19.1 — populations and ecosystems

Question 1

what is ecology the study of?

Answer 1

the inter-relationships between organisms and their environment, including both non-living (abiotic) and living (biotic) factors

Question 2

what is an ecosystem?

Answer 2

a community of living organisms interacting with each other and their physical environment in a defined area

Question 3

what is a biotic factor

Answer 3

a living component of an ecosystem

Question 4

what is an abiotic factor?

Answer 4

a non-living component of an ecosystem

Question 5

what is a population?

Answer 5

organisms of the same species living together in one habitat at the same time

Question 6

what is a habitat?

Answer 6

the physical location where an organism lives

Question 7

what is a microhabitat?

Answer 7

a smaller habitat with its own microclimate within a larger habitat

Question 8

what is a niche?

Answer 8

the role of an organism in its own ecosystem, including all the biotic and abiotic conditions to which an organism is adapted to survive, reproduce and maintain a viable population

Question 9

what is competitive exclusion?

Answer 9

a principle stating that two species cannot occupy the same niche in the same environment simultaneously

Question 10

what are some examples of abiotic factors?

Answer 10

temperature, light, pH, water availability

Question 11

how does temperature influence ecosystems?

Answer 11

1. influences enzyme activity — at low temperatures, enzymes work more slowly, and at high temperatures, enzymes may denature
2. for plants and ectotherms (cold blooded animals), their metabolic rate is entirely dependent on the surroundings so temperatures outside their preferred range can reduce survival, reproductive success and population size
3. endotherms (warm blooded animals) use more energy to maintain their body temperature when it is outside their optimal temperature, which can decrease their reproductive success and population size

Question 12

how does light influence ecosystems?

Answer 12

1. increased light intensity boosts photosynthesis rate, inputting more energy into ecosystems
2. this leads to faster plant growth and higher reproduction rates which can increase their population size
3. this provides more food for animals, potentially increasing their population size as well

Question 13

how does pH influence ecosystems?

Answer 13

1. this directly influences enzyme activity, and populations are larger when pH levels are optimal for an organism’s enzymes
2. deviations from the optimal pH can lead to smaller population sizes

Question 14

how does water availability influence ecosystems?

Answer 14

1. populations are generally smaller under conditions of low water availability, as only drought-resistant species can thrive
2. low humidity increases transpiration in plants and water evaporation from animals, leading to decreased population sizes due to water stress