1. Inheritance: The transmission of certain characteristics from the parents to the children.

2. Genes control certain characteristics in an organism.

3. Allele: a pair of genes at the same locus 

• Type of allele
  • Dominant allele
  • Recessive allele
• The characteristics are usually controlled by dominant allele and characteristic from recessive allele will be covered.
• Dominant allele - represented by capital letter
• Recessive allele - represented by small letter

4. 

• The father determines the gender of the offspring because:
  • Sperm carries sex chromosome x and y while ovum only carries chromosome x