All Free Biology MCQs with Answers

4361. The diagram represents:

• A. mRNA
• B. tRNA
• C. rRNA
• D. Ribozyme

Explanation: The diagram shows tRNAThe following image shows another tRNA molecule.

4362. The formation has been depicted in the following diagram:

• A. Maltose
• B. Lactose
• C. Raffinose
• D. Sucrose

Explanation: Sucrose, commonly known as table sugar, is a disaccharide sugar composed of two simple sugar molecules or monosaccharides: glucose and fructose. Its chemical formula is C12H22O11. Sucrose is one of the most widely used and recognized sugars in the world and is commonly used as a sweetening agent in various foods and beverages.Sucrose is naturally found in many plants, where it serves as a source of energy and as a transport form for sugar in the plant. Sugar cane and sugar beet are two major commercial sources of sucrose production.

4363. Cellulose of wood, cotton and paper is an example of:

• A. Carbohydrates
• B. Nucleic acids
• C. Proteins
• D. Lipids

Explanation: Wood, cotton and paper are made up of a polysaccharide called cellulose.

4364. The main constituents of cell walls in plants, algae, fungi and eukaryotic microorganisms are:

• A. Carbohydrates
• B. Proteins
• C. Lipids
• D. Nucleic acids

Explanation: Cellulose, hemicellulose and pectins are the main components of the cell wall of plants and algae, whereas chitin is the main component of the cell wall of fungi. All of them are polysaccharide carbohydrates.

4365. In simple carbohydrates the ratio of hydrogen and oxygen is same as in:

• A. Lipids
• B. Proteins
• C. Water
• D. Nucleic acids

Explanation: By simple carbohydrates we mean monosaccharides with general formula of Cn(H2O)n. In each monosaccharide, there are two hydrogen atoms and one oxygen atom against each carbon atom.

4366. The general formula of carbohydrates is Cx(H2O)y where 'x' is the whole number:

• A. From three to many thousands
• B. From three to seven thousands
• C. From three to three thousands
• D. From seven to many thousands

Explanation: The smallest carbohydrate is a triose (monosaccharide) whereas the complex carbohydrates (Polysaccharides) may consist of hundreds or thousands of Monosaccharide units.

4367. Polyhydroxy aldehydes or polyhydroxy ketones are:

• A. Carbohydrates
• B. Lipids
• C. Proteins
• D. Nucleic acids

Explanation: Chemically carbohydrates are either polyhydroxy aldehydes or polyhydroxy ketones or their condensation products.

4368. "Complex substances which on hydrolysis yield polyhydroxy aldehyde or ketone subunits" are:

• A. Monosaccharides and oligosaccharides
• B. Glucose and fructose
• C. Monosaccharides and polysaccharides
• D. Oligosaccharides and polysaccharides

Explanation: Because these are condensationproducts of polyhydroxyaldehydes or polyhydroxy ketone units, thus they yield same upon their hydrolysis.

4369. Carbohydrates in cell combine with _ and _ and the resulting compounds are called glycoproteins and glycolipids respectively.

• A. Lipids, Proteins
• B. Carbohydrates, Proteins
• C. Carbohydrates, Lipids
• D. Proteins, Lipids

Explanation: When carbohydrates are conjugated with proteins they yield glycoproteins and when conjugated with lipids they yield glycolipids. Both of them are part of biological membranes.

4370. Both glycoproteins and glycolipids are components of:

• A. Plant cell walls
• B. Algal cell walls
• C. Fungal cell wall
• D. Biological membrane

Explanation: Basic framework of cellular membranes is provided by proteins and lipids, however carbohydrates are conjugated with them to synthesize glycoproteins and glycolipids which act as cell markers and tissue markers.