Principles of Inheritance and Variation Test

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Principles of Inheritance and Variation Test - 45

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Weekly Quiz Competition

Question 1
1 / -0

How many type of gametes are found in F $_1$ progeny of cross between AABBCC and aabbcc?

A
3

B
8

C
27

D
64

Solution

A cross between AABBCC and aabbcc genotypes produces F $_1$ hybrid with AaBbCc genotype. Total number of types of gamete produce by an organism is 2 $^n$ , where n is the number of heterozygous genes present. The hybrid AaBbCc is heterozygous for three genes, thus total possible gametes by it = 2 $^3$ =8. The gametes produced by AaBbCc are "ABC, ABc, AbC, aBC, abC, aBc, abc and Abc". Correct answer is B.
Question 2
1 / -0

Sickle cell anaemia is an example of

A
Epistasis

B
Codominance

C
Pleiotropy

D
Incomplete dominance
Solution
- Epistasis is the non-allelic gene interaction where the presence of one gene masks or alters the expression of another gene thereby not allowing the later one to express fully. P
- Pleiotropy is the condition where a gene has its own independent effect but also modifies the expression of a completely different gene quantitatively.
- When both recessive and dominant traits are expressed in a heterozygous genotype; it is codominance.
- Incomplete dominance is the condition when none of the factors of a gene is dominant and the phenotype of a heterozygous dominant individual is a blend of dominant and recessive traits.
- Sickle cell anaemia is caused by a point mutation in Hb $^b$ gene, that codes the $\beta$ -chain, the mutated allele Hb $^s$ encodes the abnormal haemoglobin molecules which stick to one another and cause stiffness and sickle shape of red blood cells. The heterozygotes,
- Hb $^b$ Hb $^S$ , show increased resistance to malaria and therefore have the survival advantage in regions where malaria is a common disease.
- Thus, the mutant allele controls haemoglobin chain as well as malaria resistance which are completely different trait; sickle cell anaemia is a pleiotropic trait.
So, the correct answer is option C.
Question 3
1 / -0

Which one is an interaction of genes?

A
Recessiveness

B
Dominance

C
Epistasis

D
Pleiotropy

E
Both C and D

Solution

As we know that a trait is represented by two contrasting factors of a gene in a heterozygous individual; the allele/factor that can express itself in a heterozygous individual is called as dominant factor and its ability to express itself in heterozygous condition is dominance. The other factor whose effect is masked by the presence of dominant factor is called recessive factor and the phenomenon is recessiveness. For example tallness (T) is dominant over dwarfism (t) in plant height. Both dominance and recessiveness are attributes of an allele of a gene; not an interaction of genes.
Epistasis is the non-allelic gene interaction where the presence of one gene masks or alters the expression of another gene thereby not allowing the later one to express fully. Coat color in mouse and fruit color in squash are the examples of epistasis. Pleiotropy is the condition where a gene has its own independent effect but also modifies the expression of a completely different gene quantitatively. For example; gene governing wing shape affects the number of facets of bar-eyed Drosophila. Thus, both epistasis and pleiotropy are the examples of gene interaction.
Question 4
1 / -0

Which of the following is correct about traits chosen by Mendel?

A
Terminal pod is dominant.

B
Constricted pod is dominant.

C
Green coloured pod is dominant.

D
Tall plants are recessive.

Solution

Mendel chose seven pairs of contrasting traits, namely plant height, flower position, pod colour, pod shape, seed colour, seed shape and flower colour. The axial position was dominant to terminal flower position; green pod colour was dominant to yellow, tall plant was dominant to dwarf one and inflated pod was dominant to constricted one. Correct answer is C.
Question 5
1 / -0

In Melandrium, sex determination is of_____type.

A
XX - XO

B
ZZ - ZW

C
XX - XY

D
XY - XO

Solution

Sex determination in birds is of ZW-ZZ types in which females are heteromorphic (ZW) and males have homomorphic sex chromosomes (ZZ). In round worms and few insects (grasshopper), XX-XO mechanism of sex determination is present where females are homogametic (XX) but the male carries only one sex chromosome (XO). Hence the male grasshopper carries XO sex chromosomes.
In Melandrium, XX-XY mechanism of sex determination is present where the male plant is heterogametic and carries “XY” sex chromosome while female plant carries two copies of X-chromosomes (XX) as sex chromosomes.
Human follows XY-XX mechanisms of sex determination wherein male is heterogametic and carries “XY” sex chromosome while female carries two copies of X-chromosomes (XX) as its sex chromosomes. The absence of part or full copy of one X-chromosome in the human female is "Turner Syndrome" but the "XO" condition is not female sex determinant.
Question 6
1 / -0

Correct reason of Mendel's success was

A
He repeated each experiment several times.

B
Traits chosen by him had genes far apart so that linkage was absent.

C
He kept record of all experiments.

D
He used statistical techniques.

Solution

Mendel chose seven pairs of contrasting traits, the gene for each of which is present on seven different chromosomes of pea plant. Due to the presence on different chromosomes, Mendel's trait followed independent assortment during meiosis and produced the expected parental and recombinant phenotypes. If genes of these traits would have present together showing linkage, Mendel would not have got the expected results. Repeating the experiment, keeping records and use of statistical analysis were the secondary factors; major being the chosen traits not showing linkage.
So, the correct answer is 'Traits chosen by him had genes far apart so that linkage was absent'.
Question 7
1 / -0

A test cross is performed

A
By selfing of F $_2$ generation plants

B
By selfing of F $_1$ generation plants

C
To determine whether F $_1$ plants are homozygous or heterozygous

D
Between homozygous plants

Solution

Correct Option: C
Explanation:

The crossing of an F $_1$ progeny with a homozygous recessive parental progeny is done in order to determine whether the progeny is homozygous or heterozygous for a character under consideration. This is called a test cross. Those that are heterozygous will have one dominant and one recessive allele individuals and those that are homozygous dominant will have two dominant alleles, and those that are homozygous recessive will have two recessive alleles.
Thus, the correct answer is option C.
Question 8
1 / -0

The phenomenon of a single gene regulating several phenotypes is called as

A
Multiple allelism

B
Epistasis

C
Incomplete dominance

D
Pleiotropism

Solution

Epistasis is the non-allelic gene interaction where the presence of one gene masks or alters the expression of another gene thereby not allowing the later one to express fully. Coat colour in mouse and fruit colour in squash are the examples of epistasis.
Pleiotropy is the condition where a gene has its own independent effect but also modifies the expression of a completely different gene quantitatively. For example, gene governing wing shape affects the number of facets of bar-eyed Drosophila. When both recessive and dominant traits are expressed in a heterozygous genotype, it is codominance.
Incomplete dominance is the condition when none of the factors of a gene is dominant, the phenotype of the heterozygous dominant individual is a blend of dominant and recessive traits.
Multiple allelism is the condition where a trait is controlled by more than two alleles of a gene, for example, human blood group is governed by single gene "I" which has three alleles; I $^{A}$ , I $^{B}$ and I $^{O}$ .
The correct answer is option D.
Question 9
1 / -0

Which of the following pair of features is a good example of polygenic inheritance?

A
Hair pigment of mouse and tongue rolling in humans

B
Human height and skin colour

C
Human eye colour and sickle cell anaemia

D
ABO blood group in humans and flower colour of Mirabilis jalapa

Solution

A polygenic trait is the one that is governed by more than one gene. Human skin colour is a polygenic trait governed by more than one gene where dominant allele of each gene express only a part of trait and the full trait is expressed only in the presence of dominant alleles of all multiple genes, is called as polygenic inheritance. These genes control skin pigmentation only, no other phenotypic trait is affected by these genes. Likewise, human eye colour and hair pigment in the mouse are polygenic but tongue rolling in humans is not polygenic which makes option A incorrect. Human blood group inheritance is the example of codominance and multiple alleles. It is governed by three alleles namely $I^A$ , $I^B$ and i. Flower colour in Mirabilis jalapa is governed by two alleles of a gene that show incomplete dominance; option D is incorrect. Sickle cell anaemia is governed by two alleles of a gene $Hb^b$ and $Hb^s$ which makes option C incorrect. The correct option is B.

Question 10

1 / -0

When pure long plant having white flower is crossed with pure dwarf plant having red flower, the dwarf progeny in F

_2

generation will be

1/16

2/16

4/16

9/16

Solution

As we know that tallness (T) is dominant over dwarfism (t) and red colour (R) is dominant over white (r) flower colour.

Parent Generation, P

_1

: TTRR x ttrr

_1

generation : TtRr (tall plant, red flower)

_2

generation : TtRr x TtRr

Gametes TtRr----> TtRr	TR	Tr	tR	tr
TR	TTRR (tall plant, red flower)	TTRr (tall plant, red flower)	TtR R (tall plant, red flower)	TtRr (tall plant, red flower)
Tr	TTRr (tall plant, red flower)	TTrr (tall plant, white flower)	TtRr (tall plant, red flower)	Ttrr (tall plant, white flower)
tR	TtRR (tall plant, red flower)	TtRr (tall plant, red flower)	ttRR (dwarf plant, red flower)	ttRr (dwarf plant, red flower)
tr	TtRr (tall plant, red flower)	Ttrr (tall plant, white flower)	ttRr (dwarf plant, red flower)	ttrr (dwarf plant, white flower)

Thus, dwarf progeny in F

_2

generation= 4/16; C is correct answer.

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Principles of Inheritance and Variation Test - 45

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Principles of Inheritance and Variation Test - 45

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SHARING IS CARING

Question 1

3

8

27

64

Solution

Question 2

Epistasis

Codominance

Pleiotropy

Incomplete dominance

Solution

Question 3

Recessiveness

Dominance

Epistasis

Pleiotropy

Both C and D

Solution

Question 4

Terminal pod is dominant.

Constricted pod is dominant.

Green coloured pod is dominant.

Tall plants are recessive.

Solution

Question 5

XX - XO

ZZ - ZW

XX - XY

XY - XO

Solution

Question 6

He repeated each experiment several times.

Traits chosen by him had genes far apart so that linkage was absent.

He kept record of all experiments.

He used statistical techniques.

Solution

Question 7

By selfing of F2_22​ generation plants

By selfing of F1_11​ generation plants

To determine whether F1_11​ plants are homozygous or heterozygous

Between homozygous plants

Solution

Question 8

Multiple allelism

Epistasis

Incomplete dominance

Pleiotropism

Solution

Question 9

Hair pigment of mouse and tongue rolling in humans

Human height and skin colour

Human eye colour and sickle cell anaemia

ABO blood group in humans and flower colour of Mirabilis jalapa

Solution

Question 10

1/16

2/16

4/16

9/16

Solution

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By selfing of F $_2$ generation plants

By selfing of F $_1$ generation plants

To determine whether F $_1$ plants are homozygous or heterozygous