O Level Biology

Explain why most foods must be digested before they can be absorbed

Understand the concept of a balanced diet

Name the diseases and describe the symptoms resulting from deficiencies of vitamin C (scurvy), vitamin D (rickets), calcium (rickets) and iron (anaemia)

List the principal sources of, and describe the dietary importance of, carbohydrates, lipids, proteins, vitamins (C and D only), mineral salts (calcium and iron only), fibre (roughage) and water

Relate the structure of xylem vessels to their function, limited to: (a) thick walls with lignin (details of lignification are not required) (b) no cell contents (c) cells joined end-to-end with no cross walls to form a long continuous tube

State the functions of xylem as transport of water and mineral ions, and support

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