Heredity and Evolution Test

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Heredity and Evolution Test - 14

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Weekly Quiz Competition

Question 1
1 / -0

When a gene exists in more than one form, the different forms are called:

A
Heterozygous

B
Complementary genes

C
Genotypes

D
Alleles

Solution

Alleles are the two forms of a gene that attribute to contrasting traits. The two alleles express two different phenotypes. The allele which shows its effect even in the heterozygous condition is known as the dominant allele and the allele which is unable to express itself in the heterozygous condition (in presence of the dominant allele) is known as the recessive allele.
So, the correct answer is option D.
Question 2
1 / -0

The dwarf trait of the F$$_1$$ generation pea plants observed in Mendel's experiments is a ________ character.

A
Recessive

B
Dominant

C
Incomplete dominant

D
Codominant

Solution

Mendel, in his experiments, observed seven characters, tall and dwarf were one of them. Among those seven characters, he observed the dominant and recessive alleles. He found that tall was dominant over dwarf i.e. phenotype was Tall with the Tt in which 'T' represents tall & 't' represents dwarf.
So, the correct answer is option A.
Question 3
1 / -0

When a tall plant with round seeds (TTRR) crossed with a dwarf plant with wrinkle seeds (ttrr), the F$$_{1}$$ generation consists of tall plants with round seeds. What would be the proportion of dwarf plant with wrinkle seeds in F$$_{1}$$ generation?

A
1/4

B
1/16

C
0

D
1/2

Solution

Here in this case, tall and round are the dominant characters that are strong enough to express even when heterozygous in nature.
Tall plant with round seeds: TTRR
Gametes produced: TR
Short plant with wrinkled seeds: ttrr
Gametes produced: tr
Crossing of the gametes will yield the F$$_1$$ generation.
TR x tr $$\rightarrow$$ TtRr (F$$_1$$ generation)
Here, the dominant character tall and round are represented by T and R respectively and thus, it expresses round seeds and tall phenotype.
Hence, the number of short plants in F$$_1$$ generation is zero.
Thus, the correct answer is option C.
Question 4
1 / -0

Mendel's laws of inheritance are applicable only for:

A
Asexual reproduction

B
Sexual reproduction

C
Vegetative propagation

D
All of the above
Solution
- Mendel's laws of inheritance explain well about heredity and are thus applicable only in the case of sexual reproduction.
- According to Mendel's laws of inheritance:-
- Law of independent assortment - Allele pairs separate independently during the formation of gametes.
- Law of dominance - Some alleles are dominant while some others are recessive. An organism with at least one dominant allele will express the dominant character.
- Law of segregation - Alleles for a trait separate when gametes are formed.
  Hence, the correct answer is option B.
Question 5
1 / -0

An allele is said to be dominant if:

A
It is expressed only in heterozygous condition.

B
It is expressed only in homozygous condition.

C
It is expressed in both homozygous and heterozygous conditions.

D
It is expressed only in second generation.

Solution

Alleles are the two individual genes in a particular gene pair that occupy the same locus or position on a homologous pair of chromosomes.
An allele may be dominant or recessive. If the allele is expressed in both homozygous (TT or tt) and heterozygous (Tt) conditions, then it is a dominant allele. Recessive alleles express in only homozygous conditions.
So, the correct answer is option C.
Question 6
1 / -0

Mendel, for his studies chose pea plants and considered many contrasting characteristics present in the pea plants. One of characteristics not considered by him was

A
Plant height

B
Plant colour

C
Pod shape

D
Pod colour

Solution

Mendel chose some pairs of 7 contrasting characters for his study on genetics-based on Pisum sativum. The characters chosen were:
1. Flower colour is purple or white
2. Flower position is axial or terminal
3. Stem length is long or short
4. Pod shape is inflated or constricted
5. Pod colour is yellow or green
6. Seed shape is round or wrinkled
7. Seed colour is yellow or green
Plant colour was not one of the characteristics chosen by him and thus, B is the correct option.
Question 7
1 / -0

The laws put forward by Mendel are

A
Laws of germplasm

B
Laws of origin of species

C
Laws of recapitulation

D
Laws of inheritance

Solution

Mendel proposed some Laws of Inheritance. They are three in number.
1. Law of Dominance
2. Law of Segregation
3. Law of independent assortment.
Question 8
1 / -0

F$$_1$$ generation of a cross between a red-flowered plant (RR) and a white-flowered plant (rr) predominantly consisted of red-flowered plants (Rr). This indicates that the red flower trait is:

A
Dominant

B
Assorted

C
Recessive

D
Hybrid

Solution

A dominant trait is one that masks the effect of a recessive trait in heterozygous condition. So, in the cross between a red-flowered plant (RR) and a white-flowered plant (rr), if red-flowered plants are produced in the first generation (Rr), it is evident that the red flower trait is dominant over the white flower trait. The allele for the red colour flower (R) is masking the effect of the white colour flower allele (r).
So, the red colour trait is the dominant one and the white colour trait is recessive.
Question 9
1 / -0

Which genotype represents a true dihybrid condition?

A
TtRr

B
ttrr

C
Ttrr

D
TrRR
Solution
- A dihybrid cross considers two pairs of contrasting characters. TtRr genotype is obtained from the dihybrid cross of TTRR and ttrr which are true-breeding homozygous dominant and homozygous recessive breeding lines.
- TtRr genotype consists of both dominant and recessive alleles for two different traits. Hence, it's a dihybrid genotype.
- On the other hand, other genotypes given in the questions contain heterozygous alleles for either one of the two traits or none at all.
So, the correct answer is 'TtRr'.
Question 10
1 / -0

Heterozygous purple-flowered plant was crossed with homozygous recessive white-flowered plant. The observed phenotype is

A
All purple

B
All white

C
50% purple, 50% white

D
75%

Solution

Heterozygous Purple flower - Pp
Gametes : P and p
Recessive white flower: pp
Gametes: p
Fusion thus yields: Pp (Purple) and pp (white)
The ratio is 1:1
Hence, it is 50% purple and 50% white.

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Re-Attempt Weekly Quiz Competition

Heredity and Evolution Test - 14

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Heredity and Evolution Test - 14

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Question 1

Heterozygous

Complementary genes

Genotypes

Alleles

Solution

Question 2

Recessive

Dominant

Incomplete dominant

Codominant

Solution

Question 3

1/4

1/16

0

1/2

Solution

Question 4

Asexual reproduction

Sexual reproduction

Vegetative propagation

All of the above

Solution

Question 5

It is expressed only in heterozygous condition.

It is expressed only in homozygous condition.

It is expressed in both homozygous and heterozygous conditions.

It is expressed only in second generation.

Solution

Question 6

Plant height

Plant colour

Pod shape

Pod colour

Solution

Question 7

Laws of germplasm

Laws of origin of species

Laws of recapitulation

Laws of inheritance

Solution

Question 8

Dominant

Assorted

Recessive

Hybrid

Solution

Question 9

TtRr

ttrr

Ttrr

TrRR

Solution

Question 10

All purple

All white

50% purple, 50% white

75%

Solution

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