Plant Biology Flashcards
WHAT IS NEEDED FOR THE HEALTHY GROWTH OF SEEDLINGS?
Cress seeds are very easy to grow. Normally you would keep them well watered in a warm, light position with plenty of oxygen available.
What is the method to finding out what conditions are best for crowing seeds
- Take five boiling tubes and place a small piece of cotton wool at the bottom of each.
- Set up the five tubes so that the seeds are kept in the following conditions:
A Damp, warmth, light, and air
B Dry, warmth (15 - 20°C), light and air C Damp, cold (2 - 4°C), air, dark D Damp, warmth, dark, air
E Damp, warmth, light, no oxygen (use previously boiled water and then pour on a thin layer of cooking oil on top of the seeds). - Place exactly ten cress seeds on the cotton wool in each tube.
What was the appearance of the cress with
Dampness, warmth, light and air?
And what % germinated.
Bright green. Tall. Seeds swollen and germinated. Big healthy shooted leaves.
100%
What was the appearance of the cress with
Dry, warmth, light and air?
And what % germinated.
None germinated. They were still dry shrivelled up seeds. Without moisture they cannot grow
What was the appearance of the cress with
Dampness, coldness, darkness and air?
And what % germinated.
No leaves. Small shoots. Seeds are swollen. Only beginning to germinate.
60%
What was the appearance of the cress with
Dampness, warmth, dark and air?
And what % germinated.
Pale yellow leaves. Very tall. Seeds are semi swollen. Tall yellow shoots.
90%
What was the appearance of the cress with
Dampness, warmth, light and no oxygen?
And what % germinated.
Swollen seeds. No shoots. None germinated.
What are the vital conditions for germination
Damp, warmth, air
Why do plants need light to healthily grow
The light means they will have nice green healthy leaves. This is necessary for photosynthesis.
Equation for photosynthesis
Light
Carbon dioxide + water ————————-> glucose + oxygen
Chlorophyll
What is the method when testing leaves for starch
- De-starch the plant by placing it in the dark for 48hrs. This will mean it will use up all its starch reserves so that any starch produced will be as a result of the experiment.
- Using tinfoil cover half the surface of a leaf from a normal plant.
- Leave under the light for 2-3 days.
- Carefully cut your leaf from the plant, and another leaf from a variegated geranium.
- Use forceps to dip both leaves into a beaker of boiling water for about 30s. This stops the chemical reactions in the cells of the leaf.
Place the leaves into separate boiling tubes.
Pour enough alcohol into each boiling tube to cover the leaves. - Put the tubes into your beaker of boiled water. It will still be very hot. Leave for about 10 minutes. Observe what happens to the alcohol and the leaves.
Remove each leaf with forceps. Dip them in the hot water to soften them.
Place the leaves on a white tile. Add a few drops of iodine solution to each leaf.
Record the colour of each leaf.
What effect does the alcohol have on the leaves
It extracted the chlorophyll making the ethanol a green solution. The leaf turned whiter/light yellow
Why was it necessary to remove the chlorophyll before using the iodine?
So that you can clearly see the colour change.
What difference did you observe in the colour of the leaf where the black card had been?
The coloured part stayed the same and didn’t photosynthesise because it wasn’t exposed to any sunlight. Where there was no card the leaf went blue black with iodine.
Explain the difference in the leaf
There was no starch where it was covered so it wasn’t able to Photosynthesise. The part wich had light was able to photosynthesise to produce starch.
Iodine + starch → blue/black
lots of light = lots of photosynthesis = Starch made.
