Practice question
Question
Which spore is thick-walled and diploid?
Explanation
Zygospore results from conjugation of progametangia of compatible mating types, undergoes karyogamy becoming transient diploid (2n) nucleus within thick, melanized, warty wall containing multiple layers of sporopollenin-like material conferring resistance to UV, desiccation and microbial attack. Prior to germination meiosis reduces ploidy producing haploid sporangiospores capable of germination. Conidia, ascospores, basidiospores are typically haploid and thin-walled adapted for wind dispersal, not diploid survival. Zygospore therefore represents only diploid thick-walled resting spore in early fungal groups like Rhizopus, allowing survival through adverse seasons.