Blue-eyed male (bb) x blue-eyed female (bb) Male parent
Parent genotype Gametes produced Offspring genotype • All of the offspring will be blue-eyed (bb). ? TEST TUBE
8. The gene for wet earwax (W) is dominant over the gene for dry earwax (w). a. Carry out two of the following genetic crosses: i. Male (WW) x Female (WW)
ii. Male (WW) x Female (Ww) iii. Male (Ww) x Female (Ww) iv. Male (ww) x Female (ww)
b. For each of the crosses, identify the percentage of offspring that will have: i. wet earwax ii. dry earwax
c. What term is used to describe individuals that are Ww?
Pedigree charts A pedigree chart is a type of family tree that shows patterns of inheritance. • Males are represented by squares. Females are represented by circles.
• A solid square or circle represents an affected individual. An open square or circle represents an unaffected individual.
• Roman numerals represent the generation. Normal numbers represent individuals. • Horizontal lines link a male and female who have a child. Vertical lines link a child to its parents.
Look at the following pedigree chart, which shows how albinism (lack of melanin) is inherited over three generations of a family:
I 1 2 3 4 II 56 8 III 10 11 79 12 13 : Fig. 4.12 A pedigree chart to represent the pattern of inheritance for albinism 36 Elements of Science
Female with albinism Male with albinism Female without albinism Male without albinism