Plant tissues, organs and organ systems Flashcards
Identify the different types of tissue on a leaf
- Epidermal tissue
- Palasade mesophyll
- Spongy mesophyll
What is the epidermis? Relate its structure to its function
- The outer layer of a plant
- Made of a single layer of cells to allow diffusion of gases.
- Usually clear to allow light to pass through to the choloplasts in the pallisade layer below it
- tough to protect the plant and prevent water loss
What is the pallisade mesophyll layer? Relate its structure to its function
- A tissue which is under the epidermis.
- Near the surface, it contains tightly packed regular shaped cells which have more chloroplasts than other plant cells, this is so that they can use sunlight to produce energy for the plant.
What is the spongy mesophyll layer? Relate its structure to its function.
- It is a tissue found under the pallisade mesophyll layer
- The cells are more spherical which gives them a greater surface area and gaps between them which contain air, this allows them to maximise gaseous exchange.
How do gases enter and leave the leaves of a plant?
The top and underside of a leaf contains pores called stomata. There are a lot more stomata on the underside. Each stoma has a pair of guard cells which control the size of the opening allowing more or less gas to enter or leave the leaf.
What is the meristem and what is its function?
This is region of the plant which produces stem cells and therefore where much of the plants growth occurs. They are mainly found in the tips of the shoots and ends of the roots.
What is a root
Roots are plant organs and are found below the soil. Usually white as they do not contain chlorophyll they absorb water by osmosis and minerals by active transport. Some roots can store starch. They anchor the plant into the ground. The roots have root hairs which are specialised cells and absorb water and minerals.
What is a shoot?
The stem, leaves and buds at the tip of a young plant. It contains meristem at the tip, here new cells are produced which allow the shoot to grow towards the light.
What is a leaf?
It is a plant organ and the major site of photosynthesis. The leaves have stomata which open and close to regulate the loss of water.
What is transpiration?
The loss of water through leaves is called transpiration. This allows the plant to pull water up through the from the roots and through the rest of the plant in an unbroken stream.
What are the functions of transpiration?
- To provide water for the plant cells to keep them turgid
- To provide water for photosythesis in cells
- To transport minerals to the leaves
What is the function of the xylem tissue?
It transports water up through the stem of the plant from the roots to the leaves
What is the function of the phloem cells?
They transport the sugars made in photosythesis from the leaves to all of the other parts of the plant.
What is translocation in plants?
It is the movement of dissolved sugars through the plant in the phloem cells.
