Unit 3 Flashcards
Biodiversity
Biodiversity is the term used to describe the variety of species present in an ecosystem.
What does an ecosystem consist of?
An ecosystem consists of all the organisms (the community) living in a particular habitat and the non-living components with which the organisms interact.
Definition of a niche
A niche is the role that an organism plays within a community.
Competition
Competition in ecosystems occurs between organisms when resources are in short supply.
Intraspecific competition
Intraspecific competition involves organisms of the SAME species competing for the same resources in an ecosystem.
E.g. mates, food, light, nutrients, space
Interspecific competition
Interspecific competition involves individuals of DIFFERENT species competing for one or a few resources in an ecosystem.
E.g. food, living space
Producer
An organism which produces its own food by photosynthesis.
Consumer
A consumer is an organism that has to consume food to gain energy.
E.g. carnivore, herbivore or omnivore.
Population
The number of individuals within A species living in a particular area.
Community
A community is all of the living organisms living in an ecosystem.
Carnivore
A carnivore is an organism that only consumes animal material.
Herbivore
A herbivore is an organism that only consumes plant material.
Omnivore
An omnivore is an organism that will consume both plant and animal material to obtain amino acids for protein synthesis.
Biotic factors
Biotic factors are LIVING factors which can affect biodiversity in an area.
Examples:
- competition for resources
- disease
- grazing
- predation
Competition for resources, disease, food availability, grazing and predation are biotic factors.
Abiotic factors
Abiotic factors are NON-LIVING factors which can affect biodiversity in an area.
Examples:
- light intensity
- soil moisture
- pH
- temperature
Indicator species
Indicator species are species that by their presence or absence indicate environmental quality or levels of pollution in an area.
E.g. lichen
Photosynthesis - raw materials
Water, carbon dioxide
Photosynthesis - products
Oxygen, glucose
Photosynthesis energy source
Energy comes from sunlight.
The Energy (sunlight) is captured by chlorophyll.
In photosynthesis light energy is captured by chlorophyll and turned into chemical energy by a series of enzyme controlled reactions.
Photosynthesis equation
Light glucose
CO2 + H2O ———————————-> C6H12O6 + O2
Chlorophyll
Enzymes
Photosynthesis 3 essential requirements
Light, chlorophyll, enzymes
Photosynthesis process summary
In photosynthesis, light energy is captured by chlorophyll and turned into chemical energy by a series of enzyme controlled reactions.
Photosynthesis- stage 1: the light reactions stages explained
1) light energy is trapped by chlorophyll in the chloroplasts.
2) this energy is then converted into chemical energy stored in molecules of ATP, these are passed onto the second stage.
3) in the same set of reactions, water molecules are split into hydrogen and oxygen molecules.
4) excess oxygen diffuses from the cell and is released into the air as a waste product.
5) the hydrogen attaches to hydrogen acceptor molecules which carry it to the next stage.
Photosynthesis- stage 2: carbon fixation
Carbon fixation also take space in the chloroplasts. This energy in the ATP, made in stage 1, is used to combine the hydrogen (from stage 1) with carbon dioxide.
This produces the sugar glucose.
This is all controlled by enzymes.
Photosynthesis- stage 2: carbon fixation
Equation
Enzymes
H2 + CO2 ————————> C6H1206
ATP
What type of competition is more intense?
Intraspecific because animals of the same species are competing for all the same resources.
Whereas interspecific competition involves animals of different species competing for a few of the same resources
Predator
An animal that hunts other animals for food.
Prey
An ANIMAL that is hunted by another animal.
(Plants are not prey)?
Food chain
Shows the feeding relationships between individuals.
Food web
A diagram to show all of the interlinking food chains within an ecosystem.
Ecosystem
An ecosystem consists of all the organisms (the community) living in a particular habitat and the non-living components with which the organisms interact.
What factors determine an organisms niche?
Feeding habits
Habitat
Place in the food chain
Life history
What does a niche relate to?
- Resources organisms require in the ecosystem (e.g. light, nutrient availability)
- interactions with other organisms in the community (e.g. competition, predation)
- conditions it can tolerate (e.g. temperature)
What are animals in competition for?
Food
Space
Water availability
Mates
What are plants in competition for?
Nutritients
Water
Space
Light/ sunlight
Comparison of intraspecific and interspecific competition.
Intraspecific competition is more intense than interspecific competition because members of the same species will have the same resource demands.
How are abiotic factors measured?
Light intensity- light meter/ probe
Soil moisture - moisture meter
pH - pH meter/ probe
Temperature- thermometer
Possible sources of error when measuring abiotic factors and how they can be minimised
Light meter
- accidental covering of the probe (observer or clouds may cast a shadow)
- lean back to not cast a shadow, take multiple readings, take the readings at the same time of day for repeating the experiment.
Soil moisture
- moisture from previous readings may be left on the probe and affect the next reading.
- wipe the equipment down to remove moisture/ dirt.
Temperature
- readings may be unreliable
- hold meter in the same position/ depth, take multiple readings.
Limitation for all: not enough samples taken within the area.
- take multiple readings/samples to have more reliable results and calculate an average.
Pitfall trap
Pitfall traps are used to measure small invertebrates that live in the ground.
Limitations/ errors - some animals in the trap may eat other captives, not enough samples taken
Solutions - check traps regularly and record, set up more traps within the sample sight.
Quadrats
Used to sample plants and and slow moving animals.
Limitations- not enough samples taken, biased placing of the quadrats.
For results to be reliable, repeat samples are needed.
To avoid biased results place the quadrats randomly.
Effects of biotic and abiotic factors on biodiversity and distribution of organisms.
Both biotic and abiotic factors can increase or decrease biodiversity in an area and affect the distribution of organisms.
E.g
Abiotic - temperature
Biotic - grazing (if high levels of grazing then low biodiversity as all plants are eaten)
(There are other factors)
Human influences that effect biodiversity
Human influences that impact biodiversity and the distribution of organisms do so in a negative way. These include:
- air pollution
- water pollution
- deforestation
- desertification
- overfishing
Photosynthesis summary equation
Carbon dioxide + water –(light energy)–> sugar + oxygen
Photosynthesis stage 1- light reactions
During the light reaction, light energy from the sun is trapped by chlorophyll in the chloroplasts and is converted into chemical energy which is used to generate ATP.
Water splits to produce hydrogen and oxygen. Oxygen diffuses out of the cell.
Describe the fate of sugar which is produced by photosynthesis
The chemical energy in sugar is available for respiration or the sugar can be converted into other substances such as starch and cellulose.
Plant uses of glucose made in photosynthesis
Respiration to release energy.
Stored as starch and changed back into sugar when needed.
Used to make cellulose to build cell walls.
Photosynthesis limiting factors
Limiting factors limit the rate of photosynthesis.
3 limiting factors for photosynthesis:
- CO2 concentration
- light intensity
- temperature
If any factor limits the rate of photosynthesis then it will have an overall negative impact on plant growth and will slow the overall rate of photosynthesis.
Know the effects of limiting factors on photosynthesis for analysing a graph
In jotter
Practice questions
Energy in the food chain
As energy travels from one level of the food chain to the next, only 10% of the energy is passed on through GROWTH.
At each stage, 90% of energy is lost as:
- heat
- movement
- undigested materials
Food chain
Producer->primary consumer->secondary consumer-> tertiary consumer
Pyramid of numbers
A pyramid of numbers is a diagram that shows the number of organisms at each stage of the food chain.
USUALLY, as you go up the pyramid the numbers of organisms decreases and the size of the organisms increases.
(However sometimes this is not the case and the pyramid is irregular).
Pyramid of energy
A pyramid of energy is a diagram that shows the total energy present at each stage of the food chain.
(It is always a pyramidal shape as there is less energy as it goes up the food chain because energy is lost).
Measured in kJ/m²/year.
Comparing pyramid of numbers and energy
A pyramid of numbers is always representative due to the size of the organisms present.
Pyramids of energy will be represented as true pyramids no matter the size of the organisms because energy is always lost at each stage of the food chain.
Impact of human population of food production
An increasing human population requires an increasing food yield.
Fertilisers
Fertilisers can increase food yield as they provide chemicals such as nitrates which increase crop yield.
Pesticides
Pesticides can increase crop yield by killing unwanted animals and plants that would reduce crop yield.
How do plants use and obtain nitrates?
Nitrated are dissolved in the soil and are absorbed by plants through their roots.
Plants use nitrates to produce amino acids which are used to make proteins.
How do animals obtain amino acids?
Animals consume plants or other animals to obtain amino acids needed for protein synthesis.
Fertilisers and nitrates
Fertilisers can be added to the soil to increase the nitrate concentration.
Impact of fertilisers on freshwater ecosystems
If fertilisers leak into fresh water rivers or streams it adds unwanted extra nitrates into the water.
- fertilisers leach into freshwater river and streams adding extra unwanted nitrates.
- increase in nitrates causes algal bloom.
- algal bloom blocks light, killing aquatic plants below.
- bacteria in water use up large quantities of oxygen from the river reducing the oxygen available for other organisms and they die.
- bacteria feed on dead plants and algae and increase in numbers.
- biodiversity decreases.
- biodiversity is decreased.
Impacts of GM crops
The use of GM crops can reduce the use of fertilisers and pesticides.
as they are genetically modified to grow in infertile soils and resistant to pests.
Pesticides - impact of food chains
The use of pesticides can destroy food chains as they build up in the bodies of organisms over time. (bioaccumulation.)
As pesticides are passed along the food chain the toxicity increases and can reach lethal levels. (Biomagnigication)
This is because the chemical isn’t broken down by animals tissue.
Bioaccumulation
Bioaccumulation is the build up of toxic substances in living organisms.
Pesticides alternatives - biological control
Biological control is the use of natural predators rather than chemical pesticides to control pests.
Alternatives - Biological control and GM crops
Biological control and GM crops can reduce the need of fertilisers and pesticides.
Species definition
A species is a group of organisms able to interbreed and produce fertile offspring.
Species and their niches
Each organism is adapted to survive in its niche.
These adaptions allow them to compete for food, escape from predators or fend off disease.
The organism passes on the favourable alleles (characteristics) to its offspring.
Variation
Variation is the differences between members of the same population.
Variation arises through differences in the genetic information the organisms contain.
How do differences between organisms of the same species in a population arise?
Differences between organisms of the same species arise through mutations.
What is a mutation?
A mutation is a random change to genetic information and is the only source of new alleles in a population.
Mutations can be neutral, confer an advantage or a disadvantage.
Mutations are spontaneous and are the only source of new alleles (variation).
What environmental factors can increase the rate of reactions?
- Radiation
- Some chemicals
Can INCREASE the rate of mutation.
(Mutagenic agents)
How are new alleles produced?
Through mutations.
Mutations are spontaneous and are the only source of new alleles (variation).
Adaption
Mutations lead to adaptions.
New alleles produced by mutation allow plants and animals to adapt to their environment. These adaptions can be STRUCTURAL or BEHAVIOURAL.
Behavioural adaptions
Animals can also adapt their behaviour in order to help survive.
What does variation within a population allow?
Variation within a population makes it possible for a population to EVOLVE over time in response to CHANGING ENVIRONMENTAL CONDITIONS.
What happens if a species produces more offspring than an environment can sustain?
Natural selection or survival of the fittest occur when there are selection pressures
Selection pressures examples- disease, competition, predation.
Natural selection and survival of the fittest in a population
The best adapted individuals in a population survive and reproduce, passing on favourable alleles that confer a selection advantage.
These alleles increase in frequency within the population .
What is speciation?
Speciation is the formation of a new species that occur after part of a population becomes isolated by a barrier.
The process of speciation
1) a large population is interbreeding ans sharing genes.
2) a part of the population becomes isolated by an isolation barrier. The exchange of genes is now prevented.
3) different mutations occur in each sub-population. By chance some are advantageous.
4) natural selection selects for different mutations in each group due to different selection pressures. The favourable alleles are passed on.
5) over many generations each sub-population Evolves until they become so genetically different that they are two new species.
Isolation -> mutation -> natural selection-> new species.
5) over
Isolation barriers
Geographical barriers
Ecological barriers
Behavioural barriers
Natural selection in speciation
After a population becomes isolated, different mutations occur in each sub-population. Natural selection selects for different mutations in each group due to selection pressures.
Each subpopulation evolves, until they become so genetically different, that they are 2 different species.
