Types of Variation
This type of variation shows a gradual change in a feature with no clearly distinct groups.
What is continuous variation?
These are the two main causes of variation.
What are genetic factors and environmental factors?
food, water, shelter, oxygen, warmth.
Name the resources organisms compete for
The preserved remains of plants and animals inside rocks over millions of years, that show changes in a species over time
Define a fossil
Humans.
Who chooses which individuals breed in selective breeding?
this type of variation has distinct groups with no overlap, such as tongue rolling.
What is discontinuous variation?
Random changes in genes or chromosomes are called this.
What are mutations?
a group of individuals of the same species living in the same area at the same time?
Define “population” in biological terms.
They show how organisms change over time and the order in which changes occurred.
Why are fossils good evidence for evolution?
Short stalks and large heads of grain
Name two desired traits in selectively bred wheat.
Histogram
What graphs are used to represent continuous variation?
This process in sexual reproduction mixes chromosomes so all gametes are genetically different.
What is meiosis?
Darwin studied these birds on the Galapagos Islands.
What are finches?
This famous fossil shows features of both dinosaurs and birds.
What is Archaeopteryx?
Choose parents with desired traits → breed them → select best offspring → repeat over many generations until most offspring show the desired traits.
Explain the basic process of selective breeding over several generations.
Bar Chart
What graphs are used to represent discontinuous variation?
Give an example of a characteristic influenced by both genes and environment
the phrase that summarises natural selection
What is “survival of the fittest”
Coelacanths have changed very little over millions of years
Explain how coelacanths are a stable species and are well adapted
Natural selection is driven by the environment; selective breeding is driven by human choice of traits.
Describe One key difference between natural selection and selective breeding.
clear title, even divisions/scale, labelled axes with units, drawn in pencil with ruler, uses at least 2/3 of the page.
Give two success criteria for a good graph from your notes.
explains why siblings in a family often show considerable variation in phenotypes.
what is the result of meiosis and fertilisation producing different combinations of alleles, so each zygote has a unique set of genes.
Variation in phenotypes → competition/struggle for survival → better adapted individuals survive → they reproduce and pass on their genes to the next generation
State the 4 key steps of natural selection in order.
Evolution
what is the term that describes the continuing process of natural selection that leads to gradual changes in organisms over time and this may result in the formation of new species
Extinction
what is the term given to the natural process, of a new species evolving, others which have not adapted to changes in their environment may not survive