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1

What is population size

The number of individuals in a population

2

What are the abiotic factors that influence the size of a population and explain in

Temp - each species has a different optimum temp at which it’s able to best survive. The further away from this optimum the fewer individuals in a population are able to survive and the smaller is the population that can be supported

Light - source of energy for most ecosystems, light is a basic necessity of life. The rate of photosynthesis increased as light intensity increases. The greater the rate of photosynthesis, therefore plants grow faster and grow more

pH- effects action of enzymes. Each enzyme has an optimum pH

Water and humidity- where there’s no water, populations have to be adapted to living in dry conditions. Humidity affects transpiration rate in plants and the evaporation of water from bodies in animals

3

What is the carrying capacity

the maximum stable population size of a species that an ecosystem can support

4

Give examples of how temp affects population size

In plants+cold blood animals - when temps fall below optimum - enzymes work slower and metabolic rate is reduced. Therefore have a smaller carrying capacity. At temps above optimum enzymes may denature, and carrying capacity is reduced

Warm blood animals - the further the temp of the external environment gets from their optimum frequency temperature, the more energy these organisms expend trying to maintain body temp. This leaves less energy for individual growth and so hey mature slowly and reproductive rates slower. Therefore carrying capacity of the population is reduced

5

Explain why populations never grow indefinitely

Certain factors limit growth e.g. availability of food, accumulation of waste, disease