MM#7 Mendelian Genetics

Front

If green is dominant over purple, then what is the genotype for this individual?

Back

gg

Answer explanation

When gametes unite during fertilization, the resulting zygote inherits two alleles for each gene. One allele comes from each parent. The alleles an individual inherits make up the individual’s genotype. The two alleles may be the same or different.

An organism with two alleles of the same type (BB or bb) is called a homozygote. An organism with two different alleles (Bb) is called a heterozygote. This results in three possible genotypes.

In general, when only one of two alleles is expressed in the phenotype, the expressed allele is called the dominant allele (Capital letter). The allele that isn’t expressed is called the recessive allele (lower case letter).

The expression of an organism’s genotype produces its phenotype. The phenotype refers to the organism’s characteristics, such as purple or white flowers.

Front

Tt is-

Back

heterozygous

Answer explanation

An organism with two alleles of the same type (BB or bb) is called a homozygote. An organism with two different alleles (Bb) is called a heterozygote. This results in three possible genotypes.

Front

How are the alleles represented for a homozygous recessive pea plant for height? Options: TT, Tt, tt, tT

Back

tt

Answer explanation

An organism with two alleles of the same type (BB or bb) is called a homozygote. An organism with two different alleles (Bb) is called a heterozygote. This results in three possible genotypes.

Front

Example of a heterozygous genotype: RR, Rr, rr

Back

Rr

Answer explanation

An organism with two alleles of the same type (BB or bb) is called a homozygote. An organism with two different alleles (Bb) is called a heterozygote. This results in three possible genotypes.

Front

The letters on the TOP AND SIDE of a punnett square represent ______________.

Back

The possible alleles given by the parents following meiosis.

Answer explanation

Front

Predicted percentage of homozygous recessive offspring in this cross? Options: 0%, 25%, 50%, 75%

Back

50%

Answer explanation

An organism with two alleles of the same type (BB or bb) is called a homozygote. An organism with two different alleles (Bb) is called a heterozygote. This results in three possible genotypes.

In general, when only one of two alleles is expressed in the phenotype, the expressed allele is called the dominant allele (Capital letter). The allele that isn’t expressed is called the recessive allele (lower case letter).

Front

Why do we see only tall plants in the second generation?

Back

The gene for tall height is dominant

Answer explanation

In general, when only one of two alleles is expressed in the phenotype, the expressed allele is called the dominant allele (Capital letter). The allele that isn’t expressed is called the recessive allele (lower case letter).

Front

Two brown eyed parents (Bb) have a baby. What is the chance the baby is blue eyed?

Back

25%

Answer explanation

Predicting Offspring Phenotypes

You can predict the percentages of phenotypes in the offspring of this cross from their genotypes. P is dominant to p, so offspring with either the PP or Pp genotype will have the purple-flower phenotype. Only offspring with the pp genotype will have the white-flower phenotype. Therefore, in this cross, you would expect three out of four (75 percent) of the offspring to have purple flowers and one out of four (25 percent) to have white flowers. These are the same percentages that Mendel got in his first experiment.

Front

The instructions of this allele are covered up by the other allele in a homologous pair. Symbolized by a small letter.

Back

Recessive

Answer explanation

In general, when only one of two alleles is expressed in the phenotype, the expressed allele is called the dominant allele (Capital letter). The allele that isn’t expressed is called the recessive allele (lower case letter).

Front

The instruction of one allele covers up the instruction of the other allele in a homologous pair. Symbolized by a capital letter.

Back

Dominant Allele

Answer explanation

In general, when only one of two alleles is expressed in the phenotype, the expressed allele is called the dominant allele (Capital letter). The allele that isn’t expressed is called the recessive allele (lower case letter).