Q22 of 27 Page 1


With reference to the above schematic diagram of Spermatogenesis (a) and Oogenesis (b), answer the following questions:


a) About 300 million spermatozoa may be present in a human male ejaculation at one time. Calculate how many spermatocytes will be involved to produce this number of spermatozoa.


b) How many spermatids will be formed?


c) How many chromatids are found during Oogenesis in Primary oocyte and First polar body in a human female?


(a) One spermatocyte is required to produce four spermatozoa. So-

1 spermatocyte → 4 spermatozoa


? spermatocytes → 300 million spermatozoa


= = 75 million


Therefore, 75 million spermatocytes are required to produce 300 million spermatozoa


(b) 300 million spermatids will be formed.


(c) In a primary oocyte, there are 46 chromosomes. Since each chromosome has 2 sister chromatids, therefore the total number of chromatids = 46×2 = 92 chromatids. Since Meiosis I is completed by this phase, therefore the number of chromatids = 92/2 = 46 chromatids.


More from this chapter

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20

State any two criteria for determining biodiversity hotspots. Name any two hotspots designated in India.

OR


Differentiate between in-situ and ex-situ approaches for conserving biodiversity. Give an example for each.


 21

When the gene product is required in large amounts, so transformed bacteria with the plasmid inside the bacteria are cultured on a large scale in an industrial fermenter which then synthesizes its protein. This product is extracted from the fermenter for commercial use.

a) Why is the used medium drained out from one side while fresh medium is added from the other?


(b) List any four optimum conditions for achieving the desired product in a bioreactor.


 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?