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

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(a)

VV and vv

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

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(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.

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(a)

Parent ; Tt
Dwarf progeny : tt

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

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(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.

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(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.

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(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.

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(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?

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(a)

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

Which of the following is a recessive or dominant trait in garden pea?
a) Tall stem b) Wrinkled seeds c) Green color seed coat d) Constricted pod.

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(a)

Dominant trait-tall stem
Recessive trait-winkled seed, green color coat seed constricted pod.

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.

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(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?

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(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?

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(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.

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(a)

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

A mother with blood group ‘O’ has a foetus with blood group ‘A’, father is also ‘A’ If the genes of the both the parents are inherited then the foetus should be a mixture of both the parents i.e. half ‘O’ and half ‘A’. Since the foetus is ‘A’, how can you explain the situation?

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(a)

Follow the principle of inheritance and law of dominance with gene for ‘A’ being dominant over gene for ‘O’, get the mono-hybrid cross.

When you will find the percentages of crossing over will be more
a) When linked genes are located close to each other.
b) When linked genes are located far apart from each other.
c) When genes are not linked.

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(a)

When genes are not linked.

The genes for haemophilia are located on chromosome of humans. It is normally impossible for a haemophilic father to pass the gene to his son . Why.

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(a)

It is ‘X’ linked disorder and the father passes his only ‘X’ chromosomes carrying haemophilic gene to his daughter and not to the son (who receives ‘Y’ chromosome).

In sexually reproducing organisms what is the contribution of the parents to their offspring \(\frac{1}{2} \) of their genes or \(\frac{1}{4}\) of their genes

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(a)

\(\frac{1}{2} \)

Write the sex chromosomes compliment of the following.
a) Human female & male
b) Male and Female grasshopper

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(a)

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

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(a)

By test cross, with a homozygous recessive one.

Show through a cross all the possibility of the genotypes of the progeny when a man with blood group B marries a women with blood group A, both heterozygous for the trait.

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(a)

Genotypes – I^aI^b , I^bi ,I^ai , ii

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 .

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(a)

47 chromosome, Klinefelter's syndrome.

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

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(a)

ry – 25%.

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

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(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'?

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(a)

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

Write the possible genotypes Mendel got, when he crossed F₁ tall pea plant with a dwarf pea plant.

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(a)

Tt and tt.