The Development of Understanding of Genetics & Evolution (AQA GCSE Combined Science: Trilogy: Biology): Exam Questions

1 hour13 questions
1a2 marks

The image in Figure 1 shows a fossil of a creature called Archaeopteryx. 

Suggest how this fossil was formed.

Figure 1

archaeopteryx-1
1b3 marks

Archaeopteryx is now extinct.

Give three reasons why animals may become extinct.

1c2 marks

Although it is extinct, Archaeopteryx is thought to be the ancestor of modern birds. 

Scientists can not be sure because the fossil record that would show the transition between Archaeopteryx and modern birds is incomplete. 

Suggest two reasons why there are gaps in the fossil record. 

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2a1 mark

What causes bacteria to become resistant to antibiotics? 

2b
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2 marks

MRSA is a strain of bacteria that is resistant to several different types of antibiotics, and is therefore very difficult to treat.

Table 1 shows the number of death certificates that mention MRSA in England and Wales between 2001 and 2006.

Table 1

Year

Number of death certificates that mention MRSA

2001

713

2002

794

2003

968

2004

1138

2005

1649

2006

1652

Calculate the percentage increase in the number of deaths from MRSA between 2001 and 2006.

Show clearly how you work out your answer.

2c3 marks

Explain, in terms of natural selection, why the number of people that died from MRSA increased from 2001 to 2006.

2d2 marks

How can doctors and scientists prevent the rapid increase in the number of bacteria that are resistant to antibiotics?

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3a1 mark

Gregor Mendel carried out breeding experiments on pea plants to determine how different traits are passed from parents to offspring. 

He crossed a plant with a purple flower with a plant with a white flower. 

All of the offspring had purple flowers. 

Complete the sentence using words from the box.

Cell    Gene    Chromosome    Allele

The purple trait is caused by a dominant _____________ . 

3b2 marks

Figure 2 shows a Punnett square of the cross between the two flowers. 

Complete the Punnett square in Figure 2 and explain why all the offspring are purple. 

represents the dominant purple

represents the recessive white

Figure 2

mendel-punnett-square-2
3c
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2 marks

Mendel then bred together the purple offspring from the cross shown in part (b). 

Once he had completed all of his breeding experiments on these plants he had 705 purple flowered plants and 224 white flowered plants. 

What is the ratio of purple to white flowers amongst these offspring?

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4a1 mark

Figure 3 shows a phylogenetic tree of a small selection of species that are part of the Anolis genus. 

Figure 3

anole-phylogenetic-tree-1

Using Figure 3, identify which species is most closely to Anolis gundlachi.

4b1 mark

Using Figure 3, identify which species is the most distantly related to the rest shown in the tree.

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1a3 marks

Alexander Fleming is credited with discovering the first antibiotic in 1928 when he noticed that the fungus Penicillium had prevented the growth of colonies of Staphylococcus aureus bacteria on his petri dishes.

Almost 100 years later, antibiotic resistance is one of the most pressing problems that medicine faces. 

Bacteria can evolve rapidly.

Suggest why.

1b4 marks

MRSA (Methicillin Resistant Staphylococcus aureus ) is a strain of bacteria that is resistant to methicillin, a type of antibiotic that is similar in structure to penicillin.

Explain how antibiotic-resistant bacteria like MRSA can arise.

1c4 marks

Suggest how the emergence of antibiotic resistance in bacteria can be used as evidence for Darwin’s theory of evolution.

1d1 mark

Darwin’s theory of evolution is now widely accepted.

Aside from antibiotic resistance, what other evidence has led to his theory becoming more widely accepted?

1e3 marks

The development of new antibiotics is costly and slow. Suggest why.

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2a2 marks

Fossils are vitally important for providing us with evidence of how different organisms have changed over time.

Figure 1 shows a representation of fossil records indicating how a prehistoric aquatic limbed animal (Ichthyostega) may have evolved from an earlier finned ancestor (Eusthenopteron).

Figure 1

1-4

From studying fossils, scientists believe that life on Earth began around 3 billion years ago.

Our understanding of the earliest forms of life however is lacking as the fossil record is incomplete.

Explain why.

2b4 marks

When Mount Vesuvius erupted in Italy in 79 AD, many people died in the settlements surrounding the volcano as a result of the release of molten rock and hot ash.

Many victims of the eruption were well preserved and body forms have been excavated by archaeologists.

Explain how and why humans were so well preserved after the eruption of Mount Vesuvius in 79 AD. 

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34 marks

Figure 2 below shows a drawing of a modern giraffe, and its only living relative in the family Giraffidae, the Okapi. 

Figure 2

4-1

The Okapi is sometimes referred to as a ‘living fossil’ as it has remained unchanged as a species over a long period of geographical time, and resembles closely the ancestor species that both giraffe and okapi have evolved from.

Both giraffes and okapi are herbivores and consume leaves from shrubs and trees.

Use Darwin’s theory of evolution by natural selection to explain how the giraffe’s long neck evolved.

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42 marks

Describe the main events that occurred in the late 19th and early-to-mid 20th Century that gave evidence in support of Mendel’s work.

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5a2 marks

Figure 3 shows a photograph of the Grand Canyon in Yellowstone National Park, USA.

The canyon formed over many millions of years from the erosion and weathering of rock by the Yellowstone river.

Figure 3

xnjQCYG6_canyon

Archaeologists found fossils of five different species of animal, A, B, C, D and E at the locations shown in Figure 3.

All five species are now extinct.

Give two reasons why animals become extinct.

5b2 marks

Explain why animals E and C in Figure 3 were not alive at the same time.

5c1 mark

Give one piece of evidence that scientists could have gathered from the fossils of animal D to suggest that it evolved from animal B.

5d2 marks

The fossils of animals B to E in Figure 3 support Darwin’s theory of evolution by natural selection.

Explain how.

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1a2 marks

Evidence for the existence of Gondwana comes from many ecological and geological sources. 

The speciation of elephants acts as one piece of evidence.

Figure 1 shows the distribution of fossils belonging to a species called Lystrosaurus. 

Figure 1

gondwana-map-1

Using this example, describe how studying the fossil record can provide evidence for the existence of Gondwana. 

1b1 mark

An extinct relative of the elephant is the woolly mammoth (Mammuthus primigenius).

Scientists are unsure about whether hunting by humans, climate change, or a combination of both, led to their extinction. 

Suggest an explanation for this uncertainty.

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23 marks

Figure 2 shows two species that are members of the Giraffidae family. 

Figure 2

GpFzsxfB_giraffe-vs-okapi

When people first observed the okapi (Okapia johnstoni) in the wild they thought that they were closely related to zebras, but that has since been disproved and they are now known to be a type of giraffe. 

Explain why this change in understanding has occurred. 

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3a3 marks

Draw a genetic diagram to show how self-pollination of the F1 yellow-seed plants produced mainly yellow-seed offspring in the F2 generation together with some green-seed offspring.

Use the following symbols:

Y = allele for yellow seed colour y = allele for green seed colour

3b2 marks

Using your answer to part (c) and Figure 3, describe whether Mendel's breeding experiments produced the expected ratio of phenotypes in the F2 offspring. 

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4a
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1 mark

Figure 4 shows when four different equine species existed. 

Figure 4

horse-evolution-2

Determine the number of years both Hypohippus and Merychippus existed together.

4b1 mark

Using Figure 4, state when the Equus first evolved. 

4c3 marks

By viewing the fossil record of these species scientists can get a better understanding of the way that the modern day horse evolved. 

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.

4d4 marks

Horse evolution is well documented in the fossil record. 

There are many species where gaps in the fossil record make it difficult to understand how they evolved. 

For example, it is difficult to trace the evolution of soft bodied invertebrates using the fossil record. 

Describe how soft bodied invertebrates can be fossilised and explain why we know a lot less about the evolution of soft bodied invertebrates compared to the evolution of horses. 

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