Principles of Inheritance and Variation Test

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Principles of Inheritance and Variation Test - 70

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Weekly Quiz Competition

Question 1
1 / -0

In humans, freckles is dominant over no freckles. A man with freckles marries a woman having freckles but the children have no freckles. What chances did each child have for freckles.

A
25%

B
50%

C
75%

D
100%

Solution

Freckles are dominant over non freckles. If a man with freckles marries a woman with freckles. Freckles is a condition where an organism have brown spots in his body. Freckles is represented by F(dominant) and n on freckles is f(recessive). It will be dominant over 'f' in heterozygous condition as well.Both of the parents produces FF (homozygous dominant),Ff(heterozygous dominant),Ff (heterozygous dominant), and ff(homozygous recessive) in the first progeny.So out of 4 progeny only 75% of the total progeny have the chances to be with freckles.
So, the correct option is C'.
Question 2
1 / -0

In the following pedigree chart, the mutant trait is shaded black. The gene responsible for the trait is

A
dominant and sex linked

B
dominant and autosomal

C
recessive and sex linked

D
recessive and autosomal
Question 3
1 / -0

Wife is PTC non-taster and husband is PTC taster. Their son is taster but daughters are non-tasters. This is not a sex linked trait. Which pedigree is correct?

A

B

C

D
Solution
Correct Option: A
Explanation:
People that can taste the bitter compound phenylthiocarbamide or PTC, are PTC tasters.
For some people, PTC is tasteless, and they are known as PTC non-tasters.
This inability is an autosomal recessive, occurs when the allele responsible for this trait is present in homozygous recessive condition on the autosomes.
Son is a taster and has inherited one autosome carrying the allele for this trait from his mother but a normal autosome from his father.
The daughters may be affected because one autosome they will inherit from the mother and the other one from father which may also have the allele for PTC trait.
Hence, pedigree A is correct.
Question 4
1 / -0

In all the Mendels experiments, the two alleles causing a trait were

A
dominant-recessive

B
codominant

C
incompletely dominant

D
corecessive

Solution

In Mendel's experiment, the two alleles which were observed had either dominant or recessive character for example tall T was a dominant character while t was a recessive character.
So, the correct option is 'dominant-recessive'.
Question 5
1 / -0

Study the pedigree given above and select the type of inheritance of the trait?

A
X-linked recessive

B
Y-linked

C
Autosomal recessive

D
Autosomal dominant
Question 6
1 / -0

Which is correct?

A
Birds have ZZ-ZW sex determination

B
Diosophilla has XX-XY sex determination

C
Henking discovered Y-ch

D
Grasshoppers show X-XY sex determination

Solution

A.Birds have ZZ-ZW sex determination – False, because, in birds, ZW-ZZ type of sex determination is found.

B.Drosophila has XX-XY sex determination – True

C.Henking discovered Y – Chromosomes – False because he discovered X chromosomes

D.Grasshoppers show X-XY chromosomes – False, because, in this, XX-XO type of sex determination is found.
So, the correct option is ‘Drosophila has XX-XY sex determination’.
Question 7
1 / -0

All of the following are sexual sources of genetic variation except

A
Crossing-over

B
Mutation

C
Production of offspring from two parents

D
Random fertilization
Solution
- A mutation is the permanent alteration of the nucleotide sequence of the genome of an organism, virus, or extrachromosomal DNA or other genetic elements.
- Mutations result from errors during DNA replication (especially during meiosis) or other types of damage to DNA (such as may be caused by exposure to radiation or carcinogens), which then may undergo error-prone repair (especially microhomology-mediated end joining), or cause an error during other forms of repair.
- Mutations may or may not produce discernible changes in the observable characteristics (phenotype) of an organism.
- Mutations play a part in both normal and abnormal biological processes including evolution, cancer, and the development of the immune system, including junctional diversity.
So the correct option is 'mutation'.
Question 8
1 / -0

Choose the correct answer from the alternatives given.
One pure strain of pea plants developed by Mendel had yellow seeds and another strain had green seeds. All the offsprings from crosses between these two parental strains of plants had yellow seeds. In these plants, the allele for yellow seed colour is

A
recessive to the allele for green colour

B
dominant over the allele for green colour

C
epistatic over other alleles

D
expressed only in gametes

Solution

since the two strains mated were pure, both of them must be homozygous for their seed colour. Homozygous individuals for two different colours when mated will result in the offsprings having a heterozygous genotype. In this case, since the yellow seed colour masks the effect of the green seed colour and only the yellow colour is seen in the phenotype of the offsprings, it must be the dominant phenotype over the green seed colour. So, the correct option is 'dominant over the allele for green colour'.
Question 9
1 / -0

$$F_1$$ offspring of the monohybrid cross AA $$\times$$ aa are _______.

A
All AA

B
All Aa

C
All aa

D
1/2 AA and 1/2 aa

Solution

If a cross is made between AA and aa, all the offsprings will be Aa. The F$$_1$$ generation shows the dominant phenotype. Aa is heterozygous and it has one copy of two different alleles.
So, the correct answer is 'All Aa'.
Question 10
1 / -0

Genetic variability can be created by

A
mass selection

B
mutation

C
clone selection

D
hybridization

Solution

Mutations are changes in DNA. A single mutation can have a large effect but in many cases, evolutionary change is based on the accumulation of many mutations. And this result in genetic variability.
So, the correct option is 'mutation'