NCERT Exemplar Class 11 Biology Solutions Chapter 9 Biomolecules

Get the NCERT Exemplar Class 11 Biology Solutions Chapter 7-MCQ

Question:1

It is said that the elemental composition of living organisms and that of inanimate objects (like earth's crust) are similar in the sense that all the major elements are present in both. Then what would be the difference between these two groups?

Choose the correct answer from among the following: -

a. Living organisms have more gold in them than inanimate objects
b. Living organisms have more water in their body than inanimate objects
c. Living organisms have more carbon, oxygen, and hydrogen per unit mass than inanimate objects.
d. Living organisms have more calcium in them than inanimate objects.

Answer:

The correct answer is option (c): Living organisms have more carbon, oxygen, and hydrogen per unit mass than inanimate objects.
Explanation: Living organisms have more carbon, oxygen, and hydrogen per unit mass than inanimate objects because the biochemical composition of living organisms is rich in carbon, oxygen, and hydrogen.

Question:2

Many elements are found in living organisms, either free or the form of compounds. Which of the following is not found in living organisms?
a. Silicon
b. Magnesium
c. Iron
d. Sodium

Answer:

The correct answer is option (a), Silicon
Explanation: Magnesium, iron, and sodium play important roles in biological processes, while silicon is not a major component of living beings.

Question:3

Aminoacids have both an amino group and a carboxyl group in their structure. Which one of the following is an amino acid?
a. Formic acid
b. Glycerol
c. Glycolic Acid
d. Glycine

Answer:

The correct answer is option (d), Glycine
Explanation: Glycine is the simplest amino acid with both amino and carboxyl groups.

Question:4

An amino acid under certain conditions has both positive and negative charges simultaneously in the same molecule. Such a form of amino acid is called

a. Acidic form
b. Basic form
c. Aromatic form
d. Zwitterionic form

Answer:
The correct answer is option (d), Zwitterionic form
Explanation: A zwitterion is a form of an amino acid that has both a positive charge on the amino acid and a negative charge on the carboxyl group at the same time.

Question:5

Which of the following sugars have the same number of carbon as present in glucose?
a. Fructose
b. Erythrose
c. Ribulose
d. Ribose

Answer:

The correct answer is option (a), Fructose
Explanation: Glucose and fructose are both monosaccharides, and both have 6 carbon atoms.

Question:6

An acid-soluble compound formed by phosphorylation of nucleoside is called:
a. Nitrogen base
b. Adenine
c. Sugar phosphate
d. Nucleotide

Answer:

The correct answer is option (d), Nucleotide
Explanation: When one or more phosphate groups are added to a nucleoside, it forms a nucleotide.

Question:7

When we homogenise any tissue in an acid, the acid-soluble pool represents
a. Cytoplasm
b. Cell membrane
c. Nucleus
d. Mitochondria

Answer:

The correct answer is option (a), Cytoplasm
Explanation: When we homogenise any tissue in acid, the acid-soluble pool it represents Cytoplasm. The cytoplasm contains small biomolecules that dissolve in the acid and form an acid-soluble pool.

Question:8

The most abundant component of living organisms is
a. Protein
b. Water
c. Sugar
d. Nucleic acid

Answer:

The correct answer is option (b), Water
Explanation:
Going by constituent present in the human body, water constitutes 70% of the entire body weight.

Question:9

A homopolymer has only one type of building block called monomer repeated ‘n’ number of times. A heteropolymer has more than one type of monomer. Proteins are heteropolymers usually made of
a. 20 types of monomers
b. 40 types of monomers
c. 30 types of monomers
d. only one type of monomer

Answer:

The correct answer is option (a), 20 types of monomers
Explanation:
Proteins are heteropolymers usually made of 20 types of monomers.

Question:10

Proteins perform many physiological functions. For example, some functions as enzymes. Which of the following represents an additional function that some proteins discharge?
a. Antibiotics
b. Pigment conferring colour to skin
c. Pigments making colours of flowers
d. Hormones

Answer:

The correct answer is option (d), Hormones
Explanation: Some proteins function as hormones, which regulate various processes in the body, such as insulin, glucagon, etc.

Question:11

Glycogen is a homopolymer made of
a. Glucose units
b. Galactose units
c. Ribose units
d. Aminoacids

Answer:

The correct answer is option (a), Glucose units
Explanation: Glycogen is a homopolymer made of Glucose units. It serves as the primary storage form of glucose.

Question:12

The number of ‘ends’ in a glycogen molecule would be
a. Equal to the number of branches plus one
b. Equal to the number of branch points
c. One
d. Two, one on the left side and another on the right side

Answer:

The correct answer is option (a), Equal to the number of branches plus one
Explanation: The number of ends in a glycogen molecule would be equal to the number of branches plus one, as one end is a reducing end, and all other ends are non-reducing ends.

Question:13

The primary structure of a protein molecule has
a. Two ends
b. One end
c. Three ends
d. No ends

Answer:

The correct answer is option (a), Two ends

Question:14

Which of the following reactions is not enzyme-mediated in the biological system?
a. Dissolving CO₂ in water
b. Untwining the two strands of DNA
c. Hydrolysis of sucrose
d. Formation of peptide bond

Answer:

The correct answer is option (a), Dissolving CO2 in water

Discover the Very Short Answer Type Questions of NCERT Exemplar Class 11 Biology Solutions Chapter 9

Question:1

Medicines are either man-made (i.e., synthetic) or obtained from living organisms like plants, bacteria, animals etc. and hence the latter are called natural products. Sometimes natural products are chemically altered by man to reduce toxicity or side effects. Write against each of the following whether they were initially obtained as a natural product or as a synthetic chemical.

a. Penicillin ___________________________
b. Sulfonamide ___________________________
c. Vitamin C ___________________________
d. Growth Hormone ___________________________

Answer:
A. Penicillin - Natural product
B. Sulfonamide- Synthetic product
C. Vitamin C - Natural product
D. Growth Hormone - Natural product

Question:2

Select an appropriate chemical bond among ester bond, glycosidic bond,peptide bond and hydrogen bond and write against each of the following.
a. Polysaccharide ___________________________
b. Protein ___________________________
c. Fat ___________________________
d. Water ___________________________

Answer:
a. Polysaccharides – Glycosidic bond
b. Protein - Peptide bond
c. Fats - Ester bond
d. Water - H-bond

Question:3

Write the name of any one amino acid, sugar, nucleotide, and fatty acid.

Answer:

1. Nucleotide- Adenosine
2. Amino acid- Glycine
3. Fatty acid- Oleic acid
4. Sugar- Glucose

Question:4

The reaction given below is catalysed by oxidoreductase between two substrates A and A’, complete the reaction.
A reduced + A’ oxidised

Answer:

A reduced + A’ Oxidised → A oxidised + A’reduced

Question:5

How are prosthetic groups different from co-factors?

Answer:

A prosthetic group is a non-protein component that is permanently attached to an enzyme and essential for its activity in haemoglobin.

A cofactor, on the other hand, is a non-protein substance that may be loosely bound to an enzyme and helps in its function. Cofactors can be organic or inorganic ions.

Question:6

Glycine and Alanine are different with respect to one substituent on the α - carbon. What are the other common substituent groups?

Answer:

COOH, NH 2 , and H are the common substituents in Glycine and Alanine.

Question:7

Starch, Cellulose, Glycogen, Chitin are polysaccharides found among the following. Choose the one appropriate and write against each.

a) Cotton fibre __________________________
b) Exoskeleton of cockroach __________________________
c) Liver __________________________
d) Peeled potato __________________________

Answer:

a) Cotton fibre - Cellulose
b) Exoskeleton of cockroach - Chitin
c) Liver - Glycogen
d) Peeled Potato - Starch

Explore the Short Answers of NCERT Exemplar Class 11 Biology Solutions Chapter 9

Question:1

Enzymes are proteins. Proteins are long chains of amino acids linked to each other by peptide bonds. Amino acids 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 ionisation 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.

Answer:

Explanation of this question can be summed up as below:
1. This variation triggers changes in charge of amino acid.
2. Dependence of enzyme on pH is because of the existence of charged amino acid at its active site.
3. The enzymatic activity reduces when pH is fewer than the optimal pH.

Question:2

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

Answer:

Rubber is considered a secondary metabolite because it is not directly involved in the growth or development of the plant.

Four features of rubber are:

• Rubber consists of long chains of isoprene units forming a polymer.

• Rubber is stored in vessels and acts as a defense mechanism against pathogens.

• It is not important for plant growth, but it is mostly used in industries due to its elasticity.

• It is used for the production of various products like tyres, gloves, toys etc.

Question:3

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

Answer:

Question:4

Nucleic acids exhibit secondary structure, justify with example.

Answer:

Nucleic acids, like DNA and RNA, show secondary structures due to the base pairing and hydrogen bonding between nucleotides.

RNA forms a single- stranded helical form while DNA forms a double helix. As a helix is regarded to be a secondary structure, therefore, nucleic acids are present in the secondary structure.

Question:5

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

Answer:

The statement “Living state is a non-equilibrium state to be able to perform work” explains that living organisms maintain the exchange of energy and matter with their surroundings, which prevents equilibrium. If a living system reaches the state of equilibrium, all biological activity stops.

Access the Long Answer Questions of NCERT Exemplar Class 11 Biology Solutions Chapter 9

Question:1

Formation of the enzyme-substrate complex (ES) is the first step in catalysed reactions. Describe the other steps until the formation of the product.

Answer:

After the formation of the enzyme-substrate complex, the following steps occur in an enzyme-catalyzed reaction:

Formation of transition state:

• The enzyme makes the substrate stable in its transition state and thus lowers its activation energy, which is required for the reaction.

Catalysis and Conversion:

• The enzyme after that initiates the chemical reaction by breaking bonds in the substrate or helping to form new bonds.

• This step transforms the substrate into the product.

Product Formation:

• The substrate is fully converted into the final product.

• The enzyme remains attached to the product only.

Product Release:

• The enzyme releases the product because products no longer fit perfectly in the active site.

• The enzyme returns to its original shape, ready to bind with another substrate.

Enzyme Recycling:

• The enzyme is free to catalyze another reaction, making the process speedy.

• This cycle repeats as long as substrates are available.
  
  

Question:2

What are the different classes of enzymes? Explain any two with the type of reaction they catalyse.

Answer:

Enzymes are the catalysts that increase the rate of biochemical reactions. They regulate the speed and accuracy of reactions without being used. Enzymes are mainly of six types, which are oxidoreductases, transferases, hydrolases, lyases, Isomerases and ligases.

a) Oxidoreductase: These enzymes oxidize the substrate by the addition of oxygen and the removal of hydrogen or electrons.
S reduced + S’reduced → S oxidised + S’ oxidised

b) Hydrolases: Hydrolases are the enzymes that catalyze the hydrolysis reaction by adding water such as esters, peptides etc.

Sucrose → Glucose + Fructose

Question:3

Nucleic acids exhibit secondary structure. Describe through Watson Crick Model.

Answer:

James Watson and Francis Crick gave the double helix model of DNA, which explains the secondary structure of nucleic acids.

Main features of the Watson and Crick Model:

Double Helix Structure:

• Nucleic acids such as DNA consist of two polynucleotide chains, which are twisted around each other.

• Both these chains run antiparallel, which means one strand runs in the 5' to 3' direction and the other one in the 3' to 5' direction.

Sugar-Phosphate Backbone:

• The backbone is composed of sugar and phosphate groups.

• The phosphate groups connect the 3' carbon of one sugar to the 5' carbon of the next sugar by bonds.

Base Pairing:

• The nitrogenous bases (purines and pyrimidines) are present inside the helix

• Adenine (A) pairs with Thymine (T) with two hydrogen bonds.

• Guanine (G) pairs with Cytosine (C) with three hydrogen bonds.

Question:4

What is the difference between a nucleotide and nucleoside? Give two examples of each with their structure.

Answer:

Question:5

Describe various forms of lipid with a few examples.

Answer:

Lipids are important constituents of our diet because of their high energy value. Based on their chemical composition, the classification of lipids is given below:

1- Simple lipids: These are esters of fatty acids with various alcohols. They can be further grouped into three categories:

• Fats- These are esters of fatty acids with glycerol and are solid at room temperature.

• Oils- They are also esters of fatty acids with glycerol but are liquid at room temperature.

• Waxes- Waxes are the esters of fatty acids other than glycerol.

2- Compound lipids: They are esters of fatty acids with alcohol but also contain other groups in addition to the alcohol. They are subdivided into:

• Phospholipids- These lipids contain fatty acids and glycerol along with a phosphoric acid, nitrogen, etc.

• Glycolipids- These are the compounds of fatty acids with carbohydrates and nitrogen bases but do not contain phosphoric acid.