Feeding Relationships and Cycles

Question 1

what do food chains show?

Answer 1

food chains show the energy transfer (what is eaten by what) in an ecosystem

Question 2

what do arrows show in a food chain?

Answer 2

the direction of the energy transfer

Question 3

what is meant by trophic levels?

Answer 3

the different stages in a food chain

Question 4

what is a producer?

Answer 4

green plants which photosynthesise to make their own food from the sun

Question 5

what is a primary, secondary consumer & tertiary consumer

Answer 5

primary consumer: the animal that eats the producer

secondary consumer: the animal that eats the primary consumer

tertiary consumer: The animal that eats the secondary consumer

Question 6

what are decomposers?

Answer 6

Microorganisms, e.g. bacteria that digest dead material and waste

Question 7

what do food webs show?

Answer 7

food webs show how food chains are linked

Question 8

what is meant by the term interdependant?

Answer 8

Where one organism relies on another oragnism for things like food

Question 9

Reason for a change in number of species in a food chain?

Answer 9

• Less/ more food (always state an organism)
• less/ more competition
• less/ more predation

Question 10

what are the examiners looking for when drawing pyramids of biomass?

Answer 10

• correct orders of bars
• labelled bars
• correct length off bars
• shape of pyramid

Question 11

Reasons for energy losses (and therefore loss in biomass):

Answer 11

• Some parts of the food organism are not eaten, for example, bones
• Some parts of the food organism are indigestible, e.g. fibre, meaning
  that the energy contained in those parts are passed out as waste, e.g.
  faeces
• A lot of energy is released by respiration, which powers life processes
  like movement
• A lot of energy is lost to the surroundings as heat
• Some organisms die and decompose

Question 12

Explain factors of the Carbon Cycle

Answer 12

• Respiration: Releases carbon dioxide into the atmosphere
• Photosynthesis: Carbon dioxide is taken from the air to make carbohydrates, fats and proteins
• Decomposition: Digestion (break down) of
  dead material by microorganisms released carbon dioxide back
  into the atmosphere by respiration
• Combustion: Releases carbon dioxide back into the atmosphere

Question 13

what is nitrogen fixation?

Answer 13

• The process of turning nitrogen from the air into nitrogen compounds in the soil which can be absorbed by plants.

Question 14

What are the two way nitrogen fixation can happen?

Answer 14

• Lightning – forces nitrogen to react with oxygen in the air to give nitrates
• Nitrogen fixing bacteria – turn nitrogen in the air into nitrogen compounds in the soil
  Bacteria and decomposers are essential to the nitrogen cycle.

Question 15

Explain the Nitrogen cycle

Answer 15

-Nitrogen fixing bacteria takes N2 gas out of atmosphere and converts it to nitrates
-Nitrates get taken up by the rood nodules of plants
-Plants eaten by animals
-Once animals die, they get decomposed
-Proteins get turned into ammonium ions
-Nitrifying bacteria converts ammonium ions–>Nitrites–>Nitrates