Assertion Reason Questions for Biology Chapter 9 Biomolecules

Directions: In the following questions, a statement of assertion is followed by a statement of reason.
Mark the correct choice as:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

Q.1. Assertion: The living state is a equilibrium steady state to be able to perform work.
Reason : Living process is a constant effort to prevent falling into non-equilibrium.

Answer Answer: (d) The living systems are in metabolic flux and thus, maintain the concentration of biomolecules, always remaining in nonequilibrium steady state where equilibrium is seldom achieved. No work can be carried out in equilibrium state. Living systems are therefore, regularly receiving an input of energy to prevent reaching an equilibrium and always remain in non-equilibrium steady state. Energy is obtained from metabolism. Metabolism and living state are thus, complementary and synonymous.

Q.2. Assertion: Living organisms have more nitrogen and oxygen per unit mass than inanimate objects (e.g., earth crust).
Reason: Living organisms have more Ca, Mg, Na in them than inanimate object.

Answer Answer: (c) After performing elemental analysis of a plant tissue, animal tissue, microbial paste (living matter) and of a piece of earth’s crust (animate object), it was found that all living and non-living systems are made up of same chemical i.e., elements (e.g. carbon, hydrogen, oxygen and several others). Most living organisms have relatively high abundance of carbon and hydrogen than in earth’s crust.

Q.3. Assertion: In living system, all the metabolic conversions are aided by catalyst.
Reason: The catalyst which hasten the rate of a given metabolic conversion are not proteins.

Answer Answer: (c) All the catalysts including those which hasten the metabolic conversion rate are proteins.

Q.4. Assertion: Secondary metabolites are produced in small quantities and their extraction from the plant is difficult and expensive.
Reason: Secondary metabolites can be commercially produced by using tissue culture technique.

Answer Answer: (b) Secondary metabolites are biosynthetically derived from primary metabolites but more limited in distribution in plant kingdom being restricted to a particular taxonomic group. By culture media using tissue culture technique, secondary metabolites can be produced on a large scale.

Q.5. Assertion : Comparative biochemistry provides a strong evidence in favour of common ancestory of living beings.
Reason : Genetic code is universal.

Answer Answer: (b) Comparative biochemistry provides a strong evidence for common ancestors of living beings (e.g. proteins lymph, enzymes, hormones, blood groups etc.)

Q.6. Assertion : Human diet should compulsorily contain glycine, serine and tyrosine.
Reason : Essential amino acids can not be synthesized in the human body. [AIIMS 2010]

Answer Answer: (d) Essential amino acids are those which are taken from food and not synthesized in the body whereas non-essential amino acids need not be supplied in the diet and are synthesized in the body. Glycine, serine and tyrosine are non-essential amino acids.

Q.7. Assertion : The amino acid glycine comes under the category of nonessential amino acids.
Reason : This is due to the fact that it can not be synthesised in the body. [AIIMS 2011]

Answer Answer: (c) Non-essential amino acids are those amino acids which need not be supplied in the diet because they can be synthesised by the body, particularly from carbohydrate metabolites. Glycine is one such non essential amino acid. On the contrary, essential amino acids are those amino acids which can not be synthesised in the animal body and must be supplied with food in adequate amounts. Out of twenty amino acids, eight are considered essential in human diet.

Q.8. Assertion: Amino acids are known as a-amino acids.
Reason : Amino acids are organic compounds containing an amino group and carboxylic group as substituent on the a-carbon.

Answer Answer: (a) Amino acids are organic acids (with carboxylic group – COOH) having amino group (–NH2) generally attached to α-carbon that also bears a variable hydrocarbon or alkyl group R and hydrogen. Amino acids are, therefore, substituted methanes where the four substituent groups occupy the four valency positions. These are hydrogen, carboxyl group and a variable group designated as R group.

Q.9. Assertion: Proteins are a heteropolymer.
Reason : Dietary proteins are the source of non-essential amino acids.

Answer Answer: (c) Each individual protein is a polymer of amino acids. As there are 20 types of amino acids, a protein is a heteropolymer and not a homopolymer. Amino acids can be essential or non-essential. Certain amino acids are essential for our health and they have to be supplied through our diet. Dietary proteins are thus, a source of essential amino acids. Non-essential amino acids are those amino acids which are synthesised in our body.

Q.10. Assertion: The long protein chain folds upon itself like a hollow ball giving rise to the tertiary structure.
Reason : Tertiary structure gives a 3-dimensional view of a protein.

Answer Answer: (b) The primary structure of protein depicts the sequence of amino acids in a chain or gives the positional information in a protein. Protein thread is folded in the form of a helix or in the sheet form in the secondary structure. The long protein chain is also folded upon itself like a hollow wollen ball, giving rise to the tertiary structure. This gives us a 3-dimensional view of a protein. Tertiary structure is absolutely necessary for many biological activities of proteins.

Q.11. Assertion: Amino acids are amphoteric in their function.
Reason: All amino acids are necessary for our body.

Answer Answer: (b) Proteins and amino acids are amphoteric in nature, i.e., in aqueous they possess both cationic and anionic groups. All the amino acids are necessary for the normal function of the body as they are building blocks of proteins and enzymes.

Q.12. Assertion: Nine amino acids are essential amino acids for human.
Reason: They are essential for human health.

Answer Answer: (a) Nine amino acids are referred to as the essential amino acids for human. They must be therefore, supplied through diet as our body cannot synthesize these.

Q.13. Assertion : Vegetable oils are fats which are present in plant cells in soluble form.
Reason : Vegetable oils occur only in cells of embryo.

Answer Answer: (d) Vegetable oils and fats are present in plants in insoluble form. They are extracted mostly from seeds. In several cereals, they are obtained from embryo. Olive and palm oils are obtained from flesly pericarp of the fruit. Sometimes oils are also extracted from roots, stem and leaves.

Q.14. Assertion : Unsaturated fats are more reactive compared with the saturated fats.
Reason : Unsaturated fats have only single bonds in their structure. [AIIMS 2010]

Answer Answer: (c) Compounds having double bond in their structure are more unstable compounds in comparison to single bond holders. Unsaturated fats those have double bonds in their structures are more reactive than saturated fats.

Q.15. Assertion: Palmitic acid has 20 carbon atoms including carboxyl carbon.
Reason : Arachidonic acid has 16 carbon atom including carboxyl carbon.

Answer Answer: (d) Palmitic acids and arachidonic acids are simple fatty acids. A fatty acid has a carboxyl group attached to an R group. The R group could be a methyl (–CH3), or ethyl (–C2H5) or higher number of –CH2 groups (1 carbon to 19 carbons). For example, palmitic acid has 16 carbons including carboxyl carbon. Arachidonic acid has 20 carbon atoms including the carboxyl carbon

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