Extinction

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 ?

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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.

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 ?

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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.

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?

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The mud around the fungus did not contain oxygen.

Which process did the mud around the fungus prevent?

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

What is 890 000 000 in standard form?

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Traditional classification divided organisms into kingdoms.

Who developed the traditional system of classification?

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More recent classification methods use a three-domain system.

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

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Why has classification changed over time?

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The fungus Ourasphaira giraldae is now extinct.

Give two possible causes of extinction.

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.

Animals have adaptations to survive in their environment.

These adaptations may be structural, behavioural or functional.

Draw one line from each animal adaptation to the type of adaptation it is.

Animal adaptation
Type of adaptation

Plants also have adaptations.

Orchid plants have adaptations which make them one of the most successful plant groups.

Orchids rely on insects for pollination.

Figure 2 shows an orchid.

Which two features help orchids survive?

Tick (✓) two boxes.

Many orchid species grow in tropical rainforest ecosystems.

What name describes the variety of all the different species found in an ecosystem?

Tick (✓) one box.

Some species of orchid may become extinct because of deforestation.

Give one reason why tropical rainforests are being cut down.

Give one factor that might cause a species of orchid to become extinct.

Do not refer to deforestation in your answer.

Scientists have analysed the entire genetic material of one species of orchid.

What chemical is the genetic material made from?

What is the name for the entire genetic material of an organism?