Plant Structures: Transport in Plants

• Plants have two main transport systems - the xylem and the phloem - which transport water, minerals and food around the plant.

• The xylem transports water and minerals from the roots to the rest of the plant. Water is taken in through root hair cells by osmosis and the xylem vessels, made from dead cells, allow this transport via a continuous tube.

• Transpiration is the process through which water is lost from the plant via evaporation from the leaves. This creates a flow of water from the roots to the leaves, known as the transpiration stream.

• The rate of transpiration is affected by several factors: light intensity, temperature, wind and humidity. High light intensity, high temperatures, windy conditions and low humidity all increase the rate of transpiration.

• The phloem vessels are involved in the transportation of sugars and nutrients, such as glucose, from the leaves (where they are produced via photosynthesis) to the rest of the plant in a process called translocation.

• Both the xylem and phloem vessels are located in the stem and leaves. In the stem, they form a structure known as the vascular bundle, and in the leaves, they form the veins.

• Guard cells surround the stomata (tiny pores) on the surface of leaves and can open or close to control the amount of water loss through transpiration.

• Active transport is used by the roots to absorb mineral ions from the soil, against the concentration gradient.

• Plants have a root system that anchors them into the ground, absorbs water and minerals and often functions as storage for the plant.

• The shoot system, namely the stem and the leaves, is mainly involved in photosynthesis, transpiration and transport of substances.

• The role of root hair cells, aside from absorbing water and minerals, is increased by their large surface area.

• In extreme conditions, plants have adaptations for survival. For instance, cacti have thick, waxy skin to reduce water loss, and deep or wide root systems to absorb as much water as possible.

Remember, practise questions and diagrams can be useful tools in understanding these processes in greater detail. Always refer to the specific content of your textbook and class materials to ensure comprehensive revision.