The following are F₂ results of two of Mendel's monohybrid crosse...

Question

The following are F₂ results of two of Mendel's monohybrid crosses.

(a) full pods 882
constricted pods 299
(b) violet flowers 705
     white flowers 224

For each cross, state a null hypothesis to be tested using x² analysis. Calculate the x² value and determine the p value for both. Interpret the p values. Can the deviation in each case be attributed to chance or not? Which of the two crosses shows a greater amount of deviation?

Accepted Answer

Hi everyone. Let's look at the next question. And p plants the height of the plant. It's a genetic trait that has two distinct types. Tall and short. The alley for tall height is completely dominant over the illegal for short height And a cross between two p plants that are hybrids for height, we obtained 100 offspring. Which of the following is the correct number of phenotype. So among the offspring. So we have to parent plants that are hybrids for height. So we know that the two parents crossed must be big T little T crossed with big T, little T. And we are asked to find out the correct number of phenotype sis. So phenotype will be either tall or short. So always good to remember whether we're looking for phenotype or genotype sis. So let's just look at our basic punnett square here and for a cross like this. Pretty straightforward. We know we have 25% homocide is dominant And then 50% hetero sagas and 25% homesickness. Recessive. Those are the gina types. So in terms of phenotype sis, I'm gonna highlight in yellow. All these of course with the one big T. Gene are going to be tall And that's going to be 75%. So there will be short plants. It's made very simple for us since we have 100 offspring. So we should expect somewhere around 25 short plants and 75 tall plants. So when we look at our answer choices, we see choice A says tall plants. 52 short plants. 48. Well that's more like 50 50. So not going to be our answer choice choice B. Says tall plants 100 short plant zero. Well, that's not what we would expect. Choice C. says tall plants 73 short 27. So that is very close to our 75%, ratio we'd expect. And then finally, Choice D. Says tall plants zero. Short plants, 100. Obviously, definitely not what we would expect there. It's important to remember that these are probabilities um that the 75% 25% of probabilities that we compare to the actual offspring numbers that were given as answer options. See you in the next video.

Key Concepts

Mendelian Genetics

Chi-Square (x²) Test

Null Hypothesis

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