Biology · Plant Kingdom · NEET
The protonema is the very first stage of the moss gametophyte. NCERT describes it as a creeping, green, branched and frequently filamentous stage. "Filamentous" means it looks like a thin green thread. It grows directly from a spore. Later, the leafy moss plant grows out of it as a side (lateral) bud.
Protonema is HAPLOID (n). Here is the chain: the spore is haploid (it is made by meiosis inside the capsule). The protonema grows directly from that spore by simple mitosis, so it stays haploid. Because it is part of the gametophyte, and the gametophyte is always haploid, the protonema is n. NEET has asked the ploidy of a protonemal cell directly.
From a SPORE, not a zygote. The zygote (2n) grows into the sporophyte. The sporophyte makes a capsule, and meiosis inside the capsule makes haploid spores. Each spore then germinates directly into the protonema. So the correct order is: capsule to spore to protonema. Do not confuse spore with zygote — this is a common trap.
They are the two stages of the SAME gametophyte. The protonema is the first stage: green, creeping, filamentous, thread-like. The leafy stage is the second stage: it grows from the protonema as a lateral bud, has upright slender axes with spirally arranged leaves, and is attached by rhizoids. Only the leafy stage bears the sex organs (antheridia and archegonia).
It is part of the GAMETOPHYTE. In a moss the gametophyte is the dominant (main) stage, and it has two parts: the protonema and the leafy stage. The sporophyte is the separate diploid part that grows from the zygote and makes spores. So: protonema and leafy stage = gametophyte (n); spore-making body = sporophyte (2n).
The LEAFY stage carries the sex organs, NOT the protonema. The protonema first grows a lateral bud, that bud becomes the upright leafy plant, and this leafy plant bears antheridia (male) and archegonia (female). This matters for NEET because questions may wrongly say the protonema bears sex organs.
Assertion A: The first stage of gametophyte in the life cycle of moss is protonema stage. Reason R: Protonema develops directly from spores produced in capsule. In the light of the above statements, choose the most appropriate answer.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
It is green because it contains chlorophyll and can do photosynthesis, so it makes its own food. This lets the young moss survive on its own before the leafy plant forms.
Yes. It is green and photosynthetic, so it is independent and free-living. This is one reason the moss gametophyte is called the dominant, self-supporting stage.
It is haploid (n). NCERT directly asks the ploidy of a protonemal cell of a moss in its chapter exercises, and the answer is n because it grows from a haploid spore.
The protonema comes first. It grows from the spore, and then the leafy stage grows out of the protonema as a lateral bud. Order: spore to protonema to leafy stage.
No. The protonema is a special feature of MOSSES. Liverworts have a thalloid, flat gametophyte and reproduce asexually by gemmae in gemma cups, not by a filamentous protonema.
