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Science brain teasers require understanding of the physical or biological world and the laws that govern it.


Puzzle ID:#29006
Fun:*** (2.5)
Difficulty:*** (2.28)
Submitted By:bigSWAFF_69_Aus******




A female purebred white cat and a male purebred black cat had a litter of 12 kittens. Out of the 12 kittens, all but 3 were black. How many female kittens were there?

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Mar 09, 2006

I finially got one!!! Cool; thanks for the biological lesson!!
(user deleted)
Mar 09, 2006

Your first and most likely false assumption is that the genes that impart color are on the same chromosomes as those that impart the sex of the animal. Cats have 38 chromosomes, only two of which impart the sex of the animal. Unfortuately, genetics is not as simple as a recessive and dominate alleles, that's why a brown eyed mother and a blue eyed father can have a green eyed child.
Mar 09, 2006

Mar 09, 2006

Cool!!! You are so smart!!! You too, Cradier!!
Mar 09, 2006

Sorry, I mean Cradair!!!
Mar 09, 2006

Who got it? I got it, oh yeah, *dances*. The only reason I knew the hint is because we're learning about heredity and genetics in science, so it was easy.
Mar 09, 2006

uhmm, i got it but with a different method: i subtracted it, lol!!
Mar 10, 2006

i got ie, it was 9 females...
Mar 12, 2006

well the mothod is right for humans, but not necesarily correct for animals. there are plenty of multi colored cats to prove this.

As for the sex of the animal a "purebreed" white or black doesn't mean that 100% of it's children will be that color it's just a higher probability ask any breeder that's been doing it for a very long time and they will tell you that it wouldn't be the case for the colors to hold true. out of 12 cats there is a guarentee that 1 will probly be halfwhite/black. the only way for them to turn up true is in a controlled enviroment for many generations.

There is also the ever present random mutation. It guarentees that not all offspring will breed true to the parents
Mar 14, 2006

achnid, you're right.

When the pure black and pure white mix, you could end up with almost anything in cats. Tuxedo or even tabby striped orange kitties. Genetics for color in cats is not as set as it is for plants. Even mix two completely different human races and you come up with more of a mix than following one or the other parent.
Mar 16, 2006

Another fine teaser Swaff. I see that you'll be hitting the big 100 on your teasers in no time at all.
Mar 20, 2006

This may work based on logic, but not genetics.

Not a very good one imo.
Mar 20, 2006

Another fine example of flawed science. Don't we have someone on the site who screens these?
Mar 21, 2006

I just re-read this and the science behind it is MAJORLY FLAWED. With the male being the domiant purebred black cat it would make it where the was a dominant YX for black and a xx for white. all possible combinations are as follows:

Xx, Yx, xX, xY

there will be no white cats following these statements. I have sent a "correction asking to remove this teaser due to the seriously flawed science.

I apologize nothing personal the science is just flawed to make the teaser inacurate.
Mar 21, 2006

This teaser is flawed, because no matter what the color of the cat's fur, whether the cat is male or female is a 50-50 chance.
Mar 22, 2006

My head a-splode.
-Strong Bad
Mar 27, 2006

Someone read a book once...and now has too much time on their hands.
Apr 03, 2006

agree with wordscroll.. i think fur is not guarantee whether the kitten is female or male..
Apr 08, 2006

fur color(other then calico) is not a sex linked trait
Apr 09, 2006

Actually, the colors are, for the most part, located on the sex chromosomes, the X chromosome to be exact. Thats why only female cats can have mixed colors, because the two different X chromosomes are turned on in different parts of the body.

And I happened to get this one right, by the way.
Apr 10, 2006

MEOW meow!!

Apr 21, 2006

I also agree that the science is flawed. I had a white male cat and an orange striped female. All of the offspring were female.
Apr 30, 2006

from science last year, and the simplest Punnet Square, i got that all would be black, as the tom can only pass on the dominant allele

also, i thought that they would, hypothetically, have 50% male, 50% female kittens
Jun 14, 2006

The male could either pass on the X chromosome (the dominant black gene going to a female kitten) or the Y chromosome (no color gene attached going to a male kitten).

The only possible combinations of genes are:Xx or xY.

Xx = female black kitten (one dominant black and one recessive white allele)
xY = male white kitten (one recessive white and one Y chromosome with no color attached)

Although in real life, the outcome of all 12 kittens being of one color or another is somewhat unlikely, the basic genetics is correct.
Aug 19, 2006

I'm not good with genetics.
Oct 02, 2006

The genetics of cat coats is very complex. The teaser may be good for people just starting in genetics but anyone with a little knowledge will easily see the flaw.

I don't like to criticise, but to make the teaser better it would have helped if you stated what assumptions you were making in the question. i.e "Assuming that the colour of a cats coat was linked to the X and Y chromosomes ......"

As a bit of trivia, only about 1 in 3000 male cats have a tortoiseshell coat and this may because they have Klinefelter's syndrome (carrying an extra X chromosome), and will almost always be sterile. So if you see a tortoiseshell cat you could always bet a friend it is female, You will almost cirtainly win the bet (at least you will win a lot more than you lose)

For more information visit
Feb 11, 2007

Woot! we just learned about this!
Apr 16, 2007

I did like this teaser, and I have nothing against it.
However, it's true that the science is flawed. If it were simply a matter of probability, all anomolies and mutations aside, then it would be awesome.
But gender and color are not linked. So just because you have a male black cat and a female white one, it doesn't mean that you can't have a black female or white male. As someone mentioned earlier, the chance of either gender is 50%.
I would suggest making some minor changes so that it follows the rules of genetics, such as 'how many cats will be such-and-such a color?'
It's true that cats are prone to wild color deviations, but if you make a teaser to conform to probabilites as they should work out, then I think that it's fine. I mean, if you truely tried to incorporate mutations into a teaser, you would not have a teaser at all, but an impossible problem.

I love your teasers, Swaff! I think that this one could also be really awesome with a few changes.
Jun 14, 2007

Sorry, you are wrong and I am sorry that so many people believed you and are going around thinking what you said is true. This would be true IF color was a sex-linked trait, which it is not. It does not matter the sex of the kitten because color is on autosomal chromosomes, meaning each kitten (male or female) will receive an allele from their mother and father. Sex of the kitten has nothing to do with color.
Sep 27, 2007

you have a MAJOR flaw!!!
color and sex traits are from different genes!!!!!!!!!!(and so are other traits)so, you can have ressessive color genes, but dominate sex genes and vice versa!!!!!
Jan 11, 2008

I have nothing against you, but your teaser is messed up because of the scientifical error.
Nice idea, though!
Jul 30, 2008

Actually, there is truth to the fact that sex and color being linked as in the case of calico and tortise-shell cats. Like RedPython said, there is a VERY small chance of a male tortie or claico, due to the linkage.
Apr 17, 2011

It's a pity that this site won't remove teasers that contain incorrect information. Hopefully, people will read the comments and learn something from these rather than just accept the incorrect answer given.

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