In a cross of two pure-breeding lines of tomatoes producing different fruit sizes, the variance in grams (g) of fruit weight in the F₁ is 2.25 g and the variance among the F₂ is 5.40 g. Determine the genetic and environmental variance (VG and VE) for the trait and the broad sense heritability of the trait.

Question

Accepted Answer

Hi, everyone. Let's look at our next question. It says, what does a heritability of 0. imply, let's think about the meaning of the term heritability, which is that degree to which being a typical variations of the amount of phenotype IQ variation in a trait that is due to Jenna typical variation. So to what degree is this trait influenced by genetic inheritance versus environmental factors? So we're looking at a trait in which the variation in that trait Is 60% due to Jenna typical variation and we'd expect then 40% due to environmental factors. So with that in mind, let's look at our answer choices and we want to notice that choice D is all options are correct. So we do have the possibility of more than one correct answer. So with that in mind, let's evaluate our answers. Choice. A says 40% of the phenotype variation is attributed attributed to the environment. Well, as we discussed, if 60% of the variation is due to genetic factors, then the other 40% must be attributable to environmental factors. So choice is correct. I'm not going to pick it as my answer. Since I do have that option of all the answers being correct. So I'm just gonna put a little dot next to choice a to remind myself it's correct. And then we'll look on at the other ones. Choice B says 60% of the phenotype variation is due to variation in Jena types for that trait. Well, this is also correct heritability of 0.60 does imply that 60% of the genetic variation due to genetic factors. So I'll put a dot next to choice be since that's also correct. Well, if I were on a test, I'm in a rush, I would go ahead and pick as my answer. Choice. D all options are correct because I already have more than one correct answer. But to be thorough in our video, we'll also look at choice D to evaluate it. Excuse me. Choice. See our remaining other choice. We haven't looked at yet. Choice C says the individuals compared are not mono psychotic twins. Well, this one takes a little bit more thinking through what we have to understand is when we're talking about heritability, we're comparing variations and phenotype across individuals. But if we're looking at variations in phenotype between mono psychotic twins, mono psychotic twins would have identical D N A and therefore any variation in phenotype between them is due to environmental factors. So if we're seeing a heritability of 0.6, we're not comparing variation and identical twins because they would always have a heritability of zero if you looked at fanatic variations between them. So in identical twins or mono psychotic twins to be more specific, all variation and phenotype is due to environmental factors. So choice C is correct also. So again, what is the heritability of 0.60 imply? And our answer is choice d all options are correct. See you in the next video.

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Key Concepts

Genetic Variance (VG)

Environmental Variance (VE)

Broad-Sense Heritability (H²)