ecosystems

Question 1

Population definition

Answer 1

• group of organisms of the same species living in the same habitat

Question 2

habitat definition

Answer 2

• part of an ecosystem in which particular organisms live

Question 3

community definition

Answer 3

• all the populations of different species in the same area at the same tine

Question 4

ecosystem definition

Answer 4

• a community and the non-living components of an environment (biotic and abiotic).

Question 5

niche definition

Answer 5

• an organism’s role within an ecosystem, including their position in the food web and habitat.
• Each species occupies their own niche governed by adaptation to both abiotic and biotic conditions

Question 6

carrying capacity

Answer 6

maximum population size an ecosystem can support

Question 7

biotic factors

Answer 7

impact of the interactions between organisms

Question 8

Why is most energy lost in a food web?

Answer 8

• excretion and respiration

Question 9

what is biomass

Answer 9

dry mass of the carbon containing compounds

Question 10

how can efficiency of biomass transfer be calculated?

Answer 10

• biomass transferred/ biomass intake x100

Question 11

How can humans manipulate the transfer of biomass in farming?

Answer 11

• restricting movement (and therefore respiration) of animals
• providing animals with higher energy food (increasing energy output)
• keeping animals indoors to reduce the energy transferred as heat
• removing competition and predators
• growing indoors

Question 12

what is decomposition?

Answer 12

• a chemical reaction where a compound is broken down into simpler compounds or elements.

Question 13

what is a decomposer?

Answer 13

• microscopic fungi, toadstools, bacteria
• feed on dead organic matter using extracellular enzymes and convert them into inorganic molecules e.g NH4+

Question 14

what is a saprotroph/saprobiont?

Answer 14

• Break down food externally

Question 15

What are detritovores?

Answer 15

• woodlice, maggots etc
• decompose material by eating dead/decaying material and egest organic material with a larger surface area for decomposers

Question 16

what is succession?

Answer 16

• change in the species composition of a community on an area over time, with different seres having a dominant species

Question 17

what is the pioneer species

Answer 17

• lichens etc
• resilient to harsh abiotic factors
• their death and decomposition change the abiotic factors; soil/humus forms.

Question 18

what is the second sere?

Answer 18

• mosses and smaller plants
• soil builds up with organic material
• less harsh abiotic factors

Question 19

What can be said about competition between species of different seres?

Answer 19

• each new species may change the environment in such a way that it becomes less suitable for the previous species. Outcompeted.

Question 20

How does biodiversity change throughout succession?

Answer 20

• increases generally.
• climax community will be dominated by one species which may reduce the evenness and thus the overall biodiversity

Question 21

How are pioneer species which colonise the xerosere specialised?

Answer 21

• nitrogen fixing
• grow close to rock
• seed dispersal
• rapid growth
• seeds survive long dormancy
• small
• tolerate extremes of water and temp
• soil pH changes

Question 22

what is deflected succession

Answer 22

• a plagioclimax is reached.
• maintains an earlier stage of succession.
• human activity intervenes and determines the dominant species and therefore the nature of the climax community

Question 23

how do pioneer species reproduce?

Answer 23

• self-pollination
• asexual

Question 24

growth rate in plants in pioneer vs climax?

Answer 24

• fast in pioneer
• slow in climax

Question 25

What can be said about plants tolerance in the climax community?

Answer 25

- less tolerant to extreme environments - require soil with ample water and minerals