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? asked in Science & MathematicsBiology · 9 years ago

Biology questions: Please check my answers!?

Where two alternatives for a trait are 'B' and 'b', the phenotype of a homozygous dominant individual would be expressed as

Bb.

bb.

BB.

none of the above

I'm stuck on this one because I think it's either BB or none of the above... BB because if it's homologous dominant, then it should be BB. However, it asks for PHENOTYPE, not genotype... so i'm unsure...

If two alternatives for a trait are red and white and red is dominant, the genotype of a homozygous dominant individual would be expressed as

ww.

WW.

RR.

red

rr

It's either RR or WW, but I'm not sure which because: I googled this question, and the answer it gave was WW, but I thought it was RR because the red is dominant... It was a pretty reliable source too (i use it all the time and it's never been wrong, but the question WAS worded differently)

To produce a hybrid plant you would cross-fertilize a heterozygous plant with a homozygous plant.

True

False

False because some results could be: (assuming BB and Bb crossed over) BB, BB, Bb and Bb..?

Not sure -.-

The recessive trait is not observed in the F1 (hybrid) progeny because its expression is masked by the dominant allele.

True

False

I think it's true because the parents phenotypes would be PP and pp...which means the plant's genotype is Pp...

I'm so unsure of these... I didn't need to you to completely do my hw, I just needed to check my answers; what do you guys think?

Update:

Shoot! I forgot one. :/

Mendel demonstrated from monohybrid crosses that alleles do not segregate during reproduction.

True

False

My textbook says "The pairs of alternative traits examined were segregated among the progeny of a particular cross, some individuals exhibiting one trait and some the other." That means true, right? o.O

2 Answers

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  • ?
    9 years ago
    Favorite Answer

    First question:

    What does homozygous dominant mean? Homozygous means 'same' so Bb is automatically ruled out. The dominant gene is expressed by the capital letter so BB is homozygous dominant. You're right, that phenotype means the physical characteristics, so I'm not sure? I believe it would be a mistake in your book?

    Second question:

    Assuming complete dominance, R is red and r is white. Homozygous dominant would be RR.

    Third question:

    You can produce at least ONE hybrid plant using the genotypes you have there, but ALL children will be hybrid plants if one parent is homozygous dominant and the other is homozygous recessive.

    Fourth question:

    I agree with what you said.

    Fifth question:

    I'm not sure, sorry :(

  • humanhamburger
    9 years ago

    1st Q. You should have more confidence in yourself. That question is designed to test your knowledge of the definitions. It asked you for phenotype, but all answers are genotypes.

    2nd Q. Which allele is dominant? Red. R. so homozygous dominant is RR.

    Q3 can be interpreted in different ways based on the information given. I can see the 'correct' interpretation from my mindset, but don't know if it is right for your assignment. ( I'm thinking about a test cross)

    Q4 seems to be tied into 3.

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