Chapter 3 and 4

Chapter 3 (1)

100

State two organic fertlisers

1.Crop residue/vegetation

2. (animal) manure

200

What is trickle drip irrigation?

The slow release of water to each plant through small plastic tubes

300

Describe the difference between a commercial farm and a subsistence farm.

Describe the difference between a commercial farm and a subsistence farm.

400

Adding fertilisers is one technique used to increase the yield of maize. Identify two other techniques that this farmer is using to increase the yield of maize. Only identify techniques shown in the photograph

1.adding fertilisers based on one mineral ion, gives a very small increase in crop yield / no difference in crop yield

2. organic manure is nearly as effective in increasing crop yield as NPK fertilisers

3.no fertiliser gives the lowest yield ;

500

Describe how the overuse of fertilisers can lead to the death of aquatic organisms

mineral ions leach into lakes and rivers ;

mineral ions cause, an algal bloom / algae population to increase ;

algal bloom reduces light ;

so plants die / cannot photosynthesise ;

bacteria decompose dead plants ;

decomposition uses oxygen ;

other organisms cannot respire/ lack oxygen ;

Chapter 3 (2)

400

Explain how the overuse of insecticides impacts the biodiveristy

any three from: 

kills, beneficial / other, insects; 

(which) affects the food, chain / web; 

idea that insects are eaten by organisms in higher trophic levels; 

bioaccumulation; 

insecticide resistance in organisms; 

explanation of pest-resurgence; 

leaching/run off into water sources kills aquatic life

500

Describe strategies a farmer could use to reduce water usage in agriculture

any four from:

grow varieties of crops / produce which require less water / genetically modified crops / selective breeding;

rainwater harvesting / example of;

use of trickle drip irrigation / clay pot;

mulching; recycling of water / example of;

use of reservoirs to collect run-off;