Chapter 14 Mendel and the Gene Idea Reading Guide Answers

Fill up in this diagram of a cross of round- and wrinkled-seeded pea plants.  The round allele (R) is dominant and the wrinkled allel (r) is recessive.

a. R chiliad. r

b. r                                  h. Rr  (round)

c. F_one generation              i. Rr  (round)

d. Rr j. rr  (wrinkled)

e. F₂ generation             k. three circular:one wrinkled

f. R 50. 1 RR:twoRr:1rr

A alpine pea plant is crossed with a recessive dwarf pea plant. What volition the phenotypic and genotypic ratio of offspring exist

a. if the alpine establish was TT ?

b. if the tall plant was Tt ?

a. all tall (Tt ) pltans

b. ane;ane tall (Tt ) to dwarf (tt )

You tin can apply a Punnett foursquare to decide the expected effect of a test cross, merely a shortcut is to utilize only 1 cavalcade for the recessive individual's gametes, since they produce simply one type of gamete.

A true-breeding alpine, purple-flowered pea plant (TTPP ) is crossed with a true-convenance dwarf, white-flowered constitute (ttpp ).

a. What is the phenotype of the F₁ generation?

b. What is the genotype of the F₁ generation?

c. What iv types of gametes are formed past F₁ plants?

d. Use the picture of the Punnett square to show the offspring of the F_two generation. Shade each phenotype a different colour and so yuo tin see the ratio of offspring.

e. Listing the phenotypes and ratios found in the F_ii generation.

f. What is the ratio of tall to dwarf plants?

   Of majestic- to white-flowered plants?

(Note that the alleles for each individual character segregate equally in a monohybrid cross.)

a. all tall majestic plants

b. TtPp

c. TP, Tp, tP, tp

d, meet picture

eastward. 9 alpine majestic:three tall white:3 dwarf regal:1 dwarf white

f. 12:iv or 3:1 tall to dwarf

   12:iv or three:1 regal to white

Utilise the multiplication rule to a dihybrid cross.  How would you lot determine the probability of geting an F_two offspring that is homozygous recessive for both traits?

Dihybrids produce four types of gametes. The probability of getting both recessive alleles in a gamete is one/4, and for two such gametes to join is ¼ x ¼, or ⅟ _sixteen.

a. In the following cross, what is the probability of obtaining offspring that testify all three ascendant traits?

AaBbcc x AabbCC

probability of offspring that are A_B_C_ = _____

( _ indicates that the second allele can exist either dominant or recessive without affecting the phenotype determined past the first dominant allele.)

b. What is the probability that the offspring of this cross will show at to the lowest degree two dominant traits?

c. What is the probability of offspring that show only one ascendant trait?

a. Consider the upshot for each factor every bit amonohybrid cross. The probability that a cross of Aa x Aa will produce an A_ offspring is ¾. The probability that a cross of Bb x bb will produce a B_ offspring is ½. The probability that a cantankerous of cc x CC will produce a C_ offspring is 1.

To have all of these events occur simultaneously, multiply their probabilities: ¾ x ½ x 1 = ⅜.

b. Offspring could be A_bbC_, aaB_C_ , or A_B_C_. The genotype A_B_cc is not possible. Tin can you encounter why?

Probability of A_bbC_ = ¾ x ½ x 1 = ⅜

Probability of aaB_C_ = ¼ x ½ x 1 = ⅛

Probability of A_B_C_ = ¾ x ½ x i = ⅜

Probability of offspring showing at least two dominant traits is the sum of these independent probabilities, or ⅞.

c. There is only one type of offspring that tin show just i dominant trait (aabbCc ). Tin can you lot encounter why? Its probability is ¼ x ½ x 1 = ⅛.

List the possible genotypes for the following blood groups.

a. A  _____

b. B  _____

c. AB  _____

d. O  _____

a. I ^AI ^A and I ^Ai

b. I ^BI ^B and I ^Bi

c. I ^AI ^B

d. ii

A dominant allele M is necessary for the product of the black pigment melanin; mm individuals are white. A dominant allele B results in the deposition of a lot of paint in an animal's hair, producing a black color. The genotype bb produces brown hair. 2 black animals heterzygous for both genes are bred. Fill in the tabular array for the offspring of this cantankerous.

The ratio of offspring from this MmBb x MmBb cross would be 9:3:iv, a common ratio when one cistron is epistatic to another. All epistatic ratios are modified versons of 9:three:three:1.

The height of fasten calendar week is a consequence of polygenic inheritance involving 3 genes, each of which can contribute an additional 5 cm to the base height of the plant, which is 10 cm. The tallest plant (AABBCC ) tin can reach a height of twoscore cm.

a. If a alpine establish (AABBCC ) is crossed with a base-height constitute (aabbcc ), what is the height of the F_i plants?

b. How many phenotypic classes volition there be in the F_two?

a. The parental cross produced 25-cm tall F_i plants, all AaBbCc plants with 3 units of five cm added to the base height of 10 cm.

b. As a general rule in the polygenic inheritance of a quantitative character, the number of phenotypic classes resulting from a cross of heterozygotes equals the number of alleles involved plus one. In this case, 6 alleles (AaBbCc ) + 1 = seven. Then, there will be 7 dissimilar phenotypic classes in the F₂ among the 64 possible combinations of the 8 types of F_ane gametes. These 7 classes volition go from vi dominant alleles (twoscore cm), five dominant (35 cm), 4 ascendant (xxx cm), and so on, to all 6 recessive alleles (10 cm).

Consider this full-blooded for the trait of albinism (lack of peel pigmentation) in three generations of a family. (Solid symbols represent individuals who are albinos.) From your knowledge of Mendelian inheritance, answer the following questions.

a. Is this trait caused by a dominant or recessive allele? How can you lot tell?

b. Decide the genotypes of the parents in the first generation. (Let A and a represent the alleles.) Genotype of father _____ ; of mother _____.

c. Determine the probable genotypes of the mates of the albino offspring in the second generation and the grandson 4 in the 3rd generation. Genotypes: mate i _____ ; mate 2 _____ ; grandson four _____.

d. Tin can you determine the genotype of son three in the second generation? Why or why not?

a. This trait is recessive. If it were dominant, then albinism would be nowadays in every generation, and it would be incommunicable to have albino children with ii nonalbino (homozygous recessive) parents.

b. father Aa; female parent Aa, because neither parent is albino and they take albino offspring (aa )

c. mate 1 AA (probably); mate 2 Aa; grandson iv Aa

d. The genotype of son 3 could be AA or Aa. If his wife is AA, then he could exist Aa (both his parents are carriers) and the recessive allele never would be epressed in his offspring. Even if he and his wife were both carriers (heterozygotes), there would be a ²⁴³/₁₀₂₄ (¾ ten ¾ x ¾ 10 ¾ 10 ¾) or 24% run a risk that all five children would be normally pigmented.

a. What is the probability that a mating betwixt ii carriers will produce an offspring with a recessively inherited disorder?

b. What is the probability that a phenotypically normal kid produced by a mating of two heterozygotes volition be a carrier?

a. ¼

b. ²/_iii. Of offspring with a normal phenotype, ²/₃ would be predicted to be heterozygotes and, thus, carriers of the recessive allele.

If 2 prospective parents both take siblings who have a recessive genetic disorder, what is the chance that they would take a child who inherits the disorder?

Both sets of prospective grandparents must have been carriers. The prospective parents practise not have the disorder and then they are non homozygous recessive. Thus, each has a ²/₃ chance of beingness a heterozygote carrier.

The probability that both parents are carriers is ^two/₃ x ^two/₃ = ⁴/₉ ; the chance that two heterozygotes volition accept a recessive homozygous child is ¼.

The overall adventure that a child will inherit the disease is ⁴/₉ x ¹/₄ = ¹/₉.

Should this couple have a babe that has the disease, this would plant that they are both carriers, and the chance that a subsequent child would take the disease is ¼.

Afterwards obtaining two heads from 2 tosses of a coin, the probability of tossing the coin and obtaining a head is

a. one/2

b. 1/four

c. 1/viii

d. iii/8

e. three/4

a. 1/ii

The probability of tossing 3 coins simultaneously and obtaining three heads is

a. one/ii

b. 1/iv

c. 1/8

d. 3/8

eastward. 3/4

c. ane/8

The probability of tossing three coins simultaneoulsy and obtaining two heads and 1 tail is

a. 1/2

b. ane/four

c. 1/eight

d. 3/viii

e. 3/4

d. 3/8

There are iii different means to get this issue: HHT, HTH, THH. Each effect has a probability of 1/8.

The F₂ generation

a. has a phenotypic ratio of 3:1.

b. is the issue of the self-fertilization or crossing of F_i individuals.

c. can be used to determine the genotype of individuals with the ascendant phenotype.

d, has a phenotypic ratio that equals its genotypic ratio.

e. has 16 dissimilar genotypic possibilities.

b. is the result of the self-fertilization or crossing of F_one individuals.

The base height of the dingdong plant is 10 cm. 4 genes contribute to the height of the plant, and each dominant allele contributes 3 cm to height. If you cross a 10-cm plant (quadruply homozygous recessive) with a 34-cm plant, how many phenotypic classes will in that location exist in the F_ii?

a. 4

b. five

c. 8

d. ix

e. 64

d. 9

According to Mendel's police force of segregation,

a. there is a 50% probability that a gamete volition go a dominant allele.

b. gene pairs segregate independently of other genes in gamete formation.

c. allele pairs dissever in gamete formation.

d. the laws of probability determine gamete formation.

e. in that location is a 3:i ratio in the F_ii generation.

c. allele pairs separate in gamete formation.

A 1:one phenotypic ratio in a testcross indicates that

a. the alleles are dominant.

b. one parent must accept been homozygous dominant.

c. the dominant phenotype parent was a heterozygote.

d. the alleles segregated independently.

e. the alleles are codominant.

c. the dominant phenotype parent was a heterozygote.

Carriers of a genetic disorder

a. are indicated by solid symbols on a family pedigree.

b. are involved in consanguineous matings.

c. will produce children with the disease.

d. are heterzygotes for the gene that can cause the disorder.

due east. have a homozygous recessive genotype.

d. are heterzygotes for the cistron that can cause the disorder.

If both parents are carriers of a lethal recessive gene, the probability that their child will inherit and express the disorder is

a. 1/8

b. 1/four

c. i/two

d. ane/two x i/2 x 1/4, or i/16

e. ii/3 x 2/three x 1/four, or 1/9

b. 1/4

Which phase of meiosis is most straight related to the police force of independent assortment?

a. prophase I

b. prophase 2

c. metaphase I

d. metaphase II

e. anaphase II

c. metaphase I

You lot retrieve that ii alleles for coat color in mice evidence incomplete authorisation. What is the best and simplest cross to perform in order to back up your hypothesis?

a. a testcross of a homozygous recessive mouse with a mouse of unknown genotype

b. a cross of F₁ mice to look for a one:ii:1 ratio in the offspring

c. a reciprocal cross in which the sexual activity of the mice of each coat color is reversed

d. a cantankerous of two true-convenance mice of different colors to wait for an intermediate phenotype in the F₁

east. a cantankerous of F_ane mice to look for a 9:vii ratio in the offspring

d. a cross of 2 true-convenance mice of different colors to look for an intermediate phenotype in the F₁

Which of the following homo diseases is inherited every bit a simple recessive trait?

a. Tay-Sachs disease

b. cancer

c. diabetes

d. Alzheimer'due south disease

due east. cardiovascular illness

a. Tay-Sachs disease

A multifactorial disorder

a. can ordinarily be traced to consanguineous matings.

b. is caused by recessively inherited lethal genes.

c. has both genetic and environmental causes.

d. has a collection of symptoms traceable to an epistatic gene.

east. is usually associated with quantitative traits.

d. has a collection of symptoms traceable to an epistatic cistron.

A mother with type B blood has two children, i with type A blood and one with type O blood. Her married man has blazon O claret. Which of the following could you conclude from this information?

a. The married man could not have fathered either child.

b. The husband could have fathered both children.

c. The husband must exist the father of the kid with blazon O claret and could exist the father of the blazon A child.

d. The married man could be the male parent of the child with type O blood, but not the type A kid.

e. Neither the mother nor the husband could be the biological parent of the blazon A child.

d. The husband could be the father of the child with type O blood, merely not the type A child.

In republic of guinea pigs, the dark-brown coat colour allele (B) is dominant over carmine (b), and the solid colour allele (Southward) is ascendant over spotted (s). The F_ane offspring of a cross between true-breeding brown, solid-colored guinea pigs and red, spotted pigs are crossed. What proportion of their offspring (F_ii) would be expected to be cherry-red and solid colored?

a. one/9

b. i/xvi

c. 3/16

d. ix/16

e. iii/iv

c. iii/16

A ascendant allele P causes the product of imperial pigment, pp individuals are white. A dominant allele C is also required for color production; cc individuals are white. What proportion of offspring will exist purple from a ppCc 10 PpCc cantankerous?

a. 1/8

b. iii/8

c. 1/ii

d. three/4

e. None

b. 3/8

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