# Combinations

• Jul 4th 2007, 05:12 PM
Raiden_11
Combinations
1. Two mating fruit flies each have one gene for black eyes and one for red eyes. The offspring receive one eye-colour gene from the male and one from the female.
a) Produce a tree diagram showing all the possible combinations for the offspring.
b) How many distinct combinations can be produced?
• Jul 4th 2007, 10:40 PM
earboth
Quote:

Originally Posted by Raiden_11
1. Two mating fruit flies each have one gene for black eyes and one for red eyes. The offspring receive one eye-colour gene from the male and one from the female.
a) Produce a tree diagram showing all the possible combinations for the offspring.
b) How many distinct combinations can be produced?

Hello,

to b):

[B, R] is the set of genes of the male fruit fly.
[b, r] is the set of genes of the female fruit fly.

(The genes labeled B and b have the same effect on the offspring. I only need a method to distinguish where the genes come from)

Then the offspring has the following sets of gene:

$\displaystyle [B, b]; \underbrace{[B, r]; [R, b]}_{\text{looking alike}}; [R, r];$

As you can see there are three different combinations.
• Jul 5th 2007, 09:59 AM
Raiden_11
I don't understand...?
I still don't understand........how do you figure out how many combinations there are and what about a).