Short Answer TypeMention any two contrasting traits with respect to seeds in pea plant that were studied by Mendel.
In Snapdragon, A cross between true breeding red flower (RR) plants and true breeding white flower (rr) plants showed a Progeny of plants with all pink flowers.
(a)The appearance of pink flowers is not known as blending. Why?(b)What is the phenomenon known as?
Linkage or crossing-over of genes are alternatives of each other. Justify with the help of an example.
Why is pedigree analysis done in the study of human genetics? State the conclusions that can be drawn from it.
Identify ‘a’, ‘b’, ‘c’, ‘d’, ‘e’ and ‘f’ in the table given below :
|
No. |
Syndrome |
Cause |
Characteristic of affected individuals |
Sex Male/Female/ both |
|
1 |
Down’s |
Trisomy of 21 chromosome |
‘a’ (i) (ii) |
‘b’ |
|
2 |
‘c’ |
XXY |
Overall masculine development |
‘d’ |
|
3 |
Turner |
45 with XO |
‘e’ (i) (ii) |
‘f’ |
Name the respective pattern of inheritance where F1 phenotype
(a) does not resemble either of the two parents and is in between the two.
(b) resembles only one of the two parents.
(a) Explain the phenomena of multiple allelism and co-dominanace taking ABO blood group as an example.
(b) What is the phenotype of the following:(i) IAi
(ii) i i
(a) The inheritance of ABO blood groups in humans exhibits co-dominance and multiple allelism.
Multiple allelism-: The ABO blood groups are controlled by the gene I. The I gene has three alleles, namely IA, IB and i. Since more than two alleles control a single trait thus it shows multiple allelism.
Co-dominance-: The allele IA and IB are both dominant over the allele i but they express themselves completely even in the presence of the other that is when both are present the blood group is AB . This represents co-dominance.
(b) ( i) Phenotype of IAi will be A blood group since the allele IA is dominant over the allele i
(ii) Phenotype of ii will be O blood group since the allele is recessive and expresses itself in the homozygous condition.
Long Answer Type(a) Explain a monohybrid cross taking seed coat colour as a trait in Pisum sativum. Work out the cross upto F2 generation.
(b) State the laws of inheritance that can be derived from such a cross.
(c) How is the phenotypic ratio of F2 generation different in a dihybrid cross?
(a) Why is fertilization in an angiosperm referred to as double fertilisation? Mention the ploidy of the cells involved.
(b) Draw a neat labeled sketch of L.S. of an endospermous monocot seed.
Short Answer TypeA male honeybee has 16 chromosomes whereas its female has 32 chromosomes. Give one reason.
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