Principles of Inheritance and Variation Test

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Principles of Inheritance and Variation Test - 73

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Weekly Quiz Competition

Question 1
1 / -0

$\alpha$ -1 Antitrypsin is _________________.

A
An antacid

B
An enzyme

C
Used to treat arthritis

D
Used to treat emphysema

Solution

Disorder of $\alpha$ -1-antitrypsin protein include $\alpha$ -1 antitrypsin deficiency, an autosomal codominant hereditary disorder which leads to a chronic uninhabited tissue breakdown. This causes the degradation especially of lung tissue, and eventually leads to characteristic manifestations of pulmonary emphysema.
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

Solution

The given trait cannot be sex-linked as sex-linked traits follow criss-cross inheritance and in the given pedigree, no criss-cross inheritance is being followed. The trait exhibited in the pedigree chart is autosomal recessive. An autosomal recessive trait appears in case of marriage between two heterozygous individuals (Aa x Aa = 3 Aa + 1 aa), a recessive individual with hybrid (Aa x aa = 2Aa + 2aa) and two recessives (aa x aa = all aa). It expresses its effect only in a pure or homozygous state. If the trait had been controlled by a dominant gene, then one of the parents must have possessed the dominant gene and hence the disease.
Question 3
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Choose the correct answer from the alternatives given.
Study the pedigree chart of a family showing the inheritance of sickle-cell anemia.
The trait traced in the above pedigree chart is

A
Dominant X-linked

B
Recessive X-linked

C
Autosomal dominant

D
Autosomal recessive.

Solution

In the above pedigree chart generation, If parents are unaffected but the offspring is affected. Based on this the trait traced in the above pedigree chart is autosomal recessive.
If both parents are unaffected and an offspring is affected, the trait must be recessive (parents are heterozygous carriers)
If both parents show a trait, all offspring must also exhibit the trait (homozygous recessive)
So the answer is option D 'Autosomal recessive'.
Question 4
1 / -0

In humans, polydactyly (i.e, presence of extra fingers and toes) is determined by a dominant autosomal allele (P) and the normal condition is determined by a recessive allele (p). Find out the possible genotypes of family members 1, 2 and 3 in the given pedigree.

A
1 PP, 2 Pp, 3 - pp

B
1 PP, 2 PP, 3 - pp

C
1 Pp, 2 PP, 3 - Pp

D
1 Pp, 2 Pp, 3 - pp
Solution
Correct option: D

Explanation:
- From the pedigree chart
1 - Polydactylous male (Pp)
2 - Polydactylons female (Pp)
3 - Normal Female (pp)
- Thus, Option D is correct.
Question 5
1 / -0

Study the given pedigree chart for sickle-cell anaemia and select the most appropriate option for the genotypes.

A
Genotypes of parents - $Hb^A \, Hb^5 \, Hb^A \, Hb^A$

Genotypes of 1st & 3rd child in $F_1 \, - \, Hb^A \, Hb^A \, Hb^A \, Hb^S$

B
Genotypes of parents - $Hb^A \, Hb^5 \, Hb^A \, Hb^S$

Genotypes of 1st & 3rd child in $F_1 \, - \, Hb^A \, Hb^A \, Hb^A \, Hb^A$

C
Genotypes of parents - $Hb^A \, HbA \, HbA \, Hb^S$

Genotypes of 1st & 3rd child in $F_1 \, - \, Hb^A \, Hb^A \, Hb^S \, Hb^S$

D
Genotypes of parents - $Hb^A \, Hb^S \, Hb^A \, Hb^S$

Genotypes of 1st & 3rd child in $F_1 \, - \, Hb^A \, Hb^S \, Hb^S \, Hb^S$
Question 6
1 / -0

In sickle-cell anaemia, shape of RBC's under oxygen tension becomes ____________________.

A
biconcave disc like

B
elongated and curved

C
circular

D
spherical

Solution

Sickle-cell anaemia is an inherited genetic condition in which affected individuals contain red blood cells that under low oxygen tension become biconcave disc to elongated and curved.
Question 7
1 / -0

An individual affected by phenylketonuria lacks an enzyme that converts the amino acid ______ into ______

A
tyrosine, phenylalanine

B
phenylalanine, tyrosine

C
homogentisic acid, phenylalanine

D
homogentisic acid, tyrosine

Solution

Phenylketonuria is an inherited disorder that increases the levels of a substance called phenylalanine in the blood. Phenylalanine is a building block of proteins (an amino acid). Phenylketonuria is caused by a mutated gene for the enzyme phenylalanine hydroxylase (PAH), which converts the amino acid phenylalanine ("Phe") to other essential compounds in the body, in particular tyrosine.
So, the correct answer is 'phenylalanine, tyrosine'.
Question 8
1 / -0

Given pedigree chart depicts the inheritance of attached ear lobes, an autosomal recessive trait.
Which of the following conclusions drawn is correct?

A
Parents are heterozygous

B
Parents are homozygous dominant

C
Parents are homozygous recessive

D
None of these
Question 9
1 / -0

Study the pedigree chart of a family showing the inheritance of myotonic dystrophy.
The trait under study is

A
Dominant X-linked

B
Recessive X-linked

C
Autosomal dominant

D
Recessive Y-linked
Question 10
1 / -0

It is said that Mendel proposed that the factor controlling any character is discrete and independent. His proposition was based on the

A
Results of $F_3$ generation of a cross

B
Observations that the offspring of a cross made between the plants having two contrasting characters shows only one character without any blending

C
Self pollination of $F_1$ offsprings

D
Cross pollination of $F_1$ generation with recessive parent

Solution

Mendel crossed two parent plants having contrasting characters. He found that in the first filial generation, F1 generation, the dominant of the two expressed while the recessive is suppressed. Apart from this, When the f1 generation is self crossed, in the F2 generation, these recessive characters appear again. Therefore, it is not that they have disappeared.
So, option B is the correct answer.