Biology A4.12

A horticulturalist wants to produce geraniums with specific characteristics. She knows that the trait of red flowers is governed by the allele R (RR and Rr) and the trait of white flowers is governed by the allele r(rr). The horticulturalist crosses two geraniums from the F1 generation. Look at the Punnett square to see this cross.

3 red : 1 white

Jessica's mother has the blood type AB and her father has the blood type O. Which blood type could Jessica have? Draw a Punnett square on scratch paper to help answer the question, if needed.

A

Which statement is the best physical description of a gene?

A gene is a specific segment of DNA on a chromosome.

Which statement best describes the relationship between a gene and an allele?

An allele is a variant of a gene.

Which image shows a cell with condensed chromosomes?

B

Suppose a true-breeding blue flower is crossed with a true-breeding yellow flower. In the next generation, all of the flowers are blue. What does this outcome tell you about the allele for blue flowers?

The blue allele is dominant to the yellow allele.

A horticulturalist wants to produce geraniums with specific characteristics. She knows that the trait of red flowers is governed by the allele R (RR and Rr) and the trait of white flowers is governed by the allele r (rr). The horticulturalist has a red geranium with an uncertain genetic makeup. She crosses it with a white geranium (rr) and gets a generation in which half of the plants have red flowers and half have white flowers. What does this combination of offspring tell her about the genetic makeup of the red geranium parent?

The red geranium is heterozygous for flower color (Rr).

A certain species of grasshopper can have red stripes, yellow stripes, or red and yellow stripes. An RR grasshopper has red stripes, aYY grasshopper has yellow stripes, and an RY grasshopper has red and yellow stripes. A grasshopper with red stripes mates with a grasshopper with yellow stripes. What ratio would be expected in the phenotypes of their offspring?

all with yellow and red stripes

Which term describes the form of a gene that produces a specific trait, such as eye color?

allele

A certain species of grasshopper can have red stripes, yellow stripes, or red and yellow stripes. An RR grasshopper has red stripes, a YY grasshopper has yellow stripes, and an RY grasshopper has red and yellow stripes. Which type of inheritance is this grasshopper species an example of?

codominance

In the late 1800s, Mendel predicted the existence of "units of hereditary information" or "factors." Which term names these units of hereditary information today?

genes

Which term refers to a type of trait that is usually expressed only when an organism has two identical alleles for the trait?

recessive

What do the letters in each box of a Punnett square tell?

the possible combinations of alleles in offspring based on the parents' genetic makeup