This weeks question on genitics. (Senior Scientific)

[gavin]

Just feel that I should congratulate Jane S on being spot on in every way. The question was good, and brown eyes (in this hypothetical example) come with yy which is at a frequency of 0.15 (15%) in the cross.

I do these things with proportions.

Gametes from the heterozygous female:

Y - 0.5 (lets say gamete i)
y - 0.5 (gamete ii)

Gametes from the drones:

Y - 0.7 (gamete iii)
y - 0.3 (gamete iv)

The combinations and proportions after fusion of the gametes at random are:

i x iii ie 0.5 x 0.7 = 0.35 as YY
i x iv ie 0.5 x 0.3 = 0.15 as Yy
ii x iii ie 0.5 x 0.7 = 0.35 as Yy
ii x iv ie 0.5 x 0.3 = 0.15 as yy

As Jane says, that is easier in a table of female x male gametes.

Only yy are brown eyed and they are at 0.15 or 15%. The rest (85%) are yellow-eyed.

As a check add up the proportions and they come to 1.0.

[Jane S]

Why, thank you!
Exam questions are meant to test your knowledge (on basic genetics, in this case) and your application of that knowledge. Exam candidates need to have that knowledge and be able to apply it, using the information in the question. Examiners could have used any colour, not just brown and yellow, to test this knowledge, or any other characteristic where there are two distinct different types. This basic genetics can be applied to anything, not just bees.

"Assume that bees have just two eye colours, yellow denoted by Y and brown denoted by y. If 30% of the drones that mate with a heterozygous yellow eyed queen are brown eyed drones . . . ": if there are only two eye colours and you have 30% of one colour - the inference is that the rest, 70%, are the other colour.
If the question had asked for a comment on your observations, then add it, but otherwise your comment would be wasted.

But Jon is right - in reality, any colour characteristic is determined by many genes operating together - a complicated soup indeed!

[Greengage]

Do you ever feel "I am sorry I started this"

[gavin]

Do you ever feel "I am sorry I started this"

Lol! Post #8 did looks like: 'OK. I've had enough now'!

But you are learning, right? If not, we can clarify!

G.

[Greengage]

Yes very enjoyable thanks, for all the info, some knowledgeable beekeepers on here, This is one of the better sites and because its a forum with topics people usually stick to it. Appreciate the answers.

[Mellifera Crofter]

... Exam questions are meant to test your knowledge (on basic genetics, in this case) and your application of that knowledge. Exam candidates need to have that knowledge and be able to apply it, using the information in the question. .... If the question had asked for a comment on your observations, then add it, but otherwise your comment would be wasted. ...

Yes, you're probably right, particularly with this question - but sometimes I've thought they're trying to trick us!

For example, in the March 2017 Module 8 exam, there was a short two point question (so, no big deal in terms of marks): 'What should be added to pollen to make a pollen substitute patty?' After I've wasted my two-point-worth of time answering what to use to make a pollen substitute patty, or perhaps what to add to pollen to make a pollen patty (I can't remember), I realised the question is bollocks, and then got flustered and wasted two more points of time explaining why the question doesn't make sense.

I think I've come across other examples - but I can't remember them now.
Kitta