Q27 of 27 Page 1

“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.



• Clouds and gases reflect about one-fourth of the incoming solar radiation.


• Some of the solar radiation is absorbed. But almost half of it falls on the Earth’s surfaces heating it. And therefore only a small proportion of it is reflected back.


• Earth’s surface re-emits heat in the form of infrared radiations.


• A part of the re-emitted heat does not escape into space because; atmospheric gases like methane and carbon dioxide absorb a major part of it.


• These gases radiate heat energy. With the major part of it coming back to Earth’s surface, it heats the Earth’s surface once again.


OR


The two types of population interactions are –


(a) is Amensalism


(b) is Predation


Justifications as to why (b) is important in an ecological context-


• Predation can be thought as the nature’s way of transferring energies to higher trophic levels which is fixed by the plants. Therefore, it acts as conduits for energy transfer between the different trophic levels.


• It keeps the prey population in control, thereby preventing ecosystem instability.


• Predators help in maintaining species diversity in a community by reducing the competition among the prey species which compete for food and resources.


More from this chapter

All 27 →
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?


 25

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.


 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.