Table of Contents
- 1 Why do we have to boil the leaf in water first before boiling it in alcohol?
- 2 Why ethanol containing the leaf is not directly boiled?
- 3 What happens to leaf when boiled in water?
- 4 Why is a leaf treated with boiling water and ethanol before it is subjected to the iodine test?
- 5 Why must the leaf be rinsed in water?
- 6 Why do we soak the leaf in water?
- 7 Why must the leaf be freshly picked?
- 8 What is the main reason for boiling green leaf in methylated spirit is?
- 9 Why do we need to boil the leaf first in water?
- 10 What happens to water when you boil it?
Why do we have to boil the leaf in water first before boiling it in alcohol?
This procedure kills a leaf, disrupts the cell membranes and softens the cuticle and cell walls. This makes it possible to extract the chlorophyll with hot ethanol and also allows the iodine solution to penetrate the cells and react with any starch present.
Why ethanol containing the leaf is not directly boiled?
This is because heating the green leaf directly on the flame, or boiling it in water will kill the leaf as the direct heat will damage the cells of the leaf. On the other hand, boiling the leaf in alcohol only causes the chlorophyll to break down, and the leaf gets decolourised as it loses its green colour.
What happens to leaf when boiled in water?
Boiling the leaf damages the membranes of the cells allowing the pigments to be leached out of the cells. After leaching, the iodine solution added will combine with any starch in the cells producing a dark purple to black pigment in the leaf.
Why is it important to boil the leaf?
We boil the leaf in alcohol when we are testing it for starch because to remove the green pigment chlorophyll present in it. Hence to remove the green pigment present in the leaf we boil the leaf in alcohol when we are testing it for starch.
Why do you have to boil the leaf in water the second time?
Why do you have to boil the leaf in water the second time? To soften the leaf.
Why is a leaf treated with boiling water and ethanol before it is subjected to the iodine test?
Starch testing add the leaf to boiling ethanol in a water bath for a few minutes (the boiling ethanol dissolves the chlorophyll and removes the green colour from the leaf – it turns white so it is easy to see the change in colour) add iodine solution from a dropping pipette.
Why must the leaf be rinsed in water?
Explain the significance of rinsing the leaf in water. The leaf was rinsed in water to rehydrate it. Iodine solution is an aqueous solution of iodine/potassium iodie – potassium tri-iodide; water is needed inside the leaf to enable penetration by diffusion.
Why do we soak the leaf in water?
heat a plant leaf in boiling water for 30 seconds (this kills the leaf, stopping any chemical reactions) add the leaf to boiling ethanol in a water bath for a few minutes (the boiling ethanol dissolves the chlorophyll and removes the green colour from the leaf – it turns white so it is easy to see the change in colour)
Why is it necessary to boil the leaf in alcohol during the experiment to prove the importance of sunlight in photosynthesis?
Answer: Because the hot water kills the leaf and the alcohol breaks down the chlorophyll, taking the green color out of the leaf. When you put iodine on the leaves, one of them will turn blue-black and the other will be a reddish-brown.
Why do you need to boil the plant leaf in water?
Iodine solution is used to test leaves for the presence of starch. You need to: heat a plant leaf in boiling water for 30 seconds (this kills the leaf, stopping any chemical reactions)
Why must the leaf be freshly picked?
Freshly picked raw leaves in particular are teeming with activity and vitality. Kirlian photography can measure this vitality, or life force, and it reduces when an individual plant or animal becomes sick or very old. When you eat fresh raw leaves you are taking that vitality into you.
What is the main reason for boiling green leaf in methylated spirit is?
Answer. Because methylated spirit is analcohol and when we boil the leaf in alcohol we are testing it for starch as this would remove chlorophyll from the green leaf. Deolourish leaf is than treated with iodine and blue black colour is obtained which confirms the presence of starch in green portion of leaf.
Why do we need to boil the leaf first in water?
Why do we need to boil the leaf at first in water and then in a methylated spirit? Because Methylated spirit is analcohol & when we boil the leaf in alcohol we are testing it for starch as this would remove the chlorophyll from the green leaf.
Why is leaf boiled in methylated spirits?
Why is leaf boiled in methylated spirits? Because Methylated spirit is an alcohol & when we boil the leaf in alcohol we are testing it for starch as this would remove the chlorophyll from the green leaf. Deolourish leaf is than treated with iodine & a blue black color is obtained which confirms the presence of starch in the green portion of leaf.
What happens when ethanol is heated in hot water?
After a few minutes, the parts of the leaf that contain starch turn blue-black. Note that ethanol is heated using a hot water bath. Ethanol boils at 78°C, so a tube of it boils when placed in a beaker of hot water.
What happens to water when you boil it?
In the simplest terms, when you boil water you create steam. Since solid particles don’t evaporate, the steam is pure water. Simply collect that water as it drips and you’d have purified water. When all the water evaporates, you’ll be left with a pile of solids. Think back to the times when you forgot to turn off the stove while boiling soup.