Test: Bryophytes (NCERT) - NEET MCQ

Based on the given figure, the correct option is C: A - Archegoniophore, B-Gemma cup, C-Rhizoids as it correctly identifies the labeled parts.

Fig: Female thallus of Merchantia

In the life cycle of a moss, the predominant stage is the gametophyte stage. This stage consists of two main stages: the protonema stage and the leafy stage. The protonema stage is the first stage, developing directly from a spore, while the leafy stage develops from the secondary protonema as a lateral bud. The gametophyte stage bears the sex organs and is crucial for the reproductive cycle of mosses.

- Statement I: Bryophytes are indeed referred to as the amphibians of the plant kingdom because they rely on water for sexual reproduction, needing moisture for the sperm to swim to the egg.
- Statement II: Bryophytes do contribute significantly to plant succession on barren rocks by initiating soil formation and providing a habitat for other plant species.
- Statement III: Bryophytes lack true roots, stems, and leaves. Instead, they have structures that serve similar functions but are not as complex.
- Statement IV: The sex organs in bryophytes are indeed multicellular, aiding in the reproductive process.
- Statement VI: The archegonium in bryophytes is flask-shaped and produces a single egg, crucial for sexual reproduction.To determine the correct statements about bryophytes:


- Bryophytes produce biflagellate antherozoids not zoospores.


Correct statements:

- I. Bryophytes are also called amphibians of the plant kingdom because they are dependent on water for sexual reproduction.
- II. They play an important role in plant succession on bare rocks.
- III. They lack true roots, stem or leaves.
- IV. The sex organs in bryophytes are multicellular.
- VI. Archegonium is flask-shaped and produces a single egg.

Therefore, the number of correct statements is 5 (option C).

Species of Sphagnum, a moss, provide peat that have long been used as fuel, and as packing material for trans-shipment of living material because of their capacity to hold water

Mosses primarily reproduce vegetatively by fragmentation and budding in the secondary protonema stage. This method of reproduction allows mosses to propagate asexually and colonize new areas. Fragmentation involves the breaking off of segments of the plant body to grow into new individuals, while budding involves the formation of new growths from existing structures.

Solution: Incorrect statement: 4. The sporophyte in liverworts is differentiated into a foot, seta, and rhizoid.

Explanation: The correct differentiation of the sporophyte in liverworts includes a foot, seta, and capsule, not a rhizoid.

Bryophytes are also called amphibians of the plant kingdom because these plants can live in soil but are dependent on water for sexual reproduction

Correct answer: Two

Explanation:

• Statement 1 is incorrect because the tiny leaf-like appendages are arranged in two rows, not three.
• Statement 4 is incorrect because male and female sex organs can be produced either on the same or on different thalli in liverworts.

Statement 1: Each sperm of moss has two flagella.

• This statement is correct. The sperm of mosses are biflagellate, meaning they have two flagella that they use to swim towards the egg in the presence of water.

Statement 2: Water is essential for fertilization in mosses.

• This statement is also correct. Mosses require water for fertilization because the sperm must swim through water to reach the egg for fertilization to occur.

Both statements are correct; however, Statement 2 is not the explanation for Statement 1. They are simply two facts about the reproductive requirements of mosses.

Correct answer:  one

Explanation:

• Statement 1 is correct. In mosses, the gametophyte stage is indeed the dominant stage of the life cycle.
• Statement 2 is incorrect because the protonema stage is the first stage of the gametophyte, not the second.
• Statement 3 is correct as it accurately describes the development of the leafy stage from the secondary protonema.
• Statement 4 is correct and describes the attachment of the leafy stage to the soil through rhizoids.

Correct Matching:

1. Vegetative reproduction - b) Includes fragmentation and budding in the secondary protonema
2. Sporophyte structure - a) More elaborate in mosses than in liverworts
3. Sex organs - d) Antheridia and archegonia produced at the apex of the leafy shoots
4. Capsule - c) Contains spores formed after meiosis

Explanation:

• Vegetative reproduction in mosses occurs by fragmentation and budding in the secondary protonema.
• The sporophyte in mosses is more complex compared to liverworts, consisting of a foot, seta, and capsule.
• Sex organs (antheridia and archegonia) are located at the apex of the leafy shoots.
• The capsule of the sporophyte contains spores, which are released through an elaborate dispersal mechanism.

Correct answer: 3. (b) and (d) only

Explanation:

• Statement (b) is incorrect because liverworts have a haploid gametophyte and a diploid sporophyte. The sporophyte is not free-living and does not form by spore germination.
• Statement (d) is incorrect because Marchantia is not a heterosporous bryophyte; it is a homosporous liverwort.
• Statement (a) is correct; mosses do have an elaborate mechanism of spore dispersal.
• Statement (c) is correct; vegetative reproduction in Polytrichum occurs by budding in the secondary protonema.
• Statement (e) is correct; bog moss growth can contribute to the formation of peatlands by filling ponds and lakes with soil.

Vegetative reproduction in mosses is by fragmentation and budding in the secondary protonema.

Like other plants, the embryonic development in bryophytes begins with the process of fertilization. This involves the fusion of male and female gametes, which are produced in the antheridium and archegonium respectively.
 

Role of Archegonium

• The archegonium is the female sex organ in bryophytes, and it is where the female gametes or eggs are produced.
• After fertilization, the zygote remains in the archegonium and begins to divide and grow into an embryo.
• This process takes place within the protective structure of the archegonium, which provides a suitable environment for the developing embryo.

The assertion is correct. Bryophytes, including mosses and liverworts, indeed play a significant role in plant succession on barren surfaces like rocks and nutrient-poor soil. They are often the first plants to colonize these environments.

The reason is also correct and provides an explanation for why bryophytes contribute to plant succession. Bryophytes can slowly break down rocks through their growth and the release of organic acids. As they decompose rocks, they release minerals and organic matter into the soil, which enriches it. This enriched soil becomes more hospitable for the growth of higher plants, facilitating the establishment of a more complex plant community.

In summary, bryophytes help initiate plant succession by breaking down rocks and improving soil quality, thereby creating suitable conditions for the growth of higher plants.