(4.6.3) (The development of understanding of genetics and evolution)

What is the theory of evolution?

An individual organism develops a characteristic suited for their environment this helps them survive and causes them to breed more than those without that characteristic this causes the characteristic that develops to be more prevalent in their offspring.

Why was Darwin’s theory not accepted?

The theory challenged the idea that God made all the animals and plants that live on Earth.

There was insufficient evidence at the time the theory was published to convince many scientists.

The mechanism of inheritance and variation was not known until 50 years after the theory was published.

Who is Alfred Russel Wallace?

A man who worked with Charles Darwin to publish his book about the theory of evolution by natural selection.

What did Gregor Mendel’s experiments on breeding plants show?

It showed that the inheritance of each characteristic is determined by ‘units’ that are passed on to descendants unchanged.

What are the ‘units’ Gregor Mendel discovered and where are they found?

Genes which are found on chromosomes.

What are fossils?

Remains of organisms from millions of years ago found in rocks.

When can fossils be formed?

It can be formed when parts the of organisms have not decayed because one or more of the conditions needed for decay are absent.

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

As preserved traces of organisms, such as footprints, burrows and rootlet traces.

How does bacteria become immune to antibiotics?

Mutations of bacterial pathogens produce new strains. Some strains might be resistant to antibiotics, and so are not killed. They survive and reproduce, so the population of the resistant strain rises. The resistant strain will then spread because people are not immune to it and there is no effective treatment.

What are ways to reduce the amount of bacteria that are immune to antibiotics?

Doctors should not prescribe antibiotics inappropriately, such as treating non-serious or viral infections.

Patients should complete their course of antibiotics so all bacteria are killed and none survive to mutate and form resistant strains. (strains are mutated bacteria)

The agricultural use of antibiotics should be restricted.