Tissues And Organs In Plants Flashcards
What does the epidermis do?
It protects the surface of the leaf. It is transparent, which allows light to pass through to the photosynthetic cells below.
What covers the upper epidermis and what is its function?
Athin layer of oily material called the waxy cuticle. It reduces the evaporation of water from the surface of the leaf, which helps to prevent the leaf from drying out.
What are the names of the tiny pores that the lower epidermis has?
They’re called Stomata and they allow carbon dioxide to enter the leaf and oxygen to leave. They also help to control the amount of water vapour that can pass out of the leaf.
What are on either side of the stomata?
There are guard cells.
What is below the upper epidermis?
The palisade mesophyll. This consists of palisade cells, which are packed full of chloroplasts. Most photosynthesis takes place here.
What do chloroplasts do?
They contain chlorophyll, which absorbs the light energy needed for photosynthesis.
What is under the palisade mesophyll?
The spongy mesophyll, which is full of air spaces, which allow carbon dioxide to diffuse from the stomota through the spongy mesophyll to the palisade cells.Oxygen also diffuses from the palisade cells through the spongy mesophyll to the stomata.
What does xylem tissue do?
It transports water from the roots to the stem and leaves. The xylem also transports dissolved mineral ions. These include magnesium which is used to make chlorophyll.
What does phloem tissue do?
Phloem Tissue transports dissolved sugars produced by photosynthesis from the leaves to the rest of the plant.
What is the movement of sugars and other molecules through phloem tissue called?
Translocation
What is the function of meristem tissue?
Meritem tissue is tissue that we find at growing tips, e.g. shoots and roots. They contain stem cells. These can differentiate into different types of plant tissue.
Where do the sugars that the phloem transports go?
They go to the rest of the plant, including to the growing areas of the stems and roots, where the dissolved sugars are needed for making new plant cells. Food is also transported to the storage organs where it provides an energy store for the winter.
Why are young trees particularly vulnerable to damage by animals?
Because the xylem makes up the bulk of the wood, and the phloem is found in a ring just underneath the bark. If a complete ring of bark is eaten, transport in the phloem stops and the tree will die.
What do the stomata and guard cells control?
Gas exchange and water loss
What controls the size of the stomata and their opening and closing?
Guard cells
