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Chemical Basis of Life Grade 10 Science lesson 01 Quiz 02

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Free G.C.E. O/L Science MCQ quiz on Chemical Basis of Life with 20 questions in English medium. Answer each question, see the correct answer and explanation straight away, and get your score at the end. Use the study section below to review every question and answer.

සාමාන්‍ය පෙළ Science බහුවරණ ප්‍රශ්න නොමිලේ පුහුණු වන්න.

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Chemical Basis of Life Free Online Quiz: Practice MCQs & Exam Revision

Test your understanding of the foundational principles of biology and biochemistry with this free interactive quiz on the Chemical Basis of Life. Whether you are preparing for term tests, competitive school exams, or international board evaluations, this practice test is designed to reinforce core concepts and identify knowledge gaps.

Mastering the molecular building blocks of organisms is essential for excelling in general science and advanced biology. This quiz features exam-standard multiple-choice questions (MCQs) structured to evaluate both theoretical recall and practical application.

Key Topics Covered:
Major Biomolecules: Structure, classification, and biological roles of carbohydrates, proteins, lipids, and nucleic acids (DNA & RNA).

Biochemical Food Tests: Diagnostic identification tests, including Benedict’s test for reducing sugars, Iodine test for starch, Biuret test for proteins, and Sudan III/emulsion tests for lipids.

Water & Essential Minerals: Polarity, universal solvent properties, thermal buffering, and the physiological importance of macro and micro minerals.

Enzymes & Biological Regulators: Enzyme-substrate specificity, factors affecting reaction rates (pH, temperature), and essential vitamins.

Why Take This Practice Quiz?
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Exam-Aligned Questions: Crafted around commonly tested syllabus points to mirror realistic exam difficulty.

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Who Is This Quiz For?
High school science and biology students preparing for unit assessments and final exams.

Teachers and tutors seeking a ready-made digital assessment tool for classroom review.

Independent learners looking to build a rock-solid foundation in life sciences.

All questions & answers (20)

Study mode: read every question, then open the answer. Tap to show.

  1. Q1. What is the plant wax that helps conserve water by preventing desiccation?

    • A)Keratin
    • B)Cutin
    • C)Glycogen
    • D)Osein
    Show answer & explanation

    Answer: B) Cutin

    Cutin is a waxy polymer found on the surface of plant bodies to minimize water loss.

  2. Q2. Which reagent is used to identify the presence of lipids in food?

    • A)Benedict's solution
    • B)Iodine solution
    • C)Sudan III reagent
    • D)Copper sulfate solution
    Show answer & explanation

    Answer: C) Sudan III reagent

    Sudan III reagent reacts with lipids to produce characteristic red fat globules.

  3. Q3. Which of the following biological molecules contains phosphorus in addition to C, H, O, and N?

    • A)Carbohydrates
    • B)Proteins
    • C)Lipids
    • D)Nucleic acids
    Show answer & explanation

    Answer: D) Nucleic acids

    Nucleic acids (DNA and RNA) are composed of nucleotides, which uniquely include a phosphate group containing phosphorus.

  4. Q4. What are the three components of a standard nucleotide?

    • A)Nitrogenous base, pentose sugar group, and phosphate group
    • B)Fatty acid, glycerol, and nitrogen group
    • C)Amino acid, carboxyl group, and R group
    • D)Glucose, fructose, and water molecule
    Show answer & explanation

    Answer: A) Nitrogenous base, pentose sugar group, and phosphate group

    Every nucleotide is built from a nitrogenous base, a pentose sugar, and a phosphate group.

  5. Q5. What is the primary function of RNA in living organisms?

    • A)Transferring genetic traits to offspring
    • B)Protein synthesis
    • C)Thermal insulation
    • D)Storing cellular calcium
    Show answer & explanation

    Answer: B) Protein synthesis

    While DNA handles hereditary storage, the main function of RNA is protein synthesis.

  6. Q6. Approximately what fraction of the body weight of most organisms is made up of water?

    • A)1/3rd
    • B)1/2
    • C)2/3rd
    • D)3/4th
    Show answer & explanation

    Answer: C) 2/3rd

    Water is the most abundant inorganic compound, making up about two-thirds (2/3rd) of the body weight of most organisms.

  7. Q7. Why does water act as an effective thermal regulator in living bodies?

    • A)Due to its low boiling point
    • B)Due to its high specific heat capacity
    • C)Due to its high freezing point
    • D)Due to its low density as a liquid
    Show answer & explanation

    Answer: B) Due to its high specific heat capacity

    Water has a high specific heat capacity, preventing body temperature from fluctuating rapidly with environmental changes.

  8. Q8. What unique property of water allows aquatic organisms to survive under frozen surface ice?

    • A)Ice is denser than liquid water
    • B)Density of water is higher than the density of ice
    • C)Ice dissolves all aquatic gases
    • D)Water has low cohesive forces
    Show answer & explanation

    Answer: B) Density of water is higher than the density of ice

    Because ice is less dense than liquid water, it floats to the top, leaving liquid water underneath for aquatic life.

  9. Q9. What percentage of the human body weight is composed of mineral salts?

    • A)3%
    • B)7%
    • C)17%
    • D)65%
    Show answer & explanation

    Answer: B) 7%

    Minerals account for about 7% of the total human body weight.

  10. Q10. Which mineral element makes up three-quarters of the total mineral content in the human body along with phosphorus?

    • A)Iron
    • B)Potassium
    • C)Calcium
    • D)Sodium
    Show answer & explanation

    Answer: C) Calcium

    Calcium and phosphorus together constitute about three-quarters of all mineral mass in the body.

  11. Q11. Deficiency of which mineral in humans leads to rickets and weakening of bones?

    • A)Iron
    • B)Iodine
    • C)Calcium
    • D)Potassium
    Show answer & explanation

    Answer: C) Calcium

    Calcium is essential for bone and tooth growth; its deficiency results in rickets and structural weakening.

  12. Q12. A deficiency of which mineral causes anaemia and sleepiness in humans?

    • A)Calcium
    • B)Iron
    • C)Iodine
    • D)Magnesium
    Show answer & explanation

    Answer: B) Iron

    Iron is a vital constituent of hemoglobin; deficiency leads to anemia and fatigue.

  13. Q13. Goitre or impaired development of intelligence in humans is typically caused by a deficiency of:

    • A)Sodium
    • B)Potassium
    • C)Iron
    • D)Iodine
    Show answer & explanation

    Answer: D) Iodine

    Iodine is required for the synthesis of the thyroxine hormone, and its deficiency limits growth and mental development.

  14. Q14. In plants, chlorosis in tender leaves is a classic deficiency symptom of which element?

    • A)Iron
    • B)Calcium
    • C)Potassium
    • D)Phosphorus
    Show answer & explanation

    Answer: A) Iron

    Iron is required for chlorophyll synthesis, and its deficiency causes yellowing (chlorosis) in young, tender leaves.

  15. Q15. Red and purple patches on plant leaves are typically indicative of a deficiency in:

    • A)Nitrogen
    • B)Phosphorus
    • C)Potassium
    • D)Iron
    Show answer & explanation

    Answer: B) Phosphorus

    Phosphorus deficiency in plants manifests as stunted root growth and characteristic red or purple patches on leaves.

  16. Q16. Which vitamin is primarily responsible for the formation of visual pigments and keeping skin healthy?

    • A)Vitamin A
    • B)Vitamin B
    • C)Vitamin C
    • D)Vitamin K
    Show answer & explanation

    Answer: A) Vitamin A

    Vitamin A is crucial for vision (preventing night blindness) and maintaining healthy skin tissues.

  17. Q17. Beri-beri and nervous system disorders are caused by a deficiency of:

    • A)Vitamin A
    • B)Vitamin B
    • C)Vitamin C
    • D)Vitamin D
    Show answer & explanation

    Answer: B) Vitamin B

    Vitamin B complex maintains nerve function and skin health, and its absence leads to beriberi.

  18. Q18. Scurvy, characterized by bleeding gums and delayed wound healing, is caused by a deficiency of:

    • A)Vitamin A
    • B)Vitamin C
    • C)Vitamin D
    • D)Vitamin E
    Show answer & explanation

    Answer: B) Vitamin C

    Vitamin C (ascorbic acid) is necessary for collagen synthesis; its deficiency leads to scurvy.

  19. Q19. Which vitamin controls the absorption of calcium and phosphorus, preventing conditions like osteoporosis and rickets?

    • A)Vitamin A
    • B)Vitamin C
    • C)Vitamin D
    • D)Vitamin K
    Show answer & explanation

    Answer: C) Vitamin D

    Vitamin D regulates calcium and phosphorus metabolism for strong bone growth.

  20. Q20. A delay in blood clotting is the primary deficiency symptom of:

    • A)Vitamin A
    • B)Vitamin C
    • C)Vitamin E
    • D)Vitamin K
    Show answer & explanation

    Answer: D) Vitamin K

    Vitamin K is essential for producing the biological components required for normal blood clotting.

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