Questions and Answers

Identify the positions of tissues as seen in transverse sections of non-woody dicotyledonous roots and stems, limited to: xylem, phloem and cortex

Describe translocation as the movement of sucrose and amino acids in the phloem from parts of plants that produce or release them (sources) to parts of plants that use or store them (sinks)

Explain the mechanism by which water moves upwards in the xylem in terms of a transpiration pull that draws up a column of water molecules, held together by forces of attraction between water molecules

Investigate the effects of wind speed, light intensity and temperature variation on transpiration rate

Explain: (a) the effects of wind speed, and the variation of temperature, humidity and light intensity on transpiration rate (b) how wilting occurs

Understand that water evaporates from the surfaces of the mesophyll cells into air spaces and then diffuses out of the leaves through the stomata as water vapour

Explain the importance of magnesium ions for making chlorophyll

Explain the importance of nitrate ions for making amino acids, required for the production of proteins

Identify and label the cuticle, cellular and tissue structures of a dicotyledonous leaf, as seen in diagrams or photomicrographs, and explain how these structures are adaptations for photosynthesis and gas exchange, limited to: (a) stomata and guard cells (b) spongy and palisade mesophyll cells (c) air spaces (d) vascular bundles (xylem and phloem) (e) distribution of chloroplasts (f) upper and lower epidermis

State that most leaves have a large surface area and are thin, and explain how these features are adaptations for photosynthesis