National 5 Biology - Unit 3 Life on Earth
1. Biodiversity and the Distribution of LIfe
Key Area
Key Terms
Summary of topic
Biodiversity
Parasitism
Biome
Predation
o
Biotic, abiotic and human influences are all factors that
affect biodiversity in an ecosystem.
Climate
Light
o
Grazing and predation are biotic factors; pH and
temperature are abiotic factors.
Ecosystem
Temperature
o
Organism
Nutrients
Biomes are the various regions of our planet as distinguished
by their similar climate, fauna and flora.
o
Habitat
Biotic
Global distribution of biomes can be influenced by
temperature and rainfall.
o
The range of living things that are found in an environment is
called biodiversity.
o
An ecosystem consists of all the organisms living in a
particular area and the non-living components with which
the organisms interact.
o
A niche is the role that an organism plays within a
community. It includes the use it makes of the resources in its
ecosystem and its interactions with other organisms in the
community including competition, parasitism, predation,
light, temperature and nutrient availability.
o
A habitat is the natural home or environment of an animal,
plant, or other organism.
Population
Abiotic
Species
Habitat destruction
Niche
Desertification
Community
Deforestation
Competition
Endangered species
Indicator species
Key Area
Key Terms
Summary of topic

Species: A species is a group of biologically similar organisms
which can reproduce to produce fertile offspring.

Population: A population is a group of interbreeding
organisms of a species in a particular area.

Producer: A producer is the organism in a food chain which
fixes energy and produces organic compounds which are
then available to other species in the food chain. Plants are
producers as they use energy from sunlight to produce
glucose from carbon dioxide through photosynthesis.

Consumer: Consumers are organisms which are not able to fix
energy and must consume other organisms in order to obtain
organic molecules.

Herbivore: Herbivores are animals which only consume plants.

Carnivore: Carnivores are animals which only consume other
animals.

Omnivore: Omnivores are animals which consume both
plants and animals.
Energy
2. Energy in Ecosystems
Organism
Food chain
Carnivores
Food web
Omnivores
Producers
Predator
Consumers
Prey
Decomposers
pollution
herbivores
3. Sampling techniques and measurements
Key Area
Key Terms
Quadrat
Light meters
Sampling
pH meters
Pitfall traps
Abiotic
Tree beating
Biotic
Errors
Keys
Reducing errors
Summary of topic
o
Sampling plants and animals using quantitative techniques
including quadrats and pitfall traps.
o
Evaluation of limitations and sources of error in pitfall traps
and quadrats.
o
Measuring abiotic factors including light intensity,
temperature, pH and soil moisture.
4. Adaptation, natural selection and
evolution of species
Key Area
Key Terms
Summary of topic


Mutation

Variation
Resistance

Adaptation
Species

Environmental
Speciation
conditions
Rapid selection/evolution
Natural selection



A mutation is a random change to genetic material.
Mutations may be neutral, confer an advantage or a
disadvantage.
Mutations are spontaneous and are the only source of
new alleles.
Environmental factors, such as radiation and chemicals,
can increase rate of mutation.
Variation within a population makes it possible for a
population to evolve over time in response to changing
environmental conditions.
Natural selection/survival of the fittest occurs when more
offspring are produced than the environment can sustain.
Only the best adapted individuals survive to reproduce,
passing on the genes that confer the selective advantage.
Speciation occurs after a population becomes isolated
and natural selection follows a different path due to
different conditions/selection pressures.
5. Human impact on the environment
Key Area
Key Terms
Summary of topic
o
Increasing human population requires an increased food
yield.
o
o
o
Fertilisers can leach into fresh water, causing algal blooms.
This leads to a reduction in oxygen levels.
Pesticides sprayed onto crops can accumulate in the bodies
of organisms over time.
As they are passed along food chains, toxicity increases and
can reach fatal levels.
Indicator species are species that by their presence or
absence indicate environmental quality/levels of pollution.
Biological control and GM crops may be alternatives to
mitigate the effects of intensive farming on the environment.
Human population Nutrients
Intensive farming
Reducing pollution
Monoculture
Pesticides
o
Fertilisers
Indicator species
Algal blooms
Biological control
o
o
o