Explain with the help of a flow chart that in human beings father is responsible for the sex (male or female) of the child.
Generated by claude-sonnet-4-6 · 2026-06-15 06:53 · grounding rag
Model Answer
Flow Chart:
$$\text{Father (XY)} \xrightarrow{\text{produces}} \begin{cases} \text{Sperm with X} \\ \text{Sperm with Y} \end{cases}$$
$$\text{Mother (XX)} \xrightarrow{\text{produces}} \text{Egg with X only}$$
- X sperm + X egg → XX → Girl
- Y sperm + X egg → XY → Boy
Since the mother always contributes X, the sex of the child depends on whether the father contributes X or Y chromosome. Thus, the father is responsible for determining the sex of the child.
Source: Chapter 8, Section 8.2.4 – Sex Determination
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Explanation
- The examiner wants a flow chart (arrows showing the cross) plus a one-line conclusion — both are needed for full 2 marks.
- Key point: mother is always XX, so only the paternal chromosome (X or Y) decides the sex.
- Avoid writing long paragraphs; the flow chart itself carries most marks here.