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Biology for IGCSE & O level - Biological Molecules (Section 4)

1
What is the complementary base pairing rule in DNA?
Answer
(C)
A-T, C-G
2
Which of the following is/are the chemical element(s) present in carbohydrates and lipids?
Answer
A
B
D
3
The sequence of bases in a sample of DNA is ATGCG. What would be the complementary strand of this DNA segment?
Answer
(B)
TACGC
4
Which of the following is a common characteristic of both starch and glycogen?
Answer
(B)
They are formed of glucose
5
What is the main function of cellulose in plant cells?
Answer
(B)
Structural support
6
Which of the following chemical tests is used to identify lipids?
Answer
(D)
Emulsion test
7
Which test is used to check for the presence of Vitamin C?
Answer
(D)
DCPIP test
8
What type of sugar is glucose?
Answer
(A)
Monosaccharide
9
What does the sequence of amino acids determine in a protein?
Answer
(B)
The primary structure of the protein.
10
What is the correct base pairing rule for DNA?
Answer
(C)
A-T, C-G
11
Which element is found in all organic molecules?
Answer
(C)
Carbon
12
Which of the following is a building block for proteins?
Answer
(A)
Amino acids
13
Which elements are present in proteins?
Answer
(A)
Carbon, Hydrogen, Oxygen, Nitrogen
14
Which of the following indicates a positive test for starch?
Answer
(A)
Blue-black color with iodine
15
Which of the following is a characteristic of starch?
Answer
(C)
It is a complex carbohydrate used for energy storage in plants.
16
Which color change indicates a positive test for starch using iodine?
Answer
(A)
Blue to black
17
What would be the result of a positive Benedict's test?
Answer
(B)
Yellow/orange/red precipitate
18
In the context of biological molecules, what is a monomer?
Answer
(B)
A small, repeating unit
19
What will be the color of a solution if a reducing sugar gives a positive result with Benedict's solution?
Answer
(D)
Red
20
What is a peptide bond?
Answer
(C)
A bond between two amino acids
21
Which of the following is NOT a component of a fat molecule?
Answer
(C)
Amino acids
22
What is the name given to the bond formed between amino acids in a protein chain?
Answer
(C)
Peptide bond
23
What type of bond joins amino acids together to form a polypeptide?
Answer
(B)
Peptide bond
24
Which of the following molecules is a polysaccharide?
Answer
(C)
Starch
25
If a food sample gives a positive result with Benedict's solution, which molecule is likely present?
Answer
(C)
Reducing sugar
26
What does the sequence of the bases in DNA determine?
Answer
(C)
The primary structure of a protein
27
What is the name of the reaction that breaks down large molecules by the addition of water?
Answer
(A)
Hydrolysis
28
What would the results of a positive Biuret test for a protein look like?
Answer
(C)
The solution will turn violet or purple.
29
Which of the following is an example of a monosaccharide?
Answer
(C)
Glucose
30
Which of the following would you expect to find in a molecule of a fat?
Answer
(A)
A glycerol molecule and three fatty acids
31
What is the function of enzymes?
Answer
(C)
Speed up chemical reactions
32
How does a polypeptide become a protein?
Answer
(C)
By folding into a specific 3D shape
33
Which of the following is a characteristic of unsaturated fats?
Answer
(D)
They contain double bonds.
34
Which of the following best describes a saturated fatty acid?
Answer
(C)
Has no double bonds between carbon atoms
35
Which of the following is an example of a complex carbohydrate?
Answer
(C)
Starch
36
What are the components of a nucleotide?
Answer
(B)
A sugar, a phosphate group, and a nitrogenous base
37
If a student tests for fat with ethanol, what result would suggest that the sample is fat-positive?
Answer
(C)
A white emulsion
38
What type of reaction occurs during the breakdown of a protein (hydrolysis)?
Answer
(A)
Water is added to the protein molecule.
39
What is the type of chemical bond found in water molecules?
Answer
(B)
Covalent bond
40
Which test gives a positive result with lipids?
Answer
(D)
Emulsion
41
What elements are found in all proteins?
Answer
(B)
Carbon, Hydrogen, Oxygen, Nitrogen
42
Which of the following is the correct chemical formula for a simple sugar (glucose)?
Answer
(A)
C6H12O6
43
What is the sugar component of RNA?
Answer
(C)
Ribose
44
What is the function of the base pairing rule in DNA?
Answer
(B)
To allow the DNA molecule to form a double helix
45
What is the role of enzymes in chemical reactions?
Answer
(B)
To speed up the reactions
46
What is the name for the reaction in which monomers combine to form polymers, releasing water?
Answer
(B)
Dehydration synthesis
47
Which of the following bases always pairs with Adenine in a DNA molecule?
Answer
(C)
Thymine
48
Which test would you use to test for reducing sugars?
Answer
(C)
Benedict's test
49
Which of the following is NOT a type of biological molecule?
Answer
(D)
Mineral
50
Which of the following is a lipid?
Answer
(D)
Triglyceride