From free spores to a seed
"From free spores to a seed" is a free, interactive Class 11 Biology simulation for NEET, built on the NCERT section "Homospory, heterospory and the seed habit" in Plant Kingdom. Step a lineage from a homosporous fern through heterosporous Selaginella to a gymnosperm: spore sizes split, the female gametophyte stays longer on the parent, and finally the embryo is retained inside an ovule as a seed. NEET has asked about this idea 5 times in 10 years of papers.
From the lesson Homospory, heterospory and the seed habit in Plant Kingdom. Change the values and watch what happens.
What it shows
NCERT §3.3, §3.4
Step a lineage from a homosporous fern through heterosporous Selaginella to a gymnosperm: spore sizes split, the female gametophyte stays longer on the parent, and finally the embryo is retained inside an ovule as a seed.
Controls
3 to try
- Sliderevolutionary stage 0–3 (homosporous / heterosporous / retained megaspore / seed)
- Toggleshow ploidy colour
- Readoutfree-living or retained female gametophyte
Try this
Reach the first stage where the zygote develops inside a gametophyte still on the parent.
Common mistake
The pteridophyte gametophyte depends on the sporophyte.
In NEET
10 years of papers
Asked 5 times in 10 years of NEET.
See the past questions: Plant Kingdom (chapter)
The idea behind it
NCERT §3.3
- Most pteridophytes make spores of only one kind; they are homosporous.
- Selaginella and Salvinia make two kinds: large megaspores (macrospores) and small microspores. They are heterosporous.
- Megaspores grow into female gametophytes and microspores into male gametophytes.
- In heterosporous plants the female gametophyte stays on the parent sporophyte for a variable time, and the zygote grows into a young embryo inside that female gametophyte.
- This is a forerunner of the seed habit, which is regarded as an important step in evolution.
Questions
4 answers
- What does the "From free spores to a seed" simulation show?
- Step a lineage from a homosporous fern through heterosporous Selaginella to a gymnosperm: spore sizes split, the female gametophyte stays longer on the parent, and finally the embryo is retained inside an ovule as a seed.
- What mistake does the "From free spores to a seed" simulation fix?
- A common mistake it clears up: the pteridophyte gametophyte depends on the sporophyte.
- Has NEET asked about this idea?
- Yes. NEET has asked about this idea 5 times in 10 years of papers.
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Homospory, heterospory and the seed habit" in Plant Kingdom (Class 11 Biology).
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