Question

Pink is the phenotype from the expression of a heterozygous genotype in flowers that exhibit incomplete dominance. Red and white flowers result from the two homozygous genotypes.

10. What would be the probability of getting pink flowered plants from a cross between two pink flowered plants?

11. Is there any chance of red or white flowers from a cross of two pink flowered plants? Explain your answer.

12. Explain how recombination during meiosis contributes to genetic diversity in offspring.

13. Why are females often carriers of X-linked recessive traits, but do not show the trait as often as males?

14. Why would cancer be considered a disease that is multifactorial?

Answer 1

Ans-

Lets say red colour allele is denoted by allele R

White colour allele is denoted by r

Then - pink color is in Heterozygous condition so Rr.

Cross between two pink - Rr x Rr

	R	r
R	RR	Rr
r	Rr	rr

There is. 1/2 or 50% chance of getting pink flowers

11)– 25% chance of getting red flower

25% chance - white flower.

Since both pink flowers carry one Dominant and one recessive allele , there is possibility that the offspring can inherit one R allele from each parent and be red , similarly can inherit on r Allele from each parent generation and be white.

12- recombination or crossing over is the exchange of a part or segment of genetic material between two Chromosomes. This results in various possible combinations of parental genes in gametes that fuse to form a new genetic variation in offspring which is different from either parent and unique .

13- females carry two X chromosome one inherited from each parent , for females to be affected , both X chromosome should carry recessive alleles. If one X chromosome carries lethal recessive allele and another X chromosome carries Normal dominant allele ,the Dominant allele gets exoressed over recessive ,so Heterozygous females do not show the recessive trait and are called carriers . For females to be affected , both parents have to either affected or the mother should ve a carrier and father should be affected.

Males carry X and Y chromsomesm X from mother and Y from father. So if mother is affected 100% sons will be affected , as there is only one X chromosome. They cannot have a carrier state. So males are more often affected.

14- cancer is a multifactorial disease because it can be caused due to genetic inheritence in family , environmental factors , lifestyle choices , viral pathogens , carcinogens etc . A cancer can arise from any of the above factors or sometimes from all . Hence it is multifactorial.

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