• Analysis of Carbohydrate and Nucleotide Subunits:
• Statement 1: Glycogen is a branched polymer of $\alpha$-D-glucose units. (Correct).
• Statement 2: Cellulose is an unbranched polymer of $\beta$-D-glucose units. (Correct).
• Statement 3: "Lactose is formed from units that include ribose" (Incorrect / False):
• Lactose is a disaccharide formed by $\beta(1\rightarrow 4)$-linked D-galactose and D-glucose, containing zero ribose.
• Statement 4: Adenosine is a purine nucleoside formed from adenine and D-ribose. (Correct).
• nalysis:
• Statement 3 is incorrect, hence the correct answer.

• Cellular Differentiation:
• The developmental process whereby a generic, unspecialized stem or progenitor cell undergoes selective, coordinated gene expression changes to develop stable morphological and biochemical attributes, adopting a specialized physiological role (e.g., neuron, hepatocyte, cardiomyocyte, erythrocyte).
• nalysis:
• (adoption of a specialized physiological role by a cell): Correct definition.

Correct option: (4) adoption of a specialized physiological role by a cell

• Lipid Composition of Animal Plasma Membranes:
• Phosphoglycerides (Glycerophospholipids) constitute the overwhelming majority ($\gt 50 - 70\%$) of the total phospholipid content of animal cell membranes.
• Consist of a glycerol backbone esterified to two fatty acid chains and a phosphorylated polar alcohol headgroup:

• Sphingolipids (sphingomyelin) constitute a minor fraction concentrated in lipid rafts.
• nalysis:
• (Phosphoglycerides): Correct.

Correct option: (1) Phosphoglycerides.