VCAA 2001 EXAM HELP!!!!!!!!!

[davyp3]

vcaa q8 multiple choice

In peach plants the presence or absence of hairs on friuit and colours of fruit flesh are under the control of two unlinked genes. the alleles of these two genes are as follows:


Hair on fruit:     H   Hair present
                      h   no hair present

Fruit Colour:      W yellow flesh
                       w white flesh


iN A TEST CROSS OF PLANTS, HETEROZYGOUS AT THESE TWO LOCI, IT WOULD BE REASONABLE TO EXPECT THAT:


 a) three quarters of the fruit would have hair
b)half of the fruit would have white flesh
c)all of the fruit with ahir would have yellow flesh
d)three quarters of the furit would have white flesh



whats the answer, are we crossing two heterozygous individuals or a test cross ( i think is heterzygous x homo recessive)?


answer is B

help please

[cipherpol]

http://vcenotes.com/forum/index.php/topic,18556.msg188642.html#msg188642

[Stojad]

If it says 'test cross', one individual must be homozygous recessive for both traits concerned, having the genotype hhww (hence, producing only hw gametes).

Because it states probabilities of individual traits, do a monohybrid cross of each trait concerned. The answer is not A, because from a cross of Hh x hh, 50% of the fruit have hair. The answer cannot be C because it assumes that traits are linked, where the question states they are unlinked. The answer cannot be D because a cross of Ww x ww produces 50% white flesh fruit. This leaves B as the correct answer.