**Question:** Punnett square is used to -

A. Determine the probability of offspring genotypes in a given pedigree
B. Calculate the heritability of a trait
C. Measure blood pressure in a patient
D. Assess the risk of genetic disorders in a family

**Core Concept:** A Punnett square is a visual aid used in genetics to predict the possible genotypes of offspring in a given pedigree, considering the genotypes of parents and the mode of inheritance of a specific trait.

**Why the Correct Answer is Right:**
A Punnett square is a square grid that represents the possible combinations of genotypes (abbreviated as A, B, C, etc.) for two heterozygous parents (e.g., BB × BB). By counting the number of correct combinations (e.g., BB × BB would have 16 combinations) and multiplying them, we can determine the probability of offspring genotypes.

**Why Each Wrong Option is Incorrect:**

B. Heritability calculation: A Punnett square is not used for calculating heritability, which is the proportion of phenotypic variation in a population that can be attributed to genetic factors. Heritability calculations involve statistical methods and population-based studies.

C. Blood pressure measurement: A Punnett square is not used for measuring blood pressure but for predicting offspring genotypes in a pedigree. Blood pressure measurement involves clinical examination and instrumental methods like sphygmomanometer.

D. Genetic disorder risk assessment: A Punnett square is primarily used for genotype prediction and does not directly assess the risk of genetic disorders. Risk assessment requires a thorough clinical evaluation, family history, and knowledge of specific genetic disorders and their inheritance patterns.

**Clinical Pearl:** Understanding Punnett squares is essential for genetic counselors, geneticists, and medical professionals dealing with genetic disorders. It helps predict genotype combinations and understand the inheritance patterns, which is crucial for genetic counseling and disease management.