Q25 of 27 Page 1

Certain phenotypes in human population are spread over a gradient and reflect the contribution of more than two genes. What is the term used for the types of inheritance? Describe it with the help of an example in human population.

OR


Summarize the process by which the sequence of DNA bases in Human Genome Project was determined using the method developed by Frederick Sanger. Name a free living non-pathogenic nematode who’s DNA has been sequenced.


• Such type of inheritance in which more than two genes contribute for the phenotypic traits of an individual is known as Polygenic Inheritance.


• For example, let’s assume that the skin colour in humans is controlled by three genes, namely A, B and C.


• The dominant genes A, B and C are responsible for imparting dark colour to the skin.


• The recessive genes a, b and c are responsible for light skin colour.


• The genotype with all dominant alleles AABBCC will be darkest skin colour.


• The genotype with all recessive alleles aabbcc will be lightest skin colour.


• Whereas there is another genotype AaBbCc which imparts an intermediate skin colour. This because of the presence of three dominant alleles and three recessive alleles.


OR


• The fragments of the DNA were sequenced using automated DNA sequencers.


• Thus obtained sequences were arranged based on some overlapping sequences present in them.


This alignment of sequences couldn’t be done by humans.


• As a result of this, computer based programs were developed for the purpose of aligning.


• These sequences were annotated and were assigned to each chromosome.


• Thus, the sequence of Chromosome 1 was completed.


• Caenorhabditis elegans was a free living non-pathogenic nematode who’s DNA has been sequenced.


More from this chapter

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23

Large quantities of sewage is generated every day in cities and towns, which is treated in Sewage Treatment Plants (STPs) to make it less polluting. Given below is the flow diagram of one of the stages of STP. Observe the given flow diagram and answer the questions accordingly.


(a) Why primary effluent is passed into large aeration tanks?


(b) What is the scientific term used for the sediment formed? Mention its significance.


(c) Explain the final step resulting in the formation of biogas in the large tank before the treated effluent is released into water bodies.


 24


Observe the diagram of the catalytic converter and answer the questions which follow.


(a) Name any two metals used as catalyst in the catalytic converter.


(b) Name the gases released after passing the exhaust hydrocarbons through the catalytic converter.


(c) Which other poisonous gas is missing in the exhaust pollutant of an automobile in the above diagram?


 26

(a) What is mutation breeding? Give an example of a crop and disease to which resistance was induced by mutation.

(b) Differentiate between pisciculture and aquaculture.


OR


a) If a patient is advised anti-retroviral drug, which infection is he suffering from? Name the causative organism.


b) How do vaccines prevent subsequent microbial infections?


c) How a cancerous cell differs from the normal cell?


d) Many microbial pathogens enter the gut of humans along with food. Name the physiological barrier that protects the body from such pathogens.


 27

“Indiscriminate human activities have strengthened the greenhouse effect resulting in Global Warming.” Give the relative contribution of various Green House Gases in the form of a pie chart and explain the fate of the energy of sunlight reaching the earth’s surface contributing towards Global Warming.

OR


Given below is a table depicting population interactions between species A and species B.



Name the two types of population interactions (a) and (b) depicted in the above table. Justify giving three reason, how the type of interaction (b) is important in an ecological context.