Organisms and their environment

Question 1

What is the principal source of energy input to biological systems

Answer 1

the sun

Question 2

Describe the flow of energy through living
organisms

Answer 2

light energy from the Sun and chemical energy in organisms, and its eventual transfer to the environment

Question 3

Describe a food chain

Answer 3

diagram showing the transfer of energy from one organism to the next, beginning with a produce

Question 4

Describe a food web

Answer 4

a network of interconnected food chains and interpret food
webs

Question 5

Define a producer

Answer 5

an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis

Question 6

Define a consumer

Answer 6

an organism that gets its energy by feeding on other organisms

Question 7

How can be consumers be classified by and according to what?

Answer 7

consumers may be classed as primary,
secondary, tertiary and quaternary according to
their position in a food chain

Question 8

Describe a herbivore

Answer 8

an animal that gets its energy by eating plants

Question 9

Describe a carnivore

Answer 9

an animal that gets its energy by eating other animals

Question 10

Describe a decomposer

Answer 10

an organism that gets its energy from dead or waste organic material

Question 11

Define a trophic level

Answer 11

the position of an organism in a food chain, food web or ecological pyramid

Question 12

Discuss the advantages of using a pyramid of biomass rather than a pyramid of numbers to represent a food chain

Question 13

Discuss the advantages of using a pyramid of energy rather than pyramids of numbers or biomass to represent a food chain

Question 14

Describe the carbon cycle, limited to: photosynthesis, respiration, feeding, decomposition, formation of fossil fuels and combustion

Question 15

Describe the nitrogen cycle

Answer 15

• decomposition of plant and animal protein to ammonium ions
• nitrification
• nitrogen fixation by lightning and bacteria
• absorption of nitrate ions by plants
• production of amino acids and proteins
• feeding and digestion of proteins
• deamination
• denitrification

Question 16

State the roles of microorganisms in the nitrogen cycle

Answer 16

decomposition, nitrification, nitrogen fixation and denitrification

Question 17

Explain why it is more energy efficient for humans to eat crop plants than to eat livestock that have been fed on crop plants

Question 18

Explain, in terms of energy loss, why food chains usually have fewer than five trophic levels

Question 19

Explain why the transfer of energy from one trophic level to another is often not efficient