Mendelian ratios: memorization or punnet squares?

[tdod]

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obviously its easy to figure out the ratios via punnet squares, but i am wondering if time requires memorization of any of the basic ratios.


Thoughts?

 

[FeinMS]

If you usually run out of time, it wouldn't hurt to memorize some basic ratios such as monohybrid cross, dihybrid cross. However, you can always draw it out just in case you forget them.

 

[Jepstein30]

memorize as little as possible

being able to derive things quickly on test day >> rote memorization

 

[jetsfan1234]

There is no reason you need to memorize Punnett Squares. Actually, there is no reason you even need to diagram Punnett Squares, ever. You can figure out the ratios in about 5 seconds using simple multiplication.

Example: AaBbCc x AaBbCc. What is the change of having an AABBCC baby?

It's the same as the odds of AA x BB x CC, assuming unlinked genes.

Odds of AA: 1/2 from mother x 1/2 from father = 1/4 chance
Odds of BB = 1/4
odds of CC = 1/4

1/4 x 1/4 x 1/4 = 1/64.