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

Do you think Mendel's law of inheritance would have been different if the characters he chose were located on the same chromosome? Why?

1

(a)

Mendel could not have framed the law of independent assortment, if the genes for all the characters Mendel chose, were present on the same chromosome and showed the phenomenon of linkage.

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.

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.

1

(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.

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 advantage of presence of sickle allele in the heterozygous condition?

1

(a)

Sickle allele in heterozygous condition protects the person against malaria (RBC having sickle shaped hemoglobin were readily infected with malarial parasite and with the bursting of such an RBC, parasites present in the sickled cells also die.

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.

1

(a)

When genes are not linked.

Given below is a diagrammatic sketch of the hand of a person.

a) Name or mention the genetic feature.
b) Make a pedigree of the character to mention its inheritance? What do the circles and squares in the chart represent respectively?
c) Is it a sex linked character? Give reason in support of your answer.

1

(a)

a) Polydactyly 11 fingers
b) Circles –females
Squares –male
c) No both male and female are showing it.

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

1

(a)

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

1

(a)

0%

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.

1

(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 .

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.

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

1

(a)

Tt and tt.