All Free Biology MCQs with Answers

4341. It is precursor of bile acids:

• A. Waxes
• B. Phospholipids
• C. Cholesterol
• D. Acylglyecrol

Explanation: Option C is option. Yes, cholesterol is the precursor of bile acids. Bile acids are essential for the digestion and absorption of fats and fat-soluble vitamins. They are also involved in the excretion of cholesterol from the body. Bile salts are stored in the gallbladder and released into the small intestine when food is eaten. They help to break down fats into smaller molecules that can be absorbed by the body. Bile salts also help to emulsify fats, which makes them easier to digest.

4342. All of the following biomolecules are nutritious except :

• A. Carbohydrates
• B. Lipids
• C. Nucleic acids
• D. All of these

Explanation: Option D is correct. Carbohydrates are biomolecules. Biomolecules are organic molecules that are found in living organisms. They are essential for life, and they play a variety of roles in the body. Carbohydrates are an important source of energy for the body. They are also used to store energy, and they are involved in a variety of other processes, such as cell signaling and the formation of DNA. Lipids are biomolecules. Biomolecules are the chemical compounds that make up living things. They are essential for life, and they play a variety of roles in the body. Lipids have a variety of functions in the body. They are used for energy storage, they help to form cell membranes, and they are involved in a number of other important processes. Nucleic acids are biomolecules. They are the molecules that store genetic information in all living organisms. There are two main types of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA is the genetic material of most organisms, while RNA is involved in the process of protein synthesis. The sequence of nucleotides in a nucleic acid molecule determines its function. The sequence of nucleotides in DNA determines the genetic makeup of an organism. The sequence of nucleotides in RNA determines the amino acid sequence of a protein. However, they are not nutritious biomolecules.

4343. Nucleo-histones are present in:

• A. Lysosome
• B. Ribosomes
• C. Chromosomes
• D. Mitochondria

Explanation: Option C is correct.Nucleohistones are present in chromosomes. They are a complex of DNA and histone proteins, which are responsible for packaging DNA into a compact structure. Nucleohistones are found in all eukaryotic cells, but they are most abundant in the nucleus.Histones are small proteins that are rich in basic amino acids. They have a positive charge, which allows them to bind to the negatively charged DNA. The histones wrap around the DNA, forming a nucleosome.

4344. Which of the following is the constituent or RNA molecule?

• A. Fatty acids
• B. Ribonucleic acid
• C. Ascorbic acid
• D. Deoxyribonucleic acid

Explanation: Option B is correct. Yes, ribonucleic acid (RNA) is the constituent of RNA molecules. RNA molecules are made up of nucleotides, which are composed of a sugar, a phosphate group, and a nitrogenous base. The sugar in RNA is ribose, while the sugar in DNA is deoxyribose. The phosphate group is the same in both DNA and RNA. The nitrogenous bases in RNA are adenine (A), guanine (G), cytosine (C), and uracil (U). Ribonucleic acid is a single-stranded molecule, while DNA is a double-stranded molecule. RNA is also found in the cytoplasm of cells, while DNA is found in the nucleus of cells.

4345. Type of RNA that is used to start process of replication in prokaryotic cell:

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

Explanation: Option D is correct. The type of RNA that is used to start the process of replication in a prokaryotic cell is RNA primase. RNA primase is a type of RNA polymerase that synthesizes short RNA primers that are about 10-12 nucleotides long. These primers are used to provide a starting point for DNA polymerase, which then extends the primers to form the new DNA strands. While tRNA,mRNA and rRNA are present in eukaryotic cells.

4346. Conjugated histone proteins are:

• A. Structural and regulatory
• B. Regulatory only
• C. Structure only
• D. Transport proteins

Explanation: Option A is correct. Conjugated histone proteins are a type of conjugated protein that are found in the nucleus of eukaryotic cells. They are composed of a protein core and a non-protein prosthetic group, which is typically a molecule of DNA. Histone proteins are essential for the structure and function of chromosomes. They help to package DNA into a compact form, and they also play a role in gene regulation. The structural role of histone proteins is to form nucleosomes, which are the basic units of chromatin. Nucleosomes are composed of a core of eight histone proteins, around which DNA is wrapped. The DNA is wrapped around the histone proteins in a helical fashion, and this helps to compact the DNA into a much smaller space. The regulatory role of histone proteins is to control the access of transcription factors to DNA. Transcription factors are proteins that bind to DNA and initiate the process of transcription, which is the process of copying DNA into RNA. Histone proteins can either promote or inhibit the binding of transcription factors to DNA, and this can affect the expression of genes.

4347. All of the following are conjugated molecules except:

• A. Glycolipids
• B. Nucleoproteins
• C. Glycoproteins
• D. All of these

Explanation: Option D is correct. Two different molecules belonging to different categories, usually combine together to form conjugated molecules. Glycolipids are conjugated molecules. Conjugated molecules are molecules that contain a non-protein prosthetic group, which is a group of atoms that is not part of the amino acid chain of the protein. In the case of glycolipids, the prosthetic group is a carbohydrate. Nucleoproteins are conjugated molecules. Conjugated molecules are molecules that contain a protein covalently linked to another molecule, such as a nucleic acid, a lipid, or a metal ion. The protein in a nucleoprotein is called a nucleoprotein. The nucleic acid in a nucleoprotein is either DNA or RNA. Glycoproteins are conjugated molecules. Conjugated proteins are proteins that contain a non-protein prosthetic group, such as a metal ion, a nucleic acid, or a lipid. The prosthetic group in a glycoprotein is a carbohydrate, which is why glycoproteins are also called glycoconjugates.

4348. Most of the cellular secretions are:

• A. Glycolipids
• B. Lipoproteins
• C. Glycoproteins
• D. Nucleoproteins

Explanation: Option C is correct. Yes, most of the cellular secretions are glycoproteins. This is because glycoproteins have a number of properties that make them well-suited for secretion. Glycoproteins are water-soluble: This means that they can easily dissolve in the extracellular environment. This is important for secretion, as it allows the glycoproteins to be transported out of the cell and into the extracellular space. Glycoproteins are resistant to proteolysis: This means that they are not easily broken down by enzymes. This is important for secretion, as it allows the glycoproteins to survive in the extracellular environment for long periods of time. Glycoproteins can interact with other molecules: The carbohydrate chains on glycoproteins can interact with other molecules, such as proteins, lipids, and carbohydrates. This allows glycoproteins to participate in a variety of cellular processes, such as cell-cell recognition, adhesion, and signaling.

4349. Type of conjugated molecules present in ribosomes:

• A. Glycolipids
• B. Nucleoprotein
• C. Glycoproteins
• D. Lipoproteins

Explanation: Option B is correct. Conjugated molecules are molecules that contain a non-protein prosthetic group, which is a group of atoms that is not part of the amino acid chain of the protein. In the case of ribosomes, the prosthetic group is RNA. Ribosomes are the cellular organelles that are responsible for protein synthesis. They are made up of rRNA and proteins, including nucleoproteins. Nucleoproteins are proteins that are covalently linked to nucleic acids, either DNA or RNA. The type of conjugated molecules present in ribosomes are ribonucleoproteins (RNP). RNP are molecules that contain RNA and protein. In ribosomes, the RNA is called ribosomal RNA (rRNA) and the protein is called ribosomal protein. Ribosomes are the cellular organelles that are responsible for protein synthesis. They are found in all living cells, and they are made up of rRNA and proteins. The rRNA makes up about 60% of the mass of a ribosome, and the proteins make up the remaining 40%.

4350. These are the most abundant organic compounds to be found in cells:

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

Explanation: Option D is correct. Proteins are the most abundant organic compounds in the cell, making up about 50% of the dry mass of cell.They are essential for many cellular processes, including structure, catalysis, and transport.