Unit 4: Organisms and their environment

Question 1

Use these notes: https://drive.google.com/drive/u/0/folders/1HIVIzsEmLmZsSA1jHISve4pUfhdQVv4Z

Question 2

The sun is the…

Answer 2

principal source of energy input to biological systems.

Question 3

Define Food chain

Answer 3

Define food chain as showing the transfer of energy
from one organism to the next, beginning with a
producer

Question 4

Define food web

Answer 4

Define food web as a network of interconnected food
chains

Question 5

Define producer

Answer 5

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

Question 6

Define consumer

Answer 6

Define consumer as an organism that gets its energy
by feeding on other organisms

Question 7

Define herbivore

Answer 7

Define herbivore as an animal that gets its energy by
eating plants

Question 8

Define carnivore

Answer 8

Define carnivore as an animal that gets its energy by
eating other animals

Question 9

Define decomposer

Answer 9

Define decomposer as an organism that gets its energy
from dead or waste organic matter.

Question 10

Define ecosystem

Answer 10

Define ecosystem as a unit containing all of the
organisms and their environment, interacting
together, in a given area, e.g. a lake

Question 11

Define trophic level

Answer 11

Define trophic level as the position of an
organism in a food chain or food web

Question 12

Describe how energy is transferred between
trophic levels.

Answer 12

In order for the energy to be transferred it first needs to be consumed. Between each trophic level only 10% of the energy in the previous trophic level is passed on. A lot of the energy loss comes from:
making waste products eg (urine) that get removed from the organism
as movement
as heat (in mammals and birds that maintain a constant body temperature)
as undigested waste (faeces) that is removed from the body and provides food for decomposers

Question 13

Explain why food chains usually have fewer than
five trophic levels

Answer 13

Remember from the notes

Question 14

Identify producers, primary consumers, secondary
consumers, tertiary consumers and quaternary
consumers as the trophic levels in food webs and
food chains.

Answer 14

do it.

Question 15

Construct simple food chains.

Answer 15

do it.

Question 16

Interpret food chains and food webs in terms of
identifying producers and consumers.

Answer 16

do it.

Question 17

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

Answer 17

do it.

Question 18

Describe the carbon cycle, limited to
photosynthesis, respiration, feeding,
decomposition, fossilisation and combustion.

Answer 18

Seethisvideo:https://www.youtube.com/watch?v=cWj3u8voDSg

Question 19

Discuss the effects of the combustion of fossil
fuels and the cutting down of forests on the
oxygen and carbon dioxide concentrations in the
atmosphere

Question 20

Explain the undesirable effects of deforestation on
the environment.

Question 21

List the undesirable effects of deforestation as an
example of habitat destruction, to include
extinction, loss of soil, flooding, and increase of
carbon dioxide in the atmosphere.

Question 22

State the sources and effects of pollution of water
(rivers, lakes and the sea) by chemical waste,
discarded rubbish, untreated sewage and
fertilisers.

Question 23

Explain the process of eutrophication of water in
terms of:

Answer 23

ー increased availability of nitrate and other
ions
ー increased growth of producers
ー increased decomposition after death of
producers
ー increased aerobic respiration by
decomposers
ー reduction in dissolved oxygen
ー death of organisms requiring dissolved
oxygen in water.

Question 24

Explain everything you know about acid rain:

Answer 24

https://www.youtube.com/watch?v=KEAfip6F3-8

something that isn’t mentioned in the video:
rain is naturally a bit acidic due to CO2 in the atmosphere forming carbonic acid in rain

Question 25

Define population

Answer 25

a group of organisms of the same species living in the same habitat at the same time.

Question 26

Define community

Answer 26

the population of all the animals, plants and microorganisms that are found in a particular habitat.

Question 27

Define omnivore

Answer 27

An organism which may feed on both animals and plants

Question 28

What is biomass?

Answer 28

the mass of living material in a given area.

e.g. less energy is transferred at each level of the food chain so the biomass gets smaller

Question 29

What is a key thing you should remember when asked to draw a food chain?

Answer 29

ARROWS, it has to have ARROWS

Question 30

Explain why the population of a predator is much smaller than its prey:

Answer 30

(1) Inefficient energy transfer through the trophic levels - you have to say INEFFICIENT/only 10% of energy is transferred at each level
(2) Describe processes where the energy is lost at each trophic level (e.g. respiration, faeces, etc)
(3) If they’ve asked you to talk about a specific animal in a food chain mention its POSITION in the food chain e.g. is it the primary/secondary consumer?