Adaptation, Natural Selection And The Evolution Of Species and human impact on the environment Flashcards
Define mutation
Mutations is a random and spontaneous change to genetic material and the only source of new alleles.
Mutations can be…
Advantageous- bacterial resistance to antibiotics (advantageous to bacteria)
Neutral - ear lobes free or attached
Disadvantageous- malignant melanoma (skin cancer)
Define mutagenic agents
A mutagenic agent is a factor that can increase the rate of mutations
Name mutagenic agents
Radiation
High temperatures
Some chemicals
If mutations are neutral
They have little effect on the organism with the mutation
Is mutations are harmful
They give the organism a disadvantage and so decrease its chances of survival
If mutations are beneficial
They give the organism and advantage and so increase its chances of survival.
Why are mutations important?
Mutations are the only source of new alleles
Mutations increase variation in a species
They allow a species to revolve in response to changing environmental conditions
Define adaptation
An adaptation is an inherited characteristic that makes one organism well suited to its environment. This increases their chances of survival and being able to reproduce.
Give an example of a structural adaptation
Rabbits ability to move quickly
Eagles large talons to grip onto prey
Pelicans webbed feet for swimming
Give examples of behavioural adaptations
Bats are nocturnal to avoid predators and catch prey
Lions turn paws over when attacking because fur is quieter
Genetic variation
Genetic variation within a population makes it possible for a population to evolve over time
Describe natural selection.
Living organisms often produce more offspring than the environment can support due to the limited resource available.
Natural selection is the process in which election pressures allow only the best adapted to their environment to survive and go on to reproduce and pass on the favourable alleles to the offspring. Whilst those less adapted did before producing.
Explain ‘survival of the fittest’
Darwin proposed that organisms better adapted to their environment survive.
Define genotype
The type of genes an organism has. E.g. A gene for blue eyes
Define phenotype
The physical appearance of an organism.
Define selective pressure
An aspect of the environment that selects one characteristic over another for example climate, predators or disease.
Define selective advantage.
The characteristic of an organism that enables it to survive and reproduce better than other organisms in a population in a given environment.
Define species
A species is a group of interbreeding organisms whose offspring are fertile.
Define speciation
Speciation is the process by which a new species is formed.
Describe the process of speciation.
A large group of interbreeding organisms of the same species with a common gene pool are split up by an isolation barrier that prevents gene flow.
(Geographical, ecological, reproductive)
Random and spontaneous mutations occur within each population.
Natural selection favours the best adapted. After time the barrier is removed.
There is two different species if they interbreed to produce sterile offspring.
The human population is increasing.
The increasing population requires an increases food yield.
Farmers achieve this through the use of intensive agriculture.
Name the intensive farming methods used to increase food production.
Fertilisers
Pesticides
Biological control
GM crops
Describe fertilisers.
Fertilisers are used to increase food production, get maximum crop yield and ensure food security.
Contains nitrogen, phosphorus and potassium.
N- important for plant leaves
P- important for plant roots
K- important for fruit and flowers
Natural fertilisers vs artificial
Natural
Low pollution and low cost
But variable NPK content
Artificial
Reliable NPK content
But high pollution and high cost.
Describe algal bloom
Fertilisers can leach into a fresh water source.
The nitrogen in fertilisers increase algae growth causing an algal bloom.
The Alfa bloom grows so large it blocks out sunlight and reduce light intensity which kills aquatic plants below.
The dead plants and some dead algae are eaten by decomposing bacteria.
The bacteria population increases and use up large quantities of oxygen.
Oxygen availability is reduced which means other organisms die and this reduces biodiversity in the fresh water source.
Describe pesticides
Pesticides are chemicals used to kill organisms that are in competition with or eating crop plants.
Herbicides - used to kill plants
Insecticides - used to kill insects
Define bioaccumulation
Pesticides for example DDT bioaccumulate in the bodies of organisms.
It is passed from one organism to the next through the food chain.
As the chemical is passed on up the food chain it increases in toxicity and can reach lethal levels.
The build up of harmful chemicals in the bodies of organisms.
Describe biological control
An alternative to pesticide use
Biological control is the control of a pest species by the introduction of a natural enemy or predator.
Example, using ladybirds to control greenfly infestations.
Describe GM crops
An alternative to fertilisers
Genetically modified crops are produced when a useful gene from another organism is inserted into the cells of a plant.
Define indicator species
Indicator species that indicate levels of pollution by their presence or absence.
What indicates water pollution?
Freshwater invertebrates
What indicates air pollution?
Lichen
