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Class 12 Biomolecules worksheet
CBSE Chemistry. Carbohydrates, proteins and peptides, vitamins, DNA and RNA: base pairing, mRNA and hydrogen bonds. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.
Sample questions
Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.
Section A · multiple choice
- 1.
Glucose is an:
- aldopentose
- disaccharide
- ketohexose
- aldohexose
Answer
(d) aldohexose
- 2.
Galactose is a:
- polysaccharide
- disaccharide
- monosaccharide (aldohexose)
- monosaccharide (aldopentose)
Answer
(c) monosaccharide (aldohexose)
- 3.
A deficiency of vitamin B₁ (thiamine) causes:
- beriberi
- cheilosis (cracked lips) and a sore tongue
- pernicious anaemia
- xerophthalmia and night blindness
Answer
(a) beriberi
vitamin B₁ (thiamine) is water-soluble
Section B · short answer
- 4.
What are reducing sugars? Give two examples.
Answer
Sugars that reduce Fehling's solution and Tollens' reagent because they have a free aldehyde or ketone (hemiacetal) group. Examples: glucose, fructose, maltose, lactose.
- 5.
Write the mRNA transcribed from the DNA template strand 5′-TTAACCTCTACC-3′.
Answer
3′-AAUUGGAGAUGG-5′
A → U, T → A, G → C, C → G; the mRNA runs antiparallel to the template
Section C · long answer
- 6.
Give the evidence for the open-chain structure of glucose, and explain why the cyclic structure was later proposed.
Answer
Open chain: HI gives n-hexane (six carbons in a straight chain); acetylation gives a pentaacetate (five –OH groups); HCN and hydroxylamine react (a carbonyl group); bromine water gives gluconic acid (an aldehyde). But glucose does not give Schiff's test or form a bisulphite compound, and its pentaacetate does not react with hydroxylamine; it exists as two forms (α and β) with different rotations. So it exists mainly as a six-membered ring (pyranose) formed by the C-5 –OH adding to the aldehyde.
Fresh sheets for your child
In the app, every Biomolecules sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.
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