6.6 POPULATIONS/SUSTAINABILITY

Question 1

Define carrying capacity

Answer 1

• The maximum population size for a species in a particular ecosystem
• Reached at the staitonary phase of a growth curve

Question 2

Draw a growth curve for carrying capacity

Answer 2

Question 3

Explain why growth rate slows before entering stationary phase

Answer 3

Because:
- Waste product build-up
- Some nutrients are limiting
- Abiotic factors may no longer be suitible

Question 4

Define K-stratergists

Answer 4

• Organisms that are most sensitive to limiting factors
• Their population size is determined by the carrying capacity (K)

Question 5

Define R-stratergists

Answer 5

• Organisms that are less sensitive to limiting factors
• Population size is determined by reproduction rate (R)

Question 6

Compare feautures of k-stratergists against r-stratergists

Answer 6

Question 7

Describe the predator-prey relationship

Answer 7

1) When predator population gets bigger, more prey are eaten
2) The prey population gets smaller, leaving less food for the predators
3) With less food, fewer predators can survive and their population size reduces
4) With fewer predators, fewer prey are eaten, and their population size increases
5) With more prey, the predator population increases, cycle repeats

Question 8

Define intraspecific competition

Answer 8

• Competition between individuals of the same species

Question 9

Define interspecific competition

Answer 9

• Competition between individuals of different species

Question 10

Explain the effect of increased competition

Answer 10

• Fewer organisms have sufficient resources to reproduce (decreased reproduction rate)
• Fewer organisms have sufficient resources to survive (decreases death rate)
• Thus, population size decreases overall

Question 11

Explain how intraspecific competition can stabilise flunctuations of population size in the stationary phase

Answer 11

• If population size drops, competition reduced, the population size increases back to carrying capacity
• If population size increases, competition increased, the population size decreases back to carrying capacity

Question 12

State the two effects of interspecific competition on species

Answer 12

• Affects the population size of a species
• Affects the distribution of a species in an ecosystem

Question 13

Explain what makes interspecific competition more intense

Answer 13

• Overlap between the two species niches
• Because two species cannot occupy the same niche in an ecosystem (competative exclusion principle)

Question 14

Define conservation

Answer 14

• Active and dynamic interventions by humans to maintain or improve biodiversity

Question 15

Define preservation

Answer 15

• Attempting to keep habitats as they currently are, with no change and eliminating human intervention

Question 16

State three threats to biodiveristy that result in conservation

Answer 16

1) Resource stripping
2) Habitat disruption
3) Introduction of alien species

Question 17

State and explain three reasons to conserve/preserve biodiversity

Answer 17

1) Economical - Food crops need wild varietys to increase biodiversity, plants/microbes may be used for medicines, pollinating animals can increase crop production
2) Social - Tourism benefits, aesthetic
3) Ethical - All things should be protected

Question 18

State three ways in which pollarding helps sustain small scale timber

Answer 18

• Preserves wood
• Extends lifespan
• Prevents grazing

Question 19

State how coppicing sustains small scale timber

Answer 19

• Increases shoot growth at the base

Question 20

State the five guidlines for large scale timber by FSC

Answer 20

1) Reforestation (one in one out)
2) No clear felling (cutting everything)
3) Ecological functionality
4) Selective felling
5) Benefit the local community

Question 21

State the guidline company for large scale timber

Answer 21

• FSC

Question 22

State the guidline company for fishing

Answer 22

• MSC

Question 23

State and describe the three guidlines for fishing by MSC

Answer 23

1) Sustainability - fish to maintain carrying capacity
2) Ecosystem impacts - Not damage habitats within the ecosystem
3) Good management - Obey legal restrictions, adapt and change if necessary

Question 24

State some legal restrictions of fishing by MSC

Answer 24

• Mesh sizing (small fish can escape)
• Restrict certain species
• Boat sizes
• Annual quotas
• Sail duration
• Monitoring/inspection

Question 25

State some critisisms of MSC laws

Answer 25

• Fishing zones are too large to monitor
• Monitoring is expensive
• False reporting of catch sizes
• Dead fish thrown overboard due to over quota limit

Question 26

Define aquaculture

Answer 26

• Fish farming
• A solution to overfarming of fish

Question 27

State disadvantages of aquaculture

Answer 27

• It pollutes airways
• higher risk of parasites
• Ugly

Question 28

State an alternative to fishing

Answer 28

• Aquaculture

Question 29

Describe an alternative to aquaculture

Answer 29

• Changing human eating habits (e.g to primary consumer over higher consumer)
• (However, this just passes problem to another trophic level)
• People are resistant and change is slow