Population and Sustinability

Question 1

Describe the difference between population and community

Answer 1

Population - group of organisms of the same species living in an area/habitat
Community - population of organisms of all the different species in an area/ecosystem

Question 2

Explain the importance of a niche to the survival of a species

Answer 2

Niche - role of an organism within its habitat. E.g where it eats
Survival of species is dependent to its niche
2 species can never occupy the same niche indefinitely due to competitive exclusion principle

Question 3

Define ecology

Answer 3

The study of the inter relationship between organisms and their environment including abiotic, non living and biotic,living factors

Question 4

Explain why grassland can be considered an ecosystem

Answer 4

It is an area in which there is interaction between biotic factors and abiotic factors. Biotic factors include the plant making up the grassland and the animals that graze or hunt in the grasslands.
Abiotic factors include- climate of area, light intensity and water availability

Question 5

Define the term biomass and why biomass is measured in dry mass rather than wet mass

Answer 5

BM- total mass of living material in a specific area at a given time
Dry mass more accurate because water content varies in fresh biomass, measuring wet mass given an inaccurate energy store value

Question 6

State the role and explain the function of plant within food chain

Answer 6

Plant are producers, convert energy from sunlight into chemical energy through the formation of photosynthetic products

Question 7

What is biomass and how is it transferred? How can we measure this

Answer 7

Total weight of living matter in a certain area, transferred up tropic levels through consumption.
Can be measured in terms of mass,carbon or dry mass tissue

Question 8

Give the formula for efficiency of biomass transfer

Answer 8

Efficiency - biomass transferred/biomass intake

Question 9

How can human activities affect biomass transfer

Answer 9

Light, water,temperature maximised
Increased nutrients in soil
Pests and weeds removed
Growth rate boosted

Question 10

Outline the roles of miceoganims in the nitrogen cycle

Answer 10

Nitrogen fixing bacteria e.g Rhizobium converts gaseous nitrogen into ammonia
Nitrifying bacteria convert ammonium compound into nitrites

Question 11

Outline the role of organisms in the carbon cycle

Answer 11

Respiration of plants and animals add carbon dioxide into the atmosphere
Photosynthesis of plants remove carbon dioxide from the atmosphere
Decomposers decay plant and animal material in CO2

Question 12

What is meant by primary succession

Answer 12

Where an area previously lacking of life is colonised by a community of organism

Question 13

Summaries the process of primary succession

Answer 13

Pioneer species, able to survive harsh conditions, colonise the area
They die, decompose and add nutrients to the ground
Over time, allows more complex organisms to survive

Question 14

What is the climax community and how is it reached

Answer 14

Final stage of succession, ecosystem is balanced and stacked.
Reached when the soil is rich enough to support large tress or shrubs

Question 15

Define deflected succession

Answer 15

Where succession is interrupted, usually human interference

Question 16

What is sampling

Answer 16

Selecting a group of individuals that will represent the whole target population
Measure the distribution and abundance of organism

Question 17

Give methods of sampling and explain

Answer 17

Quadrats- used in small areas, randomly or regularly placed. Frequency or % covers calculated
Transects - larger areas. Sample taken along a line that crosses the habitat . Can be combined with quadrats in the form of a belt transects

Question 18

Define carrying capacity

Answer 18

The maximum population size that a habitat can support, defined by presence of limiting factors

Question 19

Give factors that limit the maximum size of population

Answer 19

Food, wafer, light, o2, parasites, predators

Question 20

Describe the pattern of a typical predator - prey relationship in terms of population change

Answer 20

Prey is eaten by predator, resulting in predator population increasing and prey population decreasing
Fewer prey means increased competition for food, so predator population decreases
Fewer predators - more prey survives

Question 21

What is meant by intra specfic and inter specific competion

Answer 21

Intra- competition between organisms of the same species

Inter - competition between organisms of different species

Question 22

Differentiate between conservation and preservation

Answer 22

Conservation - maintains biodiversity of a habitat by allowing sustainable use of the resources there
Preservation- maintains biodiversity of a habitat by minimising human impact

Question 23

Give reasons why we conserve and preserve habitats

Answer 23

Economic - food source, natural pest control, boost tourism
Social - many organisms can be used in medicine, aesthetics
Ethical - we have responsibility to maintain habitats for future generation

Question 24

Define sustainability

Answer 24

Using resources in a way that also maintains them for future generations

Question 25

What methods allow sustainable use of an ecosystem resources

Answer 25

Timber production - coppicing to encourage growth, replacing felled trees, selective cutting
Fishing - stocks not depleted, no overfishing, can continue indefinitely

Question 26

Give an example of how the conflict between conservation and human needs can be balanced

Answer 26

Terai region
Over exploited for use in fuel.
Locals now have a responsibility to look after the forest

Question 27

Give example of how human effects are controlled in sensitive ecosystem

Answer 27

Galápagos Islands
Many species and endangered due to hunting and tourism
New species introduced, but caused damage to native species