If I handed you a black guinea pig & asked, “What’s its phenokind for hair color?” You would certainly gently organize the guinea pig, look at it and reply, “Black, you dummy … all you gotta carry out is look at it”. And I would certainly say, “Correct, & please don’t speak to me dummy”.

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If I handed you the exact same guinea pig & asked, “What’s the genotype of this guinea pig via respect to its fur color?” You wouldn’t have the ability to tell me, and also I wouldn’t have the ability to tell you either.

The reason we don’t know is that there are 2 genokinds that BOTH create a dominant trait phenoform, homozygous leading (BB) & heterozygous (Bb), & we can’t watch the actual alleles (letters) without severe clinical chromosomal-kind analysis — and that’s assuming that a Guinea Pig Genome Project has been completed for us to describe, & I don’t think it has actually.

So just how execute we number it out? We percreate a TEST CROSS !

What is it?

Test cross = the cross of an organism via an unknown leading genotype through an organism that is homozygous recessive for that trait

What does it do?

A test cross deserve to determine whether the individual being tested is homozygous dominant (pure bred) or heterozygous dominant (hybrid).

See more: Why Was The Battle Of Midway Important Quizlet, Chapter 12, Section 5



To perform an actual test cross through our black guinea pig, we would certainly require a guinea pig (of the opposite sex) that is homozygous recessive (“bb”). In various other words, we would certainly need a white guinea pig to mate through our babsence guinea pig.

We would provide them a tiny privacy, hope that the female becomes pregnant, wait for but lengthy the gestation duration of a guinea pig is, & THEN we would look at the offspring.

If any type of of the offspring from a test cross have actually the recessive trait, the genokind of the parent with the dominant trait have to be heterozygous The relicapability of a test cross rises through the number of offspring developed.

“Key Points” to remember around a TEST CROSS:

1. the organism via the leading trait is always crossed with an organism with the recessive trait

2. if ANY offspring show the recessive trait, the unrecognized genokind is heterozygous

3. if ALL the offspring have actually the leading trait, the unwell-known genoform is homozygous dominant