Biology - Ecology

Population

The number of individuals of the same species living in the same area at the same time.

Community

Multiple populations of different species living and interacting in the same area.

Ecosystem

The interaction between all the biotic and abiotic parts of the environment.

What is a stable community? inc. Interdependence

One where all the species and environmental factors are in balance so that population sizes remain fairly constant.

What are the three adaptations?

Structural, Behavioural, Functional

What is a a structural adaptation?

A physical part or feature of an organism.

e.g. fur colour

What is a behavioural adaptation?

The way an organism behaves

e.g. rabbits digging burrows

What is a functional adaptation?

Biological processes within the organism

e.g. snakes producing venom

What is the name given to organisms that live in extreme environments?

Extremophiles

What is the link between SA:V and heat loss?

With a small SA:V then heat loss is reduced.

With a big SA:V then heat loss is increased.

Biomass

The total mass of living material.

Characteristics of producers

They are at the start of every food chain.

They can photosynthesise (so normally algae or green plants).

Order of food chain

Producer, primary consumer, secondary consumer, tertiary consumer, apex predator.

Quadrat method

Use tape measures to lay out a 10×10m grid.

Use a random number generator to select random coordinates in the grid and place a quadrat there.

Count the number of species in the quadrat.

Transect method

Set up a tape measure along the area being investigated.

Place quadrats at regular intervals.

Record number of species and the abiotic factor in a table.

The carbon cycle

Carbon is taken out of the atmosphere for photosynthesis.

This carbon is used to make carbohydrates, fats and proteins.

The carbon is passed onto animals and microorganisms (decomposers) when they feed on the plants and algae.

CO2 is returned to the atmosphere during respiration.

CO2 is also returned to the atmosphere during combustion where wood or fossil fuels are burned.

The water cycle

Water enters the atmosphere by evaporation or transpiration.

The warm water vapour rises and, when it cools, condenses back into liquid water forming clouds.

Water returns to earth in precipitation.

What is the role of microorganisms?

Decomposers break down dead organisms and their waste products.

The materials they contain are returned to the environment in respiration as CO2.

What factors affect the rate of decay?

Temperature

Water availability

Oxygen availability

How is compost used?

It is produced as a natural fertiliser.

Once spread onto the soil, it is broken down further by decomposers. This allows minerals e.g. magnesium and nitrates to be absorbed by plants and used for growth.

Biogas generators

Animal or plant waste is allowed to decay anaerobically.

This produces methane gas which can be burned for heating, cooking or to generate electricity.

RP10: Milk decay

Place the same volume of milk into three beakers.

Use UI or pH meter to measure the pH of each beaker of milk.

Place each beaker into a water bath at the required temperature.

Measure the pH in each beaker at regular intervals e.g. each day.

Biodiversity

The variety of different species in an ecosystem.

Which human activities decrease biodiversity?

Producing waste which takes up space in landfill (destroying habitats) and produces toxic chemicals.

Deforestation

Global warming - flooding, coral bleaching, extreme weather events.

Atmospheric pollution releases CO2 and methane that causes climate change, acid rain, and desertification.

What are the sources of water pollution?

Toxic chemicals pesticides and herbicides runoff from agricultural land.

Untreated sewage.

Fertiliser runoff.

Eutrophication

Fertiliser runoff into lake or river.

Algae grow faster. Algal bloom.

Plants in the water are shaded by algae and cannot photosynthesise.

Some algae and plants die and are decomposed by microbes.

Microbes respire and use up oxygen.

Oxygen levels fall in the water.

Aquatic animals suffocate and die leading to decreased biodiversity.

What are the reasons for the growth in global population?

Improved technology so increased food so increased birth rate

Improved medicine, hygiene and health care so decreased death rate.

How has human land use decreased biodiversity?

Building, quarrying, farming and dumping waste has destroyed many habitats.

Peat bogs

Areas of land where plants do not fully decay when they die. The partly decomposed plant matter forms peat. The carbon is stored in the peat instead of being released into the atmosphere as CO2.

Peat bogs are often destroyed to make space for farming, to be used as compost, or to be burned as a fuel - releasing CO2.

Peat bogs are habitats for many species - destroying them decreases biodiversity.

Reasons for deforestation

To provide land for farming

To provide fuel/ crops for biofuels

For quarrying

For building

To provide wood for building materials

To provide paper

What are the effects of deforestation?

Extinction of species/ loss of biodiversity - habitats destroyed

Soil erosion

Flooding

Increased CO2 from burning and microbes respiring

What are the consequences of global warming?

Decreased biodiversity - due to extreme weather as habitats destroyed.

Change in migration patterns

Changes in where species occur

Extinctions

What is the greenhouse effect?

Solar radiation reaches the Earth

Some of the radiation is reflected back from the Earth’s surface

The greenhouse gases in the atmosphere reabsorb/trap much of this energy, so less is reflected back away from earth, and the earth becomes warmer.

What is the evidence for global warming?

Peer reviewed papers

Systematic scientific reviews

Data

Methods to protect biodiversity

Breeding programmes for endangered species

Protection and regeneration of rare habitats

Reintroduction of field margins and hedgerows - creates small habitats

Reduction of deforestation and CO2 emissions by some governments

Recycling rather than dumping in landfill

What % of biomass is passed on at each trophic level?

10%

Why is not all biomass passed on?

Some biomass is egested as faeces

Some lost as urea in urine

Some lost in respiration as CO2

Biomass lost to provide energy for movement and keeping warm

Food security

Having enough food to feed and sustain a population

Factors threatening food security

Climate change - increased droughts and floods

Increased population - due to increased birth rates in many developing countries

Changing diets - travel miles

Pests and pathogens

Costs of agriculture

Conflicts - can affect water/food supply

Increasing efficiency of food production by restricting energy transfer

Limiting movement of animals - less muscle contraction

Controlling the temperature - keeping it warm

Animals could also be fed protein supplements to increase growth

Benefits of intensive farming

Less land used

Cheaper food per person

Faster growth

Protected from weather, predation, disease

Disadvantages of intensive farming

Consumer resistance over animal welfare

Energy costs + high carbon footprint

Higher disease rate

Selective breeding can lead to a decreased gene pool

Poorer quality food

What are two techniques for sustainable fishing

Control of net size - fewer unwanted species caught as they can escape through net gaps. Juvenile fish can escape through net gaps meaning they can meet breeding age and have offspring which replenishes fish population.

Fishing quotas - limit number and size of fish that can be caught.

How is mycoprotein produced?

The fungus Fusarium is grown in a fermenter in aerobic conditions and provided with a glucose syrup as a food source. The fungal biomass is then harvested and purified to produce vegetarian protein.

A water jacket is used to maintain a constant temperature, a stirrer is used to keep the microorganisms, nutrients and temperature constant.

How can any required protein be made?

Genetic modification of bacteria

How is golden rice made?

Genetic modification - genes from another species for making vitamin A are inserted into rice DNA.