Fossils

Plesiosaurs are extinct animals that lived in the ocean.

Figure 5 shows what scientists think a living plesiosaur may have looked like.

Scientists think that the plesiosaur had smooth skin.

Suggest why the scientists cannot be certain what the skin of the plesiosaur was like.

Explain how structure A in Figure 5 helped the plesiosaur survive in the ocean.

Plesiosaurs may have moved rapidly upwards to hold their heads above the water surface to search for prey.

What type of adaptation was the rapid upwards movement?

Tick () one box.

Scientists use fossils to estimate when different types of plesiosaur existed.

Figure 6 shows when three types of plesiosaur existed.

When did plesiosaur A first evolve?

Use Figure 6.

Determine how many million years plesiosaur B existed for.

Use Figure 6.

The exact year of extinction of all plesiosaur species can only be estimated.

Which are two reasons why?

Tick () two boxes.

What evidence from Figure 6 shows that plesiosaur C might have evolved from plesiosaur B ?

Tick () one box.

Evolution can be studied using evidence from:

• fossils

• antibiotic-resistant bacteria.

Suggest two reasons why it is easier to study evolution in bacteria than to study evolution using fossils.

Give one reason why doctors are concerned about antibiotic-resistant bacteria.

Plesiosaurs are extinct reptiles that lived in the ocean.

Figure 5 shows a fossil of a plesiosaur.

Plesiosaurs may have moved rapidly upwards to hold their heads above the water surface to search for prey.

What type of adaptation was the rapid upwards movement?

Give two biotic factors that may have caused the extinction of plesiosaurs.

Describe how the plesiosaur fossil in Figure 5 could have been formed.

Scientists use fossils to study evolution.

Suggest two reasons why scientists cannot study the mutations involved in the evolution of plesiosaurs.

Do not refer to extinction in your answer.

Table 1 shows part of the classification of a plesiosaur.

Complete Table 1.

Give the binomial name of the plesiosaur in Table 1.

Figure 8 shows an evolutionary tree.

Which species in Figure 8 is most closely related to lions?

Tick (✓) one box.

Tigers are more closely related to snow leopards than to jaguars.

Draw a line on Figure 8 to show the evolution of tigers.

Label the line ‘Tiger’.

What is represented by species R on Figure 8 ?

Tick (✓) one box.

Complete the sentence.

Choose the answer from the box.

Evolution occurs by the process of.

Species can become extinct.

Give two possible causes of extinction.

Fossils are used to study the evolution of some species.

Suggest one reason why fossils are used to study evolution.

Some bacteria have evolved to be resistant to penicillin.

Penicillin is an antibiotic.

How has the process of evolution produced bacteria that are resistant to penicillin?

Write the stages, A, B, C, D and E in the correct order.

The first stage has been completed for you.

A The bacteria with mutations are more likely to survive.

B The population of bacteria is exposed to penicillin.

C The mutation for resistance to penicillin is passed on to offspring.

D Variation in the population of bacteria is caused by mutation.

E The surviving bacteria reproduce.

New antibiotics are not likely to control the spread of bacteria that are resistant to antibiotics.

What are two reasons why?

Tick (✓) two boxes.

It is estimated that 99.9% of all species that have ever existed are now extinct.

Why is the percentage of species that are extinct only an estimate? Tick (✓) one box.

What evidence is used to study species that have become extinct?

A bacterium called Clostridioides difficile (C. difficile) can infect the human digestive system. C. difficile can multiply and produce toxins. The toxins cause diarrhoea. Doctors are concerned that new strains of C. difficile may evolve. Antibiotics may not be able to kill these new strains. Explain how the evolution of antibiotic resistant C. difficile can be slowed down.

It is estimated that 99.9% of all species that have ever existed are now extinct.

Why is the percentage of species that are extinct only an estimate? Tick (✓) one box.

What evidence is used to study species that have become extinct?

A bacterium called Clostridioides difficile (C. difficile) can infect the human digestive system. C. difficile can multiply and produce toxins. The toxins cause diarrhoea. Doctors are concerned that new strains of C. difficile may evolve. Antibiotics may not be able to kill these new strains. Explain how the evolution of antibiotic resistant C. difficile can be slowed down.

The theory of evolution by natural selection was suggested by Charles Darwin in 1859. Evidence from fossils supports Darwin’s theory.

What evidence supports the theory of evolution by natural selection? Tick (✓) one box.

Figure 3 shows a fossil fly preserved in amber. The fossil formed when the amber solidified with the fly trapped inside.

Why has the fly been preserved? Tick (✓) one box.

Figure 4 shows a simplified evolutionary tree for the insect group of animals.

Figure 4

Which present day insect evolved first?

Animals A, B, C and D were ancestors of present day insects. Which animal is the most recent ancestor of both grasshoppers and beetles? Tick (✓) one box.

Name the group of present day insects which have wings which do not fold.

The house fly has the binomial name Musca domestica. Table 2 shows part of the classification for the house fly.

Complete Table 2. Choose answers from the box.

Carl Woese proposed the ‘three-domain system’ of classification. Which domain are insects in? Tick (✓) one box.

A fossil was found in rocks. The rocks were formed from mud.

The fossil is of the fungus Ourasphaira giraldae.

What is the genus of the fungus?

Tick (✓) one box.

The mud around the fungus did not contain oxygen.

Which process did the mud around the fungus prevent?

Tick (✓) one box.

The fossilised fungus is estimated to be 890 000 000 years old.

What is 890 000 000 in standard form?

Tick (✓) one box.

Traditional classification divided organisms into kingdoms.

Who developed the traditional system of classification?

Tick (✓) one box.

More recent classification methods use a three-domain system.

What is the name of the domain the fungus Ourasphaira giraldae is classified in?

Tick (✓) one box.

Why has classification changed over time?

Tick (✓) one box.

The fungus Ourasphaira giraldae is now extinct.

Give two possible causes of extinction.

A fossil was found in rocks. The rocks were formed from mud. The fossil is of the fungus Ourasphaira giraldae.

What is the genus of the fungus?

Why was the mud important during the formation of the fossil? Tick (✓) one box.

The estimated age of the fossil is in the range from 8.9 × 10⁸ years old

to 1.1 × 10⁹ years old.

Calculate the size of the range of the estimated age of the fossil.

Humans did not exist when the fungus was alive. Suggest one other reason why an accurate estimation of when this species of fungus existed is not known.

Carl Woese developed the three-domain system of classification.

Fungi are not in the domain Archaea. Which domain are fungi classified in?

Which two characteristics are features of organisms in the domain Archaea? Tick (✓) two boxes.

Carl Linnaeus lived in the 1700s. Carl Linnaeus classified living things into groups depending on their appearance. Give three types of evidence that are used now to classify living things. Do not refer to appearance in your answer.

Ammonites became extinct millions of years ago. Figure 2 is a photograph of a fossil ammonite. Figure 3 is a drawing of what scientists think a living ammonite looked like.

How was the fossil in Figure 2 formed? Tick (✓) one box.

Suggest why scientists are not certain what living ammonites looked like.

Figure 4 shows when two different types of organism were alive on Earth.

How many millions of years ago did ammonites become extinct? Use Figure 4.

Trilobites lived on Earth for 270 million years. Calculate how much longer ammonites lived on Earth than trilobites. Use Figure 4.

Suggest two factors which may have caused ammonites to become extinct.

The fossil record provides evidence for the theory of evolution by natural selection.

Which scientist proposed the theory of evolution by natural selection? Tick (✓) one box.

Figure 5 shows ammonite fossils from three different time periods.

How do the fossils in Figure 5 give evidence for the theory of evolution by natural selection? Tick (✓) one box.

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.

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.