Evolution Flashcards
Evidence for Lamarck
Changes in individuals can be acquired over time
Inheritance of acquired characteristics (lamark’s theory)
- characteristics of individuals change during their own lifetime
- the changed (acquired) characteristics are passed onto the next generation
Evidence against Lamarck
Acquired characteristics are not passed on
Natural selection (darwin’s theory)
The mechanism if evolution
- the environment ‘selects’ from already existing variations the ones that are the best suited for a particular environment (=selection pressure)
- these survive and breed and pass on their genes
- more offspring with these characteristics are produced
- not forced by environment
Give examples of selection pressures
Predators Food Disease Climate Mate finding
Why do rabbits have very long ears in the desert
As longer ears mean more SA/V therefore heat loss is more likely to occur at a larger and quicker rate
Why are stick insects adapted so well for their environment
To disguise themselves from predators
Why do peacocks have brightly coloured feathers
To attract a mate
Why do giraffes have long necks
To reach leaves off tall trees in scarce food supply
Microevolution
Small scale changes within species leading to new subspecies
Macroevolution
Large scale changes leading to a new species as explanation for origin of life and species
Darwin’s theory of evolution
All species have evolved from simple life forms which first developed more than 3 billion years ago through the process of natural selection
Name three types of recent evolution
- peppered and dark moths
- bacteria resistant to antibiotics
- sickle cell anaemia spreading in Africa as resistant to malaria
Selective breeding
Breeding only those individuals with desirable characteristics (AKA artificial selection) not due to climate disease etc
Natural selection causes
- predators, climate, disease etc
- only organisms with favourable traits survive and breed
Artificial selection causes
- mutations
- variation
- selection pressure (human choice)
- survival and reproduction
- only organisms with desirable traits are chosen to breed
What traits do farmers select for in plants
- high yield
- disease resistance
- pesticide resistance
- hardier
- flavour
- growth rate
What traits do people select for in animals
- speed
- looks
- obedience
What traits do farmers select for in animals
- more meat/milk/eggs
- more/better quality fur
- more offspring
- disease resistance
Cloning
Any procedure that produces genetically identical offspring
Cuttings
Take a small piece of plant, dip in rooting powder, plant in compost, keep in warm humid environment ie greenhouse to speed up growth
Micropropagation
Take a few cells/small parts from the plant (explants), put into culture medium (agar gel), plantlets will begin to grow
What does agar gel contain
Vitamins Minerals Nutrients Water Glucose Growth promoters
What are the advantages of micropropagation
Quick
Large number of genetically identical plants
Any time of year
No variation
Genetic modification can be introduced along the way
Puts small farms out of business as cant keep up with production rates
Reproductive cloning
Transfer of a nucleus from a somatic cells of a donor A to an egg cell from B that has no nucleus in order to form a diploid zygote with A’s DNA, the developing embryo is implanted into the uterus of a foster mother (C) to develop and give rise to a clone of A
What are the issues with reproductive cloning
-not reliable
Birth defects and abnormalities
May lead to human cloning
Could help end world hunger
Fossils
Mineralised or otherwise preserved remains of animals, plants and other organisms
3 ways fossils are formed
- harder parts of animal/plant are replaced by minerals over a long period of time
- animal/plant locked in ice, amber tar pits and so didnt decay (rare)
- casts or impressions can be found (footprints)
What can fossils tell us
- carbon dating tells us when something lived
- can help build evolutionary timeline of how plants or animals have or havent changed
- extinct animals that could be ancestors
What cant fossils tell us
- whole construction
- some missing links in evolutionary timeline if fossils not found
- colour etc exact appearance
Extinction
The permanent loss of all the members of a species from the earth
Mass extinction
Loss of a number of species at the same time
Causes of extinction
- environmental: climate change, meteorites, volcanoes
- new predators
- new diseases
- competition
