[19.1] populations and ecosystems

Question 1

what is ecology?

Answer 1

the study of the inter-relationships between organisms and their environment, which includes abiotic and biotic factors

Question 2

what is an ecosystem?

Answer 2

interaction between abiotic and biotic factors in a given area

Question 3

what is a population?

Answer 3

the number of members of a given species in a specific habitat at the same time

Question 4

what is the carrying capacity?

Answer 4

the maximum sustainable population of a species in an ecosystem given the available resources

Question 5

what is the carrying capacity determined by?

Answer 5

a combination of all factors in an ecosystem eg. predation, inter / intraspecific competition

Question 6

what affects the size of a population?

Answer 6

• effect of abiotic factors
• interactions between organisms eg. intra / interspecific competition and predation

Question 7

what is a community?

Answer 7

all of the populations of different species in a given habitat living and interacting at the same time

Question 8

what is a habitat?

Answer 8

where an organism normally lives

Question 9

what is a niche?

Answer 9

• how an organism fits into the environment
• where an organism lives and what it does there
• includes all the biotic and abiotic conditions an organism is adapted to survive in, reproduce and maintain a viable population

Question 10

what is the competitive exclusion principle?

Answer 10

the idea that no two species occupy exactly the same niche

Question 11

what are biotic factors?

Answer 11

living aspects of an ecosystem

Question 12

what are abiotic factors?

Answer 12

• non-living aspects of an ecosystem
• influences biotic factors
• determines what organisms can live in an ecosystem

Question 13

what are some examples of abiotic factors? (10)

Answer 13

1. wind
2. light intensity
3. wavelength of light absorbed by pigments for photosynthesis
4. soil pH
5. soil water content
6. soil mineral content (eg. nitrates, phosphates)
7. soil structure
8. oxygen concentration
9. carbon dioxide concentration
10. rain levels

Question 14

in what ways can biotic factors affect abiotic factors? (4)

Answer 14

1. competition
2. predation
3. parasites
4. mutualism

Question 15

what is a potential niche?

Answer 15

the range of conditions where a species could theoretically survive, set by abiotic factors only

Question 16

what is a realised niche?

Answer 16

where a species actually does live once biotic factors are introduced eg. competition, predation, disease on top of the other abiotic factors