Ecology - Topic 7 Paper 2

Topic 7

State the levels of organisation in an ecosystem?

Individuals, Population, Community, Ecosystem

What is an ecosystem?

The interaction between the living and non-living components

State the factors which plants may compete for?

* Light
* Space
* Water
* Mineral ions from soil

State the factors animals may compete for?

* Terrortority
* Mates
* Food

What is ==intra==specific competition?

Competition within a species

What is ^^inter^^specific competition?

Competition between different species

What is interdependence?

Different species in an ecosystem depend on each other for various resources, if one species is removed, the whole community will be affected

What is a stable community?

A community in which all the biotic factors and all the abiotic factors are balanced so that population sizes remain relatively constant

What are abiotic factors?

Give examples?

Non- Living factors

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* Light intensity
* Temperature
* Moisture
* Soil pH
* Soil Mineral Content
* Wind intensity and direction
* Carbon dioxide levels
* Oxygen levels

Why might Light Intensity affect an ecosystem?

Different species of plants may have different optimum light intensities for growth

Why might Temperature affect an ecosystem?

Different species of plants and animals may have different optimum temperatures for growth and survival

Why might Soil pH affect an ecosystem?

Certain plants may grow better in either acidic or alkaline soil

Soil pH may affect the appearance of a plant eg. colour of hydrangea

Why might Moisture affect an ecosystem?

Many plants cannot survive in a waterlogged soil as their roots cannot respire

Certain plants are adapted to high moisture levels

Why might Wind Intensity affect an ecosystem?

Plant seeds are more likely to germinate in locations with lower wind intensity, which may also attract animals that depend on the plant to live nearby

Why might Soil Mineral Content affect an ecosystem?

Most plants require a high level of soil minerals to grow well

Carnivorous plants catch insects to compensate for the low mineral content in soils

Why might Carbon Dioxide Levels affect an ecosystem?

Higher Carbon Dioxide Levels leads to more plant growth

Why might Oxygen Levels affect an ecosystem?

Aquatic animals cannot survive in areas with low oxygen concentrations

State the Biotic Factors which may affect an ecosystem?

* Food
* New Predators
* New pathogens
* Competition

What are adaptations?

Features that enable organisms to survive in their living environment

What are organisms which live in extreme environments called?

Extremophiles

Give 3 examples of extreme living environments?

* High Temperature
* High Pressure
* High Salt Concentration

State an example where extremophile bacteria may be found?

In Deep Sea Vents

Define Population?

A Species that occupy the same habitat

Define Habitat?

The place where an organism live

Define Community?

Populations of different species interacting

Define ecosystem?

The interaction between Biotic and Abiotic factors in an area

What do food chains show?

It shows the feeding relationships of different organisms and the flow of energy between the organisms

Define Biomass?

The total mass of living material

What are trophic levels?

The stages in a food chain

What do arrows in a food chain represent?

The direction of biomass transfer

Describe a simple food chain?

Producer → Primary Consumer → Secondary Consumer →Tertiary Consumer

What is a producer?

An organism that makes its own food

What types of organisms are producers?

Photosynthetic organisms like green plants and algae that trap energy from the Sun

What is a primary consumer?

An organism that feeds on producers

What is a secondary consumer?

An organism that feeds on primary consumers

What is a tertiary consumer?

An organism that feeds on secondary consumers

What is a predator?

A Consumer that kills

What is a prey?

An animal that gets killed and eaten by another animal

Describe the pattern of predators and prey in a stable community?

The numbers of predators and prey rise and fall in a cycles

Why are producers on the first trophic level?

Producers provide all biomass for the food chain (production for glucose via photosynthesis)

The rest of the food chain involves the transfer of this biomass

What piece of apparatus is used to measure the abundance and distribution of organisms in an area?

A Quadrat

what piece of apparatus is used to measure the distribution of organisms across a gradient?

Belt Transect

When considering the abundance of organisms, what is meant by the term “mean”?

The average number of organisms

How is arithmetic mean calculated?

The sum of each number of each organism/ The total number of each type of organism

When considering the abundance of organisms, what is meant by the term “mode”?

The most populous organism

When considering the abundance of organisms, what is meant by the term “median”?

The organism that represents the middle value when the numbers of each organism are arranged from lowest to highest

Describe how materials cycle through living and non-living components of an ecosystem?

* Organisms take in elements from their surrounding soil
* Elements are converted to complex molecules which become biomass
* Elements transferred along food chains
* Elements returned to the environment during the excretion and decomposition of dead organisms

Give 3 molecules that are cycled through ecosystems?

Oxygen, Carbon dioxide, Water

Describe the Carbon cycle?

* Plants fix carbon dioxide into organic molecules during photosynthesis
* The organic carbon-containing molecules are passed onto organisms that eat plants
* Carbon dioxide is released back into the atmosphere by respiration from plants and animals
* Burning fossil fuels also releases carbon dioxide into the atmosphere

Why is the carbon cycle important?

Carbon-containing molecules such as glucose are important for living molecules to grow and provide energy for vital functions within the cells

Describe the Water Cycle?

* Water from lakes and oceans evaporates
* The evaporated water condenses into clouds and returns to earth as precipitate (rain)
* The water from precipitation is useful for life on land
* The water then returns to rivers and oceans through surface runoff

Why is the Water- Cycle important?

Living organisms require water and the water cycle provides organisms on land with a continuous supply of water

Why are microorganisms important for cycling through materials through an ecosystem?

Microorganisms (bacteria and fungi) return carbon to the environment by releasing carbon dioxide through respiration while they decompose dead matter. The decomposition of dead matter in soil returns mineral ions to the environment for other organisms to use e.g. plants use mineral ions for growth

What is meant by decomposition?

The breakdown of dead materials into simpler organic matter

How do decomposers break down dead matter?

Decomposers release enzymes which catalyse the breakdown of dead material into smaller molecules

What are the two types of decomposition?

* Aerobic Decomposition
* Anaerobic Decomposition

What factors affect decomposition?

* Oxygen availability
* Temperature
* Water content

Why is oxygen required for decomposition?

Most decomposers require oxygen for aerobic respiration

How does the availability of oxygen affect the rate of decomposition?

* As oxygen levels increase, the rate of decomposition increase
* As oxygen levels decrease, the rate of decomposition decrease

Why can decomposition still occur in the absence of oxygen?

Some decomposers respire anaerobically

However, the rate of decomposition is slower as anaerobic respiration provides less energy

How does soil water content affect the rate of decomposition?

Decomposers need water to survive

* In moist conditions, the rate of decomposition is high
* In waterlogged soil, there is little oxygen for respiration so the rate of decomposition decreases

Why does decomposition require water?

Water is required for the secretion of enzymes and absorption of dissolved molecules

How does temperature affect the rate of reaction?

Decomposers release enzymes:

* Rate highest at 50 degrees (optimum temperature for enzymes)
* Low temperatures, enzymes work too slowly, rate decreases
* At high temperatures, enzymes denature, decomposition stops

How is the rate of change calculated when considering decay?

Rate of change= Change in value/Change in time

What is compost?

The nutrient-rich product of rapid decay of waste biological material (dead plants and animals) in optimum conditions set by gardeners and farmers

How is compost used?

Used as natural fertilisers to promote the growth of crops or garden plants

Describe how biogas generators work?

Biogas generators provide methane gas for fuel through anaerobic decomposition that occurs in animal waste

Describe how environmental conditions affect communities?

* Environmental conditions e.g. temperature, soil pH, light intensity affect the abundance and distribution of organisms within communities
* e.g. rising global temperatures have been linked to the extinction of frog species (their thin skin makes them vulnerable to temperature change)

How can temperature be bad for certain communities?

* If the temperature is too low, growth will be slower as organisms will use more energy to stay warm
* If the temperature is too high, organisms can die and water will become limited as evaporation increases

How can changes in water levels affect ecosystems?

* Animals may have to migrate to find water
* Melting ice caps may destroy the habitats of some animals

How can atmospheric gases affect ecosystems?

* Some organisms cannot survive when certain gases are present
* Polluted water can cause illness to animals that drink it

What detrimental impacts can sulfur dioxide have on the environment?

* Formed when fossil fuels containing impurities are burnt
* Sulfur dioxide can dissolve in water to form acid rain which can erode buildings and pollute water sources

What detrimental impacts can carbon monoxide have on the environment?

* Carbon monoxide is formed from the incomplete combustion of fossil fuels
* Carbon monoxide binds irreversibly to haemoglobin which prevents it from carrying oxygen
* Too much exposure can cause unconsciousness and death

Name 5 Greenhouse Gases?

* Methane
* Carbon dioxide
* Industrial gases
* Nitrogen
* Water vapor

Give 3 human activities that contribute to the increase in greenhouse gases?

* Burning fossil fuels
* Deforestation
* Large scale livestock farming

How do greenhouse gases lead to global warming?

* Greenhouse gases allow heat from the sun to enter our atmosphere
* The gases act as a blanket and trap heat in the atmosphere

State 3 negative consequences of global warming?

* Sea levels rise caused by melting ice caps
* Disrupted farming and agriculture
* Increase spread of disease in warmer climates

What is biodiversity?

The variety of different species on earth or an ecosystem

What is the importance of biodiversity?

To maintain the stability of an ecosystem

How does biodiversity ensure the stability of an ecosystem?

If reduced the dependence on particular species for resources e.g. food and shelter, so that even if one species is removed other species can still survive

Why has human consumption of resources and waste production increased?

* The rapid rise in human population
* Increase in standard of living

Where does pollution occur?

* Land
* Water
* Air

State 3 examples of water pollutants?

* Fertiliser
* Sewage
* Chemicals

How does eutrophication occur?

* Fertilisers from farms pollute the water, causing excessive algae growth, depleting oxygen in the water, causing other plants and animals to die
* Dead plants are decomposed by bacteria and the oxygen levels decrease further

State examples of air pollutants?

* Smoke
* Acidic gases

State examples of land pollutants?

* Landfill waste
* Chemicals

Which human activities reduce the land for plants and animals?

* Buildings
* Farming
* Quarrying
* Disposing of waste

Why have peat bogs been destroyed?

To produce compost to increase food production

Why does the destruction of peat bogs contribute to greenhouse effect?

Peatbogs are stores of carbon, and burning them releases a large volume of carbon dioxide into the atmosphere

Why have large-scale deforestation activities occurred?

* To provide land for cattle or rice fields
* To grow crops to produce biofuels

What is the greenhouse effect?

Greenhouse gases trap heat from the Sun in our atmosphere, keeping the temperature on Earth suitable for life

What is causing global warming?

The increase in greenhouse gases e.g. carbon dioxide and methane causing the temperature on earth to increase

What are harmful effects of deforestation?

* Destruction of many animal’s habitats
* Releases large amount of greenhouse gases

State the consequences of global warming?

* Rise in sea levels
* Melting polar ice caps
* Changing weather patterns
* Migration of animals to find suitable habitats
* Tropical diseases becoming more common
* Extinction of species

Describe the steps taken to maintain biodiversity?

* Breeding programs for endangered species
* Protection and rebuilding habitats
* Replanting field margins and hedgerows
* Reducing deforestation
* Reduce carbon emissions
* Recycling rather than disposing in landfills

What is the purpose of replanting hedgerows and field margins?

There is a higher biodiversity in the hedgerows and field margins than in the fields they surround

What does a food chain show?

It describes the feeding relationships between organisms and the resultant stages of biomass transfer