Question
Give reasons: Zona pellucid is retained for sometime after fertilization.
✓
Answer
- Fertilization of the ovum takes place in fallopian tube where it starts cleavages immediately.
- Zona pellucida which remains on the surface of the ovum prevents the implantation of the blastocyst at an abnormal site such as fallopian tube.
- Zona pellucida keeps the sticky and phagocytic trophoblast cells unexposed till the ovum reaches the uterine lumen.
- Zona pellucida also protects the ovum. Therefore zona pellucida is retained for some time after fertilization.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Why is that once a person starts taking alcohol or drugs, it is difficult to get rid of this habit? Discuss it with your teacher.
How would you explain to the farmers that apiculture is both easy and economically beneficial to them?
Describe the naming of the restriction enzymes with an example.
Mendel published his work on inheritance of characters in 1865, but it remained unrecognised till 1900. Give three reasons for the delay in accepting his work.
What are the signs and symptoms of filariasis?
Give reasons : Buttermilk is used in the dough of dhokla.
- Do all pollen grains remain viable for the same length of time? Support your answer with two suitable examples.
- How are pollen grains stored in pollen banks? State the purpose of storing pollen grains in these banks.
Answer the following question based on the figures given below:
- What do S and P denote?
- Name the parts from Which they do develop?
- What is the term given to the point of attachment of the ovules in the fruit?
- What is the ploidy of embryo and the tissues in the ovary?
- What is the function of pericarp in fruit?
Name the kind of organisms which constitute the pioneer community of xerarch and hydrarch successions respectively.
State what is apomixis. Comment on its significance. How can it be commercially used?