Fertilisers

Question 1

Give 3 uses for fertilisers.

Answer 1

Increase crop yield
Increase productivity
Ensure plants get the correct amount of nutrients

Question 2

Why does farmland soil become unproductive?

Answer 2

Crops are harvested and replanted in the same area, meaning that nutrients are constantly taken up from the soil and are not replenished.

Question 3

Compare the accuracy of application of natural and artificial fertilisers.

Answer 3

Artficial fertilisers can be applied in more precise concentrations
Natural fertilisers are bulky so may be harder for them to be applied

Question 4

Compare the speed that natural and artificial fertilisers work at.

Answer 4

Natural fertilisers work more slowly
Artificial fertilisers work more quickly.

Question 5

Compare the cost of natural and artificial fertilisers.

Answer 5

Natural fertilisers are cheap/free
Artificial fertilisers are more expensive

Question 6

How do nitrogen containing fertilisers increase plant gowth?

Answer 6

They increase the amount of amino acids/bases in the plant, which are needed for DNA production. This leads to greater plant growth, leading to larger leaves and more photosynthesis.

Question 7

Why might nitrogen containing fertilisers reduce species diversity?
Which type of plant do nitrogen rich soils favour?

Answer 7

Nitrogen soils favour grasses. This means grasses grow faster and outcompete other plants for things such as light/space, so they die

Question 8

Name 2 things reduced species diversity leads to.

Answer 8

Less habitats
Less niches

Question 9

What is leaching?

Answer 9

Rainwater dissolves nutrients so they are washed out of the soil where plants can reach, and are carried deep underground.

Question 10

What is eutrophication?

Answer 10

Nutrients enter water and their concentration increases.

Question 11

How can leaching affect drinking water?

Answer 11

Leaching causes nutrients to be carried into lakes. If the lake is used for drinking water, the water then becomes toxic.

Question 12

1. Name the factor that limits growth of algae in water.

Answer 12

Low nitrate concentration.

Question 13

2. How does leaching change the concentration of nitrates in a lake?

Answer 13

Leaching causes ion concentration to increase.

Question 14

3. Which factor no longer limits, causing algae to grow?

Answer 14

Nitrate ion concentration no longer limits.

Question 15

4. What are algal blooms and why do they occur?

Answer 15

Algal blooms are a rapid mass growth of algae. They are at the surface of the lake, so they receive the most light and grow the quickest.

Question 16

5. At lower depths of the lake, what is the limiting factor?
   What happens to the plants at the bottom?

Answer 16

Light limits at the bottom of the lake.
This means they die

Question 17

6. Why does the population of saprobionts increase?

Answer 17

Saprobionts have a lot of food as there are many plants for them to decompose. Food is no longer a limiting factor.

Question 18

7. Why does demand for oxygen increase?

Answer 18

Demand for oxygen increases as population of saprobionts increases

Question 19

8. How does the waters oxygen and nitrogen concentration change?

Answer 19

Oxygen concentration decreases as saprobiontic demand grows.
Nitrogen concentration increases as it is released from decaying organisms.

Question 20

9. Why do aerobic organisms start to die?

Answer 20

Oxygen becomes very limited.

Question 21

10. Why do anaerobic populations start to rise?

Answer 21

Many aerobic organisms have died as there is very little O2, meaning there is no competition.

Question 22

11. High anaerobic organism population causes what to happen to nitrate concentration and water?

Answer 22

Nitrogen conc rises further as organisms decay.
This turns water toxic and putrid.