Q4 of 43 Page 1

Name any two physiological barriers that provide innate immunity.

Physiological barriers are the first line of defense against pathogens. The acid in the stomach (HCl), the saliva in the mouth and tears in the eyes are examples of physiological barriers.


OR


Select two disease resistant crop varieties from the list of crop varieties given below:


Himgiri, Pusa Gaurav, Pusa Komal, Pusa A-4


Himgiri and Pusa Komal are disease resistant crop varieties.


Pusa komal is resistant to bacterial blight, whereas Himgiri is resistant to leaf rust.


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2

Name a human genetic disorder due to the following:

(a) An additional X-chromosome in a male


(b) Deletion of one X-chromosome in a female


 3

Mention one example each from plants and animals exhibiting divergent evolution.

 5

Give two reasons as to why a weed such a Calotropis flourishes in abandoned fields.

 6

Mosses and frogs both need water as a medium for fertilisation. Where does syngamy occur and how is it ensured in both these organisms?

OR


Write the basis of categorising animals as oviparous or viviparous, giving one example of each.