Extinction

Ichthyosaurs are reptiles that lived in the sea millions of years ago.

Figure 13 shows the fossilised remains of an ichthyosaur.

Suggest how the fossil in Figure 13 was formed after the ichthyosaur died.

The length of the image of the ichthyosaur in Figure 13 is 120 mm.

The real length of the ichthyosaur was 17 times longer than the image in Figure 13.

Calculate the real length of the ichthyosaur.

Give your answer in metres.

Table 5 gives the classification of the ichthyosaur in Figure 13.

Complete Table 5.

Choose answers from the box.

Ichthyosaurs were predators.

Ichthyosaurs are now extinct.

Scientists think that extinction of the ichthyosaurs was caused by increased competition with other predators for food.

Suggest two other possible causes of extinction of the ichthyosaurs.

Ichthyosaurs are reptiles that lived in the sea millions of years ago.

Figure 1 shows the fossilised remains of an ichthyosaur.

Suggest how the fossil in Figure 1 was formed after the ichthyosaur died.

The length of the image of the ichthyosaur in Figure 1 is 120 mm.

The real length of the ichthyosaur was 17 times longer than the image in Figure 1.

Calculate the real length of the ichthyosaur.

Give your answer in metres.

Table 1 gives the classification of the ichthyosaur in Figure 1.

Complete Table 1.

Choose answers from the box.

Ichthyosaurs were predators.

Ichthyosaurs are now extinct.

Scientists think that extinction of the ichthyosaurs was caused by increased competition with other predators for food.

Suggest two other possible causes of extinction of the ichthyosaurs.

Carl Linnaeus invented a classification system that places organisms into groups.

What is the name of the largest classification group in Linnaeus’s system?

Tick (✓) one box.

Linnaeus gave each species a binomial name.

Which two classification groups form the binomial name?

Tick (✓) two boxes.

Scientists think that the animals in Figure 2 all evolved from an ancestor that lived about 6 million years ago.

Figure 2 shows how the animals may have evolved.

What was the most recent time that the domestic dog and the golden jackal shared a common ancestor?

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Which present-day animal in Figure 2 is the most distant relative of the domestic dog?

Scientists think the grey wolf and the domestic dog had a common ancestor.

The common ancestor:

• lived about 32 thousand years ago

• is now extinct.

Give two possible causes of extinction.

32 thousand years ago, humans hunted other animals for food.

Wolves also hunted other animals for food.

Suggest one reason why wolves began to follow groups of humans.

Some wolves are more aggressive than other wolves.

Describe how selective breeding of wolves could produce a domestic animal that is less aggressive than the wolf.

Living organisms can be classified into groups. Trilobites are animals that lived in the sea 400 to 500 million years ago. Table 3 gives the classification of two species of trilobite.

Complete Table 3. Choose answers from the box.

Which scientist invented the classification system given in Table 3 ? Tick (✓) one box.

What is the binomial name of trilobite A ? Use information from Table 3. Tick (✓) one box.

Figure 10 shows fossils of the two species of trilobite.

Figure 11 shows:

• layers of rock in a cliff

• where the trilobite fossils were found.

A scientist made the hypothesis: ‘Trilobite B may have evolved from trilobite A.’

What two pieces of evidence from Figure 10 and Figure 11 support the scientist’s hypothesis? Tick (✓) two boxes.

Trilobites are animals that lived in the sea. Complete the sentences about how the fossils of trilobites A and B were formed. Choose answers from the box.

The animal dies and falls to the sea bed.

The of the animal decay.

Trilobites A and B are now extinct. Give three possible causes of extinction.

Suggest one reason why scientists cannot be sure what caused the trilobites to become extinct.

The theory of evolution states that organisms alive today evolved by natural selection from other species that are now extinct.

Which two scientists proposed the theory of evolution by natural selection?

Tick (✓) two boxes.

Fossils provide evidence for evolution. Figure 1 shows a fossil footprint of a dinosaur.

What is a fossil?

How was the fossil in Figure 1 formed?

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Dinosaurs are extinct. Give two causes of extinction.

Which two of the following provide evidence for evolution?

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Figure 8 shows what the extinct Siberian rhinoceros (Elasmotherium sibiricum) might have looked like.

What is the genus of the Siberian rhinoceros?

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The ‘three-domain system’ of classification places all living organisms in one of three domains.

Which domain was the Siberian rhinoceros in?

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Who developed the ‘three-domain system’ of classification?

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The horn of the Siberian rhinoceros is estimated to have been 150 cm long.

Suggest one advantage of this adaptation to the Siberian rhinoceros.

The only parts of the Siberian rhinoceros that have been found are fossilised bones.

Give one reason why only the bones of the body of the Siberian rhinoceros became fossils.

Suggest how scientists can estimate when the Siberian rhinoceros was alive.

Figure 9 shows when the Siberian rhinoceros existed and when modern humans existed.

How many million years ago did the Siberian rhinoceros become extinct?

Determine the time in years when both the Siberian rhinoceros and modern humans existed together.

Use Figure 9 and your answer to Question 06.7.

Suggest two factors that may have caused the extinction of the Siberian rhinoceros.

Figure 8 shows when two mammals existed in Asia.

Determine the number of years both Andrewsarchus and Brontotherium existed together.

The oldest fossils of human ancestors found in this area are 700 000 years old. Andrewsarchus was a carnivore and Brontotherium was a herbivore. Suggest how the extinction of Andrewsarchus could have resulted in the extinction of Brontotherium.

Information about extinct animals is often not clear because the fossil record is incomplete. Give three reasons why the fossil record is not clear for older species.

Figure 9 shows the percentage (%) survival of large mammal species in four areas of the world. The time at which humans first appeared in each of the four areas is also shown.

A mass extinction is a rapid decrease in biodiversity on Earth.

A student stated: ‘The data in Figure 9 shows that humans caused mass extinctions.’ Evaluate the student’s statement.

Give one disadvantage and one advantage of mass extinction events. Answer in terms of evolution.

Figure 10 shows a flightless bird called the dodo (Raphus cucullatus).

The dodo:

• was 1 m tall

• had a mass of 20 kg

• lived in rainforests on a tropical island

• ate fruits

• made its nest on the ground.

A female dodo laid only one egg each year.

Humans arrived on the island in the year 1507. By 1681 the dodo was extinct.

What is the genus of the dodo?

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Before the arrival of humans, there were no other large animals living on the island.

Suggest two reasons why the dodo became extinct soon after the arrival of humans.

Today, humans are cutting down large areas of tropical rainforests.

Suggest one use of the land after the trees have been removed.

Why does the removal of trees cause an increase in carbon dioxide in the atmosphere?

Tick (✓) two boxes.

What effect would an increase in carbon dioxide in the atmosphere have on global air temperature?

Tick (✓) one box.

‘Sustainable forestry’ reduces the harmful effects of cutting down trees on the environment.

Figure 11 shows a method of ‘sustainable forestry’.

Numbers 1–9 show different parts of a rainforest.

The trees are cut down in the sequence 1 – 2 – 3 – 4 – 5 – 6 – 7 – 8 – 9

• The trees are cut down in only one area at any one time.

• It takes 30 years to cut down the trees in each area.

• The trees in the ‘Old growth’ area are never cut down.

How many years would it take to cut down the trees in all of the numbered areas in Figure 11 ?

The rainforest contains:

• 750 species of trees

• 400 species of birds

• 150 species of butterflies

• many other species of plants and animals.

Explain how the pattern of cutting down trees shown in Figure 11 stops the biodiversity of the rainforest being reduced.

Fossils give evidence about organisms that lived a long time ago.

Scientists have found very few fossils of the earliest life forms.

Give one reason why.

Figure 3 is a photograph of a fossilised fish.

Suggest how the fossil in Figure 3 was formed.

The species of fish shown in Figure 3 is now extinct.

Give two possible causes of extinction.

Modern fish species have evolved from fish that lived a long time ago.

Evolution is caused by mutation and natural selection.

What is a mutation?

Tick one box.

Describe the process of natural selection.