Biology Experiment 3: Macromolecules

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Questions and Answers

What is formed when two monosaccharides undergo a dehydration reaction?

Polysaccharide

Disaccharide (correct)

Oligosaccharide

Monosaccharide

Which polysaccharide is primarily responsible for energy storage in plants?

Glycogen

Starch (correct)

Chitin

Cellulose

Which of the following polysaccharides provides structural support in plants?

Cellulose (correct)

Chitin

Starch

Glycogen

What type of sugar is lactose classified as?

Reducing sugar Signup and view all the answers

What is the main function of Benedict's reagent in chemical tests?

To identify reducing sugars Signup and view all the answers

What ions are reduced during Benedict's test when reducing sugars are present?

Copper (II) ions Signup and view all the answers

Which of the following sugars is considered a non-reducing sugar?

Sucrose Signup and view all the answers

What components make up Benedict's reagent?

Copper (II) sulfate, sodium carbonate, sodium citrate Signup and view all the answers

What color change occurs in the solution during Benedict's test due to the presence of reducing sugars?

Blue to green, yellow, orange, or red Signup and view all the answers

What is the primary purpose of Lugol's test?

To detect starch Signup and view all the answers

What does the deep blue-black color indicate during Lugol's test?

Presence of starch Signup and view all the answers

What do dehydration reactions result in?

Formation of covalent bonds Signup and view all the answers

Which of the following best describes the general formula for carbohydrates?

(CH2O)n Signup and view all the answers

In the Biuret test, which ions interact with peptide bonds to detect proteins?

Cu²⁺ ions Signup and view all the answers

Which classification includes sugars with 6 carbon atoms?

Hexoses Signup and view all the answers

Which macromolecules are proteins primarily composed of?

Amino acids Signup and view all the answers

What is a defining characteristic of aldoses?

They contain an aldehyde group. Signup and view all the answers

Why does the solution appear blue in the initial stage of Benedict's test?

Due to copper (II) ions Signup and view all the answers

What happens to copper (I) ions during the Benedict's test?

They form copper (I) oxide Signup and view all the answers

What is the primary role of polysaccharides in living organisms?

Energy storage and structural support Signup and view all the answers

Which of the following statements about hydrolysis is correct?

It breaks chemical bonds and releases energy. Signup and view all the answers

Which functional role do proteins NOT serve in living organisms?

Energy storage Signup and view all the answers

How are disaccharides formed?

By dehydration synthesis of monosaccharides Signup and view all the answers

Which of the following is an example of a pentose sugar?

Ribose Signup and view all the answers

What is one characteristic of hydrolysis reactions in biological systems?

They are catalyzed by specific enzymes. Signup and view all the answers

Which of the following describes the ratio of carbon, hydrogen, and oxygen in carbohydrates?

1:2:1 Signup and view all the answers

What type of reaction specifically joins two monosaccharides to form a disaccharide?

Dehydration Signup and view all the answers

Which monosaccharide classification contains sugars with a ketone group?

Ketoses Signup and view all the answers

What is a defining feature of the structure of disaccharides?

They are composed of two monosaccharide units. Signup and view all the answers

Which macromolecule category primarily plays a role in structural support in living organisms?

Carbohydrates Signup and view all the answers

What is the typical number of carbon atoms in a trioses monosaccharide?

3 Signup and view all the answers

Which of the following macromolecules has a significant role in energy storage?

Carbohydrates Signup and view all the answers

Which of the following sugars can be classified as a reducing sugar?

Maltose Signup and view all the answers

What role does amylopectin play in starch structure?

It acts as a storage component. Signup and view all the answers

Which of the following statements accurately describes chitin?

It is a structural polysaccharide found in arthropods. Signup and view all the answers

Which feature is key to the ability of reducing sugars to react during Benedict's test?

Free aldehyde or ketone groups. Signup and view all the answers

What is the primary structural component of plant cell walls?

Cellulose Signup and view all the answers

Which of the following is NOT a characteristic of polysaccharides?

They are usually soluble in water. Signup and view all the answers

During Benedict's test, what is the nature of the solution when no reducing sugar is present?

Blue Signup and view all the answers

What is the charge of copper ions before reduction in Benedict's reagent?

Cu+2 Signup and view all the answers

What causes the visible color change during Benedict's test when reducing sugars are present?

Formation of copper (I) oxide Signup and view all the answers

What complex is formed when Lugol's iodine solution interacts with starch?

Starch-iodine complex Signup and view all the answers

The Biuret test is specifically designed to detect which macromolecule?

Proteins Signup and view all the answers

What indicates a higher concentration of reducing sugars during Benedict's test?

Darker shades of red in the solution Signup and view all the answers

Which functional groups in amino acids are crucial for the formation of proteins?

Amino and carboxyl groups Signup and view all the answers

Which of the following statements is true regarding the reaction that occurs in the Biuret test?

Peptide bonds react with copper ions Signup and view all the answers

What is the primary role of proteins discussed in the content?

Catalyzing biochemical reactions Signup and view all the answers

Which outcome results from the precipitation of copper (I) oxide during the Benedict's test?

Formation of colored precipitates Signup and view all the answers

Study Notes

Experiment 3: Macromolecules and Living Things

Macromolecules are large, complex molecules, typically consisting of thousands or millions of atoms.
They play important roles in biological systems and synthetic materials.
Key types of macromolecules in biological systems include carbohydrates, proteins, and nucleic acids.

Dehydration

Dehydration reactions link monomers to form polymers.
A water molecule is formed during this process.
Specific enzymes speed up the formation of covalent bonds.
Energy is required for these reactions.

Hydrolysis

Hydrolysis reactions break down polymers into monomers.
Specific enzymes speed up these processes.
Reactions break bonds and release energy.

Carbohydrates

Functions include energy storage (starch and glycogen), and structural support (cellulose and chitin).
Carbohydrates are composed of carbon (C), hydrogen (H), and oxygen (O).
The ratio of C:H:O in carbohydrates is 1:2:1.
The formula for carbohydrates is (CH₂O)ₙ, where n is the number of carbon atoms.

Classification of Carbohydrates

Carbohydrates are classified as simple or complex.
- Simple carbohydrates include monosaccharides (e.g., glucose, fructose, galactose) and disaccharides (e.g., maltose, lactose, sucrose).
- Complex carbohydrates include polysaccharides (e.g., starch, glycogen, fibers).

Monosaccharides

Monosaccharides are the simplest form of carbohydrates, often called simple sugars.
They are the basic building blocks for more complex carbohydrates.
Monosaccharides consist of one sugar unit.
They follow the chemical formula (CH₂O)ₙ, where n is the number of carbon atoms.
Classified based on the number of carbon atoms and functional groups.

Classification of Monosaccharides

Monosaccharides are categorized by the number of carbon atoms (trioses, pentoses, hexoses).
Functional groups define them as aldoses (aldehyde group) or ketoses (ketone group).

Disaccharides

Disaccharides are formed when two monosaccharides combine through a dehydration reaction.
The resulting bond is a glycosidic bond.
Examples include sucrose (glucose + fructose), lactose (galactose + glucose), and maltose (glucose + glucose).

Polysaccharides

Polysaccharides are complex carbohydrates formed from long chains of monosaccharides joined by glycosidic bonds.
Categorized into storage and structural types.
- Storage polysaccharides (e.g., starch, glycogen) store energy.
- Structural polysaccharides (e.g., cellulose, chitin) provide structural support.

Benedict's Test

A test to detect the presence of reducing sugars.
Reducing sugars have a free aldehyde or ketone group.
The test reagent is blue when there's no reducing sugar.
It changes color (green, yellow, orange, or red) depending on the concentration of reducing sugar.

Benedict's Reagent

A chemical that contains copper(II) sulfate, sodium carbonate, and sodium citrate.
It is typically in an alkaline solution.

Principle Behind Benedict's Test

Copper(II) ions in the alkaline solution are reduced to copper(I) ions by reducing sugars.
This forms copper(I) oxide, which precipitates, changing the solution's color.

Lugol's Test

A test for the presence of starch.
Iodine in the solution interacts with starch molecules.
The resulting starch-iodine complex is deep blue-black.
The absence of starch results in no color change (brown).

Proteins

Proteins are large, complex macromolecules made up of amino acids linked together.
They are essential for various cellular functions (structure, catalysis, transport, defense, regulation).
Each protein has its unique three-dimensional shape.

Amino Acids

Amino acids are the building blocks of proteins.
They have an amino group (-NH₂), a carboxyl group (-COOH), and a side chain (R group) that varies between amino acids.

Biuret Test

Used to detect the presence of proteins.
The presence of proteins causes a color change in the solution (violet/purple).
The test reagent changes color from pale blue to violet or purple dependent on the amount of protein.

Vitamin C (Ascorbic Acid)

A water-soluble vitamin and antioxidant vital for growth, development, and repair in the body.
Humans cannot produce it; it must be acquired through diet.
Found in various fruits and vegetables, especially citrus fruits.

Test of Vitamin C

A titration method uses indophenol solution to quantify vitamin C.
Ascorbic acid lowers the pH and changes the color of the solution (Indophenol).
The amount of juice required to change the color is inversely proportional to the vitamin C content.

Important Instructions

Follow appropriate safety procedures (use correct equipment, read labels, dispose of chemicals properly).
Avoid cracked glassware.
Avoid cross-contamination.

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Description

Explore the crucial roles macromolecules play in living organisms. This quiz covers dehydration and hydrolysis reactions, focusing on carbohydrates, proteins, and nucleic acids. Test your knowledge on the formation and breakdown of these essential biomolecules.