EXERCISE CHAPTER 1 - MOLECULE OF LIFE

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

1.1 WATER

1. (a) FIGURE 1 shows three water molecule attracted to one another.

δ+
δ-
δ+

FIGURE 1

(i) Name the bond labeled A. [1 mark]

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(ii) In FIGURE 1, draw the symbol of polarity for water molecule B.
[1 mark]

(iii) Why must water absorb relatively large quantity of heat in order to change

its temperature? [1 mark]

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(iv) State ONE property of water based on question a(iii). [1 mark]

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(b) (i) Draw and label the bond formed when two molecules of water are joined.
[2 marks]

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

(ii) State TWO properties of water. [2 marks]

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(iii) Why must water absorb relatively large quantity of heat in order to change

its temperature? [1 mark]

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(UPS 2009/10)

2. FIGURE 2 shows a situation when compound XY dissolves in water.

FIGURE 2

(i) Name the bond that links hydrogen and oxygen atoms within the water

molecule. [1 mark]

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(ii) State the property of water shown in FIGURE 2. [1 mark]

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(iii) Give ONE example of compound XY. What is the characteristic that

allows it to dissolve in water? [2 marks]

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SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

(iv) What is the specific term to describe dissolved ions surrounded by water

molecules? [1 mark]

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3. (a) Draw one water molecule and show the polarity for each atom. [2 marks]

(b) Describe the effects of water properties to the blood circulatory system in human

body. [4 marks]

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4. Without water there will be no life. So, explain properties of water that makes it so

important to living beings based on temperature changes. [6 marks]

5. Describe THREE property of water and the importance of each. [6 marks]

1.2 CARBOHYDRATE
6. FIGURE 3 represents a molecule of glucose.

FIGURE 3

(a) What type of glucose is represented in FIGURE 3? [1 mark]

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SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

(b) Draw a disaccharide molecule formed from the above glucose molecules. Name

the disaccharide. [3 marks]

(c) Name a storage polysaccharide found in human body. [1 mark]

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(UPS 2008/09)

7. (a) Sucrose is formed from the condensation process of two monomers.

(i) What are the monomers of sucrose? [1 mark]

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(ii) Draw a structure of β-glucose. [2 marks]

(iii) State TWO functions of glucose. [2 marks]

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(b) FIGURE 4 shows a disaccharide molecule.

FIGURE 4

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

(i) Name the bond labeled Z. [1 mark]

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(ii) Identify the monomer for disaccharide molecule shown in FIGURE 4.
[1 mark]

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(iii) What is the reaction involved in the formation of disaccharide molecule

shown in FIGURE 4? [1 mark]

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8. FIGURE 5 shows a molecule of carbohydrate.

FIGURE 5

(a) Identify the molecule shown in FIGURE 5. [1 mark]

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(b) In which class does this molecular structure belongs to? [1 mark]

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(c) Give TWO characteristics of the above molecular structure. [2 marks]

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(d) Identify the monomer for the molecular structure in FIGURE 5. [1 mark]

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(e) Show the breakdown of the molecular structure in FIGURE 5. [3 mark]

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

(f) The monomers of the molecular structure shown in FIGURE 5 can join together
to form an unbranched polysaccharide. Identify this polysaccharide. [1 mark]
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(g) Why is the polysaccharide stated in 8(f) suitable as food storage? [1 mark]

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(PSPM 2003/04)

9. FIGURE 6 shows the structural formula of monosaccharide P and Q.

FIGURE 6

(a) Name monosaccharide P and Q. [2 marks]

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(b) Monosaccharide P and Q combined to form disaccharide R. While two
Monosaccharide P combined to form disaccharide S.

(i) Name disaccharides R and S. [2 marks]

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(ii) Between R and S, which is a non reducing sugar. Why? [2 marks]

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(PSPM 2004/05)

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

10. FIGURE 7 shows the structures of two types of polysaccharide. Polysaccharide A is a
component of starch and polysaccharide B is a component of plant cell wall.

FIGURE 7

(a) Name polysaccharides A and B. [2 marks]

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(b) State the specific names of the bonds labeled as P, Q and R. [3 marks]

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(c) Give ONE function of polysaccharide B. [1 mark]

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(d) Why are human unable to digest polysaccharide B? [1 mark]

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(e) Hydrolysis of polysaccharide A produces disaccharide C.

What is disaccharide C? [l mark]

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(f) Why is polysaccharide A suitable as storage material? [2 marks]

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(PSPM 2008/09)

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

11. (a) FIGURE 8.1 shows different types of polysaccharide.

FIGURE 8.1

(i) Name polysaccharide B [1 mark]

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(ii) State the monomer that forms cellulose and amylose? [2 marks]

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(iii) Why is molecule A suitable as storage material? [2 marks]

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(b) FIGURE 8.2 shows part of the structure of a polysaccharide.

FIGURE 8.2

(i) Identify the type of polysaccharide shown in FIGURE 8.2. [1 mark]
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SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

(ii) Give TWO characteristics of this polysaccharide. [2 marks]

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(iii) List TWO structural differences between this polysaccharide and

glycogen. [2 marks]

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12. FIGURE 9 shows the structure of a polysaccharide found in plant cells.

FIGURE 9

(a) Name the bond labeled Z. [1 mark]

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(b) Draw and label the structure formed from the condensation of two monomers of

Polysaccharide A. [3 marks]

(c) State the function of Polysaccharide A in plant cells. Give a reason. [2 marks]
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SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

(d) State the monomer of cellulose and its role in plants [2 marks]

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(e) Why do animal cells store energy in the forms of glycogen and not glucose?
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[2 marks]

(UPS 2012/13)

13. FIGURE 10.1 shows part of cellulose, the major component of cell walls in plants.

FIGURE 10.1

(a) Cellulose is an important raw material in the production of cloth and cellophane
because of its tensile strength. Explain briefly how cellulose provides the
strength.
[3 marks]
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(b) FIGURE 10.2 shows the structure of the amino acids alanine and cysteine.

Alanine Cysteine

FIGURE 10.2

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

(i) Draw a dipeptide based on structures in FIGURE 10.2.

[2 marks]

(ii) Name the bond formed between the two amino acids.
[1 mark]

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1.3 LIPID (PSPM 2019/2020)
14. Compare between carbohydrates and lipids [5 marks]

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15. (a) (i) Draw and label the structure of a triglyceride molecule. [3 marks]

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

(ii) How many molecules of water are lost in the formation of the triglyceride

molecule? [1 mark]

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(iii) Give ONE difference between phospholipids and triglycerides. [1 mark]
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(b) FIGURE 11 shows the structure of molecule C.

FIGURE 11

(i) Name the type of lipid for molecule C. [1 mark]

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(ii) Name the chemical reaction and bond labeled D formed in the formation

of molecule C. [2 marks]

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(UPS 2013/14)

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

16. FIGURE 12 shows the molecular structure of a triglyceride, phospholipid and
glycolipid.

FIGURE 12

(a) Name X and Y. [2 marks]

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(b) Identify the main component of the three molecules above. [1 mark]

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(c) Cold-blooded animals usually have higher proportion of unsaturated fatty acids

compared warm-blooded animals. Why? [2 marks]

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(UPS 2010/11)

17. FIGURE 13 shows the structural formula for compound A.

FIGURE 13

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

(a) Identify compound A. [1 mark]

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(b) Name the process that enables splitting of this compound in to its components.
[1 mark]

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(c) What are the products in 16(b)? [1 mark]

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(d) Which structure in compound A that causes it to be insoluble in water? What is its

characteristic? [2 marks]

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(UPS 2014/15)

18. Fat is also known as triacylglycerol or triglycerides. With the aid of diagram, describe the

breakdown of triglycerides. [6 marks]

19. With the aid of a labelled diagram, describe the structure of triglyceride. Explain how the

structure is formed. [6 marks]

1.4 PROTEIN

20. (a) FIGURE 14 shows a model of haemoglobin.

FIGURE 14

(i) Name the monomer of haemoglobin. [1 mark]

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(ii) Draw and label a structural formula of the monomer in 19(a)(i). [2 marks]

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

(iii) Name the bond that formed between the two monomers. [1 mark]

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(b) (i) State the level of structure of haemoglobin. Give a reason for your answer.
[2 marks]

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(ii) State TWO intramolecular bonds that stabilise the structure. [2 marks]
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(c) Why does a denatured protein no longer function? [2 marks]

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(UPS 2011/12)

21. FIGURE 15 shows a monomer of a molecule.

FIGURE 15

(a) Name the polymer formed from the condensation of the monomers as in

FIGURE 15. [l mark]

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(b) What are the TWO functional groups that form the monomer? [2 marks]

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(c) Why egg white hardens when heated? [2 marks]

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(UPS 2014/15)

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

22. FIGURE 16 shows a molecular structure formed when two monomers are joined
together.

FIGURE 16

(a) Identify the molecular structure in FIGURE 16. [1 mark]

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(b) What is the bond X? Draw the bond X. [2 marks]

(c) The monomers of the above molecule undergo polymerization to form amylase.

State the level of protein structure for a functional amylase. [1 mark]

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(d) A person does not die from high fever even though his body temperature exceeds
40oC. Based on the properties of enzyme, give ONE reason for this situation.
[1 mark]
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(UPS 2014/15)

23. FIGURE 17 shows a structural formula of an amino acid.

FIGURE 17

(a) Identify the TWO functional groups of this amino acid. [2 marks]

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SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

(b) Draw the formation of dipeptide molecule from the amino acid shown in

FIGURE 17. [4 marks]

24. FIGURE 18 shows the structural formula of two organic monomers M and N.

MN

FIGURE 18

(a) Identify the common name for organic materials M and N. [1 mark]

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(b) Identify the polymer that is produced from the bonding of monomers M and N.
[1 mark]

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(c) Identify the TWO functional groups found in monomers M and N and state the

characteristic of each functional group. [4 marks]

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(d) Organic monomer M and N binds to form a new compound. Name the type of
chemical reaction and its product formed from this chemical reaction. [2 marks]
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(e) In FIGURE 17, circle the atom that is expelled when the bond between organic

monomers M and N formed. [2 marks]

(PSPM 2003/04)

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

25. FIGURE 19 shows the structure of three amino acids.

FIGURE 19

(a) Name the groups labeled A, B, and C. [3 marks]

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(b) Show how valine and leucine combine to form a dipeptide. [3 marks]

(c) State TWO types of chemical bonds that maintain the configuration of

globular protein. [2 marks]

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(d) State TWO factors that can change the configuration of globular protein.
[2 marks]

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(PSPM 2005/06)

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

25. FIGURE 20 shows a structural formula for a polypeptide molecule.

FIGURE 20

(a) State the name and the number of monomers that form the polypeptide above.
[2 marks]

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(b) State the name of the bond formed in the synthesis of the polypeptide above.
Draw arrows in FIGURE 19 to show the bonds that you named. [2 marks]

(c) State the name of the reaction involved in the following processes:

(i) Adding one more monomer to the polypeptide above.
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(ii) Eliminating one monomer from the polypeptide above.
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[2 marks]

(d) Compound A will be formed when a polypeptide is combined with nucleic

acid. What is compound A and name the cell structure that contains this

compound. [2 marks]

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(e) Polypeptide structure can be folded to form an enzyme. State TWO types of

bond which maintains the configuration of an enzyme. [2 marks]

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(PSPM 2006/07)

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

27. FIGURE 21 shows two molecules of amino acids.

FIGURE 21
(a) Draw the structure as a result the combination of the two molecules.[2 marks]

(b) Name the chemical reaction involved and the type of bond formed during the

formation of dipeptide. [2 marks]

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(c) What is R in FIGURE 20? [1 mark]

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(d) Based on their structure, classify the proteins with their respective examples.
[4 marks]

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(e) Why are some proteins known as conjugated proteins? [1 marks]

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(PSPM 2007/08)

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

28. (a) FIGURE 22.1 shows a polypeptide consisting of 15 amino acids.

FIGURE 22.1

(i) Name the bond between the amino acids in the polypeptide chain.[1 mark]
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(ii) What is group X? [1 mark]

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(iii) Which level of protein structure is shown by this polypeptide? Give a
reason for your answer.
[2 marks]
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(iv) Give an example of a protein that has the same structural level as the

protein in FIGURE 22.2. [1 mark]

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(b) FIGURE 22.2 shows the general structure of an amino acid.

FIGURE 22.2

(i) Name the functional group in D and E. [2 marks]

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SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

(ii) List the FOUR groups of amino acid based on their R groups. [2 marks]

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(iii) State ONE factor that can change protein structure. [1 mark]

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(PSPM 2012/13)

29. FIGURE 23 shows different structural levels of a polymer.

FIGURE 23

(a) Name the basic unit of polymer in FIGURE 23 [1 mark]

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(b) What is the level of structure H? [1 mark]

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(c) How structure G is formed from structure F? [1 mark]

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(d) Name TWO types of interactions involve in the formation of structure H.
[2 marks]

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(PSPM 2013/14)

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

30. With the aid of a diagram, briefly explain a condensation reaction between two amino

acids. [5 marks]

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31. Describe the structure of haemoglobin [5 marks]

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SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

1.5 DNA
32. FIGURE 24 shows a structure of a nucleic acid.

FIGURE 24

(a) Name bond that forms the backbone for this nucleic acid. [1 mark]

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(b) What is the type of nucleic acid shown in FIGURE 24? [1 mark]

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(c) Draw and label a monomer for nucleic acid shown in FIGURE 24.

[2 marks]

(UPS 2013/14)

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

33. FIGURE 25 shows the structure of nitrogenous bases found in nucleic acid.

FIGURE 25

(a) Name group I and II. [1 mark]

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(b) Based on what structure are they grouped? [1 mark]

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(c) Identify X and Y. [1 mark]

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(d) Specify the bond that link X and Y. [1 mark]

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(e) In a particular DNA molecule that consists of 2,000 bases, 30 % are adenine.

What is the number of X found in this DNA molecule? [1 mark]

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SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

34. FIGURE 26 shows the structure of a polynucleotide molecule

FIGURE 26

(a) What are represented by P and S? [2 marks]

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(b) (i) Name the polynucleotide molecule in FIGURE 26. [1 mark]

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(ii) State TWO types of polynucleotide molecules in 33(b)(i) and their

functions. [4 marks]

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(c) Name the bond E. [1 mark]

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(d) Name the bond that binds S to the nitrogenous base. [1 mark]

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(e) Name the type of nitrogenous base represented by F. [1 mark]

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(PSPM 2010/11)

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

35. FIGURE 27 shows a part of a nucleic acid.

b)
FIGURE 27

(a) What is the type of nucleic acid shown in FIGURE 27? [1 mark]

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(b) Name the bond labeled A. [1 mark]

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(c) How many hydrogen bonds are formed between Adenine and Thymine?
[1 mark]

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(d) Name and draw the pentose sugar for the nucleic acid shown in FIGURE 27.
[2 marks]

(UPS 2015/16)

SDS BIOLOGY 1 (SB015)
TOPIC 1 : MOLECULES OF LIFE

36. FIGURE 28 shows the structure of a macromolecule that is made of two strands of
polymer.

FIGURE 28

(a) Identify the type of polymer and describe its arrangement. [2 marks]

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(b) Explain why the molecule has the same amount of purines and pyrimidines.
[4 marks]

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37. With the aid of a labelled diagram, describe the structure of double helix DNA [6 marks]

38. Compare the structure of DNA with RNA. [6 marks]

39. Differentiate between DNA and RNA [6 marks]

40. Describe the main components of nucleotide. [6 marks]