Why Are Identical Twins Rare?

What is the main reason for everyone having different traits?

• Different hair colors

• Different eye colors

• Different combinations of genes

• Different skin colors

What determines our traits?

• Proteins

• Reproductive cells

• Genes

• Chromosomes

How do people inherit their genes from their biological parents?

• Through mitosis

• Through meiosis

• Through sexual reproduction

• Through asexual reproduction

How many pairs of chromosomes do humans have?

• 23

• 30

• 46

• 20

What is the main difference between fraternal twins and identical twins?

• Fraternal twins inherit the same genes

• Fraternal twins inherit different genes

• Fraternal twins are always of the same sex

• Fraternal twins are always of different sexes

How many times does fertilization occur in fraternal twins?

• Once

• Twice

• Never

• Three times

How do identical twins get identical genes?

• Through two separate fertilizations

• Through one fertilization and cell splitting

• Through asexual reproduction

• Through meiosis

What happens when a fertilized egg splits into two cells?

• Fraternal twins are formed

• No twins are formed

• Identical twins are formed

• Triplets are formed

What is the main reason for identical twins looking so much alike?

• They have the same traits

• They have the same reproductive cells

• They have the same chromosomes

• They have the same proteins

What is the source of all variation in humans?

• Mitosis

• Meiosis

• Asexual reproduction

• Sexual reproduction