Question

a. Describe Mendel’s experiments.

b. What was the significance of Mendel’s results?

c. Compare and contrast dominance, codominance and incomplete dominance patterns of inheritance.

d. Does the discovery of more complex patterns of inheritance than what Mendel described invalidate his findings? Why or why not?

Answer 1

Ans a) Gregor Mendel’s experiments were stepping stones in genetics and helped in understanding a lot about genetics. He developed the hereditary model with help of pea by identifying seven characteristics of pea. He used some of the traits like height (tall vs short), seed color (yellow vs green), seed coat (wrinkled vs smooth). He used nearly 30,000 pea plants for his experiment. Mendel used species that are able to naturally self fertilize and hence he used true breeding pea plants for the experiments. He performed a number of first generation crosses which were called P or parental generation. The seeds were collected from P plants and grew them which produced offspring which was called the F1 generation. He allowed the F1 generation of plants to self fertilize naturally and collected the seeds of the F2 generation and so on which continued. Based on his experiments he was about to find out couple of Laws of Heredity which includes

Law of Segregation – In this law, it is stated that each of the trait that is inherited is by gene pair. The parent genes are separated randomly and hence the sex cells contain only one gene of the pair. Each of the offspring inherits one genetic allele from each of the parent.

Law of Independent Assortment – The genes for different traits are separately sorted from one another and hence one trait inheritance is not dependent on another.

Law of Dominance – In this law, one out of the allele will be expressed as dominant and this is the trait that will be reflected.