Organisms and their environment

Question 1

Define food chain

Answer 1

The transfer of energy from one organism to the next, beginning with a producer

Question 2

Define trophic level

Answer 2

The position of an organism in a food chain, food web, pyramid of numbers or pyramid of biomass

Question 3

Why is the transfer of energy from one trophic level to the next inefficient?

Answer 3

Because of egestion, excretion, respiration and production of inedible bones and shells

Question 4

Define food web

Answer 4

A network of interconnected food chains

Question 5

Define Producer

Answer 5

An organism that makes its organic nutrients usually from energy from sunlight through photosynthesis

Question 6

Define Consumer

Answer 6

An organism that gets its energy by feeding on other organisms

Question 7

Define Herbivores

Answer 7

An animal that gets its energy by eating plants

Question 8

Define Carnivores

Answer 8

An animal that gets its energy by eating other animals

Question 9

Define Decomposer

Answer 9

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

Question 10

Why is the pyramid of biomass better than the pyramid of numbers?

Answer 10

1. Pyramids of biomass take into account the size of organisms
2. Less misinterpreted
3. Range of numbers may be enormous

Question 11

What is the importance of the water cycle?

Answer 11

Living organisms require water- provides organisms with a constant supply of water

Question 12

How is nitrogen fixed?

Answer 12

By lightning and bacteria -root nodules of certain plants (peas, beans, clover – leguminous plants) take N2 gas and change it into nitrates in the soil

Question 13

What produces ammonium ions?

Answer 13

Decomposers break dead matter down into ammonium ions

Question 14

What converts ammonia into nitrites and nitrates

Answer 14

Nitrifying bacteria

Question 15

What absorbs nitrate ions?

Answer 15

Plants

Question 16

What release nitrogen back into the atmosphere?

Answer 16

Denitrifying bacteria

Question 17

What is deamination?

Answer 17

Removal of the amine group in an amino acid

Question 18

What is nitrogen fixation?

Answer 18

is when N2 and H2 combine to form ammonium ions then nitrate if oxygen is present

Question 19

What are legumes used for?

Answer 19

To avoid using so much nitrogen- containing fertiliser so therefore it is less expensive

Question 20

What is nitrification?

Answer 20

When ammonium ions are produced by the decomposition of amino acids and are oxidised first to nitrite then to nitrate

Question 21

What is denitrifying?

Answer 21

When nitrate is converted to nitrogen gas

Question 22

Define population

Answer 22

A group of organisms of one species living in the same area at the same time

Question 23

Define Ecosystem

Answer 23

A unit containing the community of organisms and their environment interacting together

Question 24

Define community

Answer 24

All of the populations of different species in an ecosystem

Question 25

What is population growth controlled by?

Answer 25

Food supply

Predation and disease

Question 26

Why has the population size increased significantly?

Answer 26

Because of improved technology leading to an abundance of food and improved medication and health care

Question 27

Describe the sigmoid growth curve?

Answer 27

Log phase
Exponential phase
stationary phase
death phase