Which row is correct for parts of a phospholipid molecule?
▶️ Answer/Explanation
Ans: D
In phospholipids, the tails (fatty acid chains) can be saturated or unsaturated, and these same tails are found in triglycerides. The head group is always polar and identical in phospholipids, not variable like the tails. Therefore, the correct answer is D.
Which statements could be used to describe enzyme molecules and antibody molecules?
- Hydrogen bonds stabilise the structure of the protein and are important for it to function efficiently.
- Hydrophilic R-groups point in to the centre of the molecule and cause it to curl into a spherical shape.
- The tertiary structure of the protein molecule plays an important role in the functioning of the protein.
▶️ Answer/Explanation
Ans: C
Statement 1 is correct as hydrogen bonds maintain protein structure. Statement 3 is correct as tertiary structure determines function. Statement 2 is incorrect because hydrophobic (not hydrophilic) R-groups point inward. Therefore, the correct combination is 1 and 3 only.
Which description lists all the components of a human haemoglobin molecule?
▶️ Answer/Explanation
Ans: D
Human hemoglobin has 4 polypeptide chains (2 α and 2 β – not identical) and 4 haem groups (each binding one O₂ molecule). Options A/B are wrong about haem count, C is wrong about polypeptide identity.
The diagram shows a triglyceride.
What will be the products after hydrolysis of this triglyceride?
▶️ Answer/Explanation
Ans: B
Triglycerides hydrolyze into 1 glycerol and 3 fatty acids. The diagram shows 2 saturated (no double bonds) and 1 unsaturated (with double bond) fatty acids. Glycogen (A/C) is incorrect as it’s a carbohydrate, not a lipid breakdown product.