Answer:
Leaf are usually flattened green extension from the stem of a vascular plant.
a) Leaves functions :
- primary sites of photosynthesis and produces food for plants.
- leaves are an essential part of stem system and connect through vascular system to the rest of the plant so that free movements and exchange of nutrients, water and end products of photosynthesis.
b) leaves are differentiate into three types of tissues: dermal tissue, vascular tissue, and ground tissue. Dermal tissue protects the plant, and controls gas exchange in leaves, vascular tissues helps in translocation of nutrients and water.