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Class 10 Chemistry Chapter 25 Biochemistry Class Test 3 PDF | Punjab Board 2027 Model Papers
Chemistry 10th Class Chapter 25 Biochemistry Test 3
Prepare for your exams with the Class 10 Chemistry Chapter 25: Biochemistry Class Test 3, part of the Punjab Board 2027 Model Papers. Based on the new syllabus issued by PECTAA Punjab, this chapter-wise test series is designed to help students revise important concepts, practice exercise questions, and prepare effectively for their Class 10 Chemistry examinations. Students can also use the Full Unit Test, including exercise questions, for comprehensive revision and exam preparation.
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Chapter: 25
Total Time: 35 min
(Test # 3)
Chemistry
Total Marks: 25
ABCD
1ABCD
2ABCD
3ABCD
ABCD
4ABCD
5ABCD
6ABCD
ABCD
7ABCD
8ABCD
NOTE:Four possible answers A, B, C and D to each question are given. The choice which you think is correct, fill that circle in front of that question with Marker or Pen ink. Cutting or filling two or more circles will result in zero mark in that question.
Q.1:(08)
1.
Functional groups present in fructose are:
(A) Hydroxyl and aldehyde
(B) Hydroxyl and Ketone
(C) Hydroxyl and ester
(D) Hydroxyl and amide
Answer: (B). Fructose is a ketohexose: it has several –OH groups and one ketone (C=O) group.
2.
Healthy eating recommends reducing intake of:
(A) Fruits and vegetables
(B) Whole grains and lean proteins
(C) Saturated fats, sugar and sodium
(D) Water and fibre
Answer: (C). Too much saturated fat, sugar and sodium is linked with heart disease, obesity and high blood pressure.
3.
Sucrose is present in:
(A) Milk and meat
(B) Sugar cane and sugar beets
(C) Grains only
(D) Fruits only
Answer: (B). Table sugar (sucrose) is extracted from sugar cane and sugar beet.
4.
Which functional group is present in a fat?
(A) Carboxyl group
(B) Ester group
(C) Carbonyl group
(D) Hydroxyl group
Answer: (B). A fat is a triester of glycerol and fatty acids (–COO– ester linkage).
5.
Fibrous proteins are found in:
(A) Blood only
(B) Muscles, hair, nails, skin and connective tissues
(C) Brain only
(D) Liver only
Answer: (B). Fibrous proteins (keratin, collagen, myosin) are structural proteins.
6.
All proteins are formed by linking together molecules called:
(A) Fatty acids
(B) Glucose units
(C) Amino acids
(D) Nucleotides
Answer: (C) Amino acids.
7.
Which function is not performed by proteins in our body?
(A) They serve as chemical messengers.
(B) They serve as storage of energy-rich fuel.
(C) They store genetic information.
(D) They serve as catalysts for biochemical reactions.
Answer: (C). Genetic information is stored in nucleic acids (DNA), not in proteins.
8.
A long chain composed of many amino acid molecules is called:
(A) Monopeptide
(B) Dipeptide
(C) Polypeptide
(D) Oligopeptide
Answer: (C) Polypeptide.
(PART – I)
Q.2 Write short answers to following questions.(6×2=12)
i.
What is the difference between glucose and fructose?
Ans: Both have the formula C6H12O6 but different structures. Glucose is an aldohexose (contains an aldehyde group, –CHO) and forms a six-membered (pyranose) ring. Fructose is a ketohexose (contains a ketone group, C=O) and forms a five-membered (furanose) ring. Fructose is sweeter than glucose.
ii.
What are carbohydrates?
Ans: Carbohydrates are polyhydroxy aldehydes or ketones, or compounds that give these on hydrolysis. Their general formula is Cx(H2O)y. Examples: glucose, sucrose, starch and cellulose. They are the main source of energy.
iii.
Give two examples of denaturation of proteins.
Ans: (1) Boiling an egg: heat coagulates the albumin (white turns solid). (2) Curdling of milk by acid (lactic acid or lemon juice): the casein protein coagulates.
iv.
What are the sources of starch and cellulose?
Starch: wheat, rice, maize, potato and other cereals and tubers.
Cellulose: cotton, wood, plant cell walls, vegetables and fibrous parts of plants.
Cellulose: cotton, wood, plant cell walls, vegetables and fibrous parts of plants.
v..
What are the sources of vitamin D?
Ans: Sunlight (the skin makes vitamin D), fish liver oil, oily fish, egg yolk, milk, butter and liver.
vi.
How many amino acids are present in human body?
Ans: About 20 standard amino acids are present in the human body (9 of them are essential and must come from food).
(PART – II)
Note: Attempt the following question.
Q.3: Give a detail comparison between DNA and RNA.(5)
| Point | DNA | RNA |
|---|---|---|
| Full name | Deoxyribonucleic acid | Ribonucleic acid |
| Strands | Double stranded (double helix) | Single stranded |
| Sugar | Deoxyribose | Ribose |
| Nitrogen bases | A, T, G, C | A, U, G, C |
| Location | Mainly in the nucleus | Nucleus and cytoplasm |
| Types | One main type | mRNA, tRNA, rRNA |
| Function | Stores and transmits genetic information; replicates | Carries the code and helps in protein synthesis |
| Stability | More stable | Less stable |
