Energy & Ecosystems

Question 1

Arbuscular mycorrhiza fungi (AMF) are fungi which grow on, and into, the roots of plants. AMF can increase the uptake of inorganic ions such as phosphate.
(a) Suggest one way in which an increase in the uptake of phosphate could increase plant growth

Answer 1

Used to produce named phosphate compound in cells;

e.g. ATP / ADP / phospholipids / DNA / RNA / RuBP / TP /GP etc.

Question 2

Arbuscular mycorrhiza fungi (AMF) are fungi which grow on, and into, the roots of plants. AMF can increase the uptake of inorganic ions such as phosphate.
Suggest one way in which AMF may benefit from their association with plants.

Answer 2

Example of a carbon-containing biological compound e.g. carbohydrate / amino acid / vitamin;

Question 3

Explain why an increase in shoot biomass can be taken as a measurement of net primary productivity.

Answer 3

1. Represents dry mass / mass of carbon;
2. Represents gross production minus respiratory losses;
3. Accept: NPP = GPP −R.

Question 4

Artificial fertiliser is used to replace mineral ions removed from the land when crops are harvested. One of the mineral ions is nitrate.
Give two examples of biological molecules containing nitrogen that would be removed when a crop is harvested.

Answer 4

Two suitable examples;
Examples
1.      amino acid / protein / polypeptide / peptide;
2.      nucleic acid / nucleotide / base;
3.      DNA;
4.      RNA;
5.      ATP / ADP;
6.      NAD / NADP (reduced or not);
7.      Cyclic AMP / cAMP;
8.      Chlorophyll;

Question 5

Farmland previously used for growing crops was left for 30 years and developed into woodland. During this period, ecologists recorded an increase in the diversity of birds in the area.
(a) Name the process that resulted in the development of woodland from farmland.

Answer 5

Succession;

Question 6

Explain the increase in the diversity of birds as the woodland developed.

Answer 6

1. Greater variety / diversity of plants / insects / more plant / insect species;
   Neutral: more plants.
2. More food sources / more varieties of food;
   Neutral: more food / more / greater food source (singular).
3. Greater variety / more habitats / niches;

Question 7

Explain why CO2 uptake is a measure of net productivity.

Answer 7

Shows (gross) photosynthesis / productivity minus respiration / more carbon dioxide used in photosynthesis than produced in respiration;