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NCERT Exemplar · Class 11 · Biology

Chapter 9: Biomolecules

Practice each question, then open the answer or worked solution.

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SHORT ANSWER TYPE QUESTIONS

5 questions
Q1Written answer

Enzymes are proteins. Proteins are long chains of amino acids linked to

each other by peptide bonds. Aminoacids have many functional groups

in their structure. These functional groups are, many of them at least,

ionisable. As they are weak acids and bases in chemical nature, this

ionization is influenced by the pH of the solution. For many enzymes, activity

is influenced by the surrounding pH. This is depicted in the curve below,

explain briefly.

NCERT Exemplar Solutions of Class 11 Biology Chapter 9 Biomolecules-1

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Worked solution

The dependence of enzyme on pH is due to the presence of charged amino acid at its active site, variation causes changes in charge of amino acid. The enzymatic activity decreases when pH is less than the optimum pH.

Q2Written answer

Is rubber a primary metabolite or a secondary metabolite? Write four sentences about rubber.

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Worked solution

Rubber is secondary metabolite because the of its unknown function in plants physiology

It is obtained from plant as exude which is sticky

Rubber is used for synthesizing tyre, eraser etc.

Q3Written answer

Schematically represent primary, secondary and tertiary structures of a hypothetical polymer say for example a protein

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NCERT Exemplar Solutions of Class 11 Biology Chapter 9 Biomolecules-2

Q4Written answer

Nucleic acids exhibit secondary structure, justify with example.

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Worked solution

DNA and RNA are known to exist in the form of a helix. DNA forms double helix and RNA forms a single-stranded helical form. As helix is considered to be a secondary structure, therefore, nucleic acids exist in secondary structure.

Q5Written answer

Comment on the statement “living state is a non-equilibrium steady-state to be able to perform work”.

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Worked solution

In a biological system, metabolic reactions always remain on and influx and efflux of metabolites take place constantly, hence it can be said that living state is a non-equilibrium steady state which can perform work.