topic 10

Question 1

define ecosystem

Answer 1

a life-supporting environment. Includes the living organisms and the way they interact with biotic and abiotic factors

Question 2

what are trophic levels

Answer 2

describe the hierachical position of an organism in a food chai/web and describes its feeding relationship with other organisms

Question 3

what do the pyramids of numbers show

Answer 3

• comparision of the number of organisms at each trophic level
• usually, the number decreases at each trophic level
• usually pyramid-shaped, but sometimes not

Question 4

advantages and disadvantages of pyramid of numbre

Answer 4

adv :
- easy to measure

disadv
- can be distored by large organisms

Question 5

what does pyramid of biomass show

Answer 5

representation of biomass at different trophic levels in an ecosystem

Question 6

adv and disadv of pyramid of biomass

Answer 6

adv:
- always pyramid shaped

disadv;
- measuring dry mass involves destroying the organism

Question 7

what does the pyramid of energy show

Answer 7

represent how much energy is retained in form of new biomass at each trophic level

Question 8

adv and disadv of pyramid of energy

Answer 8

adv
It takes account of the rate of production over a period of time

disadv
The rate of biomass production of an organism is required

Question 9

what is abundance

Answer 9

relative representation of a species in a particular ecosystem

Question 10

what are two ecological techniques to measure abundance of species

Answer 10

1. quadrats : find individual counts or percentage cover
   - allow sample areas to be compared
   0 useful for plants and animals that dont move much
   0 quantitative measuring technique

limitation : can only be used on small are, randomness, hard to decide if an organisms should be counted if it is only partially in the quadrat

2. capture/recapture ; for animals that move around (tullgren funnel, pooter, tree branch disturbance

Question 11

what is distribution

Answer 11

where a species of an orgnaims is found in the environment and how it is arranged - this can change throughout things like migration

Question 12

what is uniform distribution

Answer 12

• resources are thinly but evenly spread

Question 13

what is clumped distribution

Answer 13

herds/groups of plants/animals with specific resource requirements clump where these resources are found

Question 14

what is random distribution

Answer 14

plentiful resources and no antagonism