Organisation - Plants / Transpiration / Translocation Flashcards
What is the function of epidermal tissue in the plant?
Where is the located?
It covers the whole plant.
The tissues are covered with waxy cuticle which helps to reduce water loss by evaporation.
It’s the very top layer.
What is the function of the palisade mesophyll tissue in the plant?
This is where most of the photosynthesis occurs as it contains lots of chloroplasts.
Located near the top so it can photosynthesis more.
What is the function of spongy mesophyll tissue?
It contains air spaces to allow gases to diffuse in and out of the cells which increases the rate of diffusion of gases.
What is the function of xylem and phloem in the plant?
They form a network of vascular bundles to transport water, mineral ions and food around the water and take away glucose produced by photosynthesis.
They support the structure of the plants.
What is the function of the meristem tissues?
Where is it located?
It allows plant cells to differentiate (change) into different types so they are able to grow.
It is found in the growing tips of roots and shoots
What is the function of lower epidermis?
It has lots of little holes called stomata, which allows CO2 to diffuse directly into the leaf.
The guard cells control the opening and closing of the stomata, according to the environmental conditions.
Where does translocation occur in the plant and how?
Translocation occurs in the phloem tubes.
* It’s made up of elongated living cells with small pores in the end walls to allow cell sap to flow through
* It transports food (mainly dissolved sugars) made in the leaves to the rest of the plant for immediate use or storage
* The transport is in both directions.
Where is transpiration stream and what does it do in the plants?
Transpiration occurs in the xylem tissues.
* It’s made up of dead cells joined end to end with no end walls between them.
* It has a hole in the middle which is straightened with a legnin
* It carries water from the roots adn to the stem and leaves.
Takes substances up only
What is transpiration?
- It’s the loss of water from the plants at the leaves caused by evaporation and diffusion of water from plant’s surface.
- It creates a slight storage of water in the leaf, so more water is drawn up from the rest of the plant through the xylem vessels to replace it.
- Due to water drawn up from the roots, there’s a constant transpiration stream of water through the plant.
Why does the water escapes from the leaves during transpiration?
- As there’s more water inside the plant than in the air outside, the water escapes the leaves through the stomata by diffusion.
Name the four factors that affect the transpiration rate.
- Light intensity
- Temperature
- Air flow
- Humidity
How does light intensity and temperature affects the rate of transpiration?
Light intensity:
The more and brighter the light, the greater the transpiration rate, meaning the somata (where the water escapes) closes in the dark and no exchange of gases happen and very little water can escape, which lowers the transpiration rate.
Temperature:
During warm temperatures, the water particales have a lot more energy to evaporate and diffuse out of stomata, meaning a faster transpiration rate.
How does air flow affects the transpiration rate?
If the air flow is poor around the leaf, the water vapour only surrounds the leaf and doesn’t move away, meaning there’s high concentration of water particles outside the leaf AND inside the leaf, which makes the rate of diffusion of water slower as well as the rate of transpiration.
Good air flow meaning water vapour is swept away from outside the leaf, and the diffusion can happen at a faster rate.
How does humidity affect the transpiration rate?
If the air is humid, there’s already a lot of water in the air, which slows the rate of diffusion from inside to outside of the leaf.
The leafs need dry air around them for a faster transpiration rate.
What are guard cells?
They are adapted for gas exchange and controlling water loss within a leaf.
