Our atmospheric is responsible for refraction and occurs in a medium of gradually changing index of refractive. So, light rays undergo refraction continuously before it reaches the earth when it coming from the sun or stars on entering the earth’s ...

(i) Xylem transports water, amino acids and other substances in plants. (ii) Phloem transports soluble products of photosynthesis in plants. (iii) Transpiration helps in absorption of water. (iv) Material like sucrose is transferred into phloem tissue using energy from ATP.