Cell Division & Genetics

Academic Context

Modern Montessori School Middle Years Programme Biology Year Level: 5 students are evaluated on a unit titled Cell division and Genetics / Stretch Task. The assessment follows Middle Years Programme (MYP) Criterion A — Knowing and Understanding, Criterion B — Inquiring and Designing, Criterion C — Processing and Evaluating, and Criterion D — Reflecting on the Impacts of Science. The teachers for this course are Muna, Ala, and Asem.

Genetic Disorders Comparison

A mammalian population expresses two genetic conditions with distinct molecular profiles and phenotypic outcomes. Disorder $X$ is a point mutation caused by a single base substitution in a gene encoding an essential enzyme; it causes metabolic defects but allows survival through reproductive age. Disorder $Y$ is a chromosomal mutation involving the duplication of an entire chromosome, which typically results in death before reproductive age. The increased severity of Disorder $Y$ is due to gene dosage imbalances that disrupt cellular function more extensively than the localized protein function changes seen in Disorder $X$.

Questions & Discussion

(a) Identify the type of mutation for Disorder $X$ and Disorder $Y$. Explain the difference at the molecular or chromosomal level.

(b) Predict and justify how Disorder $X$ might affect protein function differently from Disorder $Y$.

(c) Explain why Disorder $Y$ has more severe phenotypic effects than Disorder $X$, using your understanding of gene dosage and cellular function.

(d) Discuss how the survival differences between individuals with Disorder $X$ and Disorder $Y$ would influence the frequency of these mutations in the population over multiple generations.