Stem Cells

The question asks for the two key properties that classify a cell as a stem cell. These are the defining features that distinguish stem cells from other cell types.

A stem cell is defined as an undifferentiated cell with two critical properties: self-renewal (the ability to copy itself through mitosis, maintaining a pool of unspecialised cells) and differentiation (the ability to develop into specialised cell types under the right conditions).

The option 'Self-renewal and differentiation potential' directly matches both defining properties of stem cells. Neither specialisation, antibody production, nor structural features like a large nucleus are defining properties of stem cells.

We need to find the two core properties that define a stem cell — not features of differentiated cells or unrelated cellular characteristics.

Specialisation is the opposite of what stem cells do — stem cells are unspecialised. This option contradicts the definition of a stem cell and can be eliminated immediately.

Antibody production is a function of specialised immune cells (B cells), not stem cells. Stem cells divide by mitosis, not meiosis. Both features in this option are incorrect.

These are structural features and do not represent functional properties that define stem cells. In fact, mature red blood cells lack a nucleus, but they are differentiated cells, not stem cells.

'Self-renewal and differentiation potential' is the only option that correctly identifies the two defining functional properties of a stem cell.

The question tests understanding of what actually changes during differentiation. A common misconception is that differentiation involves changes to DNA, but this is incorrect.

Every cell in your body contains the same complete DNA (the full genome). Differentiation does not change the DNA sequence — it changes which genes are expressed (switched on or off). A liver cell and a skin cell have the same DNA, but different genes are active.

When a stem cell differentiates into a red blood cell, genes controlling haemoglobin production are switched on and other genes are switched off. The DNA itself remains unchanged — this is the principle of gene expression, not genetic modification.

The correct answer is: 'No change — the full DNA sequence is retained in all body cells.' Differentiation is about gene expression, not gene changes.

We need to determine what happens to the DNA specifically during differentiation into a red blood cell — not what happens to the cell's shape or function.

Genes are not added to a cell's DNA during differentiation. All body cells already contain the gene for haemoglobin — it is simply switched on during red blood cell development.

Genes are not deleted during differentiation. Even cells that don't use certain genes still retain them. Differentiation involves switching genes off, not removing them.

Halving of DNA occurs during meiosis (formation of sex cells), not during differentiation. Differentiated body cells are diploid and retain the full DNA complement.

The only scientifically accurate option is: 'No change — the full DNA sequence is retained in all body cells.' Differentiation operates through gene expression, not DNA modification.