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Biomolecules — NEET MCQs with answers
All the carbon compounds obtained from living tissues can be called biomolecules. Grinding a tissue in trichloroacetic acid separates an acid-soluble pool, with thousands of small compounds, from an acid-insoluble fraction containing proteins, nucleic acids, polysaccharides and lipids. All the elements present in a sample of earth's crust are also present in living tissue, but the relative abundance of carbon and hydrogen is higher in living organisms.
Topics in this chapter
- 9.1 How to Analyse Chemical Composition?
- 9.2 Primary and Secondary Metabolites
- 9.3 Biomacromolecules
- 9.4 Proteins
- 9.5 Polysaccharides
- 9.6 Nucleic Acids
- 9.7 Structure of Proteins
- 9.8 Enzymes
Free practice questions
How many types of terminals (ends) are named for a protein chain in NCERT?
- A. One
- B. Two
- C. Three
- D. Four
Show answer
Answer: B — Two terminals are named: N-terminal (first amino acid) and C-terminal (last amino acid).
NCERT Class 11 Biology · Ch 9 · 9.7 Structure of Proteins
Carotenoids and anthocyanins, as given in NCERT Table 9.3, are examples of:
- A. Alkaloids
- B. Pigments
- C. Terpenoids
- D. Drugs
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Answer: B — NCERT Table 9.3 lists Carotenoids and Anthocyanins under the category 'Pigments'.
NCERT Class 11 Biology · Ch 9 · 9.2 Primary and Secondary Metabolites · Table 9.3
Which of the following correctly lists the three amino acids shown in NCERT Figure 9.1?
- A. Tryptophan, phenylalanine, tyrosine
- B. Lysine, valine, tyrosine
- C. Glutamic acid, proline, cysteine
- D. Glycine, alanine, serine
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Answer: D — NCERT: glycine (R=H), alanine (R=methyl), serine (R=hydroxy methyl) are the three shown.
NCERT Class 11 Biology · Ch 9 · 9.4 Proteins
To detect the inorganic elements in a living tissue, a destructive experiment is done in which the tissue is fully burnt. The residue remaining is called:
- A. Slurry
- B. Filtrate
- C. Ash
- D. Retentate
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Answer: C — NCERT: when the tissue is fully burnt, all carbon compounds are oxidised to gaseous form (CO2, water vapour) and removed; what remains is called 'ash', which contains inorganic elements.
NCERT Class 11 Biology · Ch 9 · 9.1 How to Analyse Chemical Composition?
Cellulose cannot hold I2 (iodine) because it:
- A. Contains nitrogen amino-sugars
- B. Is a heteropolymer
- C. Does not contain complex helices
- D. Is made of fructose units
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Answer: C — NCERT: cellulose does not contain complex helices and hence cannot hold I2.
NCERT Class 11 Biology · Ch 9 · 9.5 Polysaccharides
Carbonic anhydrase, which greatly speeds CO2 hydration, is present within the:
- A. Mitochondrial matrix only
- B. Nucleus
- C. Cell wall
- D. Cytoplasm
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Answer: D — The enzyme carbonic anhydrase is present within the cytoplasm.
NCERT Class 11 Biology · Ch 9 · 9.8 Enzymes
Which of the following biomolecules is a polymer of monomers?
- A. Cholesterol
- B. Fatty acid
- C. Protein
- D. Glycerol
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Answer: C — Proteins, nucleic acids and polysaccharides are polymers built from monomers (amino acids, nucleotides, monosaccharides). Lipids are the exception; among the options, protein is the polymer.
NCERT Class 11 Biology · Ch 9 · 9.3 Biomacromolecules
Which of the following sets contains ONLY pyrimidine bases?
- A. Cytosine, Uracil, Thymine
- B. Guanine, Cytosine, Uracil
- C. Adenine, Thymine, Uracil
- D. Adenine, Guanine, Cytosine
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Answer: A — Pyrimidines are cytosine, uracil and thymine. Adenine and guanine are purines, so any set containing them is wrong.
NCERT Class 11 Biology · Ch 9 · 9.6 Nucleic Acids
In proteins, which type of helices are observed?
- A. Only right handed helices
- B. Only left handed helices
- C. Neither; only sheets
- D. Both left and right handed equally
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Answer: A — NCERT: 'In proteins, only right handed helices are observed.' (classic trap)
NCERT Class 11 Biology · Ch 9 · 9.7 Structure of Proteins
According to Table 9.1, nitrogen is present in earth's crust in 'very little' amount but in the human body it forms:
- A. 18.5%
- B. 3.3%
- C. 9.5%
- D. 0.3%
Show answer
Answer: B — NCERT Table 9.1: nitrogen is 'very little' in earth's crust and 3.3% in the human body.
NCERT Class 11 Biology · Ch 9 · 9.1 · Table 9.1
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