Class 12th Biology 2013 Set2 Delhi Board Paper Solution
Question 30
(a) Draw a labelled schematic diagram of the transverse section of a mature anther of an angiosperm plant.
(b) Describe the characteristic features of an insect pollinated flower.
OR
(a) Describe the events of spermatogenesis with the help of a schematic representation.
(b) Write two differences between spermatogenesis and oogenesis.
Answer
(a)
(b) Majority of Insect pollinated flowers are
1. Large
2. Colourful
3. Fragnant
4. Rich in nectar
5. Flowers pollinated by flies and beettles secrete foul odours to attract them.
OR
(a)
(i) Spermatogenesis starts at the age of puberty
(ii) Spermatogonia are present on the inside wall of semniferous tubules multiply by mitotic divisions and increase in numbers.
(iii) Each spermatogonium is diploid and contain 46 chromosomes
(iv) Some of spermatogomia called primary spermato cytes undergo meiosis I to produce 2 equal haploid cells called - secondary spermatocytes with 23 chromosomes each
(v) Secondary spermatocyte undergo second meiotic division to produce 4 equal haploid spermatids.
(vi) Spermatid later transform into spermatozoa.
(b)
| Spermatogenesis | Oogenesis |
| (i) It occurs in testes | It occurs in ovaries |
| (ii) A spermato gonium forms 4 spermatozoa | An oogonium forms one ovum |
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