Biology questions about genotype, phenotype, offsprings....etc. PART II?

Question

I am really struggling with these materials...any help would be greatly appreciated!

8. In pea plants, a gene R produces red flowers and is dominant to a gene r, which produces white flowers. A gene T produces tall plants and is dominant to a gene t for short plants. If a plant that is homozygous for red flowers and heterozygous for tallness is crossed with a plant that is short and white, what will be the phenotypic ratio of the parents?

A) one tall red:one short red

B) nine tall red:three short red:three tall white:one short white

C) three tall red:one short red:one tall white

D) one short white:two short red:one tall white

9. Human skin color is thought to be determined by at least three pairs of alleles. If dark skin (D) is dominant to light skin (d), the genotypes that will produce the darkest skin are

A) D1d1 D2d2 D3d3.

B) D1D1 D2d2 d3d3.

C) d1d1 D2D2 D3d3.

D) D1d1 D2d2 D3D3.

Answer 1

Peter's answer's right, as far as i know.

The genotype is the exact genetic makeup while the phenotype is the character/traits (eg-hair or eye colour) that u show outwardly.

Ur phenotype depends a lot on ur genotype, but can be modified by ur activities to an extent.

Like, if u play a lot in sun, u get tanned, so u turn brownish if u r white.

ur genotype, in turn, depends on genes. The genes r present in ur chromosomes (DNA in the chromosomes, to be precise).

You get chromosomes from ur parents. They are present in every person in pairs.



Imagine ur mum & dad. Dad's got TT (2)for tallness and mum tt (2) for shortness.You can't get all 4 of these, only two (a pair). So, one Dad's T and one Mom's t goes to u.

Your combination would be Tt. Since T is dominant, you are gonna be tall.

If i go on, You will definitely get confused(if u aren't already!!). I'm guessing u r in 8th grade something.

Don't worry....you'll get the hang of it!! If u think right, genetics is kinda cool.

Answer 2

8.A - RrTt & Rrtt.

9.The one with3 dominant alleles A or D.