Free Biological Molecules MCQs with Answers
1,790 Biological Molecules MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
The chapter covers water's polarity and biological roles, carbohydrates, lipids, proteins and nucleic acids, including their monomers, bonds, structures and functions. It also distinguishes RNA from DNA and explains conjugated molecules such as glycoproteins, glycolipids and nucleoproteins, which combine organic molecules with a non-protein component.
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1741. Lipids are chemically
- A. Acids
- B. Alcohols
- C. Ethers
- D. Esters
Explanation: Lipids are chemically classified as esters because they are formed through a reaction between fatty acids and an alcohol (typically…
Correct answer: Esters- A. Proteins
- B. Amino acids
- C. Carbohydrates
- D. Esters
Explanation: Lipids are predominantly made up of fatty acids and glycerol. The ester bond formed between these components categorizes lipids as esters.
Correct answer: Esters1743. Saponification of a fat:
- A. Always results in the formation of soaps.
- B. Results in the formation of esters.
- C. Results in the formation of waxes.
- D. Results in the formation of glycerol and soap.
Explanation: Saponification is a chemical process where fats or oils react with an alkali, such as sodium hydroxide (NaOH) or potassium hydroxide…
Correct answer: Always results in the formation of soaps.- A. Monohydroxy alcohols
- B. Dihydroxy alcohols
- C. Trihydroxy alcohol
- D. All of the above
Explanation: Waxes are esters formed from the reaction of fatty acids with long-chain monohydroxy alcohols, which have one hydroxyl group.
Correct answer: Monohydroxy alcohols- A. Presence of single bonds between carbon atoms.
- B. Presence of Double bonds between carbon atoms
- C. Presence of Triple bonds between carbon atoms.
- D. Absence of bond between carbon atoms.
Explanation: Saturated fatty acids contain a single bond between the carbon atoms, this is a fact
Correct answer: Presence of single bonds between carbon atoms.- A. Palmitic acid
- B. Archachidic acid
- C. Stearic acid
- D. Oleic acid
Explanation: Option D is correct. Oleic acid is the unsaturated fatty acid. Fatty acids are classified into saturated and unsaturated fatty acids.
Correct answer: Oleic acid- A. Inside the nucleus
- B. Inside the cytoplasm
- C. Inside the plasma membrane
- D. inside the mitochondrial matrix
Explanation: Option C is correct.Phospholipids arrange themselves in a bilayer in the plasma membrane of a cell.
Correct answer: Inside the plasma membrane- A. Valine acid
- B. Alamine acid
- C. Arginine acid
- D. Methionine acid
Explanation: Sickle cell anemia results from the single amino acid substitution of valine for glutamic acid in the beta-chain owing to a nucleotide…
Correct answer: Valine acid- A. Amino groups on the amino acids
- B. R- groups on the amino acids·
- C. Peptide bonds
- D. Amino acids sequences within protein molecules
Explanation: Diversity refers to different types of proteins.
Correct answer: R- groups on the amino acids·- A. Hydrogen groups of adjacent amino acids
- B. Functional group of the amino acids
- C. Carboxyl group and amino group
- D. Functional group and hydrogen group of adjacent amino acid
Explanation: Carboxyl or COOH- a group of one amino acid and Amine or NH3+ of another Amino acid are responsible for forming peptide bonds.
Correct answer: Carboxyl group and amino group1751. Myoglobin combines with:
- A. Four oxygen molecules
- B. Three oxygen molecules
- C. Two oxygen molecules
- D. One oxygen molecule
Explanation: Myoglobin is a protein found in muscle tissues with a tertiary structure comprising a single polypeptide chain.
Correct answer: One oxygen molecule- A. Hairs
- B. Haemoglobin
- C. Muscle cells
- D. Nails
Explanation: Hemoglobin is indeed an example of a globular protein. It's a protein found in red blood cells that helps transport oxygen throughout the…
Correct answer: Haemoglobin- A. Renin
- B. Insulin
- C. Caesin
- D. Prolactin
Explanation: Casein is a type of protein that is naturally present in milk. It makes up about 80% of the total protein content in cow's milk.
Correct answer: Caesin- A. Proline
- B. Glutamine
- C. Valine
- D. Glycine
Explanation: Option C is correct. In sickle cell anemia, glutamic acid in the hemoglobin molecule is replaced by valine.
Correct answer: Valine- A. R-group
- B. Amino group
- C. Carboxyl group
- D. Hydrogen of alpha carbon
Explanation: Option A is correct.Amino acids mainly differ from each other by the difference in their R-group.
Correct answer: R-group- A. Coordinate bond
- B. Covalent bond
- C. Hydrogen bond
- D. Ionic bond
Explanation: Hydrogen bonds play a crucial role in determining the secondary structure of proteins.
Correct answer: Hydrogen bond- A. Thymine
- B. Adonine
- C. Guanine
- D. Cytosine
Explanation: DNA contains the following bases: adenine, guanine, cytosine, and thymine.
Correct answer: Thymine- A. TAC
- B. UAC
- C. AUG
- D. CCA
Explanation: Anticodons are as follow:A = U( in case of RNA)A=T ( in case of DNA)C=G( same in both cases)
Correct answer: UAC- A. Mg+ ions
- B. Na- ions
- C. Proteins
- D. Ribosomal RNA
Explanation: The attachment of two subunits of ribosomes on a single mRNA is controlled by Mg2+ ions.
Correct answer: Mg+ ions- A. 2
- B. 3
- C. 5
- D. 4
Explanation: Building blocks of nucleic acids, i.e., DNA and RNA. A nucleotide consists of a sugar molecule attached to a phosphate group and a…
Correct answer: 3