in humans brown eyes(B) is dominant over blue if 2 heterozygous parents have kids what is the probability they

Question

a] the first kid will be a boy?
b]the first 2 kids will have blue eyes?
c]the first 2 kids will be blue eyed girls?
d]4 kids will be brown eyed boys?

YA THIS IS A HIGH SCHOOL QUESTION FYI.

Answer 1

Ummm I don't know I'm still in High School sorry.

Answer 2

Sounds like a science question from homework, anyway, it's all really a case of probablity. This can be solved through the use of a punnet square however. I can't really illustrate that however, so I'll try to explain.

Heterozygous means they have two different genes. I'm assuming B for the dominant Brown, and b for the recessive blue. The dominant, in a heterozygous pair, always dominate over the blue, so someone may be Brown eyes, but have Bb for thier genetic code. The Brown always overrides the recessive blue. To have blue eyes, one must have both b recessive genes.

Also, one must take the chances of male, or female, which is a 50%, The females always donates and X, while the male has a 50% chance of donation an X or a Y

The total combinations are

BBXX - 1/8 - Brown Eyes Female
BBXY - 1/8 - Brown Eyes Male
BbXX - 1/4 - Brown Eyes Female
BbXY - 1/4 - Brown Eyes Male
bbXX - 1/8 - Blue Eyes Female
bbXY - 1/8 - Blue Eyes Male

Blue Eyes - 1/4
Brown Eyes - 3/4

Brown Eyed Boy - 3/8
Brown Eyed Girl- 3/8

Blue Eyed Boy- 1/8
Blue Eyed Girl- 1/8


So to solve your problems...

A -The probability of a boy? 50%, that's a given
B - That is 1/4 multiplied by 1/4, or 1/16 chance
C- That is 1/8 multipled by 1/8, or 1/64
D - That's 3/8 times 3/8 times 3/8 times 3/8, or 3/8^4, or 81/4096

Hope that helps you out =D

Answer 3

The probability of having a blue-eyed child is 1/4
The probabilty of having a brown-eyed child is 3/4

Answer 4

assuming eye color is unrelated to gender (i.e. blue can occur in both X and Y chromosome):

a 1/2

b 1/16

c 1/16

d 1/8^4 = 1/4048

Answer 5

a) .5
b) 1/16
c) 1/64
d) .019

Answer 6

(a) 50%
(b) 6.25%
(c) 1.5625%
(d) 1.978%