Q21 of 50 Page 1

What are Methanogens? Name the animals they are present in and the role they play there.

Some bacteria can grow anaerobically on cellulosic material producing large amount of methane gas along with carbon dioxide and hydrogen. They are called methanogens.


The animals they are present in are the cattle specifically the rumen of cattle (a part of stomach) where a lot of cellulosic material of food are present. Methanogens help in breaking down of this cellulose to help in the digestion of the same and this plays an important role in the nutrition of cattle.


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17

Identify the following pairs as Homologous or Analogous organs :

(i) Sweet potato and potato


(ii) Eye of octopus and eye of mammals


(iii) Thorns of Bougainvillea and tendrils of Cucurbits.


(iv) Fore limbs of Bat and Whale.


 18

List the post-fertilization events in angiosperms.

 27

There are many animals that have become extinct in the wild but continue to be maintained in Zoological parks.

(i) What type of biodiversity conservation is observed in this case ?


(ii) Explain any other two ways which help in this type of conservation.


 29

(a) Draw a labelled diagrammatic view of human male reproductive system.

(b) Differentiate between :


(i) Vas deferens and vasa efferentia


(ii) Spermatogenesis and spermiogenesis


OR


(a) Explain the phenomenon of double fertilization.


(b) Draw a labelled diagram of a typical anatropous ovule.