1. TEST CROSSES

2. TESTCROSS used to tell what genes an organism has
Example: The genes of a TALL PARENT are UNKNOWN
- COULD HAVE _____
BOTH LOOK ALIKE !

3. TESTCROSS used to tell what genes an organism has
Cross an UNKNOWN parent with a ____________________________
and see results
Offspring give a clue about the
unknown parent’s genes

4. TESTCROSS t 50% will be TALL All offspring will 50% will be SHORT
T T
T t t t
50% will be TALL
50% will be SHORT
All offspring will
be TALL

5. DEAF DOGS
Deafness in dogs is caused by a recessive allele. Deaf dogs have the genotype dd.
A HEARING dog could have 2 possible GENOTYPES
______ ______
How do we tell which one it is?

6. TESTCROSS HEARING PARENT WITH DEAF PARENT
D D
D d d d
If you get some deaf puppies, you know
parent genotype was Dd NOT DD.

7. DRAGONS Firebreathing (F) in dragon is a dominant trait
Firebreathing (F) in dragon is a dominant trait
NON-firebreathing (f) is recessive.
A firebreathing dragon could have 2 possible GENOTYPES
______ ______
How do we tell which one it is?

8. TESTCROSS FIREBREATHING PARENT WITH NON-FIREBREATHER
F F
F f f f
If you get some NON-fire breathing dragons you know parent genotype was Ff NOT FF.