Topic 1- Plants Flashcards
Recall the method of the investigation of water loss in plants
1) tie a polythene bag around the stem and pot of a plant. (Prevents water from evaporating from the soil in the pot)
2) place it inside a bell jar that stands on a vasalined glass plate. (Prevents exchange of gases with the outside of the jar)
3) leave in partly exposed, sunny site
4) observe the bell jar after 24 hours
What is the result and conclusion of the investigation of water loss in plants?
Result- droplets of water have formed on the inside of the bell jar.
Conclusion- the water from the inside of the jar must’ve come from the plant because there no water can pass into the jar or evaporate from the soil.
Recall the method of the investigation of the rate of transpiration from a plant cutting
1) cut a shoot from a plant and place it in a measuring cylinder
2) pour a thin layer of oil over the water.(prevents evaporation of water directly from the surface of the water)
3) weigh the whole apparatus
4) record results in a table
5) leave for a set period of time
6) weight the apparatus again
7) calculate the change in mass
What is the result and conclusion of the investigation of the rate of transpiration from a plant cutting?
Result- the mass of the apparatus will have decreased.
Conclusion- water has been lost from the measuring cylinder. Water couldn’t evaporate directly from the surface of the water. It must have travelled up the stem of the plant and evaporated from the leaves. (Transpiration)
What are the factors that affect the result of the investigation of the rate of transpiration from a plant cutting?
Humidity
Movement of air
Healthy cuttings will lose water steadily
Unhealthy cuttings may not work as well
Recall the method of the investigation of stomata. (Epidermal impression of a leaf)
1) the upper surface of the leaf is painted with a thin layer of clear nail varnish.
2) leave for 10-15 minutes to allow the varnish to dry
3) remove the layer of varnish by attaching clear sticky tape to it, peeling it from the leaf surface and sticking it to a microscope slide.
4) observe the slide with. Microscope and count the number of stomata in the field of view.
5) repeat for lower part of leaf and compare results
What is the result and conclusion of investigating stomata?
Result- the lower surface contains the highest number of stomata.
Conclusion- the function of the stomata is to allow gas exchange between the cells of the leaf and the air. However, water is also lost by diffusion through open stomata. Having most of the stomata on the lower surface of the leaf shades them from the heat of the sun, and is an adaptation to reduce water loss.
Name five pieces of equipment needed for the investigation of water loss in plants and state what you may experiance
Bell jar Glass plate Vaseline Plant Polythene bag Experience water droplets at the top of the bell jar
What is a stomata?
Pores in the surface of the leaf that allow water to pass out.
They allow gaseous exchange to occur.
What is a stoma?
A gap in the guard cell that allows water to pass out
Recall the method of the investigation of comparing water loss from leaves
1) four leaves are removed from a green plant and their stem’s are covered in vaseline. (Prevents water loss from the cut ends)
2) leaf 1- vaseline on upper surface of leaf
Leaf 2- vaseline on lower surface of leaf
Leaf 3- vaseline on upper and lower surface of leaf
Leaf 4- no vaseline
State the appearance and explanation of the leaf that has vaseline covering the upper surface of the leaf during the investigation of water loss from leaves
Appearance- slightly wrinkled
Explanation- there are less stomata on the upper surface of a leaf. The vaseline has only prevented a small amount of water loss.
State the appearance and explanation of the leaf that has vaseline covering the lower surface of the leaf during the investigation of water loss from leaves
Appearance- almost fresh
Explanation- stomata found on the lower surface of the leaf. The vaseline has prevented most of the water loss.
State the appearance and explanation of the leaf that has vaseline covering the upper and lower surface of the leaf during the investigation of water loss from leaves
Appearance- fresh
Explanation- the vaseline prevented water loss through both surfaces of the leaf
State the appearance and explanation of the leaf that has no vaseline during the investigation of water loss from leaves
Appearance- wrinkled and dried out
Explanation- water had been lost through stomata of both surfaces
What are the three environmental factors affecting transpiration?
Temperature
Humidity
Wind speed
How does the temperature affect transpiration?
Temperature increases, water molecules have more kinetic energy. Therefore, move faster , causing an increase in transpiration.
How does humidity affect the rate of transpiration?
An increase of humidity means the lower the concentration gradient of water between air and the intercellular spaces in the spongy layers of a leaf. A decrease of diffusion of water out of stomata
How does wind speed affect the rate of transpiration?
An increase of wind speed carries away more water vapour from near the leaf’s surface and increases the rate of diffusion of water vapour out of the stomata
Recall the method of the investigation of using a simple potometer to measure transpiration rate
1) set bubble to 0 by using the tap to release water from the water reservoir.
2) measure the time taking for the bubble to move a set distance.
OR
measure how far the bubble moves in a set period of time.
3) record results
4) repeat experiment
What happens during the investigation of using a simple potometer to measure transpiration rate?
An air bubble is introduced into the capillary tube at the start.
As water evaporates through the stomata of the leaves, water is drawn up the capillary tube causing the bubble to move
What does the wax cuticle allow the plant to do?
Reduce water loss
What doe the pallisade layer contain?
Chloroplasts for photosynthesis
In the structure of a leaf, what does the air space allow the leaf to do?
Allow gaseous exchange
What do the xylem transport?
Water
What do the phloem transport?
Sugar
What do the spongy layer contain?
Large air spaces to allow gaseous exchange
What is the transpiration stream?
The constant flow of water through a plant
Describe the 7 steps of the transpiration stream
1) water enters the plants through root hair cells by osmosis.
2) water moves from cell to cell in the root by osmosis.
3) water moves into the xylem by osmosis.
4) water molecules stick together and this causes water to be pulled up the xylem as a column.
5) water moves from cell to cell by osmosis.
6) water evaporates from some of the leaf cells, causing more water to be pulled up the xylem.
7) water diffuses from the air spaces in the spongy layer out of the stomata into the air
How does water enter the plant?
Water enters the plant from an area of high water concentration to an area of low concentration in the root hair cell, through a partially permeable membrane.(osmosis)
What allows the root cell to take in more water faster?
The increased surface area
How are minerals up taken by the plant when the plant has a higher concentration?
Active transport
What are factors that affect active transport?
>needs energy >energy is released during respiration Any factor that effects respiration affects active transport: > glucose concentration > oxygen > temperature > toxic substances
What do phloem vessels transport?
Transport sugar and other substances that are produced by cells to all other parts of the plant
What do xylem vessels transport?
Transports water and mineral ions from roots to the rest of the plant
What are groups of phloem and xylem vessels called?
Vascular bundles
What are the phloem’s functions?
Carries sugar from the photosynthetic areas to other parts of the plant.
Sugar is moved to other parts of the plant for use in respiration and converted into starch for storage.
What are the xylem’s functions?
Transport water from the roots to the rest of the plant
Transport minerals such as KPN around the plant dissolved in water.
Support the plant. Xylem vessels in the shoots and roots of mature plants are inflexible and strong to give support to the plant.
Recall the method for the investigation of a dye through a flowering plant
1) take a white flower with a long stalk e.g. A chrysanthemum and cut the stalk carefully lengthwise.
2) put each half of the stalk into a measuring cylinder containing either plain water or water to which food dye has been added.
3) tape the measuring cylinders to the plastic tray so that they don’t fall over.
4) leave the flower for a few hours
5) observe where the dye ends up in the flower head
Give an explanation of the results obtained of the investigation into the movement of a dye through a flowering plant
Water and dye are pulled up through xylem vessels. When they reach the petals, the water evaporates from pores in the petal surface but the dye remains in the cells of the petals. The petal became coloured as dye accumulates in them. This procedure could be useful for producing quantities of unusually coloured flowers
What is water important for, for plants?
Photosynthesis
Transport of minerals
Support
How does water support the structure of a plant?
The pressure of the vacuoles pushing against the cell walls keep the cells turgid
What are the minerals needed for healthy plant growth and what are the signs of deficiency?
Nitrogen- poor growth
Phosphate- poor root growth
Potassium- yellow leaves
