Concept explainers
Videos
In four-o’clocks, the allele for red flowers is incompletely dominant to the allele for white flowers, so heterozygotes have pink flowers. What ratios of flower colors would you expect among the offspring of the following crosses: (a) pink × pink,(b) white × pink, (c) red × red, (d) red × pink,(e) white × white, and (f) red × white? If you specifically wanted to produce pink flowers, which of these crosses would be most efficient?
To determine:
The ratio of flower colors that would be expected among the offspring of the crosses pink × pink, white × pink, red × red, red × pink, white × white, and red × white.
Introduction:
According to Mendel's conclusion, a pair of factors control the expression of a trait (a term that was used by Mendel for genes), and each factor of the pair segregate from each other during gamete formation.
Explanation of Solution
In four-o’ clocks, alleles of the red flowers are incompletely dominant to the allele for white flowers. Consider that genotype of red flowers is AA, then genotype of white flowers would be aa. Pink flowers are producing from the cross of these two flowers so its genotype would be Aa.
Condition (a)
The cross of two pink flowers (Aa×Aa) is taking place means the formed gametes would be A and a from both the parents. The ratio of the flowers that are expected to produce among the offspring of this cross is shown in the Punnett square.
| ♀/♂ | A | a |
| A | AA Red flowers |
Aa Pink flower |
| a | Aa Pink flower |
aa White flower |
The obtained ratio of red flowers, pink flowers, and white flowers is 1:2:1.
Condition (b)
The cross of white and pink flower (Aa×aa) is taking place means one parent will produce two different types of gametes that is A and a, and another parent will produce only one type of gamete that is a. The ratio of the flowers that are expected to produce among the offspring of this cross is shown in the Punnett square.
| ♀/♂ | A | a |
| a | Aa Pink flower |
aa White flower |
| a | Aa Pink flower |
aa White flower |
The obtained ratio of pink flowers and white flowers is 1:1.
Condition (c)
The cross of two red flowers (AA×AA) is taking place means parents will produce only dominant gametes. The ratio of the flowers that is expected to produce among the offspring of this cross is shown in the Punnett square.
| ♀/♂ | A | A |
| A | AA Red flower |
AA Red flower |
| A | AA Red flower |
AA Red flower |
All offspring that would be produced from this cross would be red flowers because both the parents are homozygous dominant.
Condition (d)
The cross of red and pink flower (AA×Aa) is taking place means one parent will produce two different types of gametes that is A and a, and another parent will produce only one type of gamete that is A. The ratio of the flowers that is expected to produce among the offspring of this cross is shown in the Punnett square.
| ♀/♂ | A | A |
| A | AA Red flower |
AA Red flower |
| a | Aa Pink flower |
Aa Pink flower |
The obtained ratio of pink flowers and red flowers is 1:1.
Condition (e)
The cross of two white flowers (aa×aa) is taking place means parents will produce only recessive gametes. The ratio of the flowers that is expected to produce among the offspring of this cross is shown in the Punnett square.
| ♀/♂ | a | a |
| a | aa White flower |
aa White flower |
| a | aa White flower |
aa White flower |
The offspring that would be produced from this cross would be white flowers because both the parents are homozygous recessive.
Condition (f)
The cross of red flowers and white flowers (AA×aa) is taking place means one parent is homozygous dominant so it would produce only dominant gamete that is A. Another parent is homozygous recessive so it will produce only recessive alleles that is a. The ratio of the flowers that is expected to produce among the offsprings of this cross is shown in the Punnett square.
| ♀/♂ | A | A |
| a | Aa Pink flower |
Aa Pink flower |
| a | Aa Pink flower |
Aa Pink flower |
All flowers will be of pink color because allele of red flower is incompletely dominant over the allele of white flower.
To determine:
The cross that would be most efficient to produce pink flowers.
Introduction:
Inheritance is a mechanism in which traits of the parents transfer into the offsprings of the next generation. Gregor Mendel was a monk, and he discovered three laws that describe the inheritance of factors from parents to offsprings.
Explanation of Solution
The cross of red and white flowers would be more efficient to produce pink flowers. Red flowers are homozygous dominant means the genotype of these flowers would be AA, and white flowers are homozygous recessive, which means its both gametes are recessive means aa. The cross of red flower and white flowers is as follows:
| ♀/♂ | A | A |
| a | Aa Pink flower |
Aa Pink flower |
| a | Aa Pink flower |
Aa Pink flower |
It can be observed from the cross that all the produced offsprings are pink in color. Therefore, the cross of red flower and white flower would be efficient to produce pink flowers.
Want to see more full solutions like this?
Chapter 3 Solutions
ND STONY BROOK UNIVERSITY LOOSELEAF GENETICS: FROM GENES TO GENOMES
- Individuals of genotype AaBb were mated to individuals of genotype aabb. One thousand offspring were counted, with the following results: 474 Aabb, 480 aaBb, 20 AaBb, and 26 aabb. What type of cross is it? Are these loci linked? What are the two parental classes and the two recombinant classes of offspring? What is the percentage of recombination between these two loci? How many map units apart are they?arrow_forwardIn the common daisy, genes A and B control flower color. Both genes have a dominant allele (A or B) and a recessive allele (a or b). At least one copy of each dominant allele is required for flowers to be colorful instead of white. (Explain and Justify your answers) 21.1) Predict the genotypes and phenotypes of the F1 progeny of a cross between two white-flowered plants, one homozygous AA and the other homozygous BB. A) AA bb, white B) aa BB, white C) Aa Bb, colorful D) Aa Bb, white E) aa bb, colorful 21.2) Predict the phenotypic ratio of the F2 progeny of a cross between two white-flowered plants, one homozygous AA and the other homozygous BB. A) 3 colorful : 1 white B) 9 colorful : 7 white C) 9 white : 7 colorful D) 15 white : 1 colorful E) 15 colorful : 1 white 21.3) The inheritance pattern of daisy flower color provides an example of what type of gene interaction? A) additivity…arrow_forwardIn cats, there is a gene that codes for fur colour on the X chromosome. One allele gives black fur, and the other gives orange fur. A cat that has one of each allele (heterozygous) has fur that has large patches of orange and large patches of black. This fur colour is called tortoiseshell (A) a) is this strict Mendelian, incomplete dominance, or co-dominance? (Choose only one and explain) b) is it possible for male cats to have the tortoiseshell fur colour? Explain. If a female fruit fly homozygous for white eyes is crossed with a red-eyed male, what percentage of the offspring would have white eyes? (eye colour is x-linked and white is recessive) a) 100% b) 0% c) 50%. d) 25%arrow_forward
- In mice, the allele C for colored fur is dominant over the allele c for white fur, and the allele V for normal behavior is dominant over the allele v for waltzing behavior, a form of discoordination. Give the genotypes of the parents in each of the following crosses: (a) Colored, normal mice mated with white, normal mice produced 29 colored, normal and 10 colored, waltzing progeny. (b) Colored, normal mice mated with colored, normal mice produced 38 colored, normal, 15 colored, waltzing, 11 white, normal, and 4 white, waltzing progeny. (c) Colored, normal mice mated with white, waltzing mice produced 8 colored, normal, 7 colored, waltzing, 9 white, normal, and 6 white, waltzing progeny.arrow_forwardA male dog with the genotype GgBb is crossed with a female dog with the genotype GgBb. Set up a punnet square Note: Gray hair (GG) is dominant over white hair (gg); Black eyes (BB) is dominant over red eyes (bb). (a) How many out of 16 have gray fur and black eyes? (b) How many out of 16 have gray fur and red eyes? (c) How many out of 16 have white fur and black eyes? (d) How many out of 16 have white fur and eyes red? Write the phenotypic ratio.arrow_forwardWhat gamete must be donated by the father monster, and what is its probability? a) g l — 12.5% b) g l — 25% c) g l — 75% d) g l — 37.5%arrow_forward
- The genes for tall vine, D, and yellow seeds, G, are dominant over their respective alleles for dwarf, d, and green, g. What phenotypes and genotypes are expected from each of the following crosses? Include phenotypic and genotypic ratios. 6. a) heterozygous tall, homozygous yellow x homozygous tall, heterozygous yellow b) dwarf, heterozygous yellow x heterozygous tall, green c) homozygous tall, homozygous yellow x heterozygous tall, green d) heterozygous tall, heterozygous yellow x heterozygous tall, heterozygous yellowarrow_forward1) A cross is made between two plants differing in four independently-assorting gene loci, AABBCCDD x aabbccdd, to produce an F, which is then self-fertilized. If the capital letters represent alleles with a completely dominant phenotypic effect, (a) how many different genotypes are possible in the F;? (b) what proportion of the F; will be homozygous dominant for all genes? (c) what proportion of the F; would have an ABCD phenotype? 2) Would your answers to (a), (b), and (c) be different if the initial cross were AAbbCCdd x aaBBccDD?arrow_forwardIn guinea pigs, black hair colour (B) is dominant and brown hair colour (b) is recessive. Long hair (L) is dominant and short hair (l) is recessive. Answer the following questions: (a) Find the gamete types for the cross: BbLl X BbLL (b) What are the phenotypes of the parent generation? (c) What are the genotypes and phenotypes of the F1 generation?arrow_forward
- In a plant, a tall variety was crossed with a dwarf variety. All F1 plants were tall. When F1 * F1 plants were interbred, 9/16 of the F2 were tall and 7/16 were dwarf. (a) Explain the inheritance of height by indicating the number of gene pairs involved and by designating which genotypes yield tall and which yield dwarf. (Use dashes where appropriate.) (b) What proportion of the F2 plants will be true breeding if selffertilized? List these genotypes.arrow_forwardIn summer squash, white fruit color(W) is dominant over yellow fruit color(w). If a squash plant homozgous for white is crossed with a plant homozygous for yellow, what will the genotypic ratio be for F2 generation? A)1:1B)3:1C)1:1:1:1D)1:2:1arrow_forwardtype P = n! (p)* (q)"* х! (n - х)! Practice Problem: You cross a true-breeding pea plant with red flowers to a true-breeding pea plant with white flowers. All of your offspring have red flowers. Which gene is dominant? Why? What is the genotype of your offspring? You then cross the offspring to each other. What ratio do you expect? Why? You count 1000 plants and look at their flowers. Your results are as follows: 740 red 260 white Does this follow a simple Mendelian inheritance pattern? Why or why not? DADT 2 MEA SUDI ND D LUT IONSarrow_forward
Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning