Ap Biology Unit 2 Study Guide
Biology Unit 2 Module 2
1.1: Explain the uptake of ions by active transport in roots; * Emphasize the role of the endodermis.
Most plants secure the water and minerals they need from their roots. The path taken is: soil -> roots -> stems -> leaves The minerals (e.g., K+, Ca2+) travel dissolved in the water (often accompanied by various organic molecules supplied by root cells).Less than 1% of the water reaching the leaves is used in photosynthesis and plant growth. Most of it is lost in transpiration.
However, transpiration does serve two useful functions: * It provides the force for lifting the water up the stems. * It cools the leaves.
Water and minerals enter the root by separate paths which eventually converge …show more content…
It is interrupted by the Casparian strip in roots, air spaces between plant cells and the cuticula of the plant. Structurally, the apoplast is formed by the continuum of cell walls of adjacent cells as well as the extracellular spaces, forming a tissue level compartment comparable to the symplast. The apoplastic route facilitates the transport of water and solutes across a tissue or organ. This process is known as apoplastic transport. The apoplast is important for all the plant's interaction with its environment. The main carbon source (carbon dioxide) needs to be solubilized in the apoplast before it is taken up by chloroplasts and consumed during photosynthesis. In the roots, ions diffuse into the apoplast of the epidermis before being taken up into the symplast by specific ion channels and being pulled by the plant's transpiration stream, which also occurs completely within the boundaries of the apoplast. Similarly, all gaseous molecules emitted and received by plants such as plant hormones and other pheromones must pass the apoplast. The apoplast is also a site for cell-to-cell communication. During local oxidative stress, hydrogen peroxide and superoxide anion can diffuse through the apoplast and transport a warning signal to neighboring cells. In addition, a local alkalinization of the apoplast due to such a stress can travel within minutes
1.1: Explain the uptake of ions by active transport in roots; * Emphasize the role of the endodermis.
Most plants secure the water and minerals they need from their roots. The path taken is: soil -> roots -> stems -> leaves The minerals (e.g., K+, Ca2+) travel dissolved in the water (often accompanied by various organic molecules supplied by root cells).Less than 1% of the water reaching the leaves is used in photosynthesis and plant growth. Most of it is lost in transpiration.
However, transpiration does serve two useful functions: * It provides the force for lifting the water up the stems. * It cools the leaves.
Water and minerals enter the root by separate paths which eventually converge …show more content…
It is interrupted by the Casparian strip in roots, air spaces between plant cells and the cuticula of the plant. Structurally, the apoplast is formed by the continuum of cell walls of adjacent cells as well as the extracellular spaces, forming a tissue level compartment comparable to the symplast. The apoplastic route facilitates the transport of water and solutes across a tissue or organ. This process is known as apoplastic transport. The apoplast is important for all the plant's interaction with its environment. The main carbon source (carbon dioxide) needs to be solubilized in the apoplast before it is taken up by chloroplasts and consumed during photosynthesis. In the roots, ions diffuse into the apoplast of the epidermis before being taken up into the symplast by specific ion channels and being pulled by the plant's transpiration stream, which also occurs completely within the boundaries of the apoplast. Similarly, all gaseous molecules emitted and received by plants such as plant hormones and other pheromones must pass the apoplast. The apoplast is also a site for cell-to-cell communication. During local oxidative stress, hydrogen peroxide and superoxide anion can diffuse through the apoplast and transport a warning signal to neighboring cells. In addition, a local alkalinization of the apoplast due to such a stress can travel within minutes