Fruit colour in squash in an example of: 
(b) Epistasis is the phenomenon of suppression of phenotypic expression of gene by a nonallelic gene which shows its own effect. A dominant epistatic allele suppresses the expression ofa nonallelic gene whether the latter is dominant or recessive. For example, fruit colour of Summer Squash (Cucurbita pepo) is governed by a gene which pruduces yellow colour in dominant state (Y-) and green colour in recessive state (yy).
A man whose father was colour blind marries a woman who had a colour blind mother and normal father. What percentage of male children of this couple will be colour blind?
(c) Colour blindness is a X-chromosome linked character.
In a population of 1000 individuals 360 belong to genotype AA, 480 to Aa and the remaining 160 to aa. Based on this data, the frequency of allele A in the population is: 
If two pea plants having red (dominant) coloured flowers with unknown genotypes are crossed, 75% of the flowers are red and 25% are white. The genotypic constitution of the parents having red coloured flowers will be
How many pairs of contrasting characters in pea plants were studied by Mendel in his experiments ? [2015 RS]
(c) Seven pairs of contrasting characters were selected in pea plant and studied by Mendel in his experiment.
Which is the most common mechanism of genetic variation in the population of sexually reproducing organism? [2015 RS]
(c) The most common cause of variations is recombination in the organism which are reproduced by sexual way.
Alleles are : [2015 RS]
(b) Alleles are defined as alternative form of same gene.
In his classic experiments on pea plants, Mendel did not use [2015 RS]
In the following human pedigree, the filled symbols represent the affected individuals. Identify the type of given pedigree. [2015 RS]
(b) Autosomal recessive is a type of disorder in which two copies of an abnormal gene must be found for the disease in the affected person.
A colour blind man marries a woman with normal sight who has no history of colour blindness in her family. His son also marries a woman whose family has no history of color blindness. What is the probability of their grandson through the Son being colour blind?
The wings of a bird and the wings of an insect are : [2015 RS]
(a) The bird's wings and insect's wings are analogous in structure. They show convergent evolution having similar adaptive functional structure developing in different species.
Which of the following most appropriately describes haemophilia ? 
(b) Hemophilia A and hemophilia B are inherited in an X-linked recessive pattern. The genes associated with these conditions are located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, it is very rare for females to have hemophilia. A characteristic of X-linked inheritance is that fathers cannot pass Xlinked traits to their sons.
A tall true breeding garden pea plant is crossed with a dwarf true breeding garden pea plant. When the F1 plants were selfed the resulting genotypes were in the ratio of 
Phenotypic ratio : 3: 1 (Tall :Dwarf) Genotypic Ratio: 1:2:1 (Homozygous Tall : Heterozygous Tall : Dwarf)
Match the terms in Column-I with their description in Column-II and choose the correct option : 
Pick out the correct statements : 
(a) Haemophilia is a sex-linked recessive disease
(b) Down's syndrome is due to aneuploidy
(c) Phenylketonuria is an autosomal recessive gene disorder.
(d) Sickle cell anaemia is a X-linked recessive gene disorder
(d) Sickle cell disease is inherited in an autosomal recessive pattern.
In a testcross involving F1 dihybrid flies, more parental-type offspring were produced than the recombinant-type offspring. This indicates 
(c) When two genes in a dihybrid cross are situated on the same chromosome, the proportion of parental gene combinations are much higher than the non-parental or recombinant type. This is also called incomplete linkage.
A cell at telophase stage is observed by a student in a plant brought from the field. He tells his teacher that this cell is not like other cells at telophase stage. There is no formation of cell plate and thus the cell is containing more number of chromosomes as compared to other dividing cells. This would result in 
(b) This phenomenon is known as Polyploidy, wherein the cells contain more than two paired (homologous) sets of chromosomes. Polyploidy is often seen in the case of plants. The major cause of polyploidy is the non - disjunction of sister chromatids during meiotic recombination. This condition is actually useful in development of new crop varieties.