Biology - 15 Genetics and Evolution - 15.6 Fossils and Extinction & 15.7 More About Extinction & 15.8 Antibiotic Resistant Bacteria

When do fossils form?

when one or more of the conditions for decay are absent

Fossil record

chronological collection of life's remains in sedimentary rock layers

Extinction

term describing a species that no longer has living individuals

Reasons for extinction [5]:

- new predators

- new pathogens

- change in environmental conditions

- loss of habitat

- competition from other species

Mass extinction event

time when vast numbers of species abruptly vanish

Where does evidence for mass extinction events come from?

the fossil record

Mass extinction events [3]

- asteroids

- volcanic eruptions

- climate change

What is the common accepted theory as to the mass extinction event that killed the dinosaurs?

asteroid collision with the Earth in Chicxulub, Mexico

How do bacteria become resistant? [3]

- random mutations to DNA occur when bacteria multiply

- when treated with antibiotics, some will be resistant

- the resistant bacteria multiply and cannot be treated with the antibiotic

General measures to prevent antibiotic resistance [3]

- only using antibiotics when absolutely necessary

- patients must finish their course of antibiotics

- restrict agricultural use of antibiotics

Medical measures to prevent antibiotic resistance [4]

- only use antibiotics when necessary

- specific bacteria treated with specific antibiotics

- hospitals have a high standard of hygiene

- patients infected with resistant bacteria must be isolated

MRSA

Methicillin-Resistant Staphylococcus Aureus

How did MRSA become resistant?

it was treated with many antibiotics and gained resistance to each one