Dr. Register's Science Resources

Genotype and phenotype

Instructions:

In a basic cross using one trait which occurs as a dominant/recessive, a possibility of four different genotypes can be produced. The following examples include crosses between parents who are pure for the trait tall (TT), pure for the trait short (tt), or hybrid (Tt). For each cross you will determine which offspring are possible in terms of genotype, and what the appearance of the offspring will be in terms of phenotype. (Be sure and include your first and last name in the space provided at the bottom!)

Figure 1: Questions 1-3

	T	T
T
T

1. Which four offspring are possible from this match?

2. How many of the offspring look tall?

3. How many of the offspring look short?

Figure 2: Questions 4-6

	T	T
T
t

4. Which four offspring are possible from this match?

5. How many of the offspring look tall?

6. How many of the offspring look short?

Figure 3: Questions 7-9

	T	T
t
t

7. Which four offspring are possible from this match?

8. How many of the offspring look tall?

9. How many of the offspring look short?

Figure 4: Questions 10-12

	t	t
T
T

10. Which four offspring are possible from this match?

11. How many of the offspring look tall?

12. How many of the offspring look short?

Figure 5: Questions 13-15

	t	t
T
t

13. Which four offspring are possible from this match?

14. How many of the offspring look tall?

15. How many of the offspring look short?

Figure 6: Questions 16-18

	t	t
t
t

16. Which four offspring are possible from this match?

17. How many of the offspring look tall?

18. How many of the offspring look short?

Figure 7: Questions 19-21

	T	t
T
T

19. Which four offspring are possible from this match?

20. How many of the offspring look tall?

21. How many of the offspring look short?

Figure 8: Questions 22-24

	T	t
T
t

22. Which four offspring are possible from this match?

23. How many of the offspring look tall?

24. How many of the offspring look short?

Figure 9: Questions 25-27

	T	t
t
t

25. Which four offspring are possible from this match?

26. How many of the offspring look tall?

27. How many of the offspring look short?

First and Last Name:

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