Question

Life cycle of Spirogyra/Chlamydomonas
A) Haplbiontic/Haplontic
B) Diplobiontic
C) Haplodiplobiontic
D) Diplontic

Answer 1

Grey crescent is the cortical region formed in the egg of frog just after Fertilisation has occurred which is seen located at the opposite side from the entry side of sperm.

Complete answer:
Haplodiplobtic life cycle is a type of life cycle where there is alteration between haploid and diploid generations where Fertilisation of diploid cell give rise to haploid cells after meiosis which later forms diploid by the fusion of those two haploid cells.

Based on the information given in the hint, the life cycle of chlamydomonas is as follows where zygote undergoes meiosis as soon as fertilisation occurs and produced for haploid spores which can later develop into four individuals. Each individual attain sexual maturity and can undergo mitotic cell division and produce haploid gamete again which later fuses with the opposite sex gamete and produce zygote and the life cycle continues. As we see there is no production of diploid cells anywhere in the life cycle of Chlamydomonas therefore Chlamydomonas is haplobiontic.

Hence, the correct answer is option A.

Note: Spirogyra also undergoes similar kind of cell division and fusion as of Chlamydomonas where there is no production of diploid cells, therefore Spirogyra is also considered as haplobiontic.