Why do humid conditions decrease the rate of transpiration?
Humid conditions decrease the rate of transpiration because water vapour diffuses more rapidly into dry air then humid air.
Why does an increase in light intensity increase the rate of transpiration?
An increase in light intensity increase the rate of transpiration because the stomatal pores are only open for water to leave the leaf when it is light.
Name parts of the organ system used to transport materials around a plant.
Plants transport materials through the xylem and phloem in the roots, stem and the leaves.
Where on a leaf would you find stomatal pores?
Stomatal pores are found on the bottom surface of a leaf.
What 4 things does a plant need for photosynthesis?
These are the things that plants need for photosynthesis:
- carbon dioxide
- light (a source of energy)
- chlorophyll (the green pigment which captures the energy from light)
What do plants make from photosynthesis?
These are the things that plants make by photosynthesis:
What happens to the oxygen made in photosynthesis?
Oxygen can be used in respiration by other plant cells.
Any oxygen not needed is released into the air from the leaves.
List 4 ways in which the leaf is adapted for photosynthesis.
There are 4 things
- water (brought by xylem in the veins)
- carbon dioxide (diffuses though stomatal pore and mesophyll tissue)
- light (passes through transparent epidermis)
- chlorophyll (in palisade cells lined up at top of cell to get the light)
What does plant meristem tissue do and where is it found?
Plant meristem tissue is found at the tips of roots and shoots. It is made up of rapidly dividing cells which make the plant grow.
What is the word equation for photosynthesis?
The word equation for photosynthesis is carbon dioxide + water → glucose + oxygen
Sometimes people add light and chlorophyll on top of the arrow to show that it is necessary but is not used up or made by the reaction.
Why do windy conditions increase the rate of transpiration?
Windy conditions increase the rate of transpiration because wind moves water vapour away from the leaf leaving dry air behind. This dry air can hold more water vapour. This is called maintaining a concentration gradient.
What does a potometer measure?
A potometer measures the rate of transpiration of a plant. We use it to study how different factors affect the rate.
How do plants store extra sugar?
Plants store extra sugar as starch. This is insoluble and so cannot be dissolved and washed away.
Name 3 ways that plants reduce water loss.
Plants reduce water loss by
- having a waxy layer on their leaves
- having stomatal pores on the protected underside of the leaf only
- closing stomatal pores at night when the plant is not photosythesising.
How can you show that water moves up a plant through the xylem tissue?
You can show that water moves up a plant through the xylem tissue by putting celery into water which contains dye. After a few hours you will be able to see the dye has stained the xylem if you cut the celery high up on the stem. If you leave it longer it will move into the leaves.
What is the job of the stomatal pores?
Stomatal pores are tiny holes (you can see them with a light microscope) which allow the movement of carbon dioxide and oxygen gases in and out of leaves.
Water vapour also leaves the leaf this way.
What is in a vascular bundle?
A vascular bundle contains xylem and phloem tissue. It carries materials dissolved in water around the plant and is sometimes called a vein.
How does water get from the roots to the top of a tall tree?
Water gets from the roots to the top of a tall tree by transpiration.
This means that the water is in one continuous column of liquid from root hair cell up the xylem to the leaf. It moves when the water at the top end of this column evaporates from the mesophyll and diffuses out of the leaf.
What is the difference between transpiration and translocation?
Transpiration is the flow of water from root hair cell though the xylem in the root, stem and leaf.
Translocation is the movement of food molecules around a plant through phloem tissue.
What is the glucose produced in photosynthesis used for?
The glucose produced in photosynthesis is used
- as a fuel in respiration
- to make other substances
- stored as starch
- it can be used to build new parts of the plant
- to make fruit sweet.
What is the name of the chemical that plants use to capture light energy need for photosynthesis?
The chemical which absorbs the light energy needed to make photosynthesis happen is called chlorophyll. It is a green substance which is held inside plant cells in small objects called chloroplasts.
How are xylem tissues adapted to it job/ function?
Xylem vessels are involved in the movement of water through a plant from its roots to its leaves (transpiration).
The adaptations of the xylem are
- hollow tubes of dead cells so there is nothing to break the column of water from root to leaf
- thick, cellulose cell walls strengthened with lignin to stop the sides collapsing.
How is phloem tissue/cells adapted to do their job/ functions?
Phloem's job is to move dissolved sugars around the plant. It is made of columns of living cells. The cell walls of these cells do not completely break down, but instead form small holes at the ends of the cell. The ends of the cell are referred to as sieve plates. The connection of phloem cells effectively forms a tube which allows dissolved sugars to be transported.
Leaf spongy mesophyll cells are specialised to do an important job. What is it?
Leaf spongy mesophyll cells have big air spaces and a large surface area to make the diffusion of gases easier/faster.
Give 4 factors that affect the rate of transpiration.
The factors that affect the rate of transpiration are
- wind speed
- light intensity
How is the leaf epithelial layer (skin) adapted for photosynthesis?
The leaf epithelial layer (skin) is adapted for photosynthesis by being transparent. This means that it lets light through to the palisade layer below so photosynthesis can happen.
Why does heat increase the rate of transpiration?
Hot conditions increase the rate of transpiration because
- when it is hot more water evaporates from the leaf
- diffusion happens faster with higher temperatures because particles vibrate more quickly.
How are root hair cells adapted to do their job better?
Root hair cells are adapted for the efficient uptake of water by osmosis, and mineral ions by active transport by having a large surface area.
What is the job of phloem tissue?
The job of phloem tissue is to carry sugars from photosynthesis in the leaves around the plant.
How do gases get in and out of a plant?
Gases get in and out of a plant by diffusing through the open stomatal pores.