Biology - Understanding of genetics + evolution

Darwin’s theory of natural selection (or survival of the fittest)

Individuals in a species show a wide range of variation due to random mutations.

Individuals with the characteristics most suited to the environment are most likely to survive and reproduce.

Advantageous alleles are passed on to offspring at a higher rate.

Over time these characteristics become more common and the species evolves.

Why was the acceptance of evolution slow?

Challenged the idea that god made all life on earth.

Insufficient evidence.

Mechanisms of inheritance and variation was not yet known.

Lamarck’s (incorrect) theory of evolution

A more frequently used characteristic become better and stronger and is more likely to be passed onto offspring than a lesser used characteristic.

How does speciation occur?

Two populations become geographically isolated.

Within each population there was genetic variation.

In the separate environments there were different selection pressures.

In each population the alleles that gave a survival advantage were selected for.

Eventually the two populations can no longer breed to produce fertile offspring and are separate species.

4 ways fossils can form

From parts of organisms that have not decayed because a condition needed for decay is not present.

When parts of the organism are replaced by minerals as they decay.

As preserved traces of organisms such as footprints or burrows.

From the hard parts of animals that do not decay easily.

Reasons why the fossil record is incomplete

Fossils destroyed by geological activity e.g. an earthquake.

Oldest organisms were soft bodied so few traces left behind.

Fossils buried very deep so hard to find.

Meaning of extinction

All organisms of a species have died out

Factors that could lead to extinction

Changes to environment e.g. climate change

New predators

New diseases

New, more successful competitors

A single catastrophic event e.g. volcanic eruption

What is MRSA?

A very dangerous bacteria that is resistant to most antibiotics

What is antibiotic resistance an example of?

The theory of evolution by natural selection

Sequence of classification

Kingdom, Phylum, Class, Order, Family, Genus, Species

King Philip Came Over For Gran’s Spaghetti

What is Linnaeus’ binomial naming system?

Genus species