M5 Exam Question

Question 1

Crops use light energy to produce photosynthetic products.
Describe how crop plants use light energy during the light-dependent reaction. (5)

Answer 1

1. Excites electrons / electrons removed (from chlorophyll);
2. Electrons move along carriers/electron transter chain releasing
   energy;
3. Energy used to join ADP and Pi to form ATP;
4. Photolysis of water produces protons, electrons and oxygen;
5. NADP reduced by electrons / electrons and protons / hydrogen;

Question 2

After harvesting, the remains of crop plants are often ploughed into the soil.
Explain how microorganisms in the soil produce a source of nitrates from these remains (5)

Answer 2

1.Protein/amino acids/DNA into ammonium compounds /
ammonia;
Accept: any named nitrogen containing compound e.g. urea.
2. By saprobionts;
Accept: saprophytes.
3. Ammonium/ammonia into nitrite;
4.Nitrite into nitrate;
5.By nitrifying bacteria/microorganisms;