Ecology

?

Biology revision

Recall what an ecosystem is

An ecosystem is the interaction of a community of living organisms with the non-living (abiotic) parts of their enviroment.

1 of 39

Biology revision

Describe which resources animals and plants compete for, and why they do this

in a community, each species depends on other species for food, shelter, pollination, seed dispersal,etc. If one species is removed it can affect the whole community; this is known as independence.

Within any community the different plants and animals are often independent:

  • plants produce food by photosynthesis
  • animals eat plants
  • animals pollinate plants
  • animals eat other animals
  • animals use plant and animal material to build nests and shelters
  • plants need the nutrients from animal droppings and decay
2 of 39

Biology revision

Explain the terms 'interdependence' and 'stable community'

independence - when if one species is removed or becomes very numerous it can affect the whole community.

a stable community is one where all the species and enviromental factors are in balance so that population sizes remain fairly constant.

3 of 39

Biology revision

Name some abiotic and biotic factors that affect communities

abiotic factors:

  • light intensity
  • temperature
  • moisture levels
  • soil pH and mineral content
  • wind intensity and direction
  • the carbon dioxide levels for plants
  • the availability of oxygen for aquatic animals

Biotic factors:

  • availability of food
  • new predators arriving 
  • new pathogens
  • new competitors
4 of 39

Biology revision

Explain how a change in an abiotic or biotic factor might affect a community

abiotic factors - a non living condition that influences or affects an ecosystem and the organisms in it.

biotic factors - a living thing, like an animal or plant, that influences or affects an ecosystem.

5 of 39

Biology revision

Describe structural, behavioural and functional adaptations of organisms

Structural adaptations - for example the shape or colour of the organism or part of the organism

behavioural adaptations - for example migration to move to a better climate for the summer or winter, basking to absorb energy from the sun and to warm up, and tool-using to obtain food

functional adaptations - related to processes such as reproduction and metabolism, for example, delayed implantations of embryos or antifreeze in cells.

6 of 39

Biology revision

Describe what an extremophile is

Extremophiles have adaptations that enable them to live in enviroments with extreme conditions of salt, temperature, or pressure. 

7 of 39

Biology revision

Represent the feeding relationships within a community using a food chain and describe these relationships

See the source image

All food chains begin with a producer which synthesises new molecules. On land this is usually a green plant that makes glucose by phtotsynthesis. Producers are aeten by the primary consumers which in turn may be eaten by secondary consumers and then tertiary consumers.

8 of 39

Biology revision

Explain how and why ecologists use quadrats and transects

a quadrat is a sample area used for measuring the abundance and distribution of organisms in the field.

when working out the number of a species in a field, you would find out the mean of the amount of species there are in 10 randomly placed 1m x 1m quadrats. Then you would divide the area of the field by the area of the quadrat, and then times that answer by the mean amount of species. 

when using a transect you would do the exact same thing but instead of placing the quadrats randomly, you would place them in a line at place the quadrats at regular intervals. 

9 of 39

Biology revision

Describe and interpret predator-prey cycles

In a stable community, the number of predators and prey rise and fall in linked cycles.

If thereis plenty of food available, the prey animals grow and reproduce successfully, so numbers increase.

As prey animal numbers go up, there is plenty of food available for the predators, so predators can reproduce successfully and predator numbers increase. 

The high number of predators eat a larger proportion of the prey animals, so prey numbers fall. 

With fewer prey animals, there is then less food for the predators, so they are less successful and predator numbers fall.

With the reduction in predators, and the good food supply that results from fewer animals, prey numbers go up again and the cycle repeats itself 

10 of 39

Biology revision

Describe the processes involved in the carbon cycle

Processes in the carbon cycle:

  • photosynthesis: Carbon dioxide + water -> glucose + oxygen 
  • Respiration: glucose + oxygen -> carbon dioxide + water 
  • Combustion: fossil fuels or wood + oxygen -> carbon dioxide
  • The carbon cycle returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis
  • The decay of dead plants and animals by microorganisms returns carbon to the atmosphere as carbon dioxide
11 of 39

Biology revision

Describe the processes involved in the water cycle

The water cycle provides fresh water for plants and animals on land before draining into the seas. Water is continuously evaporated, condensed and precipitated 

See the source image

12 of 39

Biology revision

Bio ONLY: Explain how temperature, water and availability of oxygen affect the rate of decay of biological material

Temperature - the chemical reactions in microorganisms work faster in warmer conditions. They slow down and might even stop if conditions are too cold. Decay also stops if it gets too hot. The enzymes in the decomposers are denatured.

Moisture - most microorganisms gorw faster in moist conditions. The moisture makes it easier for them to digest their food and also prevents them from dying out. 

Oxygen - although some microorganisms are anaerobic, most decomposers respire aerobically. This means they need oxygen to break down food and transfer energy, grow, and reproduce. Therefore, decay takes place more rapidly in aerobic conditions.

13 of 39

Biology revision

Bio ONLY: Explain how the conditions for decay are optimised by farmers and gardeners, and the reasons for this

Gardeners and farmers try to provide optimum conditions for the rapid decay of waste organic matter. They do this by using compost. Compost is the perfect way to create natural fertilisers efficiently because it creates a warmer, and more moist place for the microorganisms to aerobically respire and decompose, which enhances the speed of decay by a significant amount compared to if it was cold, dry and contained no oxygen.

14 of 39

Biology revision

Bio ONLY: Describe how methane gas can be produced from decaying materials for use as a fuel

Methane gas can be produced when bacteria decompose waste material in anaerobic conditions. So plants and animal waste is put into biogas generators at around 30oC (the temperature when the bacteria work best) and in anaerobic conditions, decomposers will produce methane gas for use as fuel. 

15 of 39

Biology revision

Describe what biodiversity is, why it is important, and how human activities affect it

biodiversity is the variety of all the different species of organisms on Earth or within an ecosystem.

High biodiversity helps ensure the stability of ecosystems by reducing the dependence of one species on another for food, shelter, and the maintenance of the physical enviroment.

Human reduce the amount of land available for other animals and plants by building, quarrying, farming, and dumping waste. 

16 of 39

Biology revision

Describe the impact of human population growth and increased living standards on resource use and waste production

The future of the human species on Earth relies on us maintaining a good level of biodiversity. Many human activity are reducing biodiversity and only recently have measures been taken to address the problem. 

Rapid growth in the human population and an increase in the standard of living mean that increasingly more resources are used and more waste is produced

17 of 39

Biology revision

Explain how pollution can occur, and the impacts of pollution

Pollution can occur on land, from landfill and from toxic chemicals such as pesticides and herbicides, which may also be washed from land to water. 

Pollution can occur in water from sewage, fertilisers, or toxic chemicals.

Pollution kills plants and animals, which can reduce biodiversity.

18 of 39

Biology revision

Describe how humans reduce the amount of land available for other animals and plants

  • More and more land is used for building houses, shops, industrial sites, and roads on. This destroys the habitats of other living organisms and reduces biodiversity.
  • We use billions of acres of land around the world for farming. Whatever people farm, the natural animal and plant populations are destroyed.
  • We dig up vast areas of land for quarries to obtain rocks and metal ores, reducing the land available for other organisms.
  • The waste produced by humans pollutes the enviroment and processing it takes up land, affecting biodiversity.
19 of 39

Biology revision

Explain the consequences of peat bog destruction

The destruction of peat bogs and other areas of peat to produce garden compost reduces the area of this habitat and thus the biodiversity associated with it

The decay and burning of peat also releases carbon dioxide into the atmosphere.

20 of 39

Biology revision

Bio ONLY: Explain how environmental changes can affect the distribution of species in an ecosystem (temperature, water and atmospheric gases)

seasonal changes: temperature, the amount of rainfall, and availability of water, levels of dissolved gases in the water and the hours of daylight can all the distribution of species. e.g. some animals migrate to avoid the cold while others only appear when conditions are favourable

Geographical changes: many animals and plants have specific adaptations that enable them to survive and reproduce in particular geographical conditions

as a result of human interaction: There are some positive examples like; maintaining rainforests, reducing water pollution and monitoring pH, restricting access to sites of special scientific interest and conservation measures such as replanting hedgegrows and woodlands. 

However there are some disadvantages like: global warming and climate change, the effects of acid rain on soil and pollution from farms and factories 

21 of 39

Biology revision

Describe what deforestation is and why it has occurred in tropical areas 

deforestation is the removal of a forest or stand of trees from land which is then converted to a non-forest use. 

Large-scale deforestation in tropical areas has occured to provide land fro cattle and for rice fields and to grow crops for biofuels.

 

22 of 39

Biology revision

Explain the consequences of deforestation

  • It increases the amount of carbon dioxide released into the atmosphere in two ways:
    • Burning the trees leads to an increase in carbon dioxide levels from combustion 
    • the dead vegetation decomposes and the microorganisms use up oxygen and release more carbon dioxide as they respire.
  • reduces the rate at which carbon dioxide is removed from the atmosphere 
  • lose a vital carbon dioxide 'sink'
23 of 39

Biology revision

Describe how the composition of the atmosphere is changing, and the impact of this on global warming

Levels of carbon dioxide and methane in the atmosphere are increasing, and contributing to global warming

24 of 39

Biology revision

Describe some biological consequences of global warming

Biological consequences of global warming include loss of habitat when low-lying areas are flooded by rising sea levels, changes in the distribution patterns of species in areas where temperature or rainfall has changed, and changes to the migration patterns of animals.

25 of 39

Biology revision

Describe both positive and negative human interactions in an ecosystem and explain their impact on biodiversity

As a result of human interaction: 

positive changes:

  • maintaining rain forests
  • reducing water pollution and monitoring pH
  • Restricting access to sites of special scientific interest
  • Conservation measures such as replanting hedgegrows and woodlands

Negative changes:

  • global warming and climate change 
  • the effects of acid rain on soil 
  • pollution from farms and factories 
26 of 39

Biology revision

Describe programmes that aim to reduce the negative effects of humans on ecosystems and biodiversity

  • breeding programmes fro endangered species
  • protection and regeneration of rare habitats 
  • reintroduction of field margins and hedgegrows
  • reduction of deforestation and carbon dioxide emissions 
  • recycling resources
27 of 39

Biology revision

Bio ONLY: Explain the term 'food security' and describe biological factors that threaten it

Food security is having enough food to feed a population.

Factors affecting food security include:

  • increasing birth rates
  • changing diets in developed countries resulting in scarce food resources being transported around the world 
  • New pets and pathogens affecting farming
  • enviromental changes affecting food production 
  • the cost of agricultural inputs 
  • conflicts affecting access to water or food
28 of 39

Biology revision

Bio ONLY: Explain how the efficiency of food production can be improved

The efficiency of food production can be improved by restricting energy transfer from food animals to the enviroment. This can be done by limiting their movement and by controlling the temperature of their surroudings.

Some animals are fed high protein foods to increase growth.

29 of 39

Biology revision

Bio ONLY: Explain the term 'factory farming', including examples, and ethical objections

Intesive farming uses machines, fertilisers, man-power and high-yield crops to maximise the amount of food produced.

ways of increasing the efficiency of food production include:

  • Limiting the movement of food animals so they don't use their muscles much. This reduces the need for respiration and so they have more biomass available from their food for growth.
  • Controlling the temperature of the surroundings so the animals do not have tio use much biomass in respiration for keeping warm or wooling down. Again this leaves more biomass for growth
30 of 39

Biology revision

Bio ONLY: Explain the importance of maintaining fish stocks at a level where breeding continues

Fish stocks in the ocean are declining. Therefore it is important to maintain fish stocksat at a level where breeding continues successfully, otherwise certain species may disappear completely in some areas, for example, cod in the northwest Atlantic and Bluefin Tuna in the Mediterranean. 

31 of 39

Biology revision

Bio ONLY: Explain some methods that can help to conserve fish stocks

A way people conserve fish population include controlling the size of the holes in the net so only the biggest fish get caught and the smaller fish can be free to grow. 

Another way that plays an important role in the conservation of fish stocks at a sustainable level is the introduction of fishing quotas. (they strictly enforced a limit on the amount and type of fish they are allowed to catch)

32 of 39

Biology revision

Bio ONLY: Describe how modern biotechnology is used in food production, including the fungus Fusarium as an example

Modern biotechnology techniques enable large quantities of microorganisms to be cultured for food

The fungus Fusarium is useful for producing mycoprotein, a protein-rich food suitable for vegetarians. The fungus is grown on glucose syrup (made from waste starch), in aerobic conditions, and the biomass is harvested and purified. 

See the source image (http://bam.files.bbci.co.uk/bam/live/content/zrg7pv4/small)

33 of 39

Biology revision

Bio ONLY: Describe the uses of genetically modified organisms in insulin and food production

Genetically modified bacteria produce drugs such as insulin on an industrial scale.

Genetically modified crops are alos being developed to provide more food  and food with an improved nutritional value. e.g. Golden rice, with its extra vitamin A.

34 of 39

Biology revision

Bio ONLY: Describe the different trophic levels and use numbers and names to represent them

Trophic levels can be represented by numbers, starting at level 1. Further trophic levels are numbered subsequently according to how far the organism is along the food chain.

Level 1 - producers (plants and algae); Level 2 - primary consumers (herbivores); Level 3 - secondary consumers (carnivores who eat herbivores); Level 4 - tertiary consumers (canivores who eat secondary canivores).

Apex predators are carnivores with no predator

35 of 39

Biology revision

Bio ONLY: Describe what decomposers are and what they do

Decomposers break down dead plant and animal matter by secreting enzymes into the environment. Small soluble food molecules then diffuse back into the microorganism. 

36 of 39

Biology revision

Bio ONLY: Construct pyramids of biomass accurately from data and explain what they represent

pyramids of biomass can be constructed to represent the relative amount of biomass at each level of a food chain. Trophic level 1 is always at the bottom of the pyramid.

See the source image

37 of 39

Biology revision

Bio ONLY: State how much energy producers absorb from the Sun and how much biomass is transferred

Producers are mostly plants and algae that transfer about 1% of the incident energy from light for photosynthesis

Only approximately 10% of the biomass from each trophic level is transferred to the level above it.

38 of 39

Biology revision

Bio ONLY: Explain how biomass is lost between trophic levels, including the consequences of this and calculate efficiency between trophic levels

Losses of biomass occur because not all the ingested material is absorbed - some is egested as faeces, some absorbed material is lost as waste products, such as carbon dioxide and water in respiration, and water and urea in urine, and large amounts of glucose are used in respiration.

Percentage energy transfer =

(biomass in higher trophic level / biomass in lower trophic level) x 100

39 of 39

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Ecology and Environmental Science resources »