Year 11 Topic Notes

Question 1

What are the steps for selective breeding?

Answer 1

1. choose individuals with the desired feature.
2. let only these individuals reproduce.
3. choose the offspring that have the desired feature.
4. let only these individuals reproduce.
5. repeat steps 3 and 4 until you have produced a variety in which all the individuals
   show the desired feature.

Question 2

What are the factors which affect photosynthesis?

Answer 2

• temperature
• light intensity
• CO2 concentration

Question 3

What benefits are there in greenhouses?

Answer 3

• artificial heating
• artificial lighting
• additional CO2 in the air
• regular watering

Question 4

Green houses and polythene tunnels provide enhanced conditions for plants to grow for several reasons, what reasons?

Answer 4

• The transparent material allows sufficient natural light in for photosynthesis during the summer. Additional lighting gives a ‘longer day’ during the winter for valuable crops.
• The greenhouse effect also raises the temperature in the glasshouses.
• Burning fossil fuels or wood raises the temperature when the external temperature is
  too low. It also produces carbon dioxide and water vapour.
• Water vapour maintains a moist atmosphere and so reduces water loss by
  transpiration.
• All of these increase the rate of photosynthesis and therefore increase the yield. The additional cost of providing these condition must be weighed against the extra profit provided from the increased yield. The farmer must find the optimum conditions.

Question 5

What are organic fertilisers?

Answer 5

made from the faeces of a range of animals, sometimes mixed with straw. Also compost from legumes such as clover.

Question 6

What are inorganic fertilisers?

Answer 6

inorganic compounds carefully formulated to yield a specific concentration of a particular ion when applied according to the manufacturer’s instructions.

Question 7

What are fertilisers?

Answer 7

• Fertilisers provide elements needed by plants to grow such as nitrates for proteins and magnesium for the production of chlorophyll.
• There are 2 types organic and inorganic.

Question 8

What are the advantages of organic fertilisers?

Answer 8

• Improves Soil Structure
• Greater range of minerals - Releases minerals over a longer period of time.
• Less cost to farmer - already
  available on the farm.

Question 9

What are the disadvantages of organic fertilisers?

Answer 9

• Slow acting - has to be decomposed first
• Bulkier, so more difficult than inorganic fertilisers to apply
• May contains pests

Question 10

What are the advantages of inorganic fertiliser?

Answer 10

• Mineral ions release immediately so fast acting
• Contents known
• Easy to apply

Question 11

What are the disadvantages of inorganic fertilisers?

Answer 11

• Can lead to eutrophication as fertiliser is soluble
• Requires regular reapplication

Question 12

What is a stimulus?

Answer 12

Change in the animal’s surroundings.

Question 13

What is a receptor