7) If adequate water is available then the water which lost through the stomata is replaced by the water present in xylem vessel. (8) During day time the transpiration pull becomes the major driving force in the movement of water in the xylem.

Q.2 Explain transport of food and other substances in plants. A.2 (1) Carbohydrates are synthesized in the green leaves by the process of photosynthesis. (2) These photosynthetic products are transported to the various parts of the plant body. (3) Transport of photosynthetic products is known as translocation and it is performed by sieve tubes and sieve cells of vascular tissue known as phloem. (4) Besides the carbohydrates, the phloem transports amino acids, several plant hormones which are synthesized at the shoot and root tips and other substance (5) The translocation takes place in both, upward and downward directions. (6) Translocation of substances requires energy which is obtained from ATP. (7) When the material like sucrose is transferred into phloem tissue,the osmotic pressure of tissue increases leading to entry of water into it. (8) This pressure moves the...
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