Describe three differences, visible in Fig. 2.1, between root apical meristem cells and root cap cells.
Mucilage acts like a glue, joining tiny soil particles into small clumps close to the root. These clumps help keep soil water around the root tip and prevent water being lost. With reference to the cohesive and adhesive properties of water, suggest and explain how the formation of small clumps of soil helps to maintain the soil water around the root tip.
Enzymes in mucilage catalyse the breakdown of organic compounds in the soil, which increases the amount of mineral ions present in the soil. State the term used for enzymes that act outside the cells that synthesise them.
Explain the meaning of a polysaccharide.
The soil microorganisms use amino acids to make proteins. All twenty amino acids found in proteins share the same general structure. Draw the general structure of an amino acid in the space provided and use your drawing to explain how many different amino acids can exist.
Mineral ions are usually found in very low concentrations in the soil. The activity of mucilage enzymes and soil microorganisms can help to raise the amount of mineral ions. Root hair cells are specialised for taking up these mineral ions and for absorbing water from the soil. Suggest and explain how the presence of mineral ions in the root hair cell can increase the absorption of water by the root hair cells.
Suggest and explain how mineral ions inside the root hair cell can increase water absorption by the root hair cells.