Short Answer TypeRecombination DNA technology is of great importance in the field of medicine. With the help of a flow chart, show how this technology has been used in preparing genetically engineered human insulin.
Following the collision of two trains a large number of passengers are killed. A majority of them are beyond recognition. Authorities want to hand over the dead to their relatives. Name a modern scientific method and write the procedure that would help in the identification of kinship.
Many plant and animal species are on the verge of their extinction because of loss of forest land by indiscriminate use by the humans. As a biology student what method would you suggest along with its advantages that can protect such threatened species from getting extinct?
Since October 02, 2014 'Swachh Bharat Abhiyan' has been launched in our country.
(a) Write your views on this initiative giving justification.
(b) As a biologist name two problems that you may face while implementing the programme in your locality.
(c) Suggest two remedial methods to overcome these problems.
Long Answer TypeA flower of tomato plant following the process of sexual reproduction produces 240 viable seeds.
Answer the following questions giving reasons:
(a) What is the minimum number of pollen grains that must have been involved in the pollination of its pistil?
(b) What would have been the minimum number of ovules present in the ovary?
(c) How many megaspore mother cells were involved?
(d) What is the minimum number of microspore mother cells involved in the above case?
(e) How many male gametes were involved in this case?
During the reproductive cycle of a human female, when, where and how does a placenta develop? What is the function of placenta during pregnancy and embryo development?
How did Hershey and Chase established that DNA is transferred from virus to bacteria?
Hershey and Chase worked on bacteriophages (viruses that infect bacteria).
When a bacteriophage infects a bacterium, the viral genetic material gets attached with the bacterial genetic material and then, bacteria treats the viral genetic material as its own to synthesize more viral particles.
Hershey and Chase experiment were to discover whether it was a protein or DNA that entered the bacteria from virus. They carried out the following steps:
i. They labelled some phages with radioactive sulphur and the others with radioactive phosphorus.
ii. These radioactive phages were used to infect E. coli.
iii. Then, E.coli was blended and centrifuged to remove viral particles.
iv. It was observed that bacteria with radioactive DNA were radioactive while those with radioactive proteins lost their radioactivity.
This showed that it is the DNA that enters the bacteria from viruses and not proteins. Hence, it was concluded that DNA is the genetic material.
Switch
