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Biology questions, chapter 4
Nama / NameKelas / ClassTarikh / Date

Chemical Compositions in a Cell

44 marks. Use Practice to check each answer as you go, or Exam to answer everything against the clock first.

Section A: objective questions

12 marks
Choose the best answer for each question.
1

Question 1

Which property of water makes it a universal solvent?
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A
Water is polar, so it can dissolve polar solutes and ionic substances such as glucose and electrolytes.
For the teacher: Remembering, low difficulty, standard 4.1.1
Textbook p. 72
2

Question 2

Diagram 1 shows two water molecules. What does the dotted line represent?
Two water molecules with partial charges marked and a dotted line between the oxygen of one and a hydrogen of the other
Diagram 1
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A
The attraction between δ+ hydrogen of one molecule and δ- oxygen of another is a hydrogen bond.
For the teacher: Understanding, low difficulty, standard 4.1.1
Textbook p. 72
3

Question 3

Water moves up the narrow xylem tubes of a plant mainly because of
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B
Water molecules attract each other (cohesion) and the xylem wall (adhesion), producing capillary action.
For the teacher: Understanding, medium difficulty, standard 4.1.2
Textbook p. 72
4

Question 4

What is the ratio of carbon : hydrogen : oxygen in carbohydrates?
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A
Carbohydrates have the formula (CH2O)n, so the ratio is 1 : 2 : 1.
For the teacher: Remembering, low difficulty, standard 4.2.1
Textbook p. 73
5

Question 5

Which disaccharide is NOT a reducing sugar?
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C
Sucrose is a non-reducing sugar. Maltose and lactose reduce Benedict's solution; glucose is a monosaccharide.
For the teacher: Understanding, low difficulty, standard 4.2.2
Textbook p. 74
6

Question 6

Which pair of monosaccharides combine to form sucrose?
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D
Glucose + fructose gives sucrose + water by condensation. Glucose + glucose gives maltose; glucose + galactose gives lactose.
For the teacher: Applying, medium difficulty, standard 4.2.4
Textbook p. 74
7

Question 7

Which polysaccharide is the storage carbohydrate in animal liver and muscle cells?
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C
Glycogen stores glucose in muscle and liver cells; starch is the plant store and cellulose forms the plant cell wall.
For the teacher: Remembering, low difficulty, standard 4.2.5
Textbook p. 75
8

Question 8

What is removed when two amino acids join to form a dipeptide?
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C
A peptide bond forms by condensation, in which one water molecule is removed.
For the teacher: Understanding, low difficulty, standard 4.3.2
Textbook p. 76
9

Question 9

Two proteins have the same number and kinds of amino acids but behave differently. What explains this?
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B
The sequence of amino acids in the polypeptide chain differs, giving a different protein.
For the teacher: Analysing, high difficulty, standard 4.3.2
Textbook p. 76
10

Question 10

A lipid is made of one glycerol, two fatty acids and one phosphate group. This lipid is a
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D
Phospholipids have two fatty acids and a phosphate group; they form plasma membranes.
For the teacher: Understanding, low difficulty, standard 4.4.2
Textbook p. 78
11

Question 11

How many water molecules are produced when one triglyceride is formed?
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D
One glycerol + three fatty acids forms a triglyceride and 3 H2O.
For the teacher: Applying, medium difficulty, standard 4.4.3
Textbook p. 77
12

Question 12

Which statement about RNA is correct?
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B
RNA is a single chain with ribose and uracil; DNA has thymine and deoxyribose.
For the teacher: Understanding, low difficulty, standard 4.5.3
Textbook p. 80

Section B: structured questions

32 marks
Answer all questions. Write your answers in the spaces provided.
13

Question 13

Water has several properties that are important to a cell.
[1 mark] (a)State the meaning of cohesive force.
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[1 mark] (b)Water has a high specific heat capacity. State one importance of this to living organisms.
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[2 marks] (c)Explain how the polarity of water helps glucose to enter a cell.
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For the teacher: Understanding, low difficulty, standard 4.1.2
Textbook p. 72
14

Question 14

Maltose is formed from two glucose molecules.
[1 mark] (a)Name the process that forms maltose.
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[2 marks] (b)Write the word equation for the formation of maltose.
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[1 mark] (c)Maltose is heated with Benedict's solution. State the observation.
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[2 marks] (d)A student heats sucrose with Benedict's solution and sees no change. Suggest how to make the test positive.
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For the teacher: Applying, medium difficulty, standard 4.2.4
Textbook p. 74
15

Question 15

Proteins are important in the body.
[1 mark] (a)State the element that all proteins contain but carbohydrates and lipids do not.
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Nitrogen
Tick each point you got.
[2 marks] (b)State two functions of proteins.
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[2 marks] (c)Explain the effect of a lack of protein in the diet on hair and nails.
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For the teacher: Remembering, low difficulty, standard 4.3.4
Textbook p. 76
16

Question 16

A student compares two fats. Fat X is solid at room temperature and comes from animals. Fat Y is liquid and comes from fish.
[1 mark] (a)Which fat is saturated?
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[2 marks] (b)Explain your answer to (a) in terms of bonds between carbon atoms.
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[2 marks] (c)Explain why too much of fat X is harmful.
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[1 mark] (d)Name the products when a triglyceride is hydrolysed.
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For the teacher: Analysing, medium difficulty, standard 4.4.2
Textbook p. 78
17

Question 17

Diagram 2 shows part of a DNA molecule.
Part of a DNA double helix with base pairs, and one nucleotide enlarged as a phosphate group, a five-carbon sugar and a nitrogenous base
Diagram 2
[1 mark] (a)Name the sugar in a DNA nucleotide.
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[2 marks] (b)The base sequence on one chain is A-T-G-C. Write the sequence on the other chain.
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A-T, T-A, G-C, C-G.
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[1 mark] (c)What holds the two chains together?
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[2 marks] (d)State two differences between DNA and RNA.
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Any 2 points
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For the teacher: Applying, low difficulty, standard 4.5.3
Textbook p. 79
18

Question 18

A chromosome is made of DNA and protein.
A DNA double helix that winds around protein beads, then coils into a chromosome inside the nucleus of a cell
Diagram 3
[1 mark] (a)Name the protein around which DNA is wound.
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[2 marks] (b)Describe how a chromosome is formed from DNA.
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[2 marks] (c)The AUG codon on mRNA codes for methionine. Explain how the DNA sequence determines the protein made.
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For the teacher: Analysing, high difficulty, standard 4.5.5
Textbook p. 80