SB4b-c Flashcards
Why have some species of animals and plants become extinct?
Due to evolution and natural selection.
What is evolution?
The gradual change in the characteristics of a species over many generations.
What is natural selection?
How the environmental factors (such as disease, predation and climate) change the characteristics of the species in order to be able to survive (survival of the fittest).
How does evolution occur through natural selection?
- Individuals within a species may show variation because of differences in their genes.
- Individuals with characteristics most suited to the environment are most likely to survive and breed successfully.
- The alleles which have enabled these individuals to survive are then passed on to their offspring.
- New alleles also result due to mutation causing a more rapid change in species.
Describe the evolution of panthers and leopards.
Check teacher notes page 3 ‘Darwin’s Theory’.
Describe the evolution of bacteria resistance to antibiotics.
Check teacher notes page 4 ‘Darwin’s Theory’.
What is the pentadactyl limb?
A five-fingered limb structure.
What does the pentadactyl limb suggest and why?
It provides evidence for evolution and suggests that organisms with this limb structure evolved from a common ancestor rather than the different species coming to life independently of one another. This is because if vertebrates had come to life independently, you would expect them to each have differently designed limbs, but instead the parts of the limbs that they have are identical.
What does the pentadactyl limb consist of?
- Phalanges
- Carpal
- Humerus
- Ulna
- Radius
Which organisms have the pentadactyl limb?
Many vertebrates (e.g. humans, frogs, lizards, birds, whales, bats etc).
How did limbs of animals adapt to their function?
Check teacher notes page 6 ‘Development of Darwin’s Theory’ for some examples.
What is speciation?
The formation of new species.
How does speciation occur?
Usually by geographical isolation.
