Question 1

Q1: 1. Mention the advantages of selecting pea plant for experiment by Mendel.

Accepted Answer

Mendel selected the garden pea plant (Pisum sativum) for his experiments due to several advantages it offered: 1.  Well-defined Characters: The pea plant has several distinct and easily observable contrasting traits, such as tall/dwarf stems, round/wrinkled seeds, and violet/white flowers. 2.  Bisex...

Question 2

Q2: 2. Differentiate between the following - (a) Dominance and Recessive (b) Homozygous and Heterozygous (c) Monohybrid and Dihybrid.

Accepted Answer

Question 3

Q3: 3. A diploid organism is heterozygous for 4 loci, how many types of gametes can be produced?

Accepted Answer

The number of different types of gametes that a diploid organism can produce is determined by the formula $2^n$, where 'n' is the number of loci for which the organism is heterozygous. Given: The organism is heterozygous for 4 loci, so $n = 4$. Formula: Number of gamete types = $2^n$ Calculation: Nu...

Question 4

Q4: 4. Explain the Law of Dominance using a monohybrid cross.

Accepted Answer

The Law of Dominance, proposed by Gregor Mendel, states that when two individuals with pure but contrasting traits are crossed, the trait that appears in the first-generation (F1) is dominant, and the one that does not appear is recessive. This can be explained using a monohybrid cross between a tru...

Question 5

Q5: 5. Define and design a test-cross.

Accepted Answer

Definition: A test cross is a genetic cross between an organism showing a dominant phenotype (whose genotype is unknown) and another organism that is homozygous recessive for the same trait. The purpose of a test cross is to determine the genotype of the organism with the dominant phenotype (i.e., w...

Question 6

Q6: 6. Using a Punnett Square, workout the distribution of phenotypic features in the first filial generation after a cross between a homozygous female an...

Accepted Answer

Let us consider the trait for height in pea plants, where Tall (T) is dominant over dwarf (t). The cross is between a homozygous female and a heterozygous male. -   Genotype of heterozygous male: Tt -   A homozygous female can be either homozygous dominant (TT) or homozygous recessive (tt). We will...

Question 7

Q7: 7. When a cross in made between tall plant with yellow seeds (TtYy) and tall plant with green seed (Ttyy), what proportions of phenotype in the offspr...

Accepted Answer

This is a dihybrid cross. We can solve this by considering the inheritance of each trait separately and then combining the probabilities. Parental Cross: TtYy (tall, yellow) $	imes$ Ttyy (tall, green) 1. Consider the first trait (Height): -   Cross: Tt $	imes$ Tt -   Offspring Genotypes: 1 TT : 2...

Question 8

Q8: 8. Two heterozygous parents are crossed. If the two loci are linked what would be the distribution of phenotypic features in F1 generation for a dibyb...

Accepted Answer

When two heterozygous parents are crossed for two linked loci (a dihybrid cross), the distribution of phenotypic features in the offspring (often referred to as the F2 generation in this context) deviates significantly from the typical 9:3:3:1 ratio seen for unlinked genes. Linkage is the tendency o...

Question 9

Q9: 9. Briefly mention the contribution of T.H. Morgan in genetics.

Accepted Answer

Thomas Hunt Morgan (T.H. Morgan) made seminal contributions to the field of genetics through his work with the fruit fly, Drosophila melanogaster. His work provided the experimental evidence that solidified the Chromosomal Theory of Inheritance. Key contributions of T.H. Morgan include: 1.  Experime...

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