TISSUES, ORGANS & ORGAN SYSTEMS

Plant Organs

Plant Organs

Plants are also multicellular organisms and they also tend to be made up of differentiated cells, tissues and organs.

Tissues

Three types of tissue found in plants can be seen in the table below.

Tissue type Function
Epidermal tissueMesophyllXylem and phloem This covers the plantThis carries out photosynthesisThese transport substances throughout the plant

Organs

Three types of organ that can be found in a plant include:

  • stems
  • roots
  • leaves

A green plant’s leaves have been adapted for photosynthesis and they exhibit a number of features to optimise the amount of sunlight and carbon dioxide they can absorb.

Feature Function
ChlorophyllStomataVein networkThin structure

Large surface area

This is important for absorbing sunlightThese allow carbon dioxide to diffuse into the leafThis provides physical support and transports water and carbohydrates around the plantThe short distance means carbon dioxide can diffuse faster into the cells

The larger area optimises the amount of sunlight that can be absorbed into the leaf

As you would expect, the internal structure of a leaf is also well designed to optimise the efficiency of photosynthesis.

Feature Function
Waxy cuticleUpper epidermisPalisade mesophyll

Spongy mesophyll

Stoma

Guard cells

Lower epidermis

This provides protection for the cell but it’s thin structure still allows light energy to be absorbedThis layer is thin and transparent which allows the light to reach the cells more easilyThis layer contains a large number of chloroplasts which are needed to absorb the light energyAir moving through the stoma can easily pass through this layer due to the large number of air spaces

These allow carbon dioxide to enter the leaf and are positioned at the underside to help prevent excess water being lost by transpiration

These regulate the amount of water being lost via transpiration from the leaf

This is where the majority of stoma are located