Question

A purebred sweet corn plant that produces purple and smooth kernels pollinates a purebred plant that produces yellow and wrinkled kernels. When the F1 was testcrossed, four types of kernels on the cobs were observed in almost equal proportions: purple and smooth, purple and wrinkled, yellow and smooth, and yellow and wrinkled. Which of the following statement(s) are TRUE?

I. The F1 plants can only produce purple and wrinkled kernels when selfcrossed.

II. If the parent that produces yellow and wrinkled kernels was testcrossed, only one type of kernels will be observed.

III. If the F1 was selfcrossed, the F2 plants will bear four types of kernels.

1. I only
2. II only
3. III only
4. II and III only
5. I have no answer for this question.

2. Which of the following statement(s) are FALSE?

I. Allele A is dominant to allele a. Therefore A and a are possibly located at different loci.

II. Allele A is dominant to allele a. Therefore A and a are always located at the same loci.

III. Allele A is dominant to allele a. Therefore A and a are always located on a pair of homologous chromosomes.

1. I only
2. II and III only
3. I, II and III
4. None of the statements

3. Wheat pigmentation is controlled by two genes. A homozygous red wheat plant and a homozygous white wheat plant were crossed to produce F1. When F1 plants were intercrossed, about 160 wheat grains were produced. Among them 151 were red and 9 were white. Which of the following best explains this observation?

A. Red pigmentation requires the expression of both genes.

B. Absence of one of the genes shuts down the expression of the other gene.

C. One of the genes, when expressed, suppresses the function of the other gene.

D. Pigmentation can be expressed by either gene.

4. A plant species can be tall (dominant) or dwarf; its leaf can be with (dominant) or without red patches; its flower can be purple (dominant) or pink. A truebred tall, purple-flowered plant which does not have red patches on its leaf pollinated a truebred dwarf, pink-flowered plant which does not have red patches on its leaf. The F1 progeny was selfcrossed.

Among the F2 individuals, what is the probability of producing a dwarf, purple-flowered plant which has red patches on the leaf?

1. 0
2. 1/16
3. 3/16
4. 3/4

5. A tortoiseshell cat was crossed to a black cat. Which of the following statement(s) are TRUE?

I. The black cat was a male.

II. The progeny can be black, orange or tortoiseshell.

III. The female progeny will not be completely orange in colour.

1. I only
2. II only
3. I and II only
4. I, II and III

6. If two parents who are both with blood type A and have normal vision, produce a color blind son with blood type O, what is the probability that the next child is a female who has normal vision and blood type A?

1. 3/16
2. 3/8
3. 9/16
4. 1/16

7. Which of the following statement(s) are FALSE?

I. Pattern baldness heritable in man but not heritable in women.

II. Mutation can be either dominant or recessive.

III. When a trait is not manifested uniformly among individuals that show it, the trait is said to have variable expressivity.

1. I only
2. II and III only
3. I, II and III
4. None of the statements

8. Which of the following statement(s) are FALSE?

I. A man who has a copy of Y chromosome and two copies of X chromosomes will have a Barr body in each of his cell.

II. For a diploid cell (2n = 8), each primary spermatocyte has 8 DNA molecules.

III. Homologous chromosomes pair up in Prophase I in secondary oocytes.

1. I only
2. II and III only
3. I, II and III
4. None of the statements

9. Which of the following statement(s) are FALSE?

1. Both meiosis and mitosis happen during spermatogenesis.
2. Secondary oocyte of a normal human contains 23 chromosomes.
3. Pollen mother cell undergoes reduction division in the female gametophyte.
4. Megaspore undergoes three rounds of mitosis to produce antipodal cells, polar nuclei, egg cell and synergids.

10. Matt started his farm by raising a Pea-combed cock and a Rose-comb hen. Years later Matt has chickens with Pea comb, Rose comb, Single comb and Walnut comb. Which of the following statement(s) are TRUE?

I. Matt does not have a truebred chicken.

II. A testcross on the Walnut-comb chicken in Matt’s farm will result in progeny of four phenotypes.

III. If Matt repeatedly crossed the Rose-comb chickens in his farm, he has a chance to produce truebred Rose-comb chicken.Immersive Reader

1. I only
2. II only
3. I and II only
4. II and III only

Answer 1

I can answer the first 4 questions.

Q1) Let the genotype of the purple and smooth kernels = PPSS

and the genotype of the yellow and wrinkled kernels = ppss

if we cross them PPSS x ppss

Gametes ----------------> PS ps

F1----------------------------------> PpSs (Purple smooth).

if F1 is test crossed PpSs x ppss

Gametes --------------->   PS Ps pS ps ps

progeny ----------------> PpSs Ppss ppSs ppss

(Purple/smooth) (Purple wrinkled) (Yellow smooth) (Yellow wrinkled)

if F1 plants are self crossed PsSs x PpSs

Gametes -------------> PS Ps pS ps PS Ps pS ps

	PS	Ps	pS	ps
PS	PPSS Purple/smooth	PPSs Purple/smooth	PpSS Purple/smooth	PpSs Purple/smooth
Ps	PPSs Purple/smooth	PPss Purple wrinkled	PpSs Purple/smooth	Ppss Purple wrinkled
pS	PpSS Purple/smooth	PpSs Purple/smooth	ppSS Yellow smooth	ppSs Yellow smooth
ps	PpSs Purple/smooth	Ppss Purple wrinkled	ppSs Yellow smooth	ppSS Yellow Wrinkled

here 4 types of kernels are produced.

if the parent that produces yellow and wrinkled seeds is test crossed

ppss x ppss

gametes ------> ps ps

progeny ---------> ppss (yellow wrinkled only)

Therefore option D is correct.

Q2) the two alleles for a particular trait whether dominant or recessive are found on the same loci but on two homologous chromosomes. therefore option 1 is not correct.

the correct response for this question is option A

Q3) The 151: 9 is very close to 15: 1 ratio that is charactersitic of duplicate gene wherein the presence of any of the two genes or both the genes in dominant condition are required to produce red phenotype and white phenotype is produced when both the genes are in recessive condition as shown

Consider the genotype of homozygous Red plant = AABB

and genotype of the homozygous white plant = aabb

Cross -------------> AABB x aabb

Gametes --------------------> AB ab

F1 ------------------------------> AaBb (Red)

Selfing ----------------------------------> AaBb x AaBb

gametes ------------------> AB Ab aB ab AB Ab aB ab

	AB	Ab	aB	ab
AB	AABB	AABb	AaBB	AaBb
Ab	AABb	AAbb	AaBb	Aabb
aB	AaBB	AaBb	aaBb	aaBb
ab	AaBb	Aabb	aaBb	aabb

Therefore the correct option is D.

Q4) The genotype of the true breeding tall, purple flowered and leaves without red patches = TTPPrr

the genotype of true breeding dwarf, pink flowered and leaves without red patches = ttpprr

cross --------------------> TTPPrr x ttpprr

gametes -----------------> TPr tpr

F1-----------------------------> TtPprr (Tall/ purple/ no red patches)

selfing -------------> TtPprr x TtPprr

gametes -------------->   TPr, Tpr tPr tpr TPr, Tpr tPr tpr

Since there is not a single R (red allele present in the gametes), therefore there is zero percent probability that the F2 have any plant with red patches.

therefore option A is correct.

Thank you