FLASHCARDS Punnett Squares and Pedigree Charts

Front

T - tall and t = short In the punnett square below, what belongs in the missing square?

Back

tt

Answer explanation

In the Punnett square, the combination of two short alleles (tt) results in a short phenotype. Since both parents contribute a 't', the missing square must be 'tt', indicating both alleles are short.

Front

Genotype for a yellow plant (G = green, g = yellow)

Back

gg

Answer explanation

The genotype for a yellow plant is 'gg' because yellow is represented by the recessive allele 'g'. The dominant allele 'G' produces green plants, so only 'gg' results in yellow.

Front

B = brown fur b = white fur In the punnett square, what is the probability for white fur?

Back

50%

Answer explanation

In a Punnett square for a cross between brown (B) and white (b) fur, the possible genotypes are BB, Bb, Bb, and bb. The white fur genotype (bb) appears once out of four, giving a probability of 50% for white fur.

Front

Aa, DD, bB, yy are all examples of

Back

genotypes

Answer explanation

Aa, DD, bB, and yy represent combinations of alleles, which define the genetic makeup of an organism. Therefore, they are examples of genotypes, not phenotypes, which refer to observable traits.

Front

What you see, or the physical appearance.

Back

Phenotype

Answer explanation

The term 'phenotype' refers to the observable physical appearance of an organism, which aligns with the description given in the question. 'Homozygous' relates to genetic makeup, not appearance.

Front

AA and Aa always show up as

Back

dominant

Answer explanation

AA and Aa both contain at least one dominant allele (A), which is why they always show up as dominant in phenotypic expression.

Front

Each one of the boxes on the Punnett Square represents what probability of an offspring's genotype?

Back

25%

Answer explanation

Each box in a Punnett Square represents a possible genotype of the offspring. With two heterozygous parents, there are four combinations, making the probability of each genotype 25%.

Front

What ratio of the offspring from the cross shown will be homozygous recessive for the trait of tallness?

Back

0 in 4

Answer explanation

The cross does not produce any homozygous recessive offspring for tallness, indicating that all offspring will either be homozygous dominant or heterozygous. Therefore, the ratio of homozygous recessive offspring is 0 in 4.

Front

Which of the following genotypes is homozygous dominant? Options: AA, aa

Back

AA

Answer explanation

The genotype 'AA' is homozygous dominant because it consists of two identical dominant alleles. In contrast, 'aa' is homozygous recessive, containing two identical recessive alleles.

Front

Phenotype of offspring (A-Brown hair; a-blond hair)

Back

75% Brown Hair and 25% Blond Hair

Answer explanation

The genotype of the parents is likely Aa x Aa. This results in a 3:1 ratio of phenotypes, leading to 75% Brown hair (AA or Aa) and 25% Blond hair (aa). Thus, the correct answer is 75% Brown Hair and 25% Blond Hair.