6.3.2 Populations and sustainability

Question 1

Population

Answer 1

A group of organisms of the same species, living in the same habitat, at the same time.

Question 2

Carrying capacity

Answer 2

Maximum population size the environment can support.

Question 3

What factors influence population size.

Answer 3

Density independent factors:
Natural disasters
Fires

Density dependant:
Migration
Competition
Predation
Availability of food
Disease

Question 4

Limitting factor

Answer 4

Environmental resource or constraint that limits population growth.

Question 5

Migration (3)

Answer 5

Density dependant factor.

Emigration:
Movement of organisms AWAY from an area.
Decreases population of that area.

Immigration:
Movement of organism INTO an area.
Increases population size of an area.

Question 6

Competition

Answer 6

Biotic limiting factor that occurs when resources are not present in adequate amounts to satisfy the needs of all the individuals who depend on them

IntrAspecific: competition between the sAme species.

IntErspecific: competition between diffErEnt species

Question 7

Describe the population growth curve.

Answer 7

1. Lag phase:
   Slow growth phase. Few organisms are present.
2. Log phase:
   There are enough resources for each individual to survive and reproduce.
   Exponential growth in population.
   Birth rate + immigration> Death rate + emigration
3. Stationary phase: Population size is stable/ little fluctuations.
   Resources are becoming scarce.
   Growth is prevented by limiting factors.
   Birth rate + Immigration = Death rate and emigration
4. Death phase: Population size decreases.
   This is when dominant species that are better adapted outcompete those who are not.
   Death rate > Birth rate.

Question 8

Preservation and conservation.

Answer 8

Preservation:
Preventing human interference of an are or organisms.
i.e restricting human access, laws being passed.

Conservation:
Maintaining habitats, species and genotypes through active human intervention

Question 9

Three difference needs for conservation

Answer 9

Social

Economic

Ethical

Question 10

Economic reasons for conservation

Answer 10

Some species of organisms are resources that humans need.

Provides a source of income:
Medicine
Food
Clothes
Beauty products
Tourisim

Question 11

Social reasons for conservation

Answer 11

Habitats and some species are aesthetically pleasing:

Benefits the personal health of individuals as it relaxing + some landscapes allow exercise.

Tourism is also increased as a result.

Question 12

Ethical reasons for conservation.

Answer 12

All organisms have the right to exist.

Humans have a moral responsibility for leaving sustainable resources for future generations.

Question 13

Reasons for encouraging sustainability

Answer 13

Preserves the environment.

Ensures future generations have resources.

Allows comfortable living for individuals.

Allows the development of less economically developed countries (LEDCs)

Question 14

Describe sand dunes as an example of succession. (6 seral stages).

Answer 14

1. Bare sand: piece of land that has not been occupied yet.
2. Embryo dune: pioneer species—>Sea rocket
   - No soil
   - Dry
   - No nutrients
3. Yellow dune—> Lyme grass, Marram grass.
   - Arid
   - Low nutrients, an increase occurs due to plants being established.
4. Dune slack—> Willow
   - Wet conditions
   - Close to a water table
   - Saline water
5. Grey dune— > Sand sedge, heather, bracken.
   - Simple soil
   - Some nutrients
   - organic matter increased

6 Climax community—> Birch, Oak trees.

• Most stable community
• Well structured soil that retains water
• High organic matter.

Question 15

Describe the ecosystem of peat bogs:
Features
Animals, Plants

Answer 15

• Wetland: Acts as a carbon sink

Soil is acidic and decay is very slow due to wet, cold climate.

• Composed of peat: formed from decomposing vegetation.

Vegetation: Mosses, sedges, shrubs

Animals: Mainly insects

Question 16

Human activity that affects peat bogs

Answer 16

Peat is being extracted for fuel- They are dried out and burned to release thermal energy.

Peat use in agriculture:

• Increases acidity of the soil
• Improves soil structure
• Maintains water content of soil, prevents flooding of roots.

Question 17

Why do peat bogs need to be conserved? (6)

Answer 17

The ecosystem is becoming very rare do to human activity.

The ecosystem takes thousands of years to form- not replaced easily.

The ecosystem is a source of high biodiversity.

Allows flood and erosion management.

Habitats are rare and threatened.

Archaeology: preserves ancient organisms that is used to develop scientific knowledge.

Question 18

Methods of conserving peat bogs

Answer 18

UK biodiversity action plan (UKBAP): conserves and enhance biodiversity through local schemes

Ditch blocking: Raises water tables which prevent soil drying out.

Preserving vegetation: restricting access to specific plant species.

Controlling grazing

Removing seedlings: They can use up water in the soil, which can dry it out.

Preventing the extraction of peat.

Question 19

Overview of the ecosystem of the Terai region of Nepal.

Answer 19

Hot and humid climate

Composed of a diverse range of habitats including over 50 wetlands.

Contains very fertile alluvial soil: rich in nutrients.

Plants: sal tree, bamboo, pipal.
Animals: Bengal tiger, Sloth bear, Indian rhino

Question 20

Describe how human activity affects

Answer 20

Local people are reliant of the forest for agriculture:
Deforestation and clearing forests with fire.

This increases grazing and monoculture.

Question 21

Sustainable management of the Terai region of Nepal

Answer 21

Forestry stewardship:
Allows humans to exploit the land in compromise for sustainable management.

Includes:
Promotion of fruit and veg in the hills of the mountain region.
Increasing nitrogen fixing crops.
Improving soil and water content.

Question 22

How does human activity impact the Masai Mara region.

Answer 22

Farming: cultivating the land uses up nutrients in the soil.

Building homes: reduces vegetation and destroys habitats.

Question 23

Sustainable methods of managing Masai Mara

Answer 23

Ecotourism: generates income whilst supporting conservation

Fencing: prevents trampling of crops by elephants and other large mammals.

Legal hunting:
maintains the population of an ecosystem whilst generating income for humans.

Question 24

Describe sustainable methods of managing woodland.

Answer 24

Selective felling/ thinning: never clear felling which fully exposes the ground.

Coppicing and pollarding: encourages more growth and increases timber production.

Standards: tall trees, that grow between coppiced plants, which protect the soil.

Creating paths/ cycle tracks

Creating habitats: piling dead wood/ scrub

Replacing felled trees with fast growing native species.

Protecting young trees from being eating by herbivores

Question 25

Describe methods of sustainable fishing.

Answer 25

Laws being placed that have quotas to control how much fish is caught.

The use of nets with larger holes: prevents premature fish from being caught.

Fish farms: produce fish without affecting wild population in the oceans

Question 26

Describe how human activity affect the Galapagos island. (8)

Answer 26

Whaling: upset the marine ecosystem.

Introduction of foreign species: outcompete endemic species

Tourism: placing stress on the environment.

Scientific research: disturbing the population of the ecosystem by taking samples..

Increasing population of humans:
More habitats are destroyed for housing.
Energy supplies used up.
More waste

Humans bring in new diseases.

Question 27

Sustainable management of the Galapagos island.

Answer 27

Limiting human access.

Captive breeding of species like tortoises.

Strict control of the movement of foreign species.

Education about conservation methods for the local people.

Culling of feral pigs and goats.

Introduction of natural predators to reduce pest populations

Question 28

Endemic species of the Galapagos islands and how they are affected by human activity. (6)

Answer 28

• Giant tortoise:
  Introduction of goats caused interspecific competition, which goats outcompete the tortoise.
• Rock purslane:
  Introduction of goats and pigs led to increased herbivory which killed them, reducing their population.
• Scalesia tree:
  Introduction of the red guanine tree led to interspecific competition, which red guanine outcompete Scalesia.
• Daisy tree:
  Deforestation by humans to create space for infrastructure.

Land ground finch:
Introduction of domestic cats predate on the finch. The finch can also be trampled.

Blue footed boobies:
Introduction of foreign rats eat the eggs of the boobies.

Question 29

Species of the Antarctic and how they are affected by human activity. (5)

Answer 29

Blue whales and fur seals:
Being hunted by humans for meat and pelt.

Emperor penguins:
Oil spillages, from humans drilling for oil, can cause them to accidentally consume it (toxic to them).

Antarctic krill:
Krill is a keystone species for many marine animals. Overfishing for krill disrupts food chains.

Albatross:
Introduction of rats which predate on the eggs of these birds.

Question 30

Human activity that affects the Antarctic. (6)

Answer 30

Whaling and overfishing.

Discarding waste into the sea like nets, hooks affects birds and marine animals.

Discarding water/sewage pollutes the land.

Introduction of invasive species.

Drilling for oil/ bringing ships causes oil spillages.

Global warming: causing ice caps to melt and destroys habitats