You are handed a mystery pea plant with tall stems and axial flowers and asked to determine its genotype as quickly as possible. You know that the allele for tall stems (7) is dominant to that for dwarf stems (t) and that the allele for axial flowers (A) is dominant to that for terminal flowers (a). Identify ALL the possible genotypes for your mystery plant.

In humans, red-green color blindness is a sex-linked recessive trait. If a man and a woman have a color blind son, which of the following must be true?

a. The father is color blind
b. Both parents carry the allele for color blindness
c. Neither parent carries the allele for color blindness
d. The mother carries the allele for color blindness
e. The father carries the allele for color blindness

What is Mendel's second conclusion, which states that some alleles are dominant and others are recessive?

Red-green colorblindness in humans is caused by a sex-linked recessive allele. Is this true or false?

Density-dependent inhibition is explained by which of the following?

a) As cells become more numerous, the amount of required growth factors and nutrients per cell becomes insufficient to allow cell growth.

b) As cells become more numerous, the protein kinase they produce begin to compete with each other, such that proteins produced by one cell essentially cancel those produced by its neighbour.

c) As cells become more numerous, more and more of them enter the S phase of the cell cycle.

d) As cells become more numerous, the level of waste products increases, eventually slowing down metabolism.

e) As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to produce control factors.

How many sister chromatids are found in a human somatic cell nucleus during mitosis?

Examine the genotype of the child, the mother, and the possible genotypes of the father for a child with type O blood who is born to a mother with type A blood.

The diagram represents just a few of the chromosomes of a meiotic cell in a certain person. A previous study has shown that the freckles gene is located at the locus marked F, and the hair-color gene is located at the locus marked H, both on the long chromosome. The individual from whom this cell was taken has inherited different alleles for each gene (“freckles” and “black hair” from one parent, and “no freckles” and “blond hair” from the other). Predict allele combinations in the gametes resulting from this meiotic event. (It will help if you draw out the rest of meiosis, labeling alleles by name.) List other possible combinations of these alleles in this individual’s gametes.

What is the end result of mitosis?

. Imagine that you are a genetic counselor, and a couple planning to start a family comes to you for information. Charles was married once before, and he and his first wife had a child with cystic fibrosis. The brother of his current wife, Elaine, died of cystic fibrosis. What is the probability that Charles and Elaine will have a baby with cystic fibrosis? (Neither Charles, nor Elaine, nor their parents have cystic fibrosis.)

The pedigree traces the inheritance of alkaptonuria, a biochemical disorder. Affected individuals, indicated here by the colored circles and squares, are unable to metabolize a substance called alkapton, which colors the urine and stains body tissues. Does alkaptonuria appear to be caused by a dominant allele or by a recessive allele? Fill in the genotypes of the individuals whose genotypes can be deduced. What genotypes are possible for each of the other individuals?

The aging process is thought to be initiated at the cellular level. Among the changes that can occur after a certain number of cell divisions is the loss of a cell’s ability to respond to growth factors and other signals. Much research into aging is aimed at understanding such losses, with the ultimate goal of extending the human life span. Not everyone, however, agrees that this is a desirable goal. If life expectancy were greatly increased, what might be the social and ecological consequences?

In maize ( corn) plants, a dominant allele I inhibits kernel color, while the recessive allele i permits color when homozygous. At a different locus, the dominant allele P causes purple kernel color, while the homozygous recessive genotype pp causes red kernels. If plants heterozygous at both loci are crossed, what will be the phenotypic ratio of the offspring?

In tigers, a recessive allele that is pleiotropic causes an absence of fur pigmentation (a white tiger) and a cross-eyed condition. If two phenotypically normal tigers that are heterozygous at this locus are mated, what percentage of their offspring will be cross-eyed? What percentage of cross-eyed tigers will be white?