Evidence of Evolution

Question 1

Give three ways that fossils are formed

Answer 1

1. When one or more conditions for decay (e.g. water and oxygen) are absent
2. When parts of an organism are replaced by minerals during the decaying process
3. When traces of an organism (e.g. plant roots or footprints) are left behind

Question 2

Explain why scientists do not know when life began (fossils)

Answer 2

Early soft-bodied organisms rarely left behind traces

Any traces left were destroyed by geological activity

Question 3

Give four reasons that a species can become extinct

Answer 3

1. catastrophic event
2. Changes in the environment
3. A new predator/disease kills the species
4. A new species is succesful and evolves, it then competes with the species for food/water

Question 4

What is the definition of a fossil?

Answer 4

Remains of an organism from millions of years ago which is found inrocks

Question 5

Name an example of antibiotic resistant bacteria

Answer 5

MRSA

Question 6

Explain how bacteria evolve to become resistant to antibiotics

Answer 6

1. There is natural variation in a species due to random mutations
2. Variation in alleles can allow some bacteria to adapt and become reistant to antibiotics
3. These bacteria then survive and reproduce when an antibiotic is used without competition from other bacteria
4. The advantages allele for antibiotic resistance is passed on to the bacteria’s offspring, then the population of antibiotic resistant bacteria rises and spreads

Question 7

Give three ways that antibiotic resistance can be reduced

Answer 7

1. Doctors should not prescribe antibiotics innapropriately e.g. for a virus
2. Patient’s should complete the course of their antibiotic prescription so that all the bacteria are killed and cannot survive to mutate and form resistant strains
3. Restrict the use of antibiotics in agriculture

Question 8

Wooly mammoth fossils were found frozen in the north of Russia.

Explain why the mammoth’s bodies did not decay

[1 mark]

Answer 8

It was too cold so the conditions for decay were absent

Question 9

Fish fossils are found in rock

Explain why they did not decay

[2 marks]

Answer 9

There was no oxygen so the conditions for decay were absent

Parts of the fish were replaced by minerals