PPE Autumn Year 1 Variation, Evolution & Classification Pre Y12

Question 1

Organisms differ

Answer 1

All organisms re different form each other
Organisms of the same species also show variation
Organisms of the same species are similar because they have the same genes but they vary due to having different alleles (versions of genes)

Question 2

Variation

Answer 2

Adaptation- characteristic that helps an organism to survive & reproduce
Characteristics vary in a population- some organisms are better adapted for certain conditions than others

Question 3

Evolution

Answer 3

Evolution- gradual change in the characteristics of a population from one generation to the next
Theory- all organisms evolved from simple life forms over millions of years

Question 4

More than one mechanism by which evolution occurs

Answer 4

One is natural selection

Question 5

Variation leads to natural selection

Answer 5

Organisms from the same population all vary
Organisms compete with each other for food, shelter, water etc.
Better adaptations- more likely to survive & reproduce to pass on their alleles
Overtime, number of organisms with the better adaptations increases
Whole population of organisms evolves to have better adaptations

Question 6

Classification- sorting organisms into groups

Answer 6

Classification- involves naming organisms
Makes it easier for scientists to study organisms without getting confused
Organisms arranged into different groups depending on similarities & differences
Organisms are placed in groups in classification hierarchies

Question 7

Classification systems

Answer 7

Older system- based on how organisms look
DNA- how similar & different the base sequence is
Other molecules- e.g. proteins & enzymes
Early development- how they grow from an embryo to a baby