1.3 Variation in population size

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What is population size?
it is the total number of organisms of one species in a habitat.
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Organisms can grow fast and reproduce successfully when.....?
Abiotic condtions are ideal
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Why can population size of any species vary?
Because of Abiotic factors
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What are the 3 phases for a natural population?
1) slow growth as a small number of indiviuals produce to build up numbers 2) rapid growth as ever increasing number in individuals continue to reproduce. 3) Pop. growth declines until size is more or less stable, due to limiting factor like food.
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What are four abiotic factors?
Temperature, Light, pH and water/humidity.
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How does the abiotic factor TEMPERATURE affect population size?
Each species has a different optimum temp. if it falls below that , enzymes work more slowly so metabolic rate is reduces. Also if it is above optimum enzymes denature causing pop. to get smaller!low temps also require more energy to maintain body tp
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How does the abiotic factor of LIGHT affect population size?
Its the ultimate source of energy for ecosystems. High light intensity means high rate of photosynthesis, so the plants grow faster so produce more seeds and spores. This also gives other animals more food to make their population larger.
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How does the abiotic factor pH affect population size?
It affects enzyme action. Each enzyme has an optimum pH for it to work most effectivley. Populations are larger when an appropriate pH exists and smaller when it doesnt.
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How does the abiotic factor of WATER AND HUMIDITY affect population size?
Where water is scarce, populations are small and consist only of species that are well adapted to living in dry condtions. Humidity affects transpiration rates in plants and evapouration of water in animals.
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Why do populations never grow indefinetly?
Because certain factors limit growth, for example availibilty of food, accumilation of waste, disease.
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What is the difference between abiotic factors and biotic factors?
Biotic factors are living factors where as abiotic factors are non living factors.
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Card 2

Front

Organisms can grow fast and reproduce successfully when.....?

Back

Abiotic condtions are ideal

Card 3

Front

Why can population size of any species vary?

Back

Preview of the front of card 3

Card 4

Front

What are the 3 phases for a natural population?

Back

Preview of the front of card 4

Card 5

Front

What are four abiotic factors?

Back

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