2010_mock_Unit 1

(Edexcel) SNAB Unit 1 – Topic 1 and Topic 2 RESIT 2010

1. The table below refers to the formula and structure of some biological molecules.

Complete the table by writing in the name, the formula or the structure of the molecule where appropriate in the empty boxes.

Name Formula Structure

Water H2O

NH2RCHCOOH

Fatty acid H C C C C C C

HH

HH

H H H

H H H

O

O H

C

C

C H O H

C C

C

O

O H

H

H

HH

H

O H

O HH O

2

(Total 6 marks)

2. (a) Explain what is meant by the primary structure of a protein molecule.

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Tadcaster Grammar School 1

(b) Explain the role of hydrogen bonding in maintaining the structure of a globular protein such as insulin.

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(c) Describe how the structure of a fibrous protein, such as collagen, differs from the structure of a globular protein.

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(Total 8 marks)

3. Urease is an enzyme which catalyses the breakdown of urea to ammonia and carbon dioxide.

An experiment was carried out into the effect of pH on the activity of urease. 10 cm3 of pH 3 buffer solution was mixed with 1 cm3 of urease solution. This mixture was then added to 10 cm3 of urea solution and the concentration of ammonia in the mixture was measured after 60 minutes. This procedure was repeated using buffer solutions of pH 4, 5, 6, 7, 8 and 9.

The results are shown in the graph below.


1 0 0

8 0

6 0

4 0

2 0

03 4 5 6 7 8 9

p H

C on c en tra tio no f am m o n ia /a rb itra ry u n its

(a) What do these results suggest is the optimum pH for urease activity?

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(b) Suggest how the experiment could be modified to determine the optimum pH more accurately.

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(c) Explain why no ammonia was produced at pH 3.

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(d) Explain why less ammonia is produced at pH 9 than at pH 8.

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(e) Describe how this experiment could be modified to determine the effect of enzyme concentration on the activity of urease.

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(Total 11 marks)


4. Give an account of the ways in which molecules and ions move into and out of cells.

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(Allow 2 lined pages)(Total 10 marks)


5. The diagram shows a section through the heart of a mammal

B

A

C

(a) Name the parts labelled A, B and C.

A ................................................................................................................................

B ................................................................................................................................

C ................................................................................................................................(3)

(b) Each time the heart beats, the atria contract first and then the ventricles contract. Explain how this sequence of events is coordinated.

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(Total 7 marks)


6. The chart below shows the number of deaths from cardiovascular disease per 100 000 population for men and women in four countries.

N u m b ero f

d ea th sp e r

1 0 0 0 0 0p o p u la tio n

1 0 0 0 –

8 0 0 –

6 0 0 –

4 0 0 –

2 0 0 –

0 – – – ––

F ran ce S p a in E n g lan dan d W ale s

R u ss ia

W o m en

M en

–

(a) Describe the differences in the death rates shown in the chart above.

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(b) One possible reason for the differences in the death rates due to cardiovascular disease between the different countries is the quantity of fruit and vegetables eaten.

Write a suitable null hypothesis that could be tested by an epidemiologist investigating the effect of fruit and vegetable consumption on deaths from cardiovascular disease.

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V

(c) Suggest and explain two other reasons for the differences in the death rates between the countries due to cardiovascular disease.

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(Total 8 marks)

7. The diagram below shows part of a DNA molecule.

X

W

Y

Z

A d en in e

C y to s in e

(a) (i) Name the parts of the molecule represented by each of the following letters.

V ……………………………………………………………………………..

W ......................................................................................................................

X ......................................................................................................................

Y ......................................................................................................................

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(ii) Name the type of bond that holds the two strands of DNA together.

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(b) The table below shows the amino acids coded by mRNA codons.

U U UU U CU U AU U G

P h en y la lan in eP h en y la lan in eL eu c in eL eu c in e

C U UC U CC U AC U G

L eu c in eL eu c in eL eu c in eL eu c in e

A U UA U CA U AA U G

Iso leu c in eIso leu c in eIso leu c in eM e th io n in e

G U UG U CG U AG U G

Valin eVa lin eVa lin eVa lin e

U

C

A

G

Fir

st b

ase

S e co n d b ase

U C A G

Third base

U C UU C CU C AU C G

S erin eS e rin eS e rin eS e rin e

C C UC C CC C AC C G

P ro lin eP ro lin eP ro lin eP ro lin e

A C UA C CA C AA C G

T h reo n in eT h reo n in eT h reo n in eT h reo n in e

G C UG C CG C AG C G

A lan in eA lan in eA lan in eA lan in e

U A UU A CU A AU A G

Ty ro s in eTy ro s in eS to pS to p

C A UC A CC A AC A G

H istid in eH is tid in eG lu tam in eG lu tam in e

A A UA A CA A AA A G

A sp a rag in eA sp a rag in eLy sin eLy sin e

G A UG A CG A AG A G

A sp a rtic ac idA sp a rtic ac idG lu tam ic ac idG lu tam ic ac id

U G UU G CU G AU G G

C y ste in eC y ste in eS to pTry p to p h an

C G UC G CC G AC G G

A rg in in eA rg in in eA rg in in eA rg in in e

A G UA G CA G AA G G

S erin eS e rin eA rg in in eA rg in in e

G G UG G CG G AG G G

G ly c in eG ly c in eG ly c in eG ly c in e

UCAG

UCAG

UCAG

UCAG

(i) Name the process by which mRNA is formed in the nucleus.

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(ii) Reading from left to right, what is the sequence of amino acids coded by the following length of mRNA?

G A U C G U U G U A A G

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(iii) A mutation occurred so that the base cytosine was replaced by guanine in this mRNA. Using the information in the table, explain why this mutation could affect the tertiary structure of the protein formed from this mRNA.

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THE END (Total 11 marks)


2010_mock_Unit 1

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