Sarita Aggarwal solutions for बायोलॉजी [इंग्रजी] इयत्ता १२ आईएससी chapter 6 - Chromosomes, Sex-Linked Inheritance and Human Genetic Disorders [Latest edition]

According to the chromosome theory ______.

The chromosomes in eukaryotic organisms are best studied in ______.

If the linked genes are present not very far off on the chromosome, the recombinant frequency would be ______. 

If the cross over frequency of genes A, B and C are as given, between A and B = 10%, between B and C = 5%, between A and C = 5.5%, the sequence of genes on the chromosome would be ______.

The agents that cause mutations are called as ______.

When a particular chromosome is present in a single copy in a normal diploid cell it is called ______.

50% recombinants in linked genes occur when ______.

Which one of the following gives rise to a normal human female?

A haemophilic man marries a normal homozygous woman. What is the probability that their son will be haemophilic?

What is the probability that their daughter will be haemophilic? (Refer Q.9)

A female would be colour blind only if ______.

A normal woman whose father was colour blind marries a normal man. There will be ______ chance that her sons would be colour blind.

Which one is correctly matched?

The recessive genes located on X chromosome in humans are always ______.

Turner’s syndrome is due to ______.

Down’s syndrome occurs as a result of ______.

A disease caused by an autosomal primary non-disjunction is ______.

Thalassemia and sickle cell anaemia are caused due to a problem in globin molecule synthesis. Identify the correct statement from the following.

If a woman has an allele for an X-Linked condition i.e. haemophilia, on one of her X chromosomes then this chromosome can be inherited by ______

Select the incorrect statement.

What is the genetic disorder in which an individual has an overall masculine development gynaecomastia, and is sterile?

Chemical used in karyotyping to arrest the mitotic cell division at metaphase stage is ______.

Sickle cell anaemia is an example of following.

The chromosomes that do not determine the sex of an individual are called ______.

Haemophilia is due to a ______ gene.

Fruit fly Drosophila melanogaster has ______ pairs of autosomes.

The mutations that occur due to insertion or deletion of a single base of DNA segment are called ______ mutations.

If mother is a carrier of colourblind gene, there is a possibility of ______ offspring to be colourblind.

State whether the following is true or false.

A human male produces two types of gametes half containing X chromosome and half containing Y chromosome.

State whether the following is true or false.

All sons of a colour blind father will always be colour blind.

State whether the following is true or false.

Down’s syndrome is due to trisomy of chromosome number 20.

State whether the following is true or false.

Phenylketonuria exhibits itself in the homozygous recessive condition.

State whether the following is true or false.

If both parents are carriers ofthalassaemia, they need genetic counselling as there is 50% chance ofthe child being thalassaemia major.

State whether the following is true or false.

In beta thalassaemia minors, the two of the four beta globin genes are faulty.

Match the following.

Answer the following in one or two words.

A sudden, spontaneous change in the DNA of a chromosome.

Answer the following in one or two words.

Who determines the sex of the baby, male or female?

Answer the following in one or two words.

Which chromosomes do not take part in the sex determination?

Answer the following in one or two words.

Both father and mother have normal vision but son is colour blind. From whom has the son inherited the disease?

Answer the following in one or two words.

All the genes located on the same chromosome.

Answer the following in one or two words.

Kind of inheritance exhibited by haemophilia gene.

Answer the following in one or two words.

A technique by which trisomy of Down's syndrome can be detected.

Answer the following in one or two words.

A disease in which carrier individuals are resistant to malaria.

Assertion (A): In humans, the gamete contributed by the male determines whether the child produced will be male or female.

Reason (R): Sex in humans is a polygenic trait depending upon a cumulative effect of some genes on X-chromosome and some on Y-chromosome.

Assertion (A): A pair of genes is said to be linked if their recombination frequency is 50% or lower.

Reason (R): Higher frequency of crossing over is shown in linked genes if distance between them is longer.

Assertion (A): Haemophilia is a recessive sex-linked disease.

Reason (R): Haemophilia occurs due to the absence of a clotting factor in the blood.

Assertion (A): Sickle cell anaemia is an autosome linked genetically inherited disorder affecting many new born babies.

Reason (R): It is caused by substitution of valine by glutamic acid at the sixth position of the beta globin chain of haemoglobin molecule.

Assertion (A): Phenylketonuria is a recessive hereditary disorder which leads to accumulation of phenyl pyruvic acid and other derivatives in the brain.

Reason (R): The affected individual lacks an enzyme that converts amino acid phenylalanine into tyrosine.

Assertion (A): Turner's syndrome is caused by the absence of any one of the X and Y sex chromosome.

Reason (R): Such individuals show masculine as well as feminine development.