Q24 of 31 Page 1

Given below is the diagram of a human ovum surrounded by a few sperms. Observe the diagram and answer the following questions:


(a) Compare the fate of sperms shown in the diagram.


(b) What is the role of zona pellucida in this process?


(c) Analyze the changes occurring in the ovum during the process.


(d) How is the entry of sperm into the ovum facilitated?


(e) Specify the region of female reproductive system where the event represented in the diagram takes place.

(a) Sperm ‘A’ is able to penetrate the wall of ova may fertilize the ovum, whereas B and C are unable to penetrate wall of ova and they will degenerate.


(b) Zona pellucida make sure that only one sperm enters into the ovum.


(c) Entry of sperm induces completion of meiotic division of the secondary oocyte which results in the formation of second polar body and a haploid ovum.


(d) Entry of a sperm into the ovum is facilitated by an enzyme present in the acrosome of a sperm.


(e) Ampullary-isthmic junction of the fallopian tube is the place where sperm enters ova.


More from this chapter

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22

The graph given below shows the distribution of biomes:


(a) What do the ‘X’ and ‘Y’ axis represent?


(b) Identify the ‘grassland’ and ‘coniferous forest’ biomes, from the above figure.


(c) Why is ‘F’ located at the given position in the graph?

 23

A son persuades his father to replace his old mobile phone with the latest model launched in the market. He also shares the latest features it has and explains how it can be of a help to him in the modern technological world. Father is reluctant in buying a new one and tries to explain about its environmental impact. How do you think, the biologist father would try to convince his son? Justify the arguments of father and son both, by mentioning positive aspects of the behavior displayed by both of them in the situation concerned (three each).

 24

The graph given below shows the variation in the levels of ovarian hormones during various phases of menstrual cycle:


(a) Identify ‘A’ and ‘B’.


(b) Specify the source of the hormone marked in the diagram.


(c) Reason out why A peaks before B.


(d) Compare the role of A and B.


(e) Under which condition will the level of B continue to remain high on the 28thday?

 25

Explain the process of protein synthesis from processed mRNA.