All Free Biology MCQs with Answers

4601. All of the following are subunits of DNA except:

• A. Deoxyribose sugar
• B. Phosphate group
• C. Nitrogenous base
• D. Choline

Explanation: The correct answer is Choline. DNA is composed of nucleotides, which include a deoxyribose sugar, a phosphate group, and a nitrogenous base. These components form the structural framework of DNA. Choline, on the other hand, is not a component of DNA; it is a component of phospholipids in cell membranes. Therefore, choline is the correct choice as it is not a subunit of DNA.

4602. Which one of the following is an example of unsaturated fatty acid?

• A. Butyric Acid
• B. Oleic Acid
• C. Palmitic Acid
• D. Acetic Acid

Explanation: Correct answer is Oleic Acid as it is a monounsaturated fatty acid.The example of an unsaturated fatty acid among the options provided is Oleic acid.Unsaturated fatty acids are a type of fatty acid that contains one or more double bonds in their carbon chain.Butyric acid is a saturated fatty acid. It is a four-carbon chain fatty acid with no double bonds.Oleic acid is an unsaturated fatty acid. It is an eighteen-carbon chain fatty acid with one double bond located between the ninth and tenth carbon atoms from the methyl (CH3) end of the chain.Palmitic acid is a saturated fatty acid. It is a sixteen-carbon chain fatty acid with no double bonds.Acetic acid is not a fatty acid. It is a simple organic compound known as a carboxylic acid, with the chemical formula CH3COOH. It is the primary component of vinegar.

4603. Starch is present in tubers, fruits, and grains but absent in animal cells. Instead, animals have a substance stored in liver and muscles known as:

• A. Galactose
• B. Glucagon
• C. Glycogen
• D. Glucose

Explanation: Glycogen is the storage form of carbohydrate found in animals. Glycogen is the body's stored form of glucose, which is a type of sugar that serves as the main source of energy. It is a large, branched molecule made of many glucose units linked together, and it is stored primarily in the liver and muscles. When the body needs energy, glycogen is broken down to release glucose into the bloodstream for the cells to use.Galactose (A) is a monosaccharide, Glucagon (B) is a hormone, Glucose (D) is a monosaccharide and the monomer of glycogen and starch.

4604. _ is a disaccharide.

• A. Glucose
• B. Galactose
• C. Fructose
• D. Sucrose

Explanation: A disaccharide is a carbohydrate formed from two monosaccharide units. Sucrose is a disaccharide composed of one glucose unit and one fructose unit joined together. The other options are all monosaccharides.

4605. The most abundant organic compounds in a mammalian cell are:

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

Explanation: Proteins make up 18% of the cells composition in mammals. You might choose water, as it makes 70% of the cell. However, water is not an organic compound.

4606. _ is stored in animal ceIIs:

• A. Starch
• B. Cellulose
• C. Sucrose
• D. Glycogen

Explanation: Starch: Starch is not stored in animal cells. It is a complex polysaccharide and the primary energy storage carbohydrate in plants. Plants produce and store starch in various parts like tubers, seeds, and fruits. Animals cannot directly store or utilize starch as an energy reserve. Cellulose: Cellulose is also not stored in animal cells. It is another complex polysaccharide and the major structural component of the cell walls in plants. Cellulose provides rigidity and strength to plant cells but is not used as an energy storage molecule in animals. Sucrose: Sucrose is a disaccharide composed of one glucose molecule and one fructose molecule linked together. While sucrose is found in certain plants, it is not the primary energy storage carbohydrate in animal cells. Glycogen: The correct option is glycogen. Glycogen is a highly branched polysaccharide composed of glucose units and serves as the primary energy storage molecule in animals, including humans. It is the animal equivalent of starch in plants. Glycogen is stored in the liver and muscles, where it acts as a readily available source of glucose during periods of increased energy demand. When energy is needed, glycogen is broken down into glucose units, which are further utilized through cellular respiration to produce energy.In summary, option d) Glycogen is the correct option. Glycogen is stored in animal cells and acts as a readily accessible source of glucose for energy production. The other options (a) Starch, (b) Cellulose, and (c) Sucrose are not stored in animal cells; they have different functions in plants and are not used as energy reserves in animals.

4607. Pure form of cellulose is:

• A. Cotton
• B. Chitin
• C. Cellophane
• D. Paper

Explanation: The correct answer is cotton, as it is composed primarily of cellulose with minimal impurities, making it the closest to pure cellulose among the options. Chitin is a cellulose-like polysaccharide but differs chemically due to the presence of nitrogen. Cellophane is derived from cellulose but is chemically processed, which alters its original state. Paper contains cellulose but also includes other materials that make it less pure.

4608. The best example of of polysaccharide which is stored in animaIs is called:

• A. Lactose
• B. Cellulose
• C. Glucose
• D. Glycogen

Explanation: Lactose: Lactose is a disaccharide composed of one molecule of glucose and one molecule of galactose. It is commonly found in milk and dairy products. Lactose serves as an energy source for young mammals, including human infants. However, it is not the best example of a polysaccharide stored in animals. Cellulose: Cellulose is a polysaccharide and an important structural component of plant cell walls. It provides rigidity and strength to plant cells and is the most abundant organic compound on Earth. While cellulose is a polysaccharide, it is not stored in animals. Animals lack the enzymes necessary to digest cellulose effectively. Glucose: Glucose is a monosaccharide, not a polysaccharide. It is a simple sugar and serves as a primary source of energy for living organisms. Glucose is transported through the bloodstream and used by cells for energy production. It is not stored as a complex polysaccharide in animals. Glycogen: The correct option is glycogen. Glycogen is a highly branched polysaccharide composed of glucose units and serves as the primary energy storage molecule in animals, including humans. It is the animal equivalent of starch in plants. Glycogen is stored in the liver and muscles, where it acts as a readily available source of glucose during periods of increased energy demand. When energy is needed, glycogen is broken down into glucose units, which are further utilized through cellular respiration to produce energy.In summary, option d) Glycogen is the correct option. Glycogen is the best example of a polysaccharide stored in animals. It serves as an important energy reserve and is stored in the liver and muscles. The other options (a) Lactose, (b) Cellulose, and (c) Glucose are not stored as polysaccharides in animals.

4609. _ is storage form of carbohydrates in animals and humans which is equivalent to the _ in plants.

• A. Glycogen, Cellulose
• B. Starch, Cellulose
• C. Starch, Glycogen
• D. Glycogen, Starch

Explanation: Glycogen and starch are storage forms of carbohydrates in animals and plants respectively.

4610. Which of the followings sugars is/are component of nucleic acid?

• A. Tetroses
• B. Trioses
• C. Pentoses
• D. Hexoses

Explanation: The fundamental building block of nucleic acids is the nucleotide, which comprises three components: a phosphate group, a nitrogenous base, and a pentose sugar. Pentoses, such as ribose in RNA and deoxyribose in DNA, are integral to the structure of nucleic acids. Tetroses and trioses are not involved in the structure of nucleic acids; they serve as intermediates in various metabolic pathways. Hexoses, although critical in energy metabolism, do not form part of nucleic acid structures.