1.What is Genetics?
Genetics is the study of inheritance or heredity. It deals with the transmission of characters, specific for that particular type of plant or animal, from the parent to the offspring of the next generation.
2.What are alleles?
Alleles are corresponding pairs of genes located at specific positions in the Chromosome. They determine the genotype of their host organism.
3.What are multiple Alleles?
When number of traits or genetic characters are the result of more than 2 types of alleles it is called multiple alleles.
4.Explain the ABO blood group system?
The ABO blood groups system in human beings was established by K. Landsteiner. It is based on the presence or absence of certain antigens. There can be two anitigens A or B in the blood, resulting in four blood groups, namely A,B, AB and O. These are called ABO blood groups or Landsteiner blood groups.
5.What are the different blood groups and their antigen and antibody in serum?
Blood groups Antigen Antibody in the serum
A A anti B
B B anti B
AB A and B None
O None anti A and B
6.Discuss how ‘O’ blood group is considered as an universal donor?
‘Group O’ will have antibodies for ‘group A’ and B. Hence ‘group O’ will agglutinize group A and B.
Blood group of the donor Blood group of the recipient
A A and AB
B B and AB
O O, A, B, AB
From the table provided it is obvious that ‘group AB’ is universal recipient. ‘Group O’ is universal donor.
7.What is Rh factor in blood group?
Rh factor in blood was discovered by Landsteiner and Wiener in 1940. It was initially discovered in rabbits, immunized with the blood of Rhesus monkey. The human beings whose blood will get agglutinated with rabbit serum were designated as Rh+, and whose blood if not agglutinated were desig-nated as Rh-. Wrong transfusion can cause agglutination of blood in the recipient. Hence before transfusion of blood, along with identification of ABO blood group, it is necessary to test compatibility of Rh factor.
8.What is the cause for the death of a child in Erythroblastosis fetalis?
The presence of Rh+ child in the uterus of the Rh" mother can cause agglutination in the blood of the fetus. Even though such an unfortunate incident may not happen in the first pregnancy, it could occur in successive pregnancies. The death of the foetus in such cases is due to haemolytic anemia. This disease is called erythroblastosis fetalis.
9.Write short notes on Quantitive inheritance?
Charles Darwin while working on his theory of Natural selection, recognised two principal types of variations, namely continuous and discontinuous. The continuous variations show the whole range of variations in a particular character. The discontinuous variations would appear all of a sudden and show no gradation
Mendel in his work depended on sharp or alternate characters comprising discontinuous variations. For example, when tall and dwarf plants were crossed, in F( only tall plants appeared. Crossing F1 plants, produced only tall and dwarf plants in the F2 generation. Mendel discarded intermediate characters if any, seen.
Gallon, a British geneticist and statistician was interested in the study of continuous variations. He tried to find an answer for its origin. He called these characters as metrical characters and found them inherited.
10.What is the opinion of biometricians in genetics?
The biometricians believed that hereditary variations are basically continuous and quantitative. These two views remained contradictory. Later, Johansen (1903), through his work on bean seeds proved that both the views of Mendelians and biometricians were only partly correct.
YuIe (1906) suggested that quantitative variations may be controlled by large number of individual genes, with each gene having a small effect. Later on, such genes were called as polygenic systems. The hereditary processes operating through such system was explained through multiple factor hypothesis.
11.Who are mulattoes?
The inheritance of skin colour in black and white populations in United States of America was worked out and reported by C. B. Davenport in 1913. In USA, marriages between black and white individuals has resulted in a population known as mulattoes. When the mulattoes marry among themselves, all shades of ' skin colours are obtained.