6.3.2 - Populations and sustainability

Question 1

Definition of ‘Carrying Capacity’ ?

Answer 1

Carrying Capacity : The maximum stable population size that an ecosystem can support

Question 2

Define ‘Popullation’ ?

Answer 2

Population : Group of organisms of the same species living in the same habitat

Question 3

Define ‘Habitat’ ?

Answer 3

Habitat : Part of an ecosystem in which particular organisms live

Question 4

Define ‘Niche’ ?

Answer 4

Niche : An organisms role within an ecosystem, including their position in the food web and habitat. Each species occupies its own niche governed by adaptations to abiotic/ biotic conditions

Question 5

Explain how a population grows ?

Answer 5

• A population increases exponentially
• Limiting factors prevent the population from increasing ; environmental resistance

Question 6

Label the carrying capacity on the graph ?

Answer 6

Question 7

What are the different types of factors that affect a population ?

Answer 7

• Abiotic factors
• Biotic factors

Question 8

Name examples of abiotic factors that affect a population ?

Answer 8

• Light availability
• Water supply
• Water mineral content
• Temperature
• Amount of space available
• Soil pH

Question 9

What are the different types of biotic factors that affect a population ?

Answer 9

• Interspecific competition
• Intraspecific competition
• Predation

Question 10

Define ‘interspecific competition’ ?

Answer 10

Interspecific competition : Competition for the same resources between individuals from different species

Question 11

Define ‘intraspecific competition’ ?

Answer 11

Intraspecific competition : Competition for the same resources between individuals of the same species

Question 12

Define ‘Predation’ ?

Answer 12

Predation : Consumers that kill and eat other animals are known as predators, and those eaten are known as prey

Question 13

Explain the effect of intraspecific competition on the population size ?

Answer 13

• When resources are plentiful, the population increases
• As the population increases, there are more individuals competing for these resources (e.g. food and shelter)
• Resources become a limiting factor and the population can no longer grow in size and the carrying capacity has been reached
• This causes less organisms to reproduce and cause the population to decrease
• This results in less competition which means more organisms survive and reproduce causing the population to increase

Question 14

Explain the effects of interspecific competition on population size ?

Answer 14

• Species have overlapping niches resulting in COMPETITIVE EXCLUSION
• One species is better suited / adapted to the environment causing them to survive and reproduce
• The other species is less well adapted and will die, find another niche or evolve

Question 15

Explain this graph portraying the populations of a predator- prey relationship ?

Answer 15

• Initially, the number of predators increases as there is more prey available
• The number of prey then decreases as there are now more predators
  Then the number of predators decreases as there is now less prey available
• As a result, the number of prey increases as there are now fewer predators
  The cycle now repeats

Question 16

Define ‘Conservation’ ?

Answer 16

Conservation : The maintenance of biodiversity and sustainability through human action or management

Question 17

Define ‘Preservation’ ?

Answer 17

Preservation : The maintenance/ protection of habitats/ populations by restricting or banning human interference

Question 18

What are the different reasons for conserving biological resources / biodiversity ?

Answer 18

• Economic
• Ecological
• Aesthetic
• Social
• Moral / ethical
• Environmental

Question 19

Explain the economic reasons for conserving biodiversity ?

Answer 19

• Many of the medicines used today have originated from plants, fungi and bacteria
• Ecotourism a major source of income for many countries
• Ecosystems have also made major contributions to the field of science and technology

Question 20

Explain the ecological reasons for conserving biodiversity ?

Answer 20

• A more diverse ecosystem is better able to survive and adapt to environmental changes or threats
• Keystone species have a large impact on an ecosystem since many other species rely on them

Question 21

Explain the environmental reasons for conserving biodiversity ?

Answer 21

• Provide essential environmental services
• Plants absorb carbon dioxide from the atmosphere and help to reduce the greenhouse effect and climate change
• Microorganisms digest and break down the masses of organic waste that are produced by larger organisms
• Humans have water due to transpiration in plants / water cycle
• Nutrients cycle allows nutrients to renter soil and allow plants to grow

Question 22

Explain the social reasons for conserving biodiversity ?

Answer 22

• Many people enjoy spending time in the natural environment and can do activities together in nature
• Social benefits are lost if biodiversity is lost

Question 23

Explain the aesthetic reasons for conserving biodiversity ?

Answer 23

• Humans find great joy and pleasure in the beauty of nature
• It provides inspiration for creatives such as photographers, poets

Question 24

Explain the moral reasons for conserving biodiversity ?

Answer 24

• Many people believe that humans have a moral obligation to prevent the loss of biodiversity that results from human activities
• Have no right to cause extinction of other species

Question 25

Define ‘sustainability’ ?

Answer 25

Sustainability : The ability of an ecosystem to maintain (or ideally increase) its biodiversity whilst simultaneously providing humans with the resources they need over a long period of time

Question 26

What are two examples of managed ecosystems for sustainability ?

Answer 26

- Commercial fishing - Timber production

Question 27

What regulations are enforced in commercial fishing ?

Answer 27

- Fishing quotes/ limiting mass of fish caught - Ban fishing in certain areas - Increase size of fish net mesh/ holes to allow undersized/juvenile fish to escape - Limiting the size of the fishing fleet by issuing licenses - Inspecting the catch as a fishing boat returns to port - Allow fishing/ catching of certain non-endangered species only

Question 28

What two main groups of tree crops are used in commercial logging ?

Answer 28

- Fast-growing conifers - Slow-growing broad leaves trees

Question 29

What are some felling techniques ?

Answer 29

- Clear-felling - Coppicing - Pollarding

Question 30

Explain how clear-felling can be sustainable ?

Answer 30

- Limit area that is being felled - Replant trees after felling - Allow trees to fully grow before next felling - Minimise soil erosion between fillings

Question 31

What is coppicing ?

Answer 31

- Felling trees close to the ground and leaving the stump of the tree in the ground - New shoots can grow from the stump and can be harvested again - Process repeated after certain time - Coppicing can be repeated indefinitely

Question 32

What is pollarding ?

Answer 32

- Trees are cut 2-3 metres above the ground, leaving the mature tree trunk in place - New shoots can grow from the mature trunk and can be harvested again - Process repeated after certain time - Pollarding can be repeated indefinitely

Question 33

Explain the positive benefits of coppicing on biodiversity ?

Answer 33

- New stems grow faster than saplings - Extends lifespan of tree - Provide many high levels - More light available for smaller plants - Roots prevent soil erosion - Maintain soil quality - Prevent succession

Question 34

Name examples of human activities that affect biodiversity ?

Answer 34

- Burning fossil fuels - Introducing non-native species - Hunting - Loss of habitats

Question 35

Explain how burning fossil fuels affects biodiversity ?

Answer 35

- Results in large increase in the concentration of carbon dioxide in the atmosphere - This contributes to global warming

Question 36

What are the affects of global warming ?

Answer 36

- Hot climates which create extreme conditions which cause species to go extinct as they cannot adapt - Melting polar ice caps - Rising sea levels, causing flooding and - Salination of soil in coastal areas - Rising ocean temperatures and acidity

Question 37

Explain how introducing non-native species affects biodiversity ?

Answer 37

- Often have no natural competitors, predators or pathogens that help limit population growth, causing them to grow rapidly - This can cause population of native species to decrease due to competition/ disease

Question 38

Explain how hunting affects biodiversity ?

Answer 38

- Hunting can result in the over exploitation of a natural resource - This means a population may be unable to recover and go extinct

Question 39

Explain how habitat loss affects biodiversity ?

Answer 39

- Humans cut down forests/ drain wetlands which results in habitat loss - This causes species to search / compete for habitats which may cause them to go extinct

Question 40

Name examples of humans involvement in conservation ?

Answer 40

- Masai Mara National Reserve - Terai Region in Nepal - Peet Bogs

Question 41

Explain how human activity has been controlled in the Masai Mara National Reserve ?

Answer 41

- Local tribes are not allowed in the park and they have to grab their livestock on the outskirts of the park to enable vegetation in park to recover - Ecotourism is monitored to ensure natural environment is not exploited - Protects endangered species such as black rhino

Question 42

Explain why actions in the Masai Mara National Reserve is considered 'conservation' ?

Answer 42

- Local people live there - Sustainable use of land, farming, timber production - There is active work/ human management to maintain biodiversity and sustainability

Question 43

Explain how human activity has been controlled in the Terai region in Nepal ?

Answer 43

- Contains very fertile land and well-watered floodplains - Sustainable forest management to ensure livelihood for locals whilst protecting forest - To ensure sustainable agriculture, farmers are encouraged to grow crops further up in the hills - Farmers encouraged to grow more than one crop variety to increase biodiversity and nitrogen-fixing crops

Question 44

Explain how human activity has been controlled in Peet bogs ?

Answer 44

- Peat bogs are carbon sinks that are wet contains decomposed pant matter - Peet is used in compost/ fertilisers - Small trees nearby are removed to prevent drainage of water - Grazing in the area is controlled - Surface is kept as wet as possible rustling in no burning