Q.When and where does reduction division take place in the life cycle of a liverwort, a moss, a fern, a gymnosperm and an angiosperm?

Reduction division (meiosis) is the step that produces haploid spores, so in each of these plants it happens wherever spores are formed:

• Liverwort — inside the capsule of the sporophyte, where spores are produced.
• Moss — inside the capsule of the sporophyte.
• Fern — within the sporangia, where spore mother cells divide to form spores.
• Gymnosperm — inside the sporangia, that is, the microsporangium (forming microspores) and the megasporangium (forming megaspores) borne on the cones.
• Angiosperm — inside the flower, in the anther (forming microspores/pollen) and in the ovule (forming the megaspore).

The key idea links every one of these plants together: reduction division is the event that halves the chromosome number and gives rise to haploid spores. Since spores are the product of meiosis, you only need to ask where and when spores are made in each life cycle, and that is exactly where meiosis takes place.

• Liverwort — after fertilisation the zygote grows into a sporophyte made of a foot, a seta and a capsule. Meiosis occurs later, inside the capsule, where the spores are produced.
• Moss — the pattern is the same. The zygote develops into a sporophyte with a foot, seta and capsule, and meiosis takes place within the capsule to form the spores. The moss sporophyte is more elaborate than the liverwort's, but the site of reduction division is the same.
• Fern (a pteridophyte) — the dominant sporophyte bears sporangia. Within these sporangia the spore mother cells undergo meiosis to produce the spores.
• Gymnosperm — being heterosporous, it makes two kinds of spores, and meiosis happens in both sporangia. In the microsporangium the microspore mother cells divide to give microspores, and in the megasporangium (within the ovule) the megaspore mother cell divides to give megaspores. These sporangia are carried on the sporophylls of the male and female cones.
• Angiosperm — the spore-forming structures lie inside the flower. Meiosis occurs in the anther, where microspore (pollen) mother cells form the microspores, and in the ovule, where the megaspore mother cell forms the megaspore.