Interdependance

Question 1

What are food chains?

Answer 1

Food chains show the feeding relationships in a habitat.

Question 2

What is the pyramid of biomass?

Answer 2

Pyramids of biomass are charts that show the mass of living organisms at each step in a food chain. Energy is lost moving up in a food chain, and this limits the length of the chain.

Question 3

What do the arrows in a food chain show?

Answer 3

The arrows in a food chain show the direction that the energy is flowing.

Question 4

Why are there a fewer organisms at the top of the food chain compared to at the bottom of the food chain?

Answer 4

There are fewer organisms at the top of the food chain because at each stage of the food chain, energy is lost so by the time it gets to the top of the food chain, there is very little energy left.

Question 5

How is most of the energy used up in a food chain?

Answer 5

• energy released by respiration is used for movement and other life processes, and is eventually lost as heat to the surroundings
• energy is lost in waste materials, such as faeces

Question 6

What is the order of the food chain?

Answer 6

• Primary producers - primary consumers - secondary consumers - tertiary consumers

Question 7

What is biomass?

Answer 7

Biomass means the mass of living material at a stage in a food chain. The biomass goes down as you go from one stage to the next, just like the amount of energy.

Question 8

Name examples of parasites

Answer 8

• headlice - they bite other animals such as humans in order to feed off their blood
• mistletoe - the roots of mistletoe grow into the veins of the host tree to absorb nutrients and minerals.

Question 9

Name examples of mutualism

Answer 9

• ‘cleaner’ fish - these feed off the dead skin and parasites of larger fish such as sharks This provides the cleaner fish with food and keeps the larger fish clean
• chemosynthetic bacteria in deep sea vents - these use chemicals from tubeworms in order to get substances to make food. In return the tubeworms feed off substances made by the bacteria.

Question 10

What are nitrogen-fixing bacteria?

Answer 10

Peas, beans and clover are leguminous plants. They have colonies of nitrogen-fixing bacteria in nodules attached to their roots. The plants gain nitrates from the bacteria, and the bacteria gain sugars from the plants. This is another example of mutualism.