Question

please help me with this question

1a. You are breeding a species of mountain lion (2n); you cross a true breeding male that has straight yellow fur with a true breeding female that has curly red fur. The offspring have curly orange fur; based on your results, what is the mode of interaction between the alleles?

Select one:

a. Curly fur is dominant to straight fur and yellow and red fur colour show incomplete dominance

b. You can’t tell mode of interaction because you don’t know which offspring is a heterozygote

c. Curly fur is dominant to straight fur and yellow fur colour is co-dominant to red

d. Fur shape (curly/straight) is determined by simple dominant/recessive relationship between the alleles while the environment influences fur colour.

AND,

After breeding your mountain lions you also studied the ears of the offspring. The female parent had straight ears and the male parent had folded ears, amongst the offspring  - 100% of the female offspring had folded ears and 100% of the male offspring had straight ears.

What is the mode of inheritance for straight ears?

Select one:

a. Y-linked

b. X-linked dominant

c. X-linked recessive

d. Sex-limited

Answer 1

Ans- Cross between

Male- Straight and yellow fur

Female- Curly and red fur

Offspring- Curly orange fur

True breeding means both the parents are Homozygous for any trait.

Let take gene for fur type S.

NOW curly fur- SS and straight fur- ss

a- Curly fur is dominant to straight fur and yellow and red fur colour show incomplete dominance

Since the fur type in offsprings is curly. This means it is dominant over straight fur. Now for the colour as we see, there are two types of it. Yellow and orange . When both the fur colours are not dominant over each other and produces a intermediate colour, i.e orange colour. So this is incomplete dominance in which no phenotype could produce its effect or we can say that dominant phenotype cannot show its dominance.

Female parent- Straight ear

Male parent- folded ear

The offsprings which are female are 100% with folded ears and males with 100% straight ear.

If the mode of inheritance would have been Y type then it wouldn't be present in females. But it is.

Sex limited inheritance is not possible because it is only present in one type of sex i.e. either male or female.

Now X linked dominant means that male should have one X chromosome with characteristics of folded ear while females should have one or both the X chromosomes which contains character for folded ear. Lets consider that X- has gene for straight ear while X has gene for folded ears.

Means folded ear is recessive to straight ear.

Now crossing

XX × X​​​​​​Y

Offsprings- XX X​​​​​​X XY XY

Now male with straight ear and females with folded ears.

So the character is X linked dominant.

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