genetics and evolution Flashcards
who is gregor mendel?
a monk who realised characteristics in plants were passed on between generations.
what conclusions did gregor mendel reach? (3)
- characteristics in plants are determined by ‘hereditary units’.
- one ‘hereditary unit’ is passed on from each parent.
- hereditary units can be dominant or recessive.
what are fossils?
remains of organisms from thousands of years ago.
how are fossils formed in rocks? (3)
gradual replacement by minerals.
1. materials that don’t decay easily last a long time when buried.
2. as they decay they are replaced by minerals forming a rocky substance.
casts and impressions
1. when an organism is buried in soft materials like clay the clay hardens around the organism.
2. the organism decays leaving a cast of itself.
preservation (no decay happens)
1. in amber and tar there’s no oxygen or moisture so decay microbes can’t survive.
2. in glaciers it is too cold for decay microbes to work.
3. bogs are too acidic for decay microbes.
what is speciation?
the development of new species from natural selection. (when populations of the same species are too different to interbreed)
how does isolation lead to speciation?
- populations of a species are separated.
- conditions in either area are different so populations adapt.
- eventually the populations are so different they cannot breed together.
how can bacteria evolve to become antibiotic resistant?
- bacteria can develop random mutations which could be resistant to an antibiotic.
- because bacteria reproduce so quick they can evolve very quickly.
why is antibiotic resistance becoming more common?
unnecessary antibiotic prescription.
not taking full antibiotic course.
farming antibiotic use on animals.
what is classification?
organising living organisms into groups.
how are organisms named?
a 2 part latin name.
part 1 - genus the organism belongs to.
part 2 - species.
what is an evolutionary tree?
a diagram (tree) that shows how different species are related to eachother.
