All Free Biology MCQs with Answers

4351. All of the following elements present in all carbohydrates except:

• A. Carbon
• B. Hydrogen
• C. Oxygen
• D. Nitrogen

Explanation: Option D is correct. All of the following elements are present in all carbohydrates except nitrogen..Nitrogen is not a common element found in carbohydrates. Carbohydrates are organic compounds that are made up of carbon, hydrogen, and oxygen. They are the most abundant organic compounds in living organisms, and they play a variety of important roles, including energy storage, structure, and signaling. The basic unit of a carbohydrate is a sugar molecule. Sugar molecules can be linked together to form larger molecules, such as starch, cellulose, and glycogen.

4352. Which term most appropriately describes catalase, collagen and haemoglobin?

• A. Enzymes
• B. Globular proteins
• C. Fibrous proteins
• D. Polypeptides

Explanation: Option D is correct. The most appropriate term that describes catalase, collagen, and hemoglobin is proteins. Proteins are large molecules that are made up of amino acids. All proteins are made by translation of polypeptides. Since, catalase (enzyme), haemoglobin and collagen are proteins made from polypeptides.

4353. Which property of proteins enables them to act as pH buffers?

• A. They are insoluble
• B. They contain carboxyl and amino groups
• C. They have a low molecular mass
• D. They possess only secondary

Explanation: Option B is correct. The property of proteins that enables them to act as pH buffers is their amphoteric nature. This means that they have both acidic and basic properties. The acidic and basic properties of proteins are due to the amino acids that make up the protein. Amino acids have an amino group (-NH2) and a carboxyl group (-COOH). The amino group is basic, and the carboxyl group is acidic.

4354. The diagams shows a ring structure of glucose. Which form of glucose is shown and in which molecule is it present?

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: Option B is correct. In glucose, if OH group is present downward then it will be alpha carbon and if OH group is present is upward then it will be beta carbon. Hence in given digram OH group is present downward and there is starch so it will be alpha starch.

4355. Silk protein is present in:

• A. Nail
• B. Hair
• C. Plant cell wall
• D. Spider's web

Explanation: Option D is correct. Silk protein is present in spider's web. Cellulose is present in plant cell. Keratin is present in hair and nails.

4356. All of the following are true about lipids except:

• A. They store a high amount of energy
• B. They are polymer of fatty acids
• C. They play important role in insulation
• D. They are mostly hydrophobic

Explanation: Option B is correct. Lipids are not polymers of fatty acids. A polymer is a molecule made up of repeating units of a smaller molecule, called a monomer. Fatty acids are not monomers, they are the building blocks of lipids. Lipids are a diverse group of molecules that include triglycerides, phospholipids, waxes, and steroids. Triglycerides are the most common type of lipid, and they are made up of three fatty acids attached to a glycerol molecule. Phospholipids are also made up of a glycerol molecule, but they also have a phosphate group and a fatty acid. Waxes are made up of fatty acids and long-chain alcohols. Steroids are a type of lipid that has a ring structure.

4357. The cuticle is an example of:

• A. Acylglycerols
• B. Waxes
• C. Phospholipids
• D. Terpenoids

Explanation: Option B is correct. Cuticle is an example of waxes.The cuticle is an example of a protective layer. It is a thin, waxy layer that covers the outside of plants, animals, and some fungi. The cuticle helps to protect the underlying tissues from water loss, infection, and mechanical damage. In plants, the cuticle is made up of cutin, a polymer of fatty acids. Cutin is a very hydrophobic molecule, which means that it repels water. This helps to prevent water loss from the plant's leaves and other exposed tissues. The cuticle also helps to protect the plant from infection by pathogens.

4358. Which of these is constituent of waxes?

• A. Long-chain alkanes
• B. Alcohols
• C. Aldehydes
• D. Esters of long-chain fatty acids and long-chain alcohols

Explanation: Option D is correct. Yes, esters of long-chain fatty acids and long-chain alcohols are the constituents of waxes. Waxes are a type of lipid that is found in plants, animals, and some insects. They are made up of long-chain fatty acids and long-chain alcohols that are joined together by an ester bond. The long-chain fatty acids and long-chain alcohols in waxes are typically 16 to 36 carbon atoms in length. The fatty acids in waxes are usually saturated, which means that they do not have any double bonds. The alcohols in waxes can be saturated or unsaturated.

4359. All are true about ATP except:

• A. Energy currency of cell
• B. Contains ribose sugar
• C. Contains three high energy bonds
• D. Contains three phosphate groups

Explanation: Option C is correct. No, ATP does not contain three high-energy bonds. It actually contains two high-energy bonds. The high-energy bonds in ATP are the bonds between the phosphate groups. When these bonds are broken, they release a lot of energy, which can be used to power cellular processes. The third phosphate group in ATP is not considered to be a high-energy bond because it is not as easily broken. This is because the third phosphate group is linked to the second phosphate group by a phosphoanhydride bond, which is a very strong bond. The two high-energy bonds in ATP are located between the first and second phosphate groups, and between the second and third phosphate groups. When these bonds are broken, they release about 7.3 kcal/mol of energy each. This energy can be used to power a variety of cellular processes, such as muscle contraction, protein synthesis, and active transport.

4360. Vitamin A is an example of:

• A. Monoterpene
• B. Diterpene
• C. Triterpene
• D. Polyterpene

Explanation: Diterpenes (C20H32) include physiologically active groups such as vitamin A and plant growth hormones that regulate germination, flowering, and switch reproductive cycles of plants .