Topic 5B: Energy Transfer And Nutrient Cycle- 2. Farming Practices And Production

Question 1

What is a food web?

Answer 1

They show lots of food chains in an ecosystem and how they overlap

Question 2

Decomposer definition

Answer 2

• They break down dead/ undigested material, allowing nutrients to be recycled

Question 3

How do agricultural ecosystems compare to natural ones?

Answer 3

• made of mainly domesticated animals and plants used to produce food for humans
• Tries to ensure as much of the available energy from the sun is transferred to humans

Question 4

How can farmers maximise NPP (net primary production)?

Answer 4

• Limited space between plants so GPP will increase
• Increasing cultivated area and use of monoculture
• Managing abiotic and limiting factors

Question 5

How can farmers maximise NP? (Net production)

Answer 5

• Reduce movement (keep them in barn, cage, shed)
• Food provided so no faraging
• Eat digestible food so faeces decrease
• Eat more essential molecules for growth
• Keep barn warm so respiratory heat loss decreases
• Control protein intake to reduce urea
  This means more biomass is produced and more chemical energy can be stored increasing net production and the efficiency of energy transfer to humans

Question 6

How can the NPP of crops and the NP of livestock be increased?

Answer 6

• Energy lost to other organisms e.g. pests can be reduced through the simplification of food webs meaning the efficiency of energy transfer to humans increases
• Energy lost through the respiration of livestock can be reduced

Question 7

How do you get rid of pests?

Answer 7

• farmers need pest control
• They use chemical pesticides

Question 8

Pest control- Insecticides

Answer 8

• They kill insect pests that eat and damage crops
• Killing insect pests means less biomass is lost from the crops so they grow to be larger
• Meaning NPP is greater

Question 9

Pesticides- Herbicides

Answer 9

• They kill weeds
• Killing weeds can remove direct competition with the crop for energy from the sun
• They can also remove the preferred habitat or food source of the insect pests which helps to further reduce their numbers and simplify the food web

Question 10

Benefits of maximising net production?

Answer 10

• More food can be produced in a shorter space of time often at a lower cost

Question 11

Disadvantages of maximising net production by keeping animals in cages?

Answer 11

• It raises ethical issues as some people think that the conditions animals are kept in cause them pain, distress or restricts their natural behaviour so it shouldn’t be done

Question 12

Differences between agricultural and natural ecosystems ?

Answer 12

Energy inputs- In natural it’s sunlight but in agricultural it’s sunlight or lamp
Productivity- There is a higher productivity in agricultural ecosystems compared to natural ecosystem’s
Species diversity- There is higher species diversity in natural compared to agricultural
Nutrient availability- Nutrient cycle within natural ecosystem but nutrients are added in agricultural ecosystem
Stage of succession- Climax community in natural ecosystem but interrupted plagioclimax community in agricultural ecosystem