B7 - Final Mocks

L1 - Communities

Individual: One organism of one species.
Population: Lots of individuals of the same species.
Community: A group of different populations living in the same environment.
Ecosystem: A community living and interacting with non-living parts of the environment.

Plants will compete with each other for light, space, water and minerals in the soil. Animals compete with each other for food, water, mating partners and territory.

Examples of interdependence:

Bees spreading pollen.
Birds dispersing seeds in their faeces.
Trees acting as shelter.

In a stable community, populations of species remain relatively constant and are in balance with one another and the abiotic resources.

L2 - Biotic and Abiotic Factors

Biotic:

Availability of food.
Arrival of a new predator.
Competition between species.
Arrival of new pathogens.

Abiotic:

Light intensity (plants grow more slowly).
Temperature (distribution of species changes).
Water.
pH and mineral content of the soil.
Wind intensity (affects transpiration).
CO2 and O2 levels.

L3 - Adaptations

Extremophiles may be able to live in high concentrations of salt

L4 - Food Chains

L5 - Sampling Organisms

All food chains begin with a producer (usually a green plant or algae). Producers synthesise complex molecules such as glucose (known as biomass).

Organisms that eat producers are known as primary consumers.

Random sampling:

Quadrat used, coordinates generated randomly.

Transect:

Looking for change across a habitat.
Quadrat placed at fixed intervals.

L6 - Carbon Cycle

CO2 in atmosphere.
Photosynthesis (synthesis of glucose).
(Back to atmosphere through aerobic respiration)

Plants and algae take in carbon dioxide from the atmosphere, this carbon is used to make carbohydrates, fats and proteins.
(Some released back into atmosphere through respiration).
Plants and algae are eaten by animals, animals produce waste such as faeces (eventually, they also die).
Decomposers break down these remains and carry out respiration in the process (also releasing mineral ions into the soil).

Under certain conditions (lack of oxygen), decomposers cannot function effectively and the carbon in these remains can slowly turn into fossil fuels. Humans burn these fossil fuels for energy and release CO2 in the process.

L7 - Water Cycle

Water on the surface of oceans evaporates and rises through convection, it then condenses to form clouds.
This water then falls to the ground through precipitation (rain, slow, hail and sleet). This water is fresh.
The water that hits the ground can evaporate again, pass through rocks and form aquifers or form rivers/streams (eventually drains back into the sea).
Plants take up water in their roots during transpiration. Animals take in water through their food and through drinking; they remove this water in urine, faeces and when they exhale.

L8 - Decay Practical

Label a test tube "lipase" and add 5cm^3 of the lipase solution using a pipette.
Label another test tube "milk" and add 5 drops of indicator (phenolphthalein), 5cm^3 of milk and 7cm^3 sodium carbonate. The solution should be pink.
Place a thermometer into the "milk" test tube.
Place both into an electric water bath at our first temperature.
Transfer 1cm^3 of lipase solution and stir; begin a timer.
Stop timing once the milk decolourises.

L9 - Decomposition

Over time, bacteria and fungi can decompose plant material to form compost, this can then be used as a fertiliser as it is very rich in minerals.

Factors affecting decomposition:

Temperature
Moisture (Chemical reactions in decay require water)
Amount of oxygen (needed for aerobic respiration)

Anaerobic decay produces a mixture of gasses (such as methane), this mixture is referred to as "biogas". Biogas generators can be used to provide fuel for homes. This biogas cannot be stored and must be burned as soon as it is produced.

Biodiversity is the variety of all the different species of organisms on Earth or ecosystem.

Deforestation is typically done in order to free up land for rice fields, the growth of biofuels and grazing cattle (agriculture).

L10 - Waste Management

Humans are using more and more resources due to an increasing population and standard of living.

The release of fertilisers and untreated sewage into bodies of water causes dissolved oxygen levels to fall, reducing biodiversity.

Eutrophication process:

Nutrients from fertilisers enter the water and water and are used by aquatic plants.
Algae flourish and this decreases the amount of dissolved oxygen in the water as well as blocking the sunlight for aquatic plants.
Plants die and decomposition depletes oxygen further.
Ecosystem fails as oxygen levels decrease so much, reducing biodiversity.

Peat bogs contain large amounts of dead plant materials. Conditions within peat bogs cause decay to be very slow. They, therefore, contain a very large amount of trapped carbon.

Peat is used to produce cheap compost or is burned to produce energy. The destruction of these peat bogs decreases biodiversity. Once peat is extracted, it begins to decay and releases a large amount of carbon dioxide.

L11 - Global Warming

Methane is produced by bacteria in paddy fields (rice fields) or when cows pass wind.

Peer review helps to avoid false claims and ensures that published research is valid.

Consequences:

Change in migration patterns.
Rising sea levels.
Plants flowering earlier.
Destruction of habitats (melting icecaps).

L12 - Farming Techniques

Biodiversity can be maintained by:

Using breeding programmes for endangered species.
Protection and regeneration of rare habitats.
Use of field margins and hedgerows.
Passing legislation / government action.
[Individuals] Recycling waste materials.

Only ~10% of biomass is transferred from one trophic level to the next, this is because:

Not all of the material eaten by an animal can be digested and used, some passes out as waste.
Biomass used to release energy through respiration (movement and maintaining body temp).

There is less biomass available for free range chickens: biomass is used in respiration and body temp.

Intensive farming may occur in a temperature controlled shed; movement in these sheds are limited and this reduces a chicken's need to respire: less biomass is wasted. These chickens are also provided with a high protein diet.

Intensive: More efficient, can control diets and provide animals with sufficient nutrients | Diseases cam be spread more easily, antibiotics are given which could help resistant strains develop, ethical objections.

L13 - Biotechnology

Combatting falling fish stocks:

Setting strict quotas on the number of fish caught for each species.
Net size must allow smaller, less mature fish are not caught.

Bacteria can be genetically engineered to produce insulin; this can be used to treat individuals with diabetes.

GM crops could be used to produce more crops which have a greater nutritional value. Golden rice contains more vitamin A than natural rice.

Mycoprotein is produced by the fusarium fungus. This fungus is grown on glucose syrup in a fermenter. In aerobic conditions, the fusarium converts the glucose into mycoprotein which can be harvested and purified. Mycoprotein is suitable for vegetarians and it can be harvested in great quantities within a small space.