science: double award 8404/b/1h hspexe.org/hosted/sci/wp-content/uploads/2017/08/bc114h.pdf ·...

Centre Number Candidate Number

Surname

Other Names

Candidate Signature

AQA Level 1/2 Certificate

Higher Tier

June 2014

Science: Double Award 8404/B/1H

Biology Paper 1H

Tuesday 13 May 2014 9.00 am to 10.00 am

For this paper you must have:* a ruler.

You may use a calculator.

Time allowed* 1 hour

Instructions* Use black ink or black ball-point pen.* Fill in the boxes at the top of this page.* Answer all questions.* You must answer the questions in the spaces provided. Do not write

outside the box around each page or on blank pages.* Do all rough work in this book. Cross through any work you do not

want to be marked.

Information* The marks for questions are shown in brackets.* The maximum mark for this paper is 60.* You are expected to use a calculator where appropriate.* You are reminded of the need for good English and clear

presentation in your answers.

Advice* In all calculations, show clearly how you work out your answer.

For Examiner’s Use

Examiner’s Initials

Question Mark

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TOTAL

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Answer all questions in the spaces provided.

1 Figure 1 shows an ecosystem next to a lake.

Figure 1

Lake

Small plants Bushes Trees

A scientist noticed there were different species in different parts of this ecosystem.

1 (a) (i) Describe how the scientist could use a transect to find out where different plants were

growing in this ecosystem.[5 marks]

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1 (a) (ii) Give three environmental factors, other than temperature, that affect where plants can

survive.[3 marks]

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1 (a) (iii) Choose one environmental factor from your list in part (a)(ii).

Describe how the scientist could find out if the factor you chose varies in the

ecosystem and whether it changes the distribution of the plants.[3 marks]

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1 (b) The scientist went back to the ecosystem six months later.

She saw some different plants that were not there on her first visit.

Suggest why different plants will grow in the ecosystem at different times in the same

year.[1 mark]

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Question 1 continues on the next page


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1 (c) Most organisms die at temperatures above 80 �C.

Some bacteria have adapted so they can survive in very hot environments.

1 (c) (i) Give the scientific word that describes organisms which are able to survive in extreme

environments.[1 mark]

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1 (c) (ii) The bacteria survive because they have enzymes that can work at very high

temperatures.

Suggest one reason why it may be useful for scientists to find out about the enzymes

in these bacteria.[1 mark]

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2 (a) What is a pathogen?[2 marks]

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2 (b) People can be immunised to protect them from infectious diseases.

Give one reason why it is important to immunise a large proportion of the population.[1 mark]

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2 (c) (i) MRSA can infect the blood.

Before 2006, the number of MRSA infections was increasing, especially in hospitals.

Explain how the use of antibiotics resulted in an increase in MRSA infections.[2 marks]

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2 (c) (ii) Suggest reasons for the following observations.

Observation 1: MRSA is more likely to cause symptoms in a hospital patient than in

a hospital worker, even though they both have the same contact with the pathogen.[1 mark]

Reason ...........................................................................................................................

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Observation 2: Some patients are taking antibiotics which kill most of the bacteria in

their body. These patients are likely to have larger numbers of MRSA in their body

than expected.[1 mark]

Reason ...........................................................................................................................

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Observation 3: Since 2006, the number of MRSA infections in hospitals has fallen.[1 mark]

Reason ...........................................................................................................................

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3 There are different theories about how evolution occurred.

3 (a) Charles Darwin proposed a theory of evolution by natural selection.

He thought that all living things evolved from simple organisms that lived billions of

years ago.

Darwin’s theory of evolution was not accepted for a long time.

Give two reasons why Darwin’s theory of evolution by natural selection was not

accepted for a long time.[2 marks]

Reason 1 ........................................................................................................................

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Reason 2 ........................................................................................................................

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3 (b) DNA is a molecule that has a sequence of bases.

3 (b) (i) How many different types of base are there in DNA?

Tick (P) one box.[1 mark]

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3 (b) (ii) Describe the role of DNA in the production of proteins.[3 marks]

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3 (c) A protein called cytochrome is found in many different organisms.

The cytochrome gene in different organisms may have different base sequences.

3 (c) (i) Table 1 compares the base sequence of the human cytochrome gene with the base

sequence in each of five other organisms.

Table 1

OrganismNumber of differences

in base sequencecompared with human

Human 0

Chicken 58

Fruit fly 87

Mouse 31

Rat 34

Yeast 110


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Draw a bar chart to show this information.[4 marks]

3 (c) (ii) Why would a scientist show the data in a bar chart as well as in a table?[1 mark]

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3 (c) (iii) Use the data to suggest which organism is most closely related to humans.[1 mark]

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3 (c) (iv) The cytochrome gene has 312 bases. There are only nine differences between the

cytochrome gene of a rat and a mouse.

Calculate what percentage of the mouse cytochrome gene is different from the rat

cytochrome gene.[2 marks]

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3 (c) (v) Scientists may choose other genes as well as the cytochrome gene to compare

organisms.

Why is it better to give the percentage difference instead of the number of differences

in the base sequences?[1 mark]

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4 A man owned a dog. The dog died.

Some skin cells were collected from the dog. Scientists used a skin cell to produce a

clone of the dog.

Figure 2 shows some stages in the cloning process.

Figure 2

Skin cell from the dog

4 (a) Describe how an adult body cell can be used to produce a cloned animal.

Use information from Figure 2 and your own knowledge.[5 marks]

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4 (b) The cloned dog was mated with a female dog.

4 (b) (i) Name the type of cell division used to produce gametes.[1 mark]

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4 (b) (ii) The female dog gave birth to eight puppies. There were three male puppies and five

female puppies.

Figure 3

Figure 3 shows that the puppies were not identical to each other.

Explain why the puppies were not identical to each other.[2 marks]

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5 (a) Describe, using a suitable example, what is meant by ‘active transport’.[4 marks]

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5 (b) In animals, anaerobic respiration is used to supply energy to cells when there is not

enough oxygen.

5 (b) (i) Write down the word equation for anaerobic respiration in muscle cells.[2 marks]

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5 (b) (ii) Figure 4 shows how the uptake of oxygen by the muscle cells may change during

and immediately after a period of vigorous exercise, such as sprinting.

Figure 4

Period of exercise0

Oxygenuptakeby themusclecells

Time in seconds

10 20 30 40 50 60 70 80 90

Describe how the oxygen uptake by the muscle cells changed between 40 and

70 seconds.

Explain why.[5 marks]

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5 (b) (iii) Why does anaerobic respiration release much less energy, per glucose molecule, than

aerobic respiration?[1 mark]

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5 (c) The breathing system brings air into and out of the body. Sometimes, a person may

have an accident which causes breathing to stop.

There are two types of mechanical ventilator that may help the person to breathe.

One of these is a negative pressure ventilator.

5 (c) (i) How does a negative pressure ventilator cause air to enter the lungs?[1 mark]

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5 (c) (ii) Name the other type of mechanical ventilator.

Describe how this type of mechanical ventilator causes air to enter the lungs.[2 marks]

Name ...............................................................................................................................

Description.......................................................................................................................

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END OF QUESTIONS


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Acknowledgement of copyright-holders and publishers

Permission to reproduce all copyright material has been applied for. In some cases, efforts to contact copyright-holders have beenunsuccessful and AQA will be happy to rectify any omissions of acknowledgements in future papers if notified.

Copyright ª 2014 AQA and its licensors. All rights reserved.


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