6.3.2 - POPULATIONS + SUSTAINABILITY

Question 1

Define population size

Answer 1

The total number of organisms of one species in a habitat

Question 2

What causes population size to vary?

Answer 2

• Abiotic factors
• Biotic factors

Question 3

What happens when abiotic factors are ideal?

Answer 3

Organisms can grow fast and reproduce successfully

Question 4

Give an example of what happens when abiotic factors are ideal.

Answer 4

• temperature of a mammal’s surroundings is ideal for metabolic reactions to take place
  ^— don’t have to use up as much energy maintaining their body temperature —> more energy can be used for growth + reproduction (POPULATION INCREASES)

Question 5

What happens when abiotic factors are NOT ideal?

Answer 5

Organisms can’t grow as fast or reproduce as successfully

Question 6

Give an example of what happens when abiotic factors are NOT ideal.

Answer 6

• temperature of a mammal’s surroundings is significantly lower or higher than their optimum body temperature
  ^— have to use a lot of energy to maintain the right body temperature —> means less energy available for growth + reproduction (POPULATION DECREASES)

Question 7

What are abiotic factors?

Answer 7

Non-living features of an ecosystem

Question 8

What are biotic factors?

Answer 8

Living features of an ecosystem

Question 9

What is interspecific competition?

Answer 9

Competition between different species for the same resources (e.g. red + grey squirrels for food sources and habitats)

Question 10

How does interspecific competition affect population size?

Answer 10

• Means that the resources available to both populations are reduced (e.g. if they share the same food source, there will be less available to both of them)
• Both populations will be limited by a lower amount of food
• They’ll have less energy for growth + reproduction, so the population sizes with be lower for both species (e.g. populations are smaller in areas where red + grey squirrels live than if only one species lived there)
• Can affect species distribution
• If two species are competent but one is better adapted to its surroundings than the other, the less well adapted species is likely to be out-competed

Question 11

What is intraspecific competition?

Answer 11

Competition within a species for the same resources

Question 12

How does intraspecific competition affect population size?