19.2 Variation in population size

Question 1

abiotic factors

Answer 1

1. temperature
2. light
3. pH
4. water humidity

Question 2

light affect

Answer 2

rate of photosynthesis increases as light intensity does

greater rate of photosynthesis, the faster plants grow and more spores and seeds produced(carrying capacity increased)

carrying capacity of animals feeding on plants increases

Question 3

4 temperature affects

Answer 3

1. each species has optimum temp, the further away, the fewer individuals able to survive
2. in plants and cold-blooded animals, as temp falls enzymes work more slowly and metabolic rate is reduced so popn has smaller carrying capacity
3. as temp rises, enzymes denature
4. warm blooded mammals maintain constant body temp regardless of external. But, further from optimum temp, more energy used to regulate internal temp so less energy used for growth and reproduction so carrying capacity reduces

Question 4

pH affect

Answer 4

each enzyme has optimum pH where operates most effectively

popn of organisms away from appropriate pH decreases or becomes non-existent

Question 5

water and humidity effect

Answer 5

when scarce water, popn is small and made of only species adapted to dry conditions

affects transpiration rate in plants

affects evaporation of water from animal bodies

Question 6

population growth

Answer 6

(births + immigration) - (deaths + emigration)

Question 7

percentage population growth

Answer 7

population change during period/ original population