Paper Reference(s)

6131/01Edexcel GCEBiology (Salters-Nuffield)Advanced SubsidiaryUnit Test 1Monday 1 June 2009 – AfternoonTime: 1 hour 15 minutes

Materials required for examination Items included with question papersNil Nil

Instructions to CandidatesIn the boxes above, write your centre number, candidate number, your surname, initial(s) and signature.The paper reference is shown above. Check that you have the correct question paper.Answer ALL questions. Write your answers in the spaces provided in this question paper.If you need to use additional answer sheets, attach them loosely but securely inside this booklet.Show all the steps in any calculations and state the units. Calculators may be used.Include diagrams in your answers where these are helpful.

Information for CandidatesThe marks for individual questions and the parts of questions are shown in round brackets: e.g. (2).There are 7 questions in this question paper. The total mark for this question paper is 60.There are 20 pages in this question paper. Any blank pages are indicated.

Advice to CandidatesYou will be assessed on your ability to organise and present information, ideas, descriptions and arguments clearly and logically, including your use of grammar, punctuation and spelling.

Examiner’s use only

Team Leader’s use only

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Paper Reference

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This publication may be reproduced only in accordance with Edexcel Limited copyright policy. ©2009 Edexcel Limited.

Printer’s Log. No.

N34030AW850/R6131/57570 5/5/

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Answer ALL questions.

1. (a) Use the shapes given to draw a single nucleotide in the space below.

(2)

(b) The table below shows four features relating to DNA and messenger RNA (mRNA). Complete the table by writing the correct word or words in the boxes provided.

Feature DNA mRNA

Name of sugar present

Name of the group that links sugar to sugar

Number of strands in the nucleic acid

Name of base complementary to adenine

(4)

= sugar = phosphate = base

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(c) DNA replication changes the amount of DNA present. The graph below shows the amount of DNA present in a sample after one DNA replication. Complete the graph by drawing bars to represent the amount of DNA found in this sample before the first replication and after a second replication.

(2) Q1

(Total 8 marks)

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Before firstreplication

After firstreplication

After secondreplication

Am

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2. (a) The diagram below shows part of the right ventricle and two branches, labelled A and B, of the coronary artery of a heart.

The cardiac muscle cells in the shaded area were found to have a high concentration of lactic acid whilst those in the non-shaded area had no lactic acid present.

(i) Suggest which of the two branches of the coronary artery was blocked. Explain your answer.

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(ii) The blockage could have been caused by a blood clot. Describe how a blood clot is formed in an artery.

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Coronary artery

Part of right ventricle

BA

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(b) The electrical activity of a heart was studied by stimulating the sino-atrial node (SAN). The time taken for electrical activity to be detected in the atrio-ventricular node (AVN) was recorded. The time taken for electrical activity to be detected in the SAN, at the start of the next cycle, was also recorded.

The results are shown in the table below.

Area of the heart Time when electrical activity was detected / seconds

AVN 0.15

SAN 0.75

(i) Describe what happens in the atria during the 0.15 seconds before the AVN shows any electrical activity.

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(ii) Use the information in the table to calculate how often the SAN would show electrical activity in 1 minute. Show your working.

Answer: ................................. per minute(2)

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Q2

(Total 10 marks)

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3. All proteins are made of amino acids.

(a) The diagram below shows an amino acid. On the diagram place a tick ( ) in the box next to the component that makes the amino acid acidic.

(1)

(b) Describe the primary structure of a protein.

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CH3

COOH

H

H2N C

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(c) The diagram below shows a polypeptide made up of 10 amino acids. The shaded circles represent amino acids that have hydrophobic properties and the un-shaded circles represent amino acids that have hydrophilic properties.

Draw this polypeptide as it would appear in the container of water shown below.

(2)

air

water

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(d) Amylase is an enzyme that hydrolyses starch.

A student investigated the effect of the concentration of amylase on the rate of hydrolysis of starch solution. She mixed a solution of amylase, at a concentration of one arbitrary unit, with a starch solution. She timed how long it took for a measureable amount of product to be formed.

She repeated this procedure with seven different concentrations of amylase. The volume and concentration of the starch solution were kept constant.

The results of her investigation are given in the table below.

Concentration of amylase solution / arbitrary units

Time taken for a measureable amount of product to be formed / seconds

1 360

2 185

3 135

4 90

5 75

6 60

7 50

8 44

(i) What effect does doubling the concentration of amylase solution have on the time taken for a measureable amount of product to be formed?

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(ii) Explain the effect of doubling the amylase concentration on the rate of reaction.

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(iii) The investigation was repeated using DNA polymerase and starch solution but no reaction took place. Explain why no reaction took place.

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(Total 10 marks)

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4. In a rare genetic condition, familial hypercholesterolaemia, the blood low density lipoprotein (LDL) level is raised.

An adult person believed to have this condition had a test to measure the blood LDL levels. The result of this test and a reference table for familial hypercholesterolaemia are shown below.

The adult person’s blood LDL test result = 250 mg per dm3

Reference table for familial hypercholesterolaemia.

Blood LDL/ mg per dm3 Possible phenotype Possible genotype

75–175 No hypercholesterolaemia hh

200–400 Medium hypercholesterolaemia Hh

>450 High hypercholesterolaemia HH

(a) Use the above information to:

(i) Suggest the adult person’s genotype.

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(ii) Suggest three reasons why a range of blood LDL is given in the table for the hh genotype, rather than a single level.

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(b) LDL can be removed from the blood by liver cells. Liver cells have LDL receptor proteins in the cell surface membrane, which enable the cells to take up LDL from the blood.

The mutation that causes familial hypercholesterolaemia is a deletion in the DNA base sequence that codes for the LDL receptor protein.

(i) Explain how a deletion in the DNA base sequence, that codes for the LDL receptor protein, can make a receptor protein that is non-functional.

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(ii) Suggest why a person, homozygous for familial hypercholesterolaemia (HH), has the highest blood LDL level.

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(iii) The diagram below shows three DNA samples in an electrophoresis gel. One sample comes from a person with the hh genotype, one from a person with the Hh genotype and one from a person with the HH genotype.

Suggest which of the three samples comes from the person with the HH genotype. Give one reason for your answer.

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Sample Sample Sample 1 2 3

Positive terminal

Sample well

gel

Q4

(Total 10 marks)

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5. In the future, gene therapy may become a treatment for a number of inherited conditions.

(a) Describe the principles of gene therapy.

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(b) Distinguish between somatic gene therapy and germ line gene therapy.

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(Total 5 marks)

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6. A study of the uptake of sodium ions was undertaken to compare facilitated diffusion with active transport.

Two samples of tissue (P and Q), were taken from the same section of small intestine. Both samples were placed in sodium chloride solutions of the same concentration. ATP was added to the sodium chloride solution surrounding sample Q.

The sodium ion concentration inside each tissue sample was recorded every minute for5 minutes. The results are shown in the graph below.

(a) (i) Compare the uptake of sodium ions in the two samples over 5 minutes.

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Sample Q

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Con

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Sample P

0 1 2 3 4 5

Time / minutes

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(ii) Give one piece of evidence from the graph which confirms that active transport is occurring in sample Q. Explain your answer.

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(b) Describe one difference between diffusion and facilitated diffusion.

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(c) Exocytosis is another transport process that occurs in tissues.

Describe the process of exocytosis.

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.......................................................................................................................................(2) Q6

(Total 8 marks)

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7. (a) The table below shows four structural features found in two carbohydrates. Complete the table by placing a tick ( ) in the box if the feature is present and a cross ( ) if it is absent.

Structural feature Sucrose Amylopectin

Glycosidic bonds present

Side chains present

Contains more than three glucose monomers

(3)

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(b) There are several ways a person can reduce the risk of obesity and heart disease. A change of diet can reduce the risk.

The graph below shows the percentage of saturated and unsaturated fats in four different cooking oils.

Using the information in the graph, suggest which cooking oil might be the best one to reduce the risk of heart disease. Give a reason for your answer.

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Question 7 continues on the next page

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Saturated fats

Unsaturated fats

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(c) The table below shows the average daily energy taken in and energy given out of four different people.

Person Energy taken in/ KJ per day

Energy given out / KJ per day

1 9240 9240

2 9282 9330

3 9618 9198

4 8868 8868

(i) Suggest which person is most at risk of obesity. Give a reason for your answer.

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(ii) Exercise can reduce the risk of both obesity and heart disease. Suggest which person is undertaking extreme exercise. Give a reason for your answer.

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TOTAL FOR PAPER: 60 MARKS

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Q7

(Total 9 marks)