Transport in Plants

Xylem

• is a type of vascular tissue.

• is a dead tissue.

• is composed of xylem vessels.

• is responsible for translocation of organic nutrients.

Xylem vessel

• has an empty lumen with no cell content.

• has end wall degenerated and vessels are joined end to end.

• has thin cellulose cell wall.

• is responsible for the upward transport of water.

The functions of xylem is/are

• to transport of water and mineral salts.

• to translocate organic nutrients.

• to provide support to the plant part by the rigidity of cell wall.

• to provide metabolic energy.

Phloem is

• a dead tissue.

• composed of sieve tube cells and companion cells.

• responsible to provide support to the plant part.

• responsible to transport organic nutrients from leaves to other plant parts.

Phloem is responsible

• for downward translocation of organic nutrients to root cell.

• for upward translocation of minerals to stem tip.

• for providing support to the plant part.

• for providing water to the neighbouring cells.

As compared with xylem vessels, phloem sieve tube cells

• have nuclei.

• have cytoplasm.

• have mitochondria.

• have empty lumen.

A young seedling will turn yellow sooner or later if phloem is damaged. This is because

• no minerals can be transported by the damaged phloem.

• no sugars can be translocated by the damaged phloem to root cells.

• chlorophylls will be disintegrate if phloem is damaged.

• not enough magnesium is transported to new cells for synthesizing chlorophylls.

Upward movement of water by a plant will NOT be affected by extremely high temperature because

• uptake of water by root cells depends on osmosis.

• upward movement of water depends on transpiration pull.

• enzymes are not involved in the uptake and transport of water across the plant.

• xylem is involved and it is a dead tissue.