BIOLOGY 1 Marks Question

Grasshopper has XO type of sex determination.

A person suffering from color blindness is unable to differentiate between Red and Green colors.

The seed plant having the genotype RRyy will have a phenotype-Round and yellow seeds.

De Vries of Holland, Carl Correns of Germany, and V. Tschermak of Austria.

The phenotypic and genotypic ratio for dihybrid test cross are similar and can be written as 1:1:1:1.

When an organism possesses given character are dissimilar, in gene structure it is said to be homozygous. e.g.TT/tt for height character in plant.
But when an organism possesses both the alleles of given character are dissimilar, it is said to be heterozygous e.g. Tt for height character of plant.

The alleles which are able to express themselves independently when present together are called co-dominant alleles and this phenomena is known as co-dominance. e.g. AB blood group inheritance in human

The child receiving allele I^ allele from mother and i allele from father will have blood group A

Chromosomal theory of inheritance

1. Pedigree analysis a useful for the genetic counsellor to advise intending couples about the possibilities of having children's with genetic like hemophilia colour blindness etc.
2. Pedigree analysis indicates the Mendel principal are also applicable to Human Genetics with some modifications found out later like quantitative inheritance sex link character and other linkage.

Sickle Cell anaemia

Muscular dystrophy disease and Sickle cell anaemia.

W. Sutton and T. Boveri.

Phenotypic ratio of Mendel's dihybrid cross is 9:3:3:1

The changes in gene structure due to alteration in nucleotide number types and sequence at one point is called point mutation.

Inheritance of AB blood group.

The organism, in which pair of sex chromosomes dissimilar called heterogametic. e.g. male drosophila

Down's Syndrome

Haemophilia and Hypertrichosis.

The mutation in which the reading of the frame of the base sequence shifts laterally due to insertion or deletion of one or more nucleotides in the genes is called frameshift mutation. e.g. Thalassemia.

Hanking used the term X body and XX-XY types of sex determination is found in human being determined by the male as male is heterogametic.

The term linkage was given by T. H. Morgan and A. Sturtevantat first prepare the recombination map.

It is a cross involving two types of individual where the male of one type is crossed with female of second type and vice versa. It is performed to study the effect of sex on the inheritance of traits.

Walter Sutton and Theodore Boveri noted that the behaviour of chromosomes was parallel to the behaviour of genes and used chromosome movement to explain Mendel's law. Sutton and Boveri argued that the pairing and separation of a pair of chromosomes would lead to the segregation of a pair of factors they carried and united the knowledge of chromosomal segregation with Mendel's principles and presented in the form of chromosomal theory of inheritance.

Phenotypic ratio for dihybrid cross: 9:3:3:1. Genotypic ratio for dihybrid cross: 1:2:2:4:1:2:1:2:1

The morphological expression of a trait is known as phenotype whereas the gene expression of a trait is known as genotype.
Phenotype may change with age and environmental condition but genotype never changes.

First Filial Generation

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The trait which expresses the same trait for many generations as a result of its own inheritance.

Mendel considered 7 pairs of the contrasting traits of the pea plant which are also called allelomorph e.g. tall and dwarf plant, round and wrinkled seed

Genetics is the study of heredity and variation.