variation in population size

Question 1

population size

Answer 1

the number of individuals in a population

Question 2

population growth curves

Answer 2

1) a period of slow growth:
as the initially smaller number of individuals reproduce to slowly increase their numbers
2) a period of rapid growth:
- where the ever-increasing number of individuals continue to reproduce
- the population size doubles during each interval of time
- the curve becomes steep
3) population growth declines:
- size remains more or less stable
- small fluctuations of the graph can be due to; limitation in food supply or increased predation
- graph levels out

Question 3

limiting factors

Answer 3

• mineral ions are used up as population becomes larger
• other species introduced to the habitat; increase in competition
• weather which may be accompanies with unsuitable conditions e.g. increase rainfall and decrease in light intensity

Question 4

result of limiting factors

Answer 4

• growth in population slows or decreases; it may even diminish in extreme scenarios

Question 5

abiotic factors that influence the size of population

Answer 5

• temperature; - each species has a different optimum temperature
• the further away from this optimum, the smaller the population that can be supported
• light; - as the ultimate source energy for most ecosystems
• it is the basic necessity of life
• pH
• water and humidity

Question 6

effect of temperature on cold blooded animals

Answer 6

• if temperature falls below optimum, enzyme activity will decrease and therefore their metabolic activities will reduce
• populations therefore grow more slowly
• if temperature is above optimum, enzymes work less efficiently
• they gradually denature

Question 7

effect of temperature on warm blooded animals

Answer 7

• they can maintain a constant internal body temperature regardless of the external temperature
• however, the further the temperature deviates away from the optimum
• more energy will be used to maintain the constant internal body temperature
• less energy left for individual growth; they mature slowly
• less reproductive rates

Question 8

effect of temperature on plants

Answer 8

• if temperature increases
• this will increase light intensity and decrease humidity therefore providing energy for photosynthesis
• but ultimately, it could also affect availability of water that is transported in plants, which then cannot be used for hydrolysis or the transport of minerals needed

Question 9

effect of light intensity on plants

Answer 9

• as light intensity increases
• the rate of photosynthesis increases, more energy supplied
• the faster the growth rate of plants, the more spores or seeds they produce to reproduce
• as a result, population size is greater
• this then results as an increase of food supply for organisms that feed on these plants
• providing energy for growth and reproduction
• increase in population size

Question 10

effect of pH levels on enzymes

Answer 10

• each enzyme has an optimum pH at which it operates in most effectively
• if optimum deviates away from the optimum, it can lead to decrease in efficiency or even denaturation; decreasing metabolic reactions that help with growth - population size decreases
• if pH levels are within the optimum range, population size is likely to be larger

Question 11

effect water and humidity

Answer 11

• areas where water is scarce, population is more likely to be smaller and consist only of species that would be well adapted to withstand such conditions
• humidity affects rate of transpiration and the evaporation of water from animal body