Someone PLEASE help me understand this biology question!!!!!!!!

[redhen]

Quote:
HUH??? You lost me at the word "implied"

I'm to old for this crap, (it's my new mantra)

Rancher

I agree,..and i'm only 38..

 

[AquaEyes]

Dang, a genetics question, and I came late to the party.

I wonder if the original question's error was in the word "phenotype" or in the numbers in the ratio. In a typical Mendelian monohybrid classic dominant/recessive F1 X F1, the phenotypic ratio would be 3:1. In the same cross, the genotypic ratio would be 1:2:1.

The only time I can think of a phenotypic ratio being 1:2:1 would be for co-dominant alleles, such as the human ABO blood types. Two people with AB blood types would have a 1:2:1 ratio of offspring, respectively A:AB:B.

Polyploidy -- fun stuff. Without polyploidy, many of our food crops wouldn't exist, including domesticated wheat, which arose from an interspecies hybrid that spontaneously doubled its chromosomes from being a sterile triploid to being a fertile hexaploid. Strawberries can be octoploid, and generally it is assumed that the more pairs of chromosomes the plant has, the larger the fruit. Having an odd-number ploidy in plants (triploid, pentaploid, septaploid, etc) was assumed to cause infertility unanimously, but I know from my geekiness about roses that many triploid cultivars have been used for breeding (the Rosa genus contains species that are diploid, tetraploid, pentaploid, hexaploid and -- sometimes -- octaploid).

Only two mammal species I know of deviate from the "normal" diploid state -- two species of viscacha rat from South America are tetraploid.

 

[Heather118]

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Yes, I understand now. THANKS!!!!!!!!! I really appreciate your help!

 

[Heather118]

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Thank you very much for being rude, offensive, and downright judgemental. I AM NOT LAZY!
Not that you care, but I'll tell you what happened anyway. Our homework questions follow the book, but the sections are not labeled. I thought this topic was discussed in full in one section, but it was actually discussed in a later section. The book brushed the subject in the first section, but went into greater detail later. I answer the questions as I read, and because the book had not yet disgussed the topic in depth, I did not understand what the question was asking. When a topic is introduced in one section, often the index gives a page number for the intro, not the section where it goes into more depth. I found the answer later in my reading, but by that time I had already asked for help here.
And as for my "giving a quiz to the rest of you," you were under no obligation to read my question or reply. It seems to me that you were merely looking for a reason to be rude.

 

[dfr1973]

Heather, that's a rather odd layout for a textbook ... especially the index not listing every page the term is discussed (or even mentioned). Does it have a chapter summary at the end of each chapter? If so, I would skim over that at the start, then go back to the beginning of the chapter to read in0depth. Just a helpful tip from an "old" lady whose memory doesn't seem to work as well as it used to!

AquaEyes, join the fun! Great example of codominance (ABO types). My bloodbanking prof would be disappointed if she ever hears I forgot that one ... but what I remembered were the pretty flower pictures my genetics prof used to illustrate the difference between codominance and incomplete dominance (and as anticipated that was a question on the test!) The codominant flower was red and white splotchy/stripey while the incomplete dominance flower was a lovely shade of pink ... I still have not located my genetics text to verify which is which and suspect it's upstairs in my son's room, as I gave him permission to work through any of my old textbooks.

Polyploidy ... I have learned something new today.

 

[Heather118]

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It does have chapter summaries. You're right, I should start reading them first.

 

[AquaEyes]

Quote:
Thank you very much for being rude, offensive, and downright judgemental. I AM NOT LAZY!
Not that you care, but I'll tell you what happened anyway. Our homework questions follow the book, but the sections are not labeled. I thought this topic was discussed in full in one section, but it was actually discussed in a later section. The book brushed the subject in the first section, but went into greater detail later. I answer the questions as I read, and because the book had not yet disgussed the topic in depth, I did not understand what the question was asking. When a topic is introduced in one section, often the index gives a page number for the intro, not the section where it goes into more depth. I found the answer later in my reading, but by that time I had already asked for help here.
And as for my "giving a quiz to the rest of you," you were under no obligation to read my question or reply. It seems to me that you were merely looking for a reason to be rude.

Pay that person no mind. Some people don't like the light shone on things they themselves don't understand, and perhaps that poster felt uncomfortable not knowing something that you, a younger person, is learning in school right now. In other words, that post was more about the poster than about your question.

 

[Chickerdoodle13]

I'd have to agree with Aqua Eyes on this one. Phenotypically, a 1:2:1 ratio would deal with co-dominant alleles. Kind of a tricky question though if you are not paying attention!

 

[Marcymom3]

Quote:
HUH??? You lost me at the word "implied"

I'm to old for this crap, (it's my new mantra)

Rancher

me too

 

[RaZ]

Honey bees (Apis sp.) often exhibit a state called haplodiploidy that really throws off the 1:2 or 1:2:1 ratio since it's only the female offspring that have the condition.
According to our lecture today, the highest ploidy number is 38. The caveat being that research is ongoing and that number will likely get larger.
Also there can exist more that one ploidy condition within the same plant if a mutation occurs on the apical meristem.

Fascinating stuff indeed. But I'm a plant geek working on my master's degree

in Ecology.