Biology Flashcards
Define evolution
The genetic change in the characteristics of an organism over many generations.
What is a generation?
The time between a creature’s birth and having off-spring of its own.
Describe three changes in the structure of the horse, over evolutionary time.
Toes
Size
Larger teeth
Two species that share genes must have had the same…
… ancestor
Homologous structures are likely to be formed by the same… even if they have different…
…gene
…function
Analogous structures are likely to be formed by different… even though they have the same…
…genes
…functions
For example, dolphins and sharks have similar body shapes because they evolved in similar…
…environments
List the five main steps in the theory of natural selection
Variation at the start within the species.
Selective pressure, anything that causes a struggle for survival.
Fittest survive.
Inheritance for the next generation, gene passed on.
Populate, breed and pass on the gene.
What is artificial selection?
When humans interfere with natural selection. Humans breed two creatures of the same species for a common desirable characteristic.
How is it that domestic budgies now look different (in the range of colours) to wild budgies?
Originally some budgies showed different colours in the wild. Humans then bred these budgies until they were the desired colour.
What is cross breeding?
When two creatures of different species are bred to have off-spring.
Are lions and tigers the same species? why/ why not?
No, because they can not have fertile off-spring.
How does embryology show evidence for evolution?
The similarity between organisms when they are in the embryo stage shows that they have a common ancestor.
How do fossils prove evolution?
Fossils increase in complexity as you go up layers (from old to young) and increase in number, showing that organisms are increasing in complexity. There are also transitional fossils which show changes in organisms-evolution.
How can DNA and protein prove evolution?
Some organisms have very similar protein and DNA sequences showing that they are closely related. (come from a common ancestor)