B2 - SPECIFICALLY : PLANTS Flashcards
What does the epidermal tissue do?
Covers the whole plant
What does the palisade mesophyll tissue do?
Most photosynthesis happens here
What does the spongy mesophyll tissue do?
Contains big air spaces to allow gases to diffuse in and out of cells.
What do xylem and phloem do?
Transport food and water around the plant.
What is the meristem tissue?
Found at the growing tips of roots and shoots and is able to change into lots of different types of plant cells.
Epidermal tissues are covered with..
A waxy cuticle which helps to reduce water loss by evaporation.
Upper epidermis is…
Transparent so the light can pass through it to the palisade layer
Palisade layer has…
Lots of chloroplasts. Near to the top of the leaf so they can get the most light.
Xylem and phloem form…
A network of vascular bundles which deliver water and other nutrients and take away glucose produced by photosynthesis.
The tissues of leaves are adapted for…
Gas Exchange. Lower epidermis is full of stomata which let CO2 diffuse directly into leaf.
Phloem tubes transport…
Food for immediate use or for storage. This process is called TRANSLOCATION.
Phloem tubes are made of…
Elongated living cells with small pores in the end walls to allow cell sap to flow through.
Xylem tubes transport…
Water and mineral ions from the roots to the stem and leaves.
Xylem tubes are made of…
Dead cells joined end to end with no end walls between them and a hole down the middle. Strengthened with a material called lignin.
The movement of water from roots through Xylem is called…
The transpiration stream.
Transpiration is caused by…
This evaporation creates…
The evaporation and diffusion of water from a plants surface. This evaporation creates a slight shortage of water so more water is drawn up through xylem. Constant transpiration stream of water.
Transpiration rate is affected by:
Light intensity - brighter = more stomata close when it’s darker
Temperature - warmer = faster
Air flow - better the air flow the greater. Water vapour is slept away maintaining a low concentration of water in the air outside the leaf.
Humidity - the drier the air around a leaf, the faster transpiration happens.
You can estimate the rate of transpiration by…
Measuring the uptake of water by a plant - because you can assume the water update is directly related to water loss by the leaves.
How to measure the rate of transpiration?
Set up a photometer and record the starting position of the air bubble - start a stopwatch and record the distance moved by the bubble per unit time.
How are guard cells adapted?
They have a kidney shape which opens and closed the stomata.
Thin outer walls and thickened inner walls makes the opening and closing work.
Sensitive to light = close at night to save water without losing photosynthesis.
What happens when a plant is short for water?
Or has lots of water?
When plant is short of water, guard cells lose water and become flaccid making stomata close - prevents too much water vapour escaping.
When the plant has lots of water, the guard cells fill with it and go plump and turgid . Makes stomata open so gases can be exchanged.
