Name: _______________________________________________

     

 

Biology B Topic 1 End of Unit Test  

 Date:

        Time: 60 minutes   Total marks available: 58   Total marks achieved: ______                                          

 

Questions

Q1.Lipoprotein lipase is a biological catalyst and is involved in the hydrolysis of triglycerides.

(a)  For each of the statements below, put a cross in the box that corresponds to the correct statement.

(i)  A catalyst(1)

   A    decreases the rate of reaction by increasing the activation energy

   B    decreases the rate of reaction by reducing the activation energy

   C    increases the rate of reaction by increasing the activation energy

   D    increases the rate of reaction by reducing the activation energy

(ii)  Hydrolysis results in bonds between glycerol and a fatty acid(1)

   A    being broken and water being formed

   B    being broken and water being used

   C    being formed and water being formed

   D    being formed and water being used

(iii)  A triglyceride is made from(1)

   A    one glycerol and one fatty acid

   B    one glycerol and three fatty acids

   C    three glycerols and one fatty acid

   D    three glycerols and three fatty acids

(iv)  A type of bond found in a triglyceride is(1)

   A    an ester bond

   B    a glycosidic bond

   C    a hydrogen bond

   D    a phosphodiester bond

(b)  Some people have a mutation in the gene coding for lipoprotein lipase.The table below shows the mean concentration of some types of lipid in the blood of

people without the mutation and in the blood of people with the mutation.

It has been suggested that people with this mutation may be more at risk of developing cardiovascular disease (CVD).

(i)  Give two reasons why the information in the table does not support this suggestion. (2)

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(Total for Question = 6 marks)

Q2. 

Which diagram represents the structure of transfer RNA (tRNA)?

(1)

 

Q3. 

Many of the chemicals found in living organisms are polymers.

The diagram shows the structure of a monomer.

(1)

This monomer is found in

   A    DNA

   B    DNA polymerase

   C    haemoglobin

   D    mRNA

Q4. 

Glucose isomerase is an intracellular enzyme that is extracted from cells and used by

manufacturers of food products that help people lose weight. The enzyme converts glucose into fructose which is a much sweeter carbohydrate.

Explain how proteins like glucose isomerase are made in cells.

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(Total for question = 5 marks)

Q5. 

Triose isomerase is an enzyme containing two polypeptide chains.

(i)  Which of the following describes the synthesis of one of these polypeptide chains?(1)

   A    a series of condensation reactions forming peptide bonds   B    a series of condensation reactions forming glycosidic bonds   C    a series of hydrolysis reactions forming peptide bonds   D    a series of hydrolysis reactions forming glycosidic bonds

(ii)  Which of the following is the best description of this enzyme?(1)

   A    a fibrous protein with a secondary structure   B    a globular protein with a quaternary structure   C    an insoluble protein with a quaternary structure   D    a soluble protein with a primary structure

 

(Total for question = 2 marks)

Q6. 

The cells of all living organisms contain small molecules such as carbohydrates, lipids and amino acids.

The diagram shows the structure of a carbohydrate.

(i)  Which of the following molecules contains this carbohydrate?

(1)

   A    cellulose

   B    DNA

   C    RNA

   D    starch

(ii)  The diagram shows another carbohydrate.

The carbohydrate shown in the diagram is found in(1)

   A    cellulose

   B    glycerol

   C    guanine

   D    starch

 

Q7. 

Amino acids can be hydrophilic or hydrophobic. The diagram shows a polypeptide chain composed of 10 amino acids.

This polypeptide was placed in a beaker of distilled water. Draw a diagram to show the structure of this polypeptide in the beaker.

(3)

 

(Total for question = 3 marks)

Q8. 

The cells of all living organisms contain small molecules such as carbohydrates, lipids and amino acids.

(i)  The diagram shows the structure of a fatty acid.

This fatty acid is(1)

   A    cholesterol

   B    glycerol

   C    saturated

   D    unsaturated

(ii)  A triglyceride lipid molecule is made up of over 70% carbon whereas a glucose molecule is only 40% carbon.

State why lipids are the main storage molecule in many seeds.(1)

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Q9. 

Part of a DNA molecule contained 250 bases of which 22% of these bases were guanine.

(i)  Determine the number of each of the bases present.(4)

Answer ...........................................................

(ii)  Explain why some of the bases in a gene do not code for amino acids.(2)

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(Total for question = 6 marks)

Q10. 

Enzymes act as biological catalysts.Amylase is an enzyme present in saliva that catalyses the hydrolysis of starch into maltose.*(a) Describe the structure of starch.

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(b) Explain the meaning of the following terms.

(i) Catalyst

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(ii) Hydrolysis

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(c) Bread contains a high proportion of starch. If bread is chewed for a long period of time it begins to taste sweet.

Suggest why bread tastes sweet after chewing for a long period of time.

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(Total for question = 10 marks)

Q11. 

The primary amino acid sequence of a protein determines its final three-dimensional structure.

The diagram shows two amino acids, cysteine and glycine.

(i)  The chemical groups used to form a peptide bond are

(1)

   A    −NH2 and −COOH

   B    −CH2 and −COOH

   C    −CH and −CH2

   D    −NH2 and −CH

(ii)  The curliness of hair is the result of disulphide bonds between hair proteins. The more bonds, the curlier the hair.

In recent years, hair straightening has become more popular.Thioglycolate is used by hairdressers before the hair is straightened.The process is completed using a second chemical to reverse the effect of the thioglycolate.Explain how this method keeps the hair straight.

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Q12. 

The DNA base sequence for part of a gene is shown below.

Write the mRNA base sequence produced from this sequence of bases.

(2)

 

Q13. 

Explain how the dipolar nature of water is essential for living organisms.

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 Q14. Describe three differences between the processes of replication and transcription of DNA. (3)

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Q15. 

A student was investigating the effect of enzyme inhibitors on a bacterial protease enzyme.

She mixed 4 cm3 of skimmed milk with 4 cm3 of distilled water in a beaker.

She then added 2 cm3 of the enzyme to start the reaction. The reaction mixture was immediately placed in a colorimeter.

The colorimeter passes a beam of light through the reaction mixture and measures the light absorbed.

The student then took absorbance readings every 5 seconds.

She repeated the experiment using 4 cm3 of skimmed milk, 4 cm3 of distilled water, 2 cm3 of enzyme and 2 cm3 of inhibitor.

The results are shown in the table.

(i)  Explain how the student should modify her procedure to ensure that valid comparisons of different inhibitor concentrations could be made.

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(ii)  Analyse the student's data to explain the appearance of the reaction mixtures for both control and inhibitor experiments at zero time and after 25 seconds.

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Q16. Saquinavir is a drug used in the treatment of HIV.

It binds very precisely to the active site of a HIV protease enzyme and inhibits its action.

Saquinavir is described as peptidomimetic because it is a small protein-like chain designed to resemble a peptide.

Analyse this information to explain what sort of enzyme inhibitor Saquinavir is likely to be.

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Q17. 

The diagram below shows four molecules, P, Q, R and S, found in living organisms.

Name one element found in all molecules of Q that would not be found in carbohydrates.

(1).............................................................................................................................................

Q18.Many of the chemicals found in living organisms are polymers.

Which of the following molecules is made of different monosaccharides?

(1)

   A    amylose

   B    glycogen

   C    lactose

   D    maltose