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2 Biological molecules

Click on the correct answer to each question.

1 The results of testing a solution for the presence of three biological molecules are shown in the table.

Test Colour of solution after test

iodine in potassium iodide solution orangeBenedicts orangebiuret purple

Which biological molecules are present in the solution?

A reducing sugar and protein

B reducing sugar and starch

C protein only

D starch only

2 The diagrams show the structure of four monosaccharides.

O

1 2 3 4

OH

H

H

H

H

CC

OH

OHC C

HOCH

CH2OH

O

H

OH

H

OH CC

H

OHC C

HOH2C CH2OH

OH

OH

OH

H CC

OH

OHC C

C OH

CH2OH

H

OH

OH

OH

H CC

OH

HC C

C OH

CH2OH

OH

Which row in the table below identifies -glucose and -glucose?

-glucose -glucoseA 1 3B 2 1C 3 4D 4 2

Multiple-choice test

Cambridge University Press 2013 Multiple-choice test: Chapter 2

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3 Which reaction involves the hydrolysis of glycosidic bonds?

A cellulose glucose

B glucose glycogen

C protein amino acids

D triglyceride fatty acids and glycerol

4 The diagram shows a tripeptide made from three glycine amino acids.

H

HN

C

H

1 2 3 4 5 6 7 8

O

H

H

O H

H

H

H H

CN

CC

NC

C

OH

O

Which of the bonds numbered 1 to 8 represent peptide bonds?

A 1 and 7

B 2 and 8

C 3 and 6

D 4 and 5

5 The following bonds are among those found in proteins: disulfide, hydrogen, ionic and peptide bonds.

Which row shows the bonds involved in primary, secondary and tertiary protein structures?

Primary structure Secondary structure Tertiary structure

A disulfide peptide hydrogenB peptide hydrogen ionicC peptide ionic hydrogenD hydrogen peptide ionic

Multiple-choice test: Chapter 2 Cambridge University Press 2013

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6 Which of the following describes a molecule of haemoglobin?

A a central haem group enclosed by four coiled globin polypeptides

B a central globin group enclosed by four coiled haem polypeptides

C four coiled globin polypeptides, each with a central haem group

D four coiled haem polypeptides, each with a central globin group

7 Which statement about the properties of water is not correct?

A Evaporation of water is an effective means of cooling an organism.

B Large volumes of water are slow to change temperature as the environmental temperature changes.

C The solid form of water, ice, is more dense than the liquid form.

D Water is an excellent solvent for ions and polar molecules.

8 Amylopectin is formed from amylose by a plant cell detaching short lengths of an amylose chain and reattaching them as branches.

Which bonds are broken and which are formed when amylose is converted into amylopectin?

Bonds broken Bonds formed

A 1,6 1,4B 1,4 1,6C 1,4 1,4D 1,6 1,6

Cambridge University Press 2013 Multiple-choice test: Chapter 2

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9 The graph shows the variation in melting point of triglycerides with different numbers of carbon atoms in their fatty acid chains.

Number of carbon atoms infatty acid chain

Mel

ting

poin

t

What explains these results?

A Triglycerides with longer fatty acid chains have stronger intermolecular forces and so have a lower melting point.

B Triglycerides with longer fatty acid chains have weaker intermolecular forces and so have a higher melting point.

C Triglycerides with shorter fatty acid chains have stronger intermolecular forces and so have a higher melting point.

D Triglycerides with shorter fatty acid chains have weaker intermolecular forces and so have a lower melting point.

Multiple-choice test: Chapter 2 Cambridge University Press 2013

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10 In spider silk, the polypeptide chains have the amino acid sequence Gly-Ala-Gly-Ala repeated many times, and the chains pack together as shown in the diagram. The diagram shows the R groups of the two amino acids.

CH3 CH3 CH3 CH3

CH3 CH3 CH3 CH3

H H H HH H H H

CH3 CH3 CH3 CH3

H H H H

Which of the following describes this structure?

A -helix held together by hydrogen bonds

B -helix held together by ionic bonds

C -sheet held together by hydrogen bonds

D -sheet held together by ionic bonds

Cambridge University Press 2013 Multiple-choice test: Chapter 2

1A: 2A: 1B: 2B: 1C: 2C: 1D: 2D: 1correct: 2correct: 1incorrect: 2incorrect: 5A: 5B: 5C: 5D: 5correct: 5incorrect: 4A: 4B: 4C: 4D: 4correct: 4incorrect: 3A: 3B: 3C: 3D: 3correct: 3incorrect: 6A: 7A: 8A: 6B: 7B: 8B: 6C: 7C: 8C: 6D: 7D: 8D: 6correct: 7correct: 8correct: 6incorrect: 7incorrect: 8incorrect: 9A: 9B: 9C: 9D: 9correct: 9incorrect: 10A: 10B: 10C: 10D: 10correct: 10incorrect: