cell organisation Flashcards
It was important to use the same plant cutting each time to make these
experiments fair
different plants have different sizes / different numbers of
leaves / different sizes of leaves / different plants
take up different amounts of water
Suggest an explanation for the difference between the two masses on experiment with plant
loss of water (from flask with plant) from leaves / plant
1
via transpiration / via evaporation
What is the function of the stomata?
carbon dioxide in
or
oxygen out
or
control water loss
(b) Describe how water moves from roots to the leaves.
by transpiration stream / pull
1
in xylem
Plants lose water through the stomata in the leaves.
The epidermis can be peeled from a leaf.
The stomata can be seen using a light microscope.
Describe how the student might have collected the data.
mount epidermis on a slide
* count stomata in one area
* repeat in four more areas
* repeat method on other surface of leaf
* calculate mean
The plant used in this investigation has very few stomata on the upper surface of the
leaf.
Explain why this is an advantage to the plant.
less water lass by evaporation so it doesnt wilt
(d) Give three environmental conditions that would increase transpiration.
hot
1
ignore bright / sunny conditions
dry / low humidity
1
wind(y
(ii) Explain what happens to the heart in coronary heart disease.
fatty deposits / material in (coronary) arteries
allow correct points made about heart attacks
1
Page 6
narrows / blocks / reduces flow
1
decreases oxygen supply (to heart muscle)
All tools should be washed in disinfectant after using them on plants infected with
TMV.
Suggest why
to kill virus
or
to prevent virus spreading
Scientists produced a single plant that contained a TMV-resistant gene.
Suggest how scientists can use this plant to produce many plants with the
TMV-resistant gene
take cells from meristem
Some plants produce fruits which contain glucose.
Describe how you would test for the presence of glucose in fruit.
use Benedict’s solution
1
glucoses turns solution blue to orange
TMV can cause plants to produce less chlorophyll.
This causes leaf discoloration.
Explain why plants with TMV have stunted growth.
less photosynthesis because of lack of chlorophyll
* therefore less glucose made
so
* less energy released for growth
* because glucose is needed for respiration
and / or
* therefore less amino acids / proteins / cellulose for growth
* because glucose is needed for making amino acids / proteins / cellulose
4
What happens if leaves are left in potometre with water for too long
leaves wilt
1
because plants lose too much water (by evaporation)
1
through the stomata
or
because cells become plamolysed
or
stomata close
controlled by guard cells
to prevent wilting
Having a large number of stomata per mm2
of leaf surface can be a
disadvantage to a plant.
Give one disadvantage.
increased water loss
Very little water was lost when the lower surfaces of the leaves were covered
in grease.
Explain why.
the lower surface has most stomata
1
stomata are now covered / blocked (by grease)
1
so water cannot escape / evaporate from the stomata
