Energy and Biomass in Food Chains

Question 1

Why are fish stocks declining and how do you solve it?

Answer 1

• we fish too much
• ocean food chains are affected, maybe disappearance of some species of fish
• we need to maintain fish stocks at a level where fish continue to breed = sustainable for production
• fishing quotas: limits on the number and size of fish that can be caught. prevents a certain species from being overfished
• net size: different limits of the mesh size, reduces the number of unwanted and discarded fish. younger fish can escape through a larger mesh size, allowing them to reach breeding age

Question 2

Why are food miles bad?

Answer 2

• can be expensive
• bad for environment
• contributes to global warming

Question 3

How can the efficiency of food production be improved?

Answer 3

• reducing the number of stages in the food chain: you can produce a lot more food for humans by growing crops than grazing animals as you reduce the number of stages in the food chain
• restricting the energy lost by farm animals: restricting movement and heat loss saves energy, making transfer of energy from feed to animal more efficient. animal will grow faster on less food.

Question 4

How is most of the energy lost to the surroundings?

Answer 4

• they are lost as heat since respiration supplies the energy for all life processes, including movement

Question 5

What energy is the source of energy for nearly all life on Earth?

Answer 5

• energy from the Sun

Question 6

What are the arguments against factory farming?

Answer 6

• forcing animals to live in unnatural conditions is cruel
• crowded conditions mean a favourable environment for the spread of disease e.g. avian flu
• to try to prevent disease, animals are given antibiotics which may enter humans. we may become immune to those antibiotics or less effective
• they ned to be kept warm to reduce the energy they lose as heat. power from fossil fuels

Question 7

Why is the amount of energy absorbed by plants and algae very small?

Answer 7

• some energy is transmitted through the leaves
• some energy is lost heating up the leaves
• some absorbed by non-photosynthetic part of the leaves