GCSE AQA Biology Combined Science Health & Disease: Scientists believe that the firs

Question

Scientists believe that the first life on Earth was primitive anaerobic bacteria which first appeared billions of years ago.

Which domain of the three-domain classification system do these primitive anaerobic bacteria belong to?

Scientists have identified five periods of mass extinction since the fossil record began.

Figure 6 shows the timeline of the five mass extinction events.

Figure 6

Percentage of species that became extinct

100

80

60

40

20

0

50

400    300    200    100    0

Millions of years ago    Present day

Ammonites were organisms that first appeared in the oceans 415 million years ago.

Ammonites disappeared in the 5th mass extinction.

Draw a horizontal line on Figure 6 to show the time period that ammonites existed on Earth.

Label the line ‘ammonites’.

Another type of organism that existed in the oceans was called trilobites.

Trilobites existed from 544 million years ago until 278 million years ago.

How many more years did ammonites exist than trilobites?

There was an increase in the percentage of species which became extinct in the third mass extinction compared to the first mass extinction.

Calculate the percentage increase.

Scientists believe that the first life on Earth was primitive anaerobic bacteria which first appeared billions of years ago - AQA - GCSE Biology Combined Science - Question 6 - 2020 - Paper 2