A continuously varying trait need not have an exact bell-shaped distribution.

In the simplified model with no genotype-environment covariance or interaction, which components sum to phenotypic variance?

• Additive and nonadditive genetic variance
• Parental and offspring phenotypic variance
• Genetic and environmental variance

Which ratio defines broad-sense heritability H²?

• Genetic variance / phenotypic variance
• Environmental variance / phenotypic variance
• Phenotypic variance / genetic variance

Use V_P = V_G + V_E. Genetic variance stays at 40 while environmental variance falls from 40 to 10. What happens to H²?

• It rises from 0.5 to 0.8
• It falls from 0.5 to 0.2
• It stays at 0.5 in both settings

Genetic variance is 48 and phenotypic variance is 120. Enter broad-sense heritability as a decimal.

Which genetic variance component is the numerator of narrow-sense heritability, used in the basic selection-response prediction?

• The dominance variance component
• The additive variance component
• The gene-interaction variance component

A report gives H² = 0.6 for a test score in one population. A reader says genes caused 60 percent of their own score. What is the interpretation error?

• A population variance ratio is treated as an individual cause ratio
• A decimal variance ratio is treated as invalid unless written as a percentage
• A population variance ratio is treated as requiring an exact bell-shaped curve

Seedlings are randomly assigned to groups with matching genetic distributions. Only nutrient supply differs. The better-fed group grows taller on average. What does this show?

• Genetic differences cannot affect any height variation within either group
• The difference between group means directly measures each group's heritability
• Environment can change the mean without a genetic difference