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Biology for IGCSE & O level - Biological Molecules (Section 1)

1
Which of the following can be described as a building block of a long-chain molecule?
Answer
(C)
Monomer
2
What part of the DNA molecule is responsible for the information in the genetic code?
Answer
(C)
The order of the bases
3
Which of the following is NOT a component of a fat molecule (triglyceride)?
Answer
(C)
Amino acids
4
What is the function of a double helix structure in a DNA molecule?
Answer
(A)
Facilitates the replication of DNA.
5
What is the function of DNA polymerase?
Answer
(B)
To replicate DNA molecules.
6
If a sample yields a positive result for starch, what color change will be observed?
Answer
(B)
Blue-black
7
What is the primary function of carbohydrates in the body?
Answer
(B)
Energy storage and supply
8
Which type of bonds are found between the base pairs in a DNA molecule?
Answer
(C)
Hydrogen bonds
9
Which elements are found in carbohydrates and lipids but not in proteins?
Answer
(C)
Oxygen
10
What is the final color change indicating a positive result in the Benedict's test?
Answer
(D)
Red/Orange
11
What is the role of a fatty acid in the formation of a fat molecule?
Answer
(B)
It attaches to the glycerol molecules.
12
What color change indicates the presence of protein in the Biuret test?
Answer
(C)
Violet/Purple
13
Which of the following is the correct order of steps in the test for starch using iodine?
Answer
(A)
Add iodine solution, observe color change
14
What is the most basic structural unit of a DNA molecule?
Answer
(B)
A nucleotide
15
Which of the following is formed by combining fatty acids and glycerol?
Answer
(C)
A lipid
16
What is a main difference between RNA and DNA?
Answer
(D)
All of the above
17
Which type of bond is NOT found in proteins?
Answer
(D)
Glycosidic bond
18
What is the correct pairing for the bases in a DNA molecule?
Answer
(C)
A with T and C with G
19
What is the function of glycerol in a fat molecule?
Answer
(B)
It forms the backbone of the molecule.
20
Which of the following statements is true about saturated fats?
Answer
(C)
They are typically solid at room temperature.
21
Which chemical test is used to identify the presence of vitamin C?
Answer
(D)
DCPIP test
22
What is the function of the Biuret reagent in the Biuret test?
Answer
(B)
To react with peptide bonds
23
In the emulsion test, which solvent is used to dissolve lipids?
Answer
(B)
Ethanol
24
What is the significance of base pairing in DNA?
Answer
(D)
It allows for accurate replication and transmission of genetic information.
25
Which of the following is NOT an element present in biological molecules?
Answer
(D)
Helium
26
Which elements are found in all proteins?
Answer
(B)
Carbon, hydrogen, oxygen, and nitrogen
27
What is the building block for carbohydrates?
Answer
(C)
Monosaccharides
28
Which of the following is a disaccharide?
Answer
(C)
Sucrose
29
Which of the following is NOT a type of biological molecule?
Answer
(D)
Minerals
30
In DNA, the sugar molecules are joined together by:
Answer
(B)
Phosphate groups
31
What is the expected result when the iodine test is performed on a sample that contains starch?
Answer
(A)
The solution turns blue-black.
32
What is the result of the Biuret test when proteins are present?
Answer
(C)
A violet/purple solution
33
What is the primary function of enzymes in the context of biological molecules?
Answer
(C)
Catalyze biochemical reactions.
34
Which of the following is an example of a complex carbohydrate?
Answer
(D)
Starch
35
In the Iodine test, what is the color change that indicates a positive result?
Answer
(A)
Blue-black
36
Which of the following best describes a saturated fat?
Answer
(C)
Solid at room temperature
37
What is the name of the bond that holds the atoms in a water molecule together?
Answer
(B)
Covalent bond
38
Which of the following is a structural component of the cell walls of plants?
Answer
(C)
Cellulose
39
What is the role of the bases in a DNA molecule?
Answer
B
D
40
What is the basic structure of a carbohydrate?
Answer
(A)
Carbon, hydrogen, and oxygen
41
Which of the following is NOT a characteristic of fats?
Answer
(C)
They are soluble in water.
42
Which of the following is a primary function of fats in the body?
Answer
(C)
To provide long-term energy storage
43
What is a double sugar molecule?
Answer
(C)
Sucrose
44
Which of the following describes the function of cellulose in plants?
Answer
(B)
Structural support
45
What is the correct pairing of bases in a DNA molecule?
Answer
(B)
A-T and C-G
46
Which of the following is a characteristic of a double helix structure in DNA?
Answer
(C)
Two strands that run in opposite directions.
47
Which of the following is NOT a component of a nucleotide?
Answer
(C)
A fatty acid
48
What is the role of the four bases (A, T, C, G) in DNA?
Answer
(B)
To determine the sequence of amino acids in proteins
49
Which of the following is the correct base pairing rule in DNA?
Answer
(C)
A-T, C-G
50
What is the role of iodine solution in testing for starch?
Answer
(B)
It reacts to form a blue-black complex with starch.