CP Biology – Inheritance Practice Test 2026 - Free Practice Questions and Study Guide

Offspring inherit traits through one allele from each parent for every gene. Organisms are diploid, carrying two alleles for most genes, and the gametes that unite during reproduction carry just one allele per gene. When a sperm fertilizes an egg, the zygote obtains one allele from the father and one from the mother for each gene, restoring two alleles and shaping the trait combination. This explains why offspring often resemble both parents and why dominant alleles can mask recessive ones. The other ideas don’t fit with how sexual reproduction works: traits aren’t determined by only one parent, or by taking two copies from the same parent, or by not inheriting alleles at all.