How many chromosomes do human body cells contain?

How many chromosomes do human sex cells contain?

What are alleles?

What are homozygous genes?

What are heterozygous genes?

How do the sexual reproduction genes from each parent produce variation in offspring?

Why do siblings differ from each other?

What traits will somebody show if they have...a.) one dominant allele and one recessive allele
b.) two recessive alleles
c.) two dominant alleles

How do human males determine the sex of the offspring?

What's the difference between the genotype and the phenotype?