Short Answer Type(a) List the three states the annuals and biennial angiosperms have to pass through during their life cycle.
(b) List and describe any two vegetative propagules in flowering plants.
During a medical investigation, an infant was found to possess an extra chromosome 21. Decribe the symptoms the child is likely to develop later in the life.
A number of passengers were severely burnt beyond recognition during a train accident. Name and describe a modern technique that can help hand over the dead to their relatives.
The technique that can help in the identification of victims is DNA fingerprinting which distinguishes between individuals of same species by using their DNA as sample. The chemical structure of DNA is same in everyone (99.9%) except the order of base pairs, i.e. only 0.1% of DNA makes every individual unique. DNA fingerprinting exploits the highly variable repeating sequences, i.e. VNTRs for profiling. These VNTRs are highly conserved among members of the same species. Technique
This technique has following steps:
(i) DNA Isolation DNA is extracted from the cells in a high speed centrifuge.
(ii) Amplification Many copies of the extracted DNA can be made by the use of polymerase chain reaction.
(iii) Digestion of DNA by restriction endonucleases.
(iv) Separation of DNA fragments by electrophoresis.
(v) Blotting Transfer of separated DNA fragments to synthetic membranes (like nylon or nitrocellulose).
(vi) Hybridisation, with the help of a radio labelled VNTR probe (small segments of DNA which help to detect the presence of a gene in a long DNA sequence). These probes target a specific nucleotide sequence that is complementary to them.
(vii) Autoradiography Detection of hybridised DNA fragments by autoradiography.
The presence of similarities between the victims and their relatives determines their association on the basis of which dead bodies can be identified and handed over to their families.
(a) What precaution(s) would you recommend to a patient requiring repeated blood transfusion?
(b) If the advise is not followed by the patient there is an apprehension that the patient might contract a disease that would destroy the immune system of his/her body. Explain with the help of schematic diagram only how the immune system would get affected and destroyed.
(a) What is inbreeding depression?
(b) Explain the importance of ‘selection’ during inbreeding in cattle.
Explain the role(s) of the following in biotechnology.
(a) Restriction endonuclease
(b) Gel-electrophoresis
(c) Selectable markers in pBR322
Switch
