Question
Give the term/ reason:
Why does zona pellucida layer block the entry of additional sperms?

Answer

To ensure the fusion of one sperm.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

Define genetic engineering. Mention its main stages.
Answer the following questions:
During a cross involving true breeding red flowered and true breeding white flowered snapdragon plants, the F1 progeny did not show any of the parental traits, while they reappeared in F2 progenies. Explain the mechanism using Punnett Square.
The genetic code is, for the most part, universal, with few exceptions. Explain it by giving the example of mitochondria, the power house of cell.
  1. Explain the development of female gametophyte from a megaspore mother cell in an angiosperm.
  2. Draw a leballed diagram of a fully-developed embryo sac.

OR

  1. Describe the process of megasporogenesis in angiosperms, until 8-nucleate stage.
  2. Draw the labelled structure of mature embryo sac.
What is DNA fingerprinting? Mention its application.
  1. Write the scientific name of the organism Thomas Hunt Morgan and his colleagues worked with for their experiments. Explain the correlation between linkage and recombination with respect to genes as studied by them.
  2. How did Sturtevant explain gene mapping while working with Morgan?
  1. Work out a dihybrid cross upto F, generation between pea plants bearing violet-coloured axial flowers and white-coloured terminal flowers. Give their phenotypic ratio.
  2. State the Mendel's law of inheritance that was derived from such a cross.
Describe the characteristics a cloning vector must posses.
  1. Mention the contributions of the following scientists:
  1. Maurice Wilkins and Rosalind Franklin.
  2. Erwin Chargaff.
  1. Draw a double-stranded dinucleotide chain with all the four nitrogen bases. Label the polarity and the components of the dinucleotide.
Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics (use the internet).