What is the main structural component of plant cell walls?

Correct Option: B. Solution: Plant cell walls are primarily made of cellulose.

Which of the following is a polymer of fructose?

Correct Option: C. Solution: Inulin is a polymer of fructose.

Biomolecules

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Summary

Chapter 9: Biomolecules

Summary

Living organisms are composed of similar elements and compounds as non-living matter, but with higher relative abundance of carbon and hydrogen.
Chemical analysis of living tissues reveals organic compounds categorized as biomolecules.
Types of Biomolecules:
- Micromolecules: Small molecular weight compounds (<1000 Da) such as amino acids, sugars, fatty acids, glycerol, nucleotides.
- Macromolecules: Larger compounds (≥10000 Da) including proteins, nucleic acids, polysaccharides, and lipids.
Primary Metabolites: Essential compounds like amino acids and sugars found in animal tissues.
Secondary Metabolites: Additional compounds found in plants, fungi, and microbes, such as alkaloids and flavonoids.
Proteins are polymers of amino acids and perform various functions including enzymatic activity, transport, and structural roles.
Nucleic acids (DNA and RNA) serve as genetic material.
Polysaccharides are energy storage forms (e.g., starch, glycogen) and structural components (e.g., cellulose).
Lipids include fats and oils, which are glycerides formed by the esterification of fatty acids to glycerol.

Learning Objectives

Understand the chemical composition of living organisms.
Analyze the differences in elemental composition between living and non-living matter.
Identify primary and secondary metabolites in biological systems.
Classify biomolecules into micromolecules and macromolecules.
Describe the structure and function of proteins, nucleic acids, polysaccharides, and lipids.
Explain the role of enzymes in biochemical reactions and their classification.
Discuss the importance of co-factors in enzyme activity.
Recognize the significance of metabolic compounds in human welfare.

Detailed Notes

Chapter 9: Biomolecules

9.1 How to Analyse Chemical Composition?

Living organisms are composed of various chemicals, including elements and compounds.
Elemental analysis can be performed on plant, animal, or microbial tissues to obtain a list of elements such as carbon, hydrogen, and oxygen.
The relative abundance of carbon and hydrogen is higher in living organisms compared to non-living matter.

9.2 Primary and Secondary Metabolites

Primary Metabolites: Compounds essential for normal physiological processes (e.g., amino acids, sugars).
Secondary Metabolites: Compounds found in plants, fungi, and microbes that do not have identifiable functions but are useful to humans (e.g., alkaloids, flavonoids).

Table 9.3: Some Secondary Metabolites

Pigments: Carotenoids, Anthocyanins
Alkaloids: Morphine, Codeine
Terpenoids: Monoterpenes, Diterpenes
Essential Oils: Lemon grass oil
Toxins: Abrin, Ricin
Drugs: Vinblastin, Curcumin

9.3 Biomacromolecules

Biomolecules can be classified into micromolecules (molecular weight < 1000 Da) and macromolecules (molecular weight ≥ 10,000 Da).
Macromolecules include proteins, nucleic acids, polysaccharides, and lipids.

9.4 Proteins

Proteins are polypeptides formed by amino acids linked by peptide bonds.
There are 20 types of amino acids, and proteins serve various functions, including:
- Collagen: Intercellular ground substance
- Trypsin: Enzyme
- Insulin: Hormone
- Antibodies: Fight infectious agents
- Receptors: Sensory reception

Table 9.5: Some Proteins and their Functions

Protein	Functions
Collagen	Intercellular ground substance
Trypsin	Enzyme
Insulin	Hormone
Antibody	Fights infectious agents
Receptor	Sensory reception
GLUT-4	Enables glucose transport into cells

9.5 Polysaccharides

Polysaccharides are long chains of sugars, such as cellulose (homopolymer of glucose) and glycogen (energy storage in animals).
They can have reducing and non-reducing ends and may form helical structures.

9.6 Nucleic Acids

Nucleic acids consist of nucleotides and serve as genetic material (DNA and RNA).

9.7 Structure of Proteins

Proteins have a hierarchy of structures: primary, secondary, tertiary, and quaternary.

9.8 Enzymes

Enzymes are proteins that catalyze biochemical reactions, requiring optimal conditions for activity.
They lower the activation energy of reactions and exhibit substrate specificity.

Exam Tips & Common Mistakes

Common Mistakes and Exam Tips

Common Pitfalls

Misunderstanding Biomolecules: Students often confuse the definitions and classifications of biomolecules, such as distinguishing between primary and secondary metabolites.
Elemental Analysis Confusion: Many students fail to recognize that while the elemental composition of living and non-living matter may be similar, the relative abundance of elements like carbon and hydrogen is significantly higher in living organisms.
Ignoring Molecular Weights: Students may overlook the importance of molecular weights in categorizing biomolecules, particularly the distinction between micromolecules and macromolecules.
Enzyme Function Misconceptions: There is often confusion about the role of cofactors and the concept of enzyme inhibition, particularly the difference between competitive and non-competitive inhibitors.

Exam Tips

Focus on Definitions: Ensure you clearly understand the definitions of key terms such as metabolites, biomolecules, and macromolecules.
Use Tables for Comparison: When studying, create tables comparing the elemental composition of living and non-living matter to visualize differences.
Memorize Key Examples: Familiarize yourself with examples of primary and secondary metabolites, as well as common enzymes and their classifications.
Practice Diagrams: Be prepared to draw and label diagrams of biomolecules, including their structures and functional groups, as visual representation can aid in retention.
Review Enzyme Mechanisms: Understand the mechanisms of enzyme action and the role of cofactors, as well as the significance of enzyme inhibition in biochemical reactions.

Practice & Assessment

Multiple Choice Questions

Cellulose

Starch

Glycogen

Chitin

Correct Answer: B

Solution:

Starch forms helical secondary structures that can trap iodine molecules, resulting in a blue color. This property is used in the iodine test for starch.

Lipids have high molecular weights exceeding 10,000 Da.

Lipids are water-soluble and easily extracted.

Lipids are associated with cell membranes, forming vesicles in the acid-insoluble fraction.

Lipids are composed of amino acids and nucleotides.

Correct Answer: C

Solution:

Lipids, although small, are part of cell membranes that form vesicles, making them part of the macromolecular fraction.

Serve as enzymes

Provide structural support

Store and transmit genetic information

Act as energy reserves

Correct Answer: C

Solution:

Nucleic acids, such as DNA and RNA, are responsible for storing and transmitting genetic information.

They are primarily composed of nucleotides.

They increase the activation energy of biochemical reactions.

They are denatured at high temperatures and exhibit substrate specificity.

They are lipids that form cell membranes.

Correct Answer: C

Solution:

Enzymes are proteins that catalyze biochemical reactions by lowering the activation energy. They exhibit substrate specificity and are denatured at high temperatures, losing their catalytic activity.

They increase the activation energy.

They decrease the activation energy.

They serve as reactants.

They are consumed in the reaction.

Correct Answer: B

Solution:

Enzymes lower the activation energy of reactions and enhance the rate of the reactions.

It refers to the three-dimensional folding of the protein.

It is the sequence of amino acids in a polypeptide chain.

It involves the interaction of multiple polypeptide subunits.

It describes the helical or pleated sheet arrangement of the chain.

Correct Answer: B

Solution:

The primary structure of a protein is the linear sequence of amino acids in a polypeptide chain, which determines the protein's specific characteristics and function.

Enzymes increase the activation energy of biochemical reactions.

Enzymes are proteins that can be denatured at high temperatures.

Enzymes function optimally at any pH and temperature.

Enzymes do not exhibit substrate specificity.

Correct Answer: B

Solution:

Enzymes are proteins that catalyze biochemical reactions by lowering the activation energy. They exhibit substrate specificity and require optimal temperature and pH for maximal activity. High temperatures can denature enzymes.

Metal ions are permanently bound to enzymes and do not dissociate.

Metal ions form coordination bonds with the substrate and active site, enhancing enzyme activity.

Metal ions act as the primary substrate for enzyme reactions.

Metal ions are only involved in the structural stability of enzymes.

Correct Answer: B

Solution:

Metal ions form coordination bonds with the active site and substrate, playing a crucial role in enzyme activity.

Cellulose

Starch

Chitin

Inulin

Correct Answer: B

Solution:

Starch forms helical secondary structures, allowing it to hold I₂ molecules.

The presence of α-helices and β-sheets.

The sequence of amino acids in a polypeptide chain.

The three-dimensional folding pattern of a protein.

The interaction between multiple polypeptide chains.

Correct Answer: B

Solution:

The primary structure of proteins refers to the linear sequence of amino acids in a polypeptide chain.

Cellulose

Glycogen

Starch

Inulin

Correct Answer: A

Solution:

Cellulose is a homopolymer consisting of glucose monomers.

Cellulose consists of β-glucose units forming a linear chain without branching.

Cellulose is a polymer of α-glucose units with helical structures.

Cellulose can hold I₂ molecules in its helical portion.

Cellulose is a polymer of fructose.

Correct Answer: A

Solution:

Cellulose is a homopolymer made of β-glucose units linked together in a linear chain without branching. It does not form helical structures and cannot hold I₂ molecules.

Collagen

Ribulose bisphosphate Carboxylase-Oxygenase (RuBisCO)

Hemoglobin

Keratin

Correct Answer: B

Solution:

RuBisCO is the most abundant protein in the whole of the biosphere.

The sequence of nucleotides in a DNA strand.

The three-dimensional folding pattern of a protein.

The sequence of amino acids in a protein chain.

The interaction between multiple protein subunits.

Correct Answer: C

Solution:

The primary structure of a protein refers to the linear sequence of amino acids linked by peptide bonds.

Collagen

Elastin

Keratin

Albumin

Correct Answer: A

Solution:

Collagen is the most abundant protein in the animal kingdom and is a major component of connective tissues.

Polysaccharides serve as the primary genetic material in cells.

Polysaccharides are the main structural component of cell membranes.

Polysaccharides act as storage forms of energy and structural components in organisms.

Polysaccharides are the most abundant proteins in the biosphere.

Correct Answer: C

Solution:

Polysaccharides like starch and glycogen serve as energy storage molecules, while cellulose provides structural support in plant cell walls.

Cellulose

Chitin

Starch

Glycogen

Correct Answer: B

Solution:

Chitin is a complex polysaccharide found in the exoskeleton of arthropods.

Glucose

Ribulose bisphosphate Carboxylase-Oxygenase (RuBisCO)

Morphine

Collagen

Correct Answer: C

Solution:

Morphine is an alkaloid, which is a type of secondary metabolite found in plants. Secondary metabolites are not directly involved in normal growth, development, or reproduction of organisms.

A prosthetic group is a temporary cofactor that dissociates after catalysis.

A prosthetic group is a tightly bound organic compound that is part of the enzyme's active site.

A prosthetic group is a metal ion that loosely associates with the enzyme.

A prosthetic group is a protein subunit that can be removed without affecting enzyme activity.

Correct Answer: B

Solution:

Prosthetic groups are tightly bound organic compounds that are integral to the enzyme's active site, distinguishing them from other cofactors that may associate transiently.

Starch is composed of α-glucose units, whereas cellulose is composed of β-glucose units.

Both starch and cellulose are composed of β-glucose units.

Starch is a linear polymer, while cellulose is highly branched.

Cellulose can hold I₂ molecules in its helical structure, whereas starch cannot.

Correct Answer: A

Solution:

Starch is composed of α-glucose units, forming helical structures, while cellulose is composed of β-glucose units, forming linear chains. This structural difference is crucial for their respective functions and properties.

Cellulose

Starch

Inulin

Glycogen

Correct Answer: C

Solution:

Inulin is a polymer of fructose and serves as a storage carbohydrate in plants.

The three-dimensional folding of the protein.

The sequence of amino acids in the protein.

The interaction between multiple protein subunits.

The presence of alpha-helices and beta-sheets.

Correct Answer: B

Solution:

The primary structure of a protein refers to the linear sequence of amino acids in the polypeptide chain.

They are homopolymers.

They are composed of nucleotides.

They are linear chains of amino acids linked by peptide bonds.

They are primarily used for energy storage.

Correct Answer: C

Solution:

Proteins are linear chains of amino acids linked by peptide bonds, making them heteropolymers.

To store energy.

To catalyze biochemical reactions.

To serve as genetic material.

To provide structural support.

Correct Answer: C

Solution:

Nucleic acids, such as DNA and RNA, serve as the genetic material in living organisms, carrying hereditary information.

Serving as genetic material.

Acting as enzymes to catalyze biochemical reactions.

Functioning as hormones.

Providing structural support in cells.

Correct Answer: A

Solution:

Proteins do not serve as genetic material; this function is performed by nucleic acids such as DNA and RNA.

Starch is a polymer of β-glucose, while cellulose is a polymer of α-glucose.

Starch is a linear polymer, while cellulose is highly branched.

Starch forms helical structures, while cellulose forms linear chains.

Starch can hold I₂ molecules, while cellulose cannot.

Correct Answer: C

Solution:

Starch forms helical structures due to its α-glucose units, allowing it to hold I₂ molecules. Cellulose, on the other hand, consists of β-glucose units forming linear chains without helices.

Amino acids

Alkaloids

Flavonoids

Essential oils

Correct Answer: A

Solution:

Primary metabolites are compounds that have identifiable functions and play known roles in physiological processes. Amino acids are primary metabolites found in animal tissues.

Proteins

Polysaccharides

Nucleic acids

Lipids

Correct Answer: C

Solution:

Nucleic acids, such as DNA and RNA, serve as the genetic material in living organisms and are composed of nucleotides.

Cellulose

Starch

Glycogen

Inulin

Correct Answer: C

Solution:

Glycogen is the storage form of energy in animal tissues.

Starch

Cellulose

Glycogen

Inulin

Correct Answer: B

Solution:

Cellulose is a polymeric polysaccharide consisting of only one type of monosaccharide, glucose.

Catalyze biochemical reactions

Serve as genetic material

Act as a storage form of energy

Provide structural support to animal tissues

Correct Answer: C

Solution:

Polysaccharides like starch act as a storage form of energy in plants.

Chitin

Cellulose

Glycogen

Starch

Correct Answer: B

Solution:

Plant cell walls are primarily made of cellulose.

It forms helical structures.

It is a homopolymer of glucose.

It contains nitrogenous bases.

It is soluble in water.

Correct Answer: B

Solution:

Cellulose is a polymeric polysaccharide consisting of glucose monomers, making it a homopolymer. It does not form helical structures and is not soluble in water.

Polysaccharides provide flexibility due to their branched structure.

Polysaccharides provide rigidity due to their linear, unbranched structure.

Polysaccharides store energy due to their helical structure.

Polysaccharides facilitate movement due to their flexible chains.

Correct Answer: B

Solution:

The exoskeleton of arthropods is made of chitin, a complex polysaccharide that provides rigidity due to its linear, unbranched structure.

Cellulose

Glycogen

Starch

Chitin

Correct Answer: C

Solution:

Starch forms helical secondary structures and can hold iodine molecules, giving a blue color.

Cellulose has a linear structure without complex helices.

Cellulose is composed of fructose units instead of glucose.

Cellulose has a higher molecular weight than starch.

Cellulose is a homopolymer of amino acids.

Correct Answer: A

Solution:

Cellulose consists of linear chains of β-glucose units and lacks the helical structures present in starch, which are necessary to hold iodine molecules.

Morphine

Glycogen

Vinblastin

Lemon grass oil

Correct Answer: B

Solution:

Glycogen is a primary metabolite that serves as a storage form of energy in animal tissues, while morphine, vinblastin, and lemon grass oil are secondary metabolites.

It is the most abundant protein in animals, providing structural support.

It catalyzes the fixation of carbon dioxide in the Calvin cycle during photosynthesis.

It is a storage protein found in seeds.

It acts as a hormone regulating plant growth.

Correct Answer: B

Solution:

RuBisCO, or Ribulose bisphosphate Carboxylase-Oxygenase, is the most abundant protein in the biosphere and plays a crucial role in catalyzing the fixation of carbon dioxide in the Calvin cycle during photosynthesis.

Starch is composed of α-glucose units, while cellulose is composed of β-glucose units.

Starch is a polymer of amino acids, whereas cellulose is a polymer of nucleotides.

Starch is linear, whereas cellulose is highly branched.

Starch contains fructose units, whereas cellulose contains glucose units.

Correct Answer: A

Solution:

Starch is composed of α-glucose units, which allow it to form helical structures, while cellulose is composed of β-glucose units, resulting in a linear structure. This difference in structure impacts their biological functions.

They are water soluble.

They are generally small molecular weight compounds.

They are always macromolecules.

They are polymers.

Correct Answer: B

Solution:

Lipids are generally small molecular weight compounds and are not strictly considered macromolecules.

They are always macromolecules.

They are soluble in water.

They can form vesicles in aqueous solutions.

They are composed of nucleotides.

Correct Answer: C

Solution:

Lipids are generally water-insoluble and can form vesicles in aqueous solutions due to their hydrophobic nature.

Polysaccharide

Protein

Lipid

Nucleic acid

Correct Answer: D

Solution:

DNA is a nucleic acid, which is a type of macromolecule found in the acid insoluble fraction of living tissues.

Glucose

Cellulose

Morphine

Glycogen

Correct Answer: C

Solution:

Morphine is an example of a secondary metabolite, whereas glucose, cellulose, and glycogen are primary metabolites.

They are essential for basic cellular functions.

They are primarily involved in energy storage.

They include compounds like alkaloids and flavonoids.

They are the main components of cell membranes.

Correct Answer: C

Solution:

Secondary metabolites include compounds like alkaloids and flavonoids, which are not essential for basic cellular functions but have ecological importance.

They serve as genetic material.

They are components of cell walls and energy storage.

They act as enzymes catalyzing biochemical reactions.

They are the most abundant proteins in the biosphere.

Correct Answer: B

Solution:

Polysaccharides serve as structural components of cell walls in plants and fungi, and as energy storage molecules (e.g., starch in plants and glycogen in animals).

Cellulose

Chitin

Starch

Glycogen

Correct Answer: B

Solution:

Chitin is a complex polysaccharide that forms the exoskeleton of arthropods.

They form coordination bonds with the substrate and enzyme, enhancing catalytic activity.

They are permanently bound to the enzyme and do not interact with the substrate.

They are organic compounds that transiently bind to the enzyme.

They are responsible for the enzyme's primary structure.

Correct Answer: A

Solution:

Metal ions act as cofactors by forming coordination bonds with both the enzyme and the substrate, which is essential for catalytic activity.

Cellulose

Starch

Inulin

Glycogen

Correct Answer: C

Solution:

Inulin is a polymer of fructose.

Cellulose

Starch

Chitin

Inulin

Correct Answer: B

Solution:

Starch is a polysaccharide that serves as a storage form of energy in plant tissues.

They are nucleic acids with catalytic power.

They are proteins that catalyze biochemical reactions.

They are polysaccharides that store energy.

They are lipids that form cell membranes.

Correct Answer: B

Solution:

Enzymes are proteins that catalyze biochemical reactions in the cells.

They store energy.

They serve as genetic material.

They form the cell membrane.

They act as enzymes.

Correct Answer: B

Solution:

Nucleic acids, such as DNA and RNA, serve as genetic material in living organisms, carrying hereditary information.

They are composed of nucleotides.

They are composed of amino acids.

They are composed of monosaccharides.

They are composed of fatty acids.

Correct Answer: C

Solution:

Polysaccharides are long chains of monosaccharides linked together, serving as structural components or energy storage molecules.

They provide structural support.

They catalyze biochemical reactions.

They store genetic information.

They transport oxygen.

Correct Answer: B

Solution:

Enzymes are proteins that catalyze biochemical reactions in the cells.

Enzymes increase the activation energy required for reactions.

Enzymes decrease the activation energy required for reactions.

Enzymes are consumed during the reactions they catalyze.

Enzymes are only active at high temperatures.

Correct Answer: B

Solution:

Enzymes function by lowering the activation energy of biochemical reactions, thereby increasing the reaction rate without being consumed in the process.

Starch has α-glucose units, while cellulose has β-glucose units.

Starch is a homopolymer, while cellulose is a heteropolymer.

Starch is found in animal tissues, while cellulose is found in plant tissues.

Starch contains nitrogen, while cellulose does not.

Correct Answer: A

Solution:

Starch is composed of α-glucose units, whereas cellulose is composed of β-glucose units.

Coenzymes are permanently bound to enzymes and cannot be removed.

Coenzymes are inorganic metal ions that assist in enzyme activity.

Coenzymes are organic molecules that transiently associate with enzymes during catalysis.

Coenzymes are proteins that directly catalyze reactions without any other assistance.

Correct Answer: C

Solution:

Coenzymes are organic compounds that temporarily associate with enzymes during catalysis, often derived from vitamins.

Proteins

Carbohydrates

Water

Lipids

Correct Answer: C

Solution:

Water is the most abundant chemical in living organisms.

They are the primary component of cell walls.

They act as enzymes.

They are the main energy storage molecules.

They form the genetic code.

Correct Answer: B

Solution:

Proteins serve a variety of functions in living organisms, including acting as enzymes that catalyze biochemical reactions.

True or False

Correct Answer: True

Solution:

Glycogen is indeed a polysaccharide that functions as an energy reserve in animal tissues.

Correct Answer: False

Solution:

Glycogen is a storage form of energy in animals, not plants. In plants, starch serves this purpose.

Correct Answer: True

Solution:

Enzymes are proteins that catalyze biochemical reactions by lowering the activation energy required.

Correct Answer: True

Solution:

Nucleic acids are polynucleotides and are part of the macromolecular fraction found in the acid insoluble portion of living tissues.

Correct Answer: False

Solution:

Lipids are not considered macromolecules because their molecular weights do not exceed 800 Da, but they are part of the acid insoluble fraction due to their association with membranes.

Correct Answer: True

Solution:

Starch forms helical secondary structures that can hold I₂ molecules, resulting in a blue color.

Correct Answer: True

Solution:

Collagen is indeed the most abundant protein found in animals.

Correct Answer: False

Solution:

RuBisCO is the most abundant protein in the whole of the biosphere, not just in the animal world.

Correct Answer: True

Solution:

RuBisCO, or Ribulose bisphosphate Carboxylase-Oxygenase, is indeed the most abundant protein in the biosphere.

Correct Answer: False

Solution:

Starch, not cellulose, can hold iodine molecules in its helical structure, resulting in a blue color.

Correct Answer: False

Solution:

Collagen is the most abundant protein in the animal world, but Ribulose bisphosphate Carboxylase-Oxygenase (RuBisCO) is the most abundant protein in the whole of the biosphere.

Correct Answer: True

Solution:

Nucleic acids are polynucleotides, and each nucleotide consists of a nitrogenous base, a sugar, and a phosphate group.

Correct Answer: False

Solution:

Glycogen is a storage polysaccharide found in animals, not plants. Plants store energy in the form of starch.

Correct Answer: False

Solution:

Cellulose is a polymeric polysaccharide consisting of glucose, not fructose. Inulin is a polymer of fructose.

Correct Answer: False

Solution:

Cellulose is a polymeric polysaccharide consisting of only one type of monosaccharide, glucose, making it a homopolymer.

Correct Answer: True

Solution:

Collagen is indeed the most abundant protein in the animal world, as stated in the provided excerpts.

Correct Answer: False

Solution:

Ribozymes are nucleic acids, not proteins, that possess catalytic abilities.

Correct Answer: True

Solution:

Cellulose is a polymeric polysaccharide consisting of only one type of monosaccharide, glucose, making it a homopolymer.

Correct Answer: False

Solution:

Inulin is a polymer of fructose, not glucose.

Correct Answer: True

Solution:

Enzymes, which are proteins, require optimal temperature and pH for maximal activity and can be denatured at high temperatures.

Correct Answer: True

Solution:

Enzymes, which are proteins, require an optimum temperature and pH for maximal activity and can be denatured at high temperatures.

Correct Answer: False

Solution:

Ribozymes are nucleic acids, not proteins, with catalytic activity.

Correct Answer: False

Solution:

Nucleic acids are part of the acid insoluble fraction, not the acid soluble fraction.

Correct Answer: True

Solution:

Proteins are indeed heteropolymers, consisting of various amino acids linked by peptide bonds.

Correct Answer: False

Solution:

Glycogen is a polysaccharide found in animals, not plants. Starch is the equivalent polysaccharide found in plants.

Correct Answer: True

Solution:

Chitin is indeed a complex polysaccharide found in the exoskeletons of arthropods, as mentioned in the excerpts.

Correct Answer: False

Solution:

Collagen is the most abundant protein in the animal world, but Ribulose bisphosphate Carboxylase-Oxygenase (RuBisCO) is the most abundant protein in the whole of the biosphere.

Correct Answer: False

Solution:

Lipids are not considered macromolecules despite being part of the acid insoluble fraction. They have low molecular weights but are associated with membranes, which is why they appear in the macromolecular fraction.

Correct Answer: True

Solution:

Cellulose is a polymeric polysaccharide consisting of glucose units, making it a homopolymer.

Correct Answer: True

Solution:

RuBisCO, or Ribulose bisphosphate Carboxylase-Oxygenase, is indeed the most abundant protein in the biosphere, as it is essential for the process of photosynthesis in plants.

Correct Answer: False

Solution:

Proteins are heteropolymers composed of different types of amino acids.

Correct Answer: False

Solution:

Cellulose does not form complex helices and cannot hold iodine molecules.

Correct Answer: False

Solution:

Proteins are heteropolymers made of 20 different types of amino acids, not just one type.

Correct Answer: True

Solution:

Cellulose is indeed a homopolymer made up of β-glucose units, forming linear chains without branching.

Correct Answer: False

Solution:

Ribozymes are nucleic acids with catalytic power, not proteins.

Correct Answer: True

Solution:

Nucleic acids, such as DNA and RNA, are responsible for storing and transmitting genetic information.

Correct Answer: True

Solution:

Chitin is a complex polysaccharide found in the exoskeletons of arthropods and is mostly a homopolymer.

Correct Answer: False

Solution:

Enzymes often require cofactors such as metal ions or organic molecules to function properly.

Correct Answer: True

Solution:

Starch serves as a storage form of energy in plants, while glycogen serves a similar function in animals.

Correct Answer: False

Solution:

Lipids are not classified as macromolecules based on their molecular weight, which is generally less than 800 Da.

Correct Answer: True

Solution:

Starch forms helical secondary structures that can hold I₂ molecules, resulting in a blue color.

Biomolecules

AI Learning Assistant

Summary

Chapter 9: Biomolecules

Summary

Learning Objectives

Detailed Notes

Chapter 9: Biomolecules

9.1 How to Analyse Chemical Composition?

9.2 Primary and Secondary Metabolites

Table 9.3: Some Secondary Metabolites

9.3 Biomacromolecules

9.4 Proteins

Table 9.5: Some Proteins and their Functions

9.5 Polysaccharides

9.6 Nucleic Acids

9.7 Structure of Proteins

9.8 Enzymes

Exam Tips & Common Mistakes

Common Mistakes and Exam Tips

Common Pitfalls

Exam Tips

Practice & Assessment

Multiple Choice Questions

Q1.Which of the following polysaccharides is known for forming helical structures and can bind iodine?

Correct Answer: B

Q2.What is the main reason lipids are classified in the macromolecular fraction despite their smaller size?

Correct Answer: C

Q3.What is the primary function of nucleic acids in living organisms?

Correct Answer: C

Q4.Which of the following is a characteristic feature of enzymes?

Correct Answer: C

Q5.What is the role of enzymes in biochemical reactions?

Correct Answer: B

Q6.Which of the following is true about the primary structure of proteins?

Correct Answer: B

Q7.In the context of enzyme activity, which of the following statements is correct?

Correct Answer: B

Q8.In the context of enzyme activity, which of the following statements is true regarding the role of metal ions?

Correct Answer: B

Q9.Which of the following polysaccharides is known for forming helical secondary structures?

Correct Answer: B

Q10.Which of the following is a characteristic feature of the primary structure of proteins?

Correct Answer: B

Q11.Which of the following is a homopolymer made of glucose?

Correct Answer: A

Q12.Which of the following statements is true about the structure of cellulose?

Correct Answer: A

Q13.Which of the following is the most abundant protein in the biosphere?

Correct Answer: B

Q14.Which of the following best describes the primary structure of a protein?

Correct Answer: C

Q15.Which protein is the most abundant in the animal kingdom and serves as a structural component in connective tissues?

Correct Answer: A

Q16.Which of the following statements correctly describes the role of polysaccharides in living organisms?

Correct Answer: C

Q17.Which of the following polysaccharides is found in the exoskeleton of arthropods?

Correct Answer: B

Q18.Which of the following is a secondary metabolite found in plants?

Correct Answer: C

Q19.In the context of enzyme activity, which of the following best describes the role of a prosthetic group?

Correct Answer: B

Q20.Which of the following statements correctly describes the structural difference between starch and cellulose?

Correct Answer: A

Q21.Which of the following polysaccharides is a polymer of fructose and is primarily found in plants as a storage carbohydrate?

Correct Answer: C

Q22.In the context of protein structure, what is meant by the 'primary structure' of a protein?

Correct Answer: B

Q23.Which of the following is a characteristic of proteins?

Correct Answer: C

Q24.What is the primary function of nucleic acids in living organisms?

Correct Answer: C

Q25.Which of the following functions is NOT performed by proteins in living organisms?

Correct Answer: A

Q26.What is the primary structural difference between starch and cellulose?

Correct Answer: C

Q27.Which of the following is a primary metabolite found in animal tissues?

Correct Answer: A

Q28.Which type of biomolecule serves as the genetic material in living organisms and is composed of nucleotides?

Correct Answer: C