Genetics - Simple Dominance Problem?

Question

I could use some help or tips with this question. Perhaps the homozygous vs. heterozygous lack of understanding on my part is the key problem? I know I need to make a Punnett square, but am unsure where to start.

Question: In tobacco plants, a dominant allele (C) for chlorophyll gives the plants a green color, and a recessive allele (c) for lack of chlorophyll causes a plant to appear white. A tobacco plant that is homozygous dominant for green chlorophyll is crossed with a white tobacco plant.

What is the genotype of the green tobacco plant?

What is the genotype of the white tobacco plant?

What is the phenotypic ratio of the offspring?

What is the genotypic ratio of the offspring?

Thanks in advance for any help you can offer.

Answer 1

GG

gg

Gg

1

Answer 2

1. CC

2. cc

3  100% green   (4:0)

4. 100% Cc        (4:0)

Answer 3

Homozygous Dominant is CC

Homozygous Recessive = White Plant = cc

Heterozygous Dominant = Cc (not relevant to this question)

CC X cc  gives you

Cc, Cc, Cc, Cc

Phenotype = How they Look = 4:0  Green: White

Genotype = 0:4:0  Homozygous dominant : Heterozygous: Homozygous recessive