Gregor Mendel was a monk who, in 1865, suggested a theory of?

Question

inheritance based on the science of genetics. He identified heterozygous individuals for flower color that had two alleles (one r=recessive white color allele and one R=dominant red color allele). When these individuals where mated, 3/4 of the ofsprings where observed to have red flowers and 1/4 had white flowers.
We assume that each parent is equally likely to give either of the two alleles and that, if either one of two of the alleles in a pair is dominant (R), the offspring will have red flowers.
a) What is the probability that an offspring in this mating has at least one dominant allele?
b) What is the probabolity that an offspring has at least one recessive allele?
c) What is the probability that an offspring has one recessive allele, given that the offspring has red flowers?

Answer 1

Given your assumption for the parents, the four equally-likely possibilities for their offspring are RR, Rr, rR, rr. Therefore:

a) the probability is 3/4 or 75% that an offspring will have at least one dominant allele (R)
b) the probability is also 3/4 or 75% that an offspring will have at least one recessive allele (r)
c) of the 3/4 that will have red flowers, 2/3 or 66.7% will have one recessive allele (r)

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I don't know who keeps giving thumbs down to those who answered 2/3 for c) and thumbs up to those who said 1/2, but you are mistaken.

The question limits you to the offspring with red flowers. Of those, all will have at least one dominant allele, and two will have one dominant and one recessive allele. Which means 2/3 of those with red flowers will have one recessive allele. Which is 66.7%

Answer 2

I am not sure if you are asking about the crossing of two heterozygous parents, if that is what you need to know. Then
a.) 75%
b.) 75%
c.) 50%

Edit: Where are these people getting 2/3, that is completely wrong. Given their genotypes of (R,R), (R,r), (r, R), and (r, r). 2 out of 4 will have a recessive allele and a dominant allele giving them the red phenotype. Last time I checked 2/4 is 1/2 is 50%. You are not asked to completely negate the existence of white phenotype.

Answer 3

Each parent has an equal chance of giving a dominant (R) or recessive (r) allele.

The offspring will get one allele from each parent. Here are the possible combinations of alleles that the offspring can inherit.

RR, Rr, rR, rr Each one of the combinations have an equal chance of occuring since each parent has equal chance of giving R or r.

so,
25% will be RR -->red
25% will be Rr -->red
25% will be rR -->red
25% will be rr -->white

a) Knowing all that, what percent of offspring have at least one dominant (R) allele?

b) What percent have at least one recessive (r) allele?

c) Looking only at the offspring that are red, what percent of those has one recessive (r) allele?

Hint: Among your red offspring, you will have these allele pairs (RR, Rr, and rR) all in equal proportions.

Answer 4

a) 3 in 4 (75%) will have at least one dominant "R" allele
b) 3 in 4 (75%) will have at least one recessive "r" allele
c) 1 in 2 (50%) will have one recessive "r" allele, and be red.

Answer 5

This can be solved by examination. The possible combinations are: rr, Rr, rR and RR.

a) Probability of at least 1 dominant trait: 3/4 (Second, third, and fourth of four possible)

b) Probability of at least 1 recessive trait: 3/4 (First, second, and third of four possible)

c) Probability of 1 recessive given red flowers: Possible arrangements are Rr, rR and RR, so 2/3 (First and second)

Answer 6

a.) 75%
b.) 75%
c.) 67%(two thirds)


If you do the punnett square for the cross then you get one offspring that has two dominant alleles, two offspring have one dominant allele and one recessive allele, and one offspring has two recessive alleles.

Answer 7

a) 44% b) 30% c) 0%

Answer 8

siennaraine is correct
(a) 0.75
(b) 0.75
(c) 0.50