MediumBiologyHigh School (11–12)Diversity of Living Organisms › Bryophytes and PteridophytesNumericalNEETBoard Exam
A cell of the thallus of a liverwort has 9 chromosomes…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A cell of the thallus of a liverwort has chromosomes. How many chromosomes are in (a) one of its spores, (b) an antherozoid, (c) the zygote, and (d) a cell of the seta?
Need a reminder? The key ideaShow
Most pteridophytes are homosporous. Selaginella and Salvinia are heterosporous: microspores grow into male gametophytes, megaspores into female gametophytes. A megasporangium has one megaspore mother cell and makes 4 megaspores. The female gametophyte stays on the parent, and the embryo starts to grow inside it: a forerunner of the seed habit. Gametophytes are haploid, sporophytes diploid.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Haploid parts. The thallus, its gametes and the spores are haploid: the spore has and the antherozoid has chromosomes.
Step 2. Diploid parts. Fertilisation joins two haploid gametes: the zygote has . The seta grows from the zygote, so its cells have .
Answer: (a) ; (b) ; (c) ; (d) .
Discussion (0)
Log in to join the discussion.
Loading…