Question

Refer the given figure and answer the following questions.

(a) The given life cycles, (A and B) are found in protists. Identify the type of cycle A and B. 

(b) Give the examples of groups in which these two cycles (A and B) are found respectively 

(c) Differentiate between life cycle A and B.

Answer 1

 (a): A – life cycle with zygotic meiosis B – life cycle with gametic meiosis 

(b) life cycle showing zygotic meiosis is found in dinoflagellates and cellular slime moulds. life cycle showing gametic meiosis is found in majority of protozoan protists, diatoms and acellular slime moulds. 

(c) Differences between life cycle with zygotic meiosis and life cycle with gametic meiosis are as follows.

	life cycle with zygotic meiosis	life cycle with gametic meiosis
1.	Zygote is the only diploid structure in the life cycle.	All structures except gametes are diploid.
2.	The dominant individual in the life cycle is haploid hence the life cycle is haplontic.	The dominant individual in the life cycle is diploid hence the life cycle is diplontic.
3.	Meiosis takes place at the time of zygote germination.	Meiosis occurs only at the time of gamete formation.