The appropriate answer is d. Dead plants in a swampy environment is the perfect environment for the beginning of the coal forming process. Over time layers pile up in this anaerobic environment. The plant or organic material gets buried overtime by dirt or rocks. Millions of years of burial will expose the matter to heat and pressure and will eventually lead to the formation of coal and other petroleum products.
The question is about a test cross. Definition of a test cross: Generally a cross involving a homozygous recessive individual. When a single trait is being studies, a test cross is a cross between an individual with the dominant phenotype but of unknown genotype (homozygous or heterozygous) with a homozygous recessive individual. If the unknown is heterozygous, then approximately 50% of the offspring should display the recessive phenotype. If the individual is homozygous all the progeny will have the dominant phenotype. James' suggestion to use show the result of the two possible crosses with a Punnet square is a great suggestion.
Answer:
50%
Explanation:
The allele for black fur (B) is dominant to the allele for brown fur (b).
- BB or Bb = black fur
- bb = brown fur
A male homozygous black mouse (BB) is crossed with a female brown mouse (bb). The male parent only produces<em> B</em> gametes and the female parent only produces <em>b</em> gametes. The F1 offspring will be 100% heterozygous Bb.
The F1 individuals will produce <em>B</em> and <em>b</em> gametes. If we cross the F1 individuals to each other (Bb x Bb), we'll get the following F2 offspring:
- 25% BB homozygous dominant
- 50% Bb heterozygous
- 25% bb homozygous recessive
So 50% of the F2 will be homozygous (BB or bb).
1, healthy. 2, small. 3, vision. 4, bones. 5, muscles. 6, B-1. 7, B-2.
hope this was helpful!
