Biology (0610) Transport in Animals Revision Note

This document explains transport in plants for CAIE IGCSE Biology, focusing on xylem, phloem, water uptake, transpiration, and translocation. The xylem transports water and mineral ions while providing structural support, adapted with thick lignified walls, continuous tubes, and no cell contents. The phloem transports sucrose and amino acids from sources (leaves) to sinks (roots, storage organs, or growing tissues). Root hair cells, with their large surface area, absorb water by osmosis and minerals by active transport, initiating the transport pathway through root cortex cells into the xylem. Transpiration, defined as the loss of water vapour through stomata, creates a transpiration pull that draws water upward, aided by cohesive and adhesive forces. Factors affecting transpiration rate include temperature, humidity, and wind speed, while wilting occurs if water loss exceeds uptake, causing cells to become flaccid. The guide also covers translocation, the seasonal movement of sucrose and amino acids in the phloem, from roots to leaves in spring and from leaves to roots in summer and autumn. Practical investigations such as dye absorption in celery are also mentioned. This resource provides students with a clear understanding of plant transport systems, their adaptations, and their physiological importance.