In a test cross progeny of pea plats, all were bearing violet flowers. Give the genotypes of the parent pea plants.

1

(a)

VV and vv

Why do certain genes tend to be inherited together in a cell at the time of cell division?

1

(a)

When a tall pea plant was self-pollinated, one-fourth of the progency were dwarf.  Give the genotype of the parent and the dwarf progenies.

1

(a)

Parent ; Tt
Dwarf progeny : tt

What is the proof for or what indicates that the characters Mendel studied did not show blending?

1

(a)

The parental forms of the trait appear without any change in the F₂ generation.

Name and state the law of Mendel, which explains the expression of only one of the parental characters in the F₁ generation of a monohybrid cross.

1

(a)

Law of dominance states that when two individuals of a species, differing in a pair of contrasting characters are crossed, the parental character which appears in the F₁ hybrid, is said to be dominant over the trait that remains hidden (recessive).

Which law of inheritance of Mendel is universally acceptable and without any exception? State the law.

1

(a)

Law of Segregation states that the members of the allelic pair that remained together in the hybrid, segregate or separate during gametogenesis and enter different gametes.

Multiple allelism can be investigated only in populations.  Justify.

1

(a)

Though a gene exists in more than two allelic forms, in multiple allelism, a person can have only two of those alleles, because an individual has only two sets of homologous chromosomes, so multiple allelism can be studied only in a population.

If the frequency of a parental form is higher than 25% in a dihybrid test cross, what does that indicate about two genes involved?

1

(a)

If the frequency of parental forms is more than 25 the genes show linkage.

The egg of an animal contains 10 chromosomes, of which one is X-chromosome.  How many autosomes would there be in the karyotype of this animals?

1

(a)

Eighteen autosomes.

Mendel followed a definite sequence of steps in making a cross between tall and Dwarf pea plants to study the inheritance of one gene. Mention them in proper order.

1

(a)

Plant tall and dwarf -removal of anthers [emasculation] from one -transfer of pollen from second to first (pollination) - Syngamy - Seed production - Formation of pod.

Name a cross whose progenies can easily be analyzed to predict the genotype of the organism under observation?

1

(a)

Test cross.

Turner's syndrome is a sterile female generally with normal intelligence and known viable monosony in humans. Is the combination '44+YO' is also viable. Justify?

1

(a)

No, absence of even a single copy of ‘X’ chromosome (lot of important genes) results in nonviability of ‘YO’ combination.

The genetic disorders can be grouped under two broad categories- Mendelian disorders And chromosomal disorders which one of two can be traced in a family by pedigree chart? Name two such disorders.

1

(a)

Mendalian inheritance. E.g. - Hemophilia and Colour blindness.

What is the name given to the genes present in the different region [Non-Homologous] of the ‘Y’ chromosomes and what they code for?

1

(a)

Holandnic genes (holos-whole: andros –male) They code for male traits such as testes.

How will you find the genotype of an organism exhibiting a dominant phenotype trait ?

1

(a)

By test cross, with a homozygous recessive one.

What is the probability of Haemophilia in the son when a normal homozygous women is married to a Haemophilic man?

1

(a)

0%

What will be the karyotype of an individual who has developed from the zygote formed by an XX egg fertilized by a Y sperm ?Name the abnormality with which he will be suffering from .

1

(a)

47 chromosome, Klinefelter's syndrome.

What will be the percentage of gametes ry , formed by an individual with genotype RrYy ?

1

(a)

ry – 25%.

Why in a test cross, did Mendel cross a tall pea plant with a dwarf pea plant only?

1

(a)

Dwarfness is a recessive trait which is expressed only in homozygous condition, so he was sure of the genotype of the dwarf plant as it.

Why is a plant with genotype Tt referred to as heterozygous'?

1

(a)

Since the alleles for the contrasting forms of a trait are dissimilar, it is referred to as heterozygous.