Ecology Definitions

Question 1

ECOSYSTEM

Answer 1

all the biotic factors and abiotic factors in a particular area; these factors are interacting and interdependent; they make up a self-contained system which is self supporting in terms of energy flow.

Question 2

ENVIRONMENT

Answer 2

all the factors in a habitat which affect an organism; these may be either living (= biotic) or non living (= abiotic).

Question 3

POPULATION

Answer 3

all the members of one species in a habitat at one time.

Question 4

COMMUNITY

Answer 4

all the organisms in a particular habitat at one time.

Question 5

HABITAT

Answer 5

the geographical area occupied by an ecosystem.

Question 6

NICHE

Answer 6

the role of a species within an ecosystem; its location and functions - relationships/interactions with other organisms - and its effect on the environment. Two different species do not normally occupy exactly the same niche in the same habitat at the same time (= ‘competitive exclusion principle’).

Question 7

SPECIES

Answer 7

a group of potentially interbreeding individuals; which do not normally interbreed with other groups/species to produce viable, fertile offspring.

Question 8

FOOD CHAIN

Answer 8

a sequence of organisms in an ecosystem in which each is the food of the next organism in the sequence. Arrows represent energy flow through the chain.

Question 9

FOOD WEB

Answer 9

all the interconnected food chains in an ecosystem (usually complex to calculate).

Question 10

TROPHIC LEVEL

Answer 10

a feeding level in a food web - defined by the method of obtaining food; all the organisms in a particular trophic level are the same number of energy transfers away from the producers.

Question 11

PRODUCER

Answer 11

the first organism in a food chain; an autotroph (i.e capable of manufacturing organic molecules/food, normally by photosynthesis (thus, normally a plant).

Question 12

PRIMARY CONSUMER

Answer 12

the second organism in a food chain (in the second trophic level); consumes/obtains energy from the producer; (thus a herbivore).

Question 13

SECONDARY CONSUMER

Answer 13

consumes/obtains energy from the primary consumer; (thus a carnivore).

Question 14

PYRAMID OF NUMBERS

Answer 14

a representation of the number of organisms in each trophic level in an ecosystem; the width of each block is proportional to the number of organisms in each trophic level.

Question 15

PYRAMID OF BIOMASS

Answer 15

(better) a representation of the biomass in each trophic level in an ecosystem; the width of each block is proportional to the biomass in each trophic level.

Question 16

PYRAMID OF ENERGY

Answer 16

(better still) a representation of the energy in each trophic level in an ecosystem;the width of each block in proportional to the energy in each trophic level; usually measured in KJ m.-2 year-1.

Question 17

CARRYING CAPACITY

Answer 17

the maximum population that a particular environment can support.

Question 18

How does mark release recapture work?

Answer 18

1. Capture sample, mark and release;
2. Appropriate method of marking suggested / method of marking does not harm lizard;
3. Take second sample and count marked organisms;
4. Large sample, allow mixing, marking do not harm or reduce survival chance
5. Do when Population changes small, e.g. not in breeding season
6. No in No in Population = (sample1 × sample2) divided by Number marked in sample2;