Chapter 2: Mendel's Principles Of Heredity Flashcards
(28 cards)
What type of cross described the mating of an individual expressing a dominant phenotype, but whose genotype is unknown, with an individual expressing the corresponding recessive phenotype?
Test cross
A tall pea plant with purple flowers is crossed with a short pea plant with white flowers. What type of cross is this?
Di hybrid
Which of the following statements are referring to genotypes?
1) the F1 generation offspring are Tt
2) the P generation has both tall and short plants
3) the parental plant in the P generation is TT
4) the F1 generation plants are tall
1 and 3
An F1 hybrid plant from a cross between a heterozygous plant with round seeds and a plant with wrinkled seeds is allowed to self-fertilize. Each of the F2 plants with wrinkled seeds are then allowed to self-fertilize. What do you expect to see in the F3 generation?
100% wrinkled seeds
The probability of producing a dwarf plant from two heterozygous parents is 1/4. What is the likelihood that these same parent plants will produce 3 dwarf plants?
1/64 or 1.6%
If an organism has identical alleles for a given trait, it is said to be
Homozygous
What is the purpose of performing a test cross?
To determine the genotype of an organism expressing the dominant phenotype.
Two different genes will be randomly distributed into gametes during the formation of haploid cells. This statement summarizes which of Mendel’s laws?
Law of Independent Assortment
A tall pea plant with axial flowers has the genotype TtAa. What are the gamete possibilities of this plant?
1/4 TA
1/4 Ta
1/4 tA
1/4 ta
What are the possible gametes that could be formed from an organism with the genotype AaBb?
1) Aa
2) Ab
3) AaBb
4) AB
5) ab
6) aB
7) Bb
2, 4, 5, 6
If a parent with the genotype AaBb mates with a parent who is aabb, what is the probability of an Aabb offspring?
1/4
Explanation: the probability of the offspring being heterozygous for the A gene is 1/2. The probability of the offspring being homozygous recessive recessive for the B gene is 1/2. Using the product rule, 1/2 x 1/2 = 1/4
An organism’s genotype is RrYy and it produces gametes with the genotypes RY, Ry, rY, and ry with equal frequency. Which of Mendel’s laws explains this fact?
Law of independent assortment: different pairs of alleles segregate independently of each other.
Purple flower color is dominant to white flower color in pea plants. Yellow seed color is dominant to green seed color. If you cross a heterozygous pea plant with purple flowers and yellow seeds to a pea plant with white flowers and green seeds, what is the expected genotypic ratio?
1/4 PpYy
1/4 Ppyy
1/4 ppYy
1/4 ppyy
The genotype AAbbCCdd is
Homozygous
A sheep breeder has a shed that is large (L) with soft wool (S). The breeder conducts a test cross to determine whether the sheep is homozygous or heterozygous for each of those dominant traits. If 1/4 of the offspring of the test toss are large with soft wool, what is the genotype of the breeder’s sheep?
Ll Ss
Mating an organism expressing a dominant phenotype, but whose genotype is unknown, with an organism expressing the corresponding recessive phenotype is an example of a(n)
Testcross
In a series of dihybrid crosses, pea plants with round, green seeds were crossed to plants with wrinkled, yellow seeds. All of the progeny had round, yellow seeds. What conclusions can be drawn from these data?
1) round is dominant to wrinkled and green is dominant to yellow
2) round is dominant to wrinkled and yellow is dominant to green
3) wrinkled is dominant to round and green is dominant to yellow
4) wrinkled is dominant to young and yellow is dominant to green
2
A sheep breeder has a sheep that is large (L) with soft wool (S). The breeder conducts a test cross to determine whether the sheep is homozygous or heterozygous for each of these dominant traits. If all of the offspring of the test cross are large with soft wool, what is the genotype of the breeder’s sheep?
LL SS
What is the probability of having three offspring that are male?
1/8
Which of the following methods would best be applied to determine the probability of having 5 children, all female?
1) punnett square
2) product rule
3) sum rule
2
What is a branched line diagram for?
To show all the possibilities for each gene in a sequence of columns
What is a horizontal family pattern in a pedigree?What 2 things does a horizontal family pattern in a pedigree suggest?
Horizontal pattern:
Brothers and sisters in a sole generation are affected
1) the trait is recessive
2) the unaffected parents are heterozygous carriers, that they bear the recessive allele the would express the trait, but they have a dominant allele that masks it
Which of the following are true for the inheritance of a recessive trait?
1) the trait often skips a generation
2) two heterozygotes will generally have affected offspring 25% of the time
3) affected individuals will inherit a dominant gene from at least one affected parent
4) the trait is usually present in every generation
5) all offspring of two affected individuals will be affected
5) all offspring of two affected individuals will be affected
1,2,5
An inheritance pattern in which all offspring of two affected individuals are affected is most likely to be autosomal [blank] inheritance
Recessive
