Populations

Question 1

lag phase (animals)

Answer 1

• shortage of reproducing individuals so the growth rate is very slow
• (can last for few days months or years)
• period of adaptation to the new environment
• haven’t reached maturity
• gestation period

Question 2

log phase (animals)

Answer 2

• fastest population growth
• plentiful resources -> population grows at an exponential rate
• no limiting factors / lack of environmental resistance
• birth rate > death rate

Question 3

stationary phase (animals)

Answer 3

• carrying capacity -> population is roughly constant
• oscillates around carrying capacity
• birth rate = death rate

Question 4

death rate (animals)

Answer 4

• (not often seen)
• may occur when deadly disease or food runs out leading to a population crash
• death rate > birth rate

Question 5

lag phase (bacteria/yeast)

Answer 5

• bacteria/yeast are synthesising new enzymes & proteins
• slow rate of cell division

Question 6

log phase (bacteria/yeast)

Answer 6

• plentiful minerals + growth medium
• no other limiting factors
• cells divide at maximum rate
• doubling per unit time
• reproductive rate > death rate

Question 7

stationary phase (bacteria/yeast)

Answer 7

• limiting factors / environmental resistance
• growth medium is running out
• reproductive rate = death rate

Question 8

death phase (bacteria/yeast)

Answer 8

• build up of toxins/ethanol leading to rapid death of bacteria
• death rate > reproductive rate

Question 9

carrying capacity

Answer 9

number of individuals an ecosystem can sustain

Question 10

environmental resistance

Answer 10

environmental factors that slow down population growth

Question 11

what contributes to environmental resistance (bacteria/yeast)

Answer 11

• available food growth medium
• overcrowding
• competition

Question 12

what contributes to environmental resistance (animal / plant)

Answer 12

• predation
• parasitism / disease
• competition
• light intensity
• water supply
• water mineral content
• temperature
• soil pH
• space available

Question 13

if environmental resistance is increased how does this impact carrying capacity?

Answer 13

decreases as population growth decreases forcing carrying capacity to fluctuate around a lower point -> harder for organisms to survive in this new environmental.

Question 14

what are density dependant factors (generally biotic factors)

Answer 14

• disease
• competition
• predation
• parasitism
• food availability
• accumulation of toxic waste
• territory / shelter availability