Transport in plants
Plants use carbon dioxide as their source of carbon and light as their source of energy.
Transport systems are needed for:
Moving substances from where they are absorbed to where they are needed eg.
Water and mineral ions are absorbed by roots and transported in the xylem to
other parts of the plant
Moving substances from where they are produced to where they are needed
for metabolism. Eg. Sugars are produced in leaves, but glucose is needed by all
parts of the plant for respiration and for converting into cellulose for making
cell walls. Glucose is moved by phloem as part of the sucrose molecule
Moving substances to different parts of the plant for storage eg. To move
sugars into a potato tuber to store in the form of starch
Carbon dioxide: photosynthetic plant cells require carbon dioxide during daylight.
Most photosynthetic tissue is in leaves, which are adapted to absorb as much carbon
dioxide as possible by having large surface areas and being flat.
Oxygen: all plants cells require oxygen for respiration, but cells that are
photosynthesising produce enough oxygen for their own needs as it is a waste
product of photosynthesis. The branching shape of plants and network of air spaces in
the plant body provide a large surface area for effective absorption of oxygen by
diffusion.
Consequently, there is no need for a transport system for gases in plants as oxygen
and carbon dioxide are able to diffuse into and out of each cell easily.
Xylem and phloem
Xylem carries mainly water and inorganic ions (mineral salts) from roots to the parts
above the ground. The xylem sap can only move in one direction, from roots to the
rest of the plant.
Phloem carries substances made by photosynthesis from the leaves to other areas of
the plant. Phloem sap can move in different directions at the same time.
Root:
Plants use carbon dioxide as their source of carbon and light as their source of energy.
Transport systems are needed for:
Moving substances from where they are absorbed to where they are needed eg.
Water and mineral ions are absorbed by roots and transported in the xylem to
other parts of the plant
Moving substances from where they are produced to where they are needed
for metabolism. Eg. Sugars are produced in leaves, but glucose is needed by all
parts of the plant for respiration and for converting into cellulose for making
cell walls. Glucose is moved by phloem as part of the sucrose molecule
Moving substances to different parts of the plant for storage eg. To move
sugars into a potato tuber to store in the form of starch
Carbon dioxide: photosynthetic plant cells require carbon dioxide during daylight.
Most photosynthetic tissue is in leaves, which are adapted to absorb as much carbon
dioxide as possible by having large surface areas and being flat.
Oxygen: all plants cells require oxygen for respiration, but cells that are
photosynthesising produce enough oxygen for their own needs as it is a waste
product of photosynthesis. The branching shape of plants and network of air spaces in
the plant body provide a large surface area for effective absorption of oxygen by
diffusion.
Consequently, there is no need for a transport system for gases in plants as oxygen
and carbon dioxide are able to diffuse into and out of each cell easily.
Xylem and phloem
Xylem carries mainly water and inorganic ions (mineral salts) from roots to the parts
above the ground. The xylem sap can only move in one direction, from roots to the
rest of the plant.
Phloem carries substances made by photosynthesis from the leaves to other areas of
the plant. Phloem sap can move in different directions at the same time.
Root:
