Lipids Practice Questions
20 free Lipids practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which of the following is a characteristic property of all lipids?
- A They are highly soluble in water
- B They are generally water insoluble
- C They are always composed of nitrogenous bases
- D They are polymers of amino acids
Correct answer: They are generally water insoluble
Lipids are a diverse group of compounds that share the common property of being insoluble or poorly soluble in water. They are, however, soluble in organic solvents like ether and benzene.
A fatty acid is said to be 'saturated' if it:
- A Contains one or more double bonds
- B Has only single carbon bonds
- C Is linked to a phosphate group
- D Has a ring structure
Correct answer: Has only single carbon bonds
Saturated fatty acids lack double bonds between carbon atoms in their hydrocarbon chain. Unsaturated fatty acids, conversely, contain one or more double bonds.
How many carbons, including the carboxyl carbon, are present in Palmitic acid?
- A 16
- B 18
- C 20
- D 15
Correct answer: 16
Palmitic acid is a common saturated fatty acid found in plants and animals. It has a total of 16 carbons, with the formula CH3(CH2)14COOH.
Arachidonic acid is an unsaturated fatty acid that contains how many carbon atoms?
- A 16
- B 18
- C 20
- D 22
Correct answer: 20
Arachidonic acid is a polyunsaturated fatty acid with 20 carbon atoms, including the carboxyl carbon. It is a precursor for various signaling molecules like prostaglandins.
Glycerol, which is often found associated with fatty acids, is chemically:
- A Dihydroxy acetone
- B Tetrahydroxy butane
- C Monohydroxy ethane
- D Trihydroxy propane
Correct answer: Trihydroxy propane
Glycerol is a simple three-carbon sugar alcohol. Its chemical name is trihydroxy propane because it has three hydroxyl (-OH) groups attached to a three-carbon chain.
When one molecule of glycerol is esterified with three fatty acid molecules, the resulting compound is a:
- A Monoglyceride
- B Diglyceride
- C Triglyceride
- D Phospholipid
Correct answer: Triglyceride
Triglycerides are the main form of stored energy in animals. They are formed through ester linkages between the three hydroxyl groups of glycerol and three fatty acid chains.
Oils have lower melting points compared to fats. This is primarily because:
- A Oils are saturated
- B Oils contain more carbon atoms
- C Oils are found only in animals
- D Oils are typically unsaturated
Correct answer: Oils are typically unsaturated
Unsaturated fatty acids in oils prevent tight packing of molecules, resulting in lower melting points. For example, gingelly oil remains as a liquid even in winter.
Lipids that contain a phosphorylated organic compound are called:
- A Triglycerides
- B Glycolipids
- C Steroids
- D Phospholipids
Correct answer: Phospholipids
Phospholipids are compound lipids containing a phosphate group in addition to fatty acids and glycerol. They are fundamental components of biological membranes.
Lecithin is a classic example of a:
- A Simple fatty acid
- B Storage fat in adipose tissue
- C Nitrogen-free lipid
- D Membrane phospholipid
Correct answer: Membrane phospholipid
Lecithin is a common phospholipid that contains choline as a nitrogenous base. It is a major structural component of the plasma membrane in eukaryotic cells.
Which of the following lipids does NOT contain fatty acids or glycerol but is categorized as a lipid due to its solubility?
- A Cholesterol
- B Lecithin
- C Triglyceride
- D Palmitic acid
Correct answer: Cholesterol
Cholesterol is a sterol (a type of steroid) that has a complex ring structure. Although it lacks fatty acids, it is classified as a lipid because it is hydrophobic and soluble in organic solvents.
Neural tissues are particularly rich in which of the following?
- A Complex lipids
- B Simple triglycerides only
- C Pure glycerol
- D Saturated fatty acids only
Correct answer: Complex lipids
The nervous system contains a high concentration of complex lipids like sphingolipids and glycolipids. These are essential for the formation of myelin sheaths and cell signaling.
The chemical linkage formed between the carboxyl group of a fatty acid and the hydroxyl group of glycerol is a/an:
- A Peptide bond
- B Glycosidic bond
- C Ester linkage
- D Phosphodiester bond
Correct answer: Ester linkage
Esterification occurs when the -COOH group of a fatty acid reacts with the -OH group of an alcohol like glycerol. This results in the release of a water molecule and the formation of an ester bond.
Which of the following is considered a 'simple' lipid?
- A Fatty acids, glycerol
- B Lecithin phospholipid
- C Lipoprotein complexes
- D Chromolipid pigments
Correct answer: Fatty acids, glycerol
Simple lipids are esters of fatty acids with various alcohols. Fatty acids themselves and glycerol (or their simple esters like monoglycerides) are the most basic forms.
What is the general formula for a saturated fatty acid?
- A R-COOH
- B R-CHO
- C R-OH
- D R-NH2
Correct answer: R-COOH
A fatty acid consists of a carboxyl group attached to an R group. The R group can be a methyl, ethyl, or a higher number of CH2 groups (1 to 19 carbons).
Based on melting points, if a lipid is liquid at room temperature, it is called a/an:
- A Oil
- B Fat
- C Wax
- D Solid
Correct answer: Oil
The distinction between fats and oils is based on their physical state at room temperature. Lipids with lower melting points (oils) remain liquid, while those with higher melting points (fats) remain solid.
Phospholipids are described as 'amphipathic' because they contain:
- A Only hydrophobic parts
- B Only hydrophilic parts
- C Two chemically different types of glycerol
- D Hydrophilic and hydrophobic parts
Correct answer: Hydrophilic and hydrophobic parts
The phosphate group forms a polar, hydrophilic head, while the fatty acid chains form non-polar, hydrophobic tails. This dual nature is essential for forming the lipid bilayer of membranes.
In the structure of a cell membrane, the hydrophobic tails of phospholipids are protected from the aqueous environment because they point:
- A Towards the inner core
- B Towards the outer surface
- C Towards the nucleus only
- D Towards the cell wall
Correct answer: Towards the inner core
Phospholipids arrange themselves in a bilayer where the hydrophobic tails face each other in the center. This shields the water-fearing tails from the intracellular and extracellular fluids.
Which of the following is NOT a function of lipids in the body?
- A Energy storage
- B Structural component of membranes
- C Insulation and protection
- D Primary genetic material
Correct answer: Primary genetic material
Primary genetic material is composed of nucleic acids (DNA/RNA). Lipids serve as concentrated energy stores, structural barriers (membranes), and thermal insulators.
Lipids can be classified into three categories: simple, compound, and derived. Cholesterol falls under which category?
- A Simple lipids
- B Compound lipids
- C Derived lipids
- D Phospholipids
Correct answer: Derived lipids
Derived lipids are substances produced from the hydrolysis of simple or compound lipids, or they share similar physical properties. Steroids like cholesterol are considered derived lipids.
A monoglyceride consists of:
- A Two glycerols and a fatty acid
- B One glycerol and one fatty acid
- C One glycerol and three fatty acids
- D One glycerol and two fatty acids
Correct answer: One glycerol and one fatty acid
A monoglyceride is an ester formed from one molecule of glycerol and one molecule of a fatty acid. These are often intermediates in the digestion of triglycerides.