Required Practical 8

Question 1

You were told not to put the leaf midrib and leaf stalk in the blender, why?

Answer 1

No chloroplasts in the midrib

Question 2

What was the purpose of using a blender

Answer 2

To break open the cells and release organelles

Question 3

You were told to wrap tube A in aluminium foil, explain why

Answer 3

So light couldn’t reach it. As a control

Question 4

Name a part of the chloroplast where this transfer of electrons takes place

Answer 4

Granum

Question 5

DCPIP is decolourised more slowly when ammonium hydroxide is added. Use your knowledge of the light dependent reaction to suggest a reason why.

Answer 5

There is competition between DCPIP and ammonium hydroxide to accept the electrons from chlorophyll

Question 6

Some weed killers are substances that accept electrons during photosynthesis. Suggest how these substances kill weeds.

Answer 6

Slows the light dependent reactions so less ATP and NADPH are produced so it slows the light independent reaction

Question 7

Suggest one disadvantage of using these weed killers on weeds growing in a crop. Explain your answer.

Answer 7

The substance in weed killer is absorbed by the crop and reduces growth. Weed killer slows respiration

Question 8

Explain why it was important that these water potentials were the same.

Answer 8

So osmosis doesn’t happen and chloroplast doesn’t burst

Question 9

Explain how chemicals which inhibit decolorisation of DCPIP could slow the growth of weeds

Answer 9

Less ATP is produced so less GP is made