Q26 of 42 Page 1

Mention the site of fertilization of a human ovum. List the events that follow in sequence until the implantation of the blastocyst.

OR


(a) Draw a diagram of a fertilized embryo sac of a dicot flower. Label all its cellular components.


(b) Explain the development of a mature embryo from this embryo sac.


Fertilization, which is the process of fusion of male and female gamete, occurs in the ampullary-isthmic junction in fallopian tube of female humans. The various events that follow in sequence until the implantation of the blastocystare as follows:




Figure 3Transport of ovum, fertilisation and passage of growing embryo through fallopian tube.


OR


a.



Figure 4.Mature dicot embryo.


b. The development of a mature embryo from this embryo sac occurs by the following steps:



More from this chapter

All 42 →
24

Explain the process of DNA replication with the help of a replicating fork.

OR


(a) Dihybrid cross between two garden pea plant one homozygous tall with round seeds and the other dwarf with wrinkled seeds was carried.


(i) Write the genotype and phenotype of the F1 progeny obtained from this cross.


(ii) Give the different types of gametes of the F1 progeny.


(iii) Write the phenotypes and its ratios of the F2 generation obtained in this cross along with the explanation provided by Mendel.


(b) How were the observations of F2 progeny of dihybrid crosses in Drosophila by Morgan different from that of Mendel carried in pea plants ? Explain giving reasons.


 25

Explain the application of biotechnology in producing Bt cotton.

OR


Unless the vector and source DNA are cut, fragments separated and joined, the desired recombinant vector molecule cannot be created.


(a) How are the desirable DNA sequences cut ?


(b) Explain the technique used to separate the cut fragments.


(c) How are the resultant fragments joined to the vector DNA molecule ?


 1

Why is RNA more reactive in comparison to DNA?

 4

In what way is monocyte a cellular barrier with reference to immunity ?