Ecology

What is an ecosystem?

The interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment

What do plants compete with each other for?

• Light

• Space

• Water and mineral ions from the soil

What do animals compete with each other for?

• Food

• Mates

• Territory

What is interdependence?

When each species in a community depends on another species for food, shelter, pollination, seed dispersal etc… If one species is removed it can affect the entire community.

What is a stable community?

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

What are some examples of abiotic (non-living) factors that can affect a community?

• Light intensity

• Temperature

• Moisture levels

• Soil pH and mineral content

• CO₂ levels for animals

• Oxygen levels for aquatic animals

What are some examples of biotic (living) factors that can affect a community?

• Availability of food

• New predators

• New pathogens

• One species outcompeting another so numbers aren’t sufficient to breed

What are adaptations?

Features that enable them to survive in the conditions in which they normally live. These may be structural, behavioural or functional

What are extremophiles?

Organisms that live in extreme environments such as high temperature, pressure, or salt concentration

What is an example of an extremophile?

Bacteria living in deep sea vents

What can be represented by food chains?

Feeding relationships

What is a producer?

An organism that synthesises molecules. Usually a green plant/alga which makes glucose via photosynthesis

How can ecologists determine the distribution and abundance of species in an ecosystem?

Use transects and quadrats

What is a basic outline of a food chain?

Producers are eaten by primary consumers which may be eaten by secondary consumers and then tertiary consumers

What happens to the number of predators and prey in a stable community?

They rise and fall in cycles

What are predators?

Consumers that kill and eat other animals

What are prey?

Organisms that are eaten by predators

What happens to all materials in the living world?

They’re recycled to provide the building blocks for future organisms

What is the carbon cycle?

When carbon is returned from organisms to the atmosphere are carbon dioxide to be used by plants in photosynthesis

What is the water cycle?

When fresh water is provided for plants and animals on land before draining into the seas. Water is continuously evaporated and precipitated

What are microorganisms role in decomposition?

Break down organic matter into simpler forms to release carbon dioxide back into the atmosphere

What are microorganisms role in respiration?

They convert organic carbon compounds into carbon dioxide which is then released into the atmosphere

How do microorganisms assist nutrient cycling?

Break down organic matter and release mineral ions back into the soil. Then are taken up by plants for growth and development

How does temperature affect the rate of decay of biological material?

Decay works better in warmer conditions and slows down/stops if too cold. If it’s too hot the enzymes may denature.

How does moisture affect the rate of decay of biological material?

Moisture makes it easier for microorganisms to digest their food and prevents them from drying out. Decay takes place more rapidly in warm, moist conditions

How does oxygen affect the rate of decay of biological material?

Decay takes place more rapidly in aerobic conditions as oxygen is needed to break down food and transfer energy, grow and reproduce.

What do gardeners and farmers try to provide?

The optimum conditions for rapid decay of waste biological material

What is the compost produced from the decay of waste used as?

Natural fertiliser

What does anaerobic decay produce?

Methane gas

What can be used to produce methane gas as a fuel?

Biogas generators

What are some examples of environmental changes that may affect the distribution of species in an ecosystem?

• Temperature

• Availability of water

• Composition of atmospheric gases

What may environmental changes be caused by?

Seasonal, geographic or caused by human interaction

What is biodiversity?

The variety of all different species of organisms on earth, or within an ecosystem

What does a great biodiversity ensure?

The stability of ecosystems by reducing the interdependence of species for food, shelter and the maintenance of the physical environment

What does the future of the human species rely on?

Humans maintaining a good level of biodiversity

What has caused an increased use of resources?

• Rapid growth in the population

• Increase in the standard of living

Where can pollution occur?

• In water, from sewage, fertiliser or toxic chemicals

• In air, from smoke and acidic gases

• On land, from landfill and from toxic chemicals

How can humans reduce the amount of land available for other animals and plants?

By building, quarrying, farming and dumping waste

What are the issues with the destruction of peat bogs? Why are peat bogs used?

• Destruction reduces the area of a habitat and reduces biodiversity

• Carbon dioxide is released when they’re burnt

• Used to produce garden compost

Why has large-scale deforestation in tropical areas occured?

• To provide land for cattle and rice fields

• To grow crops for biofuels

What are some of the biological consequences of global warming?

• Loss of habitat

• Rising sea levels

• Changes in the distribution of species

• Rainfall and temperature changes

What are some examples of programmes to reduce the negative effects of humans on ecosystems and biodiversity?

• Breeding programmes for endangered species

• Protection and regeneration of rare habitats

• Reintroduction of field margins and hedgerows

• Recycling resources

What is included in tropic level 1?

Plants and algae that make their own food (producers)

What is included in tropic level 2?

Herbivores eat plants/algae (primary consumers)

What is included in tropic level 3?

Carnivores that eat herbivores (secondary consumers)

What is included in tropic level 4?

Carnivores that eat other carnivores (tertiary consumers). Apex predators are carnivores with no predators.

What are decomposers?

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

What do pyramids of biomass represent?

The relative amount of biomass in each level of a food chain

How much energy from light for photosynthesis do producers transfer?

1%

How much biomass from each trophic level is transferred to the level above it?

10%

What are losses in biomass a result of?

• Not all the ingested material is absorbed, some is egested as faeces

• Some absorbed materials is lost as waste

What is food security?

Having enough food to feed a population

What are some biological factors that are threatening food security?

• The increasing birth rates

• Changing diets in developed countries

• Conflicts that have arisen in some parts of the world

How can the efficiency of food production be improved?

By restricting energy transfer from animals to the environment. This can be done by limiting movement and controlling the temperature of their surroundings

What are some animals fed to increase growth?

High protein foods

Why is it important to maintain fish stocks at a level where breeding continues?

A certain species may disappear altogether

How can fish stocks be conserved?

• Control of net size

• Introduction of fishing quotas

What is the fungus Fusarium useful for?

Producing mycoprotein, a protein-rich food for vegetarians

How is Fusarium grown?

Grown on glucose syrup, in aerobic condition, and the biomass is harvested and purified

What can produce human insulin that when harvested to treat people with diabetes?

A genetically modified bacterium

What could GM crops provide? Give an example?

Provide more food or food with an improved nutritional value e.g. golden rice