SYI Polysaccharides

What type of bond forms between many monosaccharides to create polysaccharides?

• Ionic bond

• Hydrogen bond

• Covalent bond

• Glycosidic bond

• Metallic bond

Answer explanation

Polysaccharides are complex carbohydrates formed by the linkage of many monosaccharide units. This linkage happens when a glycosidic bond forms between two monosaccharides, a process that involves the loss of a water molecule. Hence, the correct answer is 'Glycosidic bond'. The other options mentioned - ionic, hydrogen, covalent, and metallic bonds - are different types of bonds that do not specifically pertain to the formation of polysaccharides.

Polysaccharides are macromolecules formed by many monosaccharides joined together through which type of reaction?

• Hydrolysis

• Condensation

• Oxidation

• Reduction

• Polymerization

Answer explanation

Polysaccharides are complex carbohydrates that are made up of more than two monosaccharide units. These monosaccharide units are linked together through a type of chemical reaction known as condensation. In this reaction, two molecules combine to form a larger molecule, releasing a smaller molecule such as water in the process. Therefore, the correct answer to the question is 'Condensation'.

In polysaccharides, chains of monosaccharides may be branched or unbranched. True or False?

• True

• False

Answer explanation

True. In polysaccharides, chains of monosaccharides can indeed be either branched or unbranched. This is a characteristic feature of polysaccharides, a complex carbohydrate that consists of a number of monosaccharides joined together by glycosidic bonds.

Glycogen is made up of which two different polysaccharides?

• Amylose and cellulose

• Amylose and starch

• Amylopectin and cellulose

• Amylopectin and amylose

• Cellulose and glycogen

Answer explanation

Glycogen is a polysaccharide that constitutes the primary short-term energy storage in animals and fungi. It is made of two different polysaccharides: Amylopectin and amylose. Amylose is a straight chain of glucose molecules, while amylopectin is a branched chain. Neither of the other options lists the correct two polysaccharides comprising glycogen.

What type of glycosidic bond is found in amylose?

• α-1,4 glycosidic bond

• α-1,6 glycosidic bond

• β-1,4 glycosidic bond

• β-1,6 glycosidic bond

• α-1,2 glycosidic bond

Answer explanation

Amylose, a type of polysaccharide found in plants, primarily forms a linear structure through α-1,4 glycosidic bonds. This bond links the 1st carbon atom of one glucose molecule to the 4th carbon atom of the next. Other options represent different types of glycosidic bonds not typically associated with amylose.

Amylopectin, a component of starch, contains both 1,4 and 1,6 glycosidic bonds between which monosaccharide?

• α-glucose and fructose

• α-glucose and α-glucose

• α-glucose and galactose

• β-glucose and fructose

• β-glucose and glucose

Answer explanation

Amylopectin, a component of starch, is a polysaccharide that consists of repeated α-glucose units. These α-glucose units are linked by both α(1→4) and α(1→6) glycosidic bonds, not with fructose or galactose. Thus, the correct answer is 'α-glucose and α-glucose'.

Glycogen is a polysaccharide primarily found in which organisms?

• Plants

• Fungi

• Animals

• Bacteria

• Protists

Answer explanation

Glycogen, a polysaccharide, serves as the secondary long-term energy storage in animal and fungal cells. It is made and stored primarily in the cells of the liver and muscles, and functions as the secondary energy reserve, with the primary energy stores being fats held in adipose tissue. Therefore, the answer is 'Animals'.

Which of the following statements about glycogen is true?

• It is made up of β-glucose

• It is primarily found in plants

• It is an unbranched molecule

• It has a similar structure to amylose

• It is an energy storage molecule

Answer explanation

Glycogen, primarily found in animals and fungi, serves as a form of energy storage. It is a branched biopolymer made of α-glucose subunits, unlike the claim that it is made of β-glucose. It differs from amylose, which is unbranched. Therefore, the statement 'It is an energy storage molecule' is true.

Cellulose consists of long chains of which type of glucose molecules?

• α-glucose

• β-glucose

• Galactose

• Fructose

• Maltose

Answer explanation

Cellulose is a complex carbohydrate, or polysaccharide, that is composed of β-glucose molecules. The structure of β-glucose allows the molecules to bond together in a straight chain, which is a characteristic feature of cellulose. Hence, among the given options, the correct answer is β-glucose.

To form a 1,4 glycosidic bond between two β-glucose molecules in cellulose, how must the glucose molecules be oriented?

• Rotated 180° to each other

• Aligned in the same direction

• Rotated 90° to each other

• Aligned in opposite directions

• Bonded through the oxygen atoms

Answer explanation

In forming a 1,4 glycosidic bond between two β-glucose molecules in cellulose, the glucose molecules must be rotated 180° to each other. This specific orientation allows the molecules to interact at the 1 and 4 carbon atoms, enabling the formation of the glycosidic bond, which is crucial for the structure and function of cellulose. It's not about aligning them or bonding through the oxygen atoms.