Genetics Worksheet (Page 3 of 8) in pdf

Genetics Worksheet Page 3

Let’s try something a little harder.

8. In Squid people, the allele for light blue skin (B) is dominant over the green (b) allele. Everyone in

Squidward’s family has light blue skin. His family brags they are ‘purebred’ line. He recently married a

nice girl with light green skin, which is recessive. What are the possible offspring outcomes? Would the

children still be considered ‘purebred’? Why or why not?

9. In goats, a recessive gene causes the goats to ‘faint’ when they are startled. A farmer breeds two

goats (that have never fainted) and their first offspring faints two days after its birth. What must the

parent’s genotypes have been? _____ x ______

10. Two short-haired guinea pigs are mated several times. Out of 100 offspring, 25 of them have long hair.

What are the probably genotypes of the parents? ______ x ______

11. A tall plant of unknown genotype is test-crossed. Of the offspring, 869 are dwarf and 912 are tall. What

is the genotype of the unknown parent? ______

12. In humans, tongue rolling is a dominant trait. Those with the recessive condition cannot roll their

tongues. Bob can roll his tongue, but his mother could not. He is married to Sally, who cannot roll her

tongue. What is the probability that their first born child will not be able to roll his tongue? __________

13. If both parents are heterozygous for both traits, what are the expected phenotypes of their offspring

and in what proportion?

14. If out of 100 offspring, 52 have red eyes and 48 have brown eyes. What are the probably genotype

and phenotype of the parents?

15. A round (R) seed plant is dominant to a wrinkled (r) seed plant. What parental genotypes will produce

offspring that are 50% homozygous dominant and 50% heterozygous?

 On the “Websites-Genetics” page, click on the links and practice monohybrid crosses ----‘Punnett square

animation’, ‘Practice crosses’, ‘Practice problems’.

Genetics Worksheet Page 3