Differentiate between the following.
(a) Apogamy and apospory
(b) Homospory and heterospory
(c) Gametophyte and sporophyte
(d) Prothallus and protonema

(a) Apogamy: Formation of haploid sporophytes from haploid cells of gametophytes without fusion of gametes. It is a type of asexual reproduction discovered by Farlow in Pteris.
Apospory: Formation of diploid gametophyte from diploid cells of sporophyte (which do not undergo meiotic cell division) This was discovered by Druery in fern Athyrium.
(b) When all the spores are of same type, i.e., same size, shape, etc., then the condition is considered as homosporous. When spores produced are of different types i.e., macro and micro spores which germinate to produce female and male gametophytes, respectively. Such condition is known as heterospory.
(c) Gametophyte: The dominant phase of life cycle in bryophytes which produces haploid gametes. These gametes unite to form zygote from which sporophytes arises.
Sporophyte: The diploid multicellular stage in the life cycle of plant which produces haploid spores that develop into gametophyte.
(d) Prothallus: The gametophyte produced by the germination of spores is thalloid and bears both male and female sex organs and is called prothallus.
Protonema: The haploid spore of a moss plant germinates to produce a branched photosynthetic filamentous juvenile stage called protonema. This is seen in bryophytes.