Problem 103 - Objective Biology for NEET

Question

Spore in bryophytes are formed (a) On the gametophyte (b) On the sporophyte (c) In the seta of sporophyte (d) In the capsule of sporophyte

Step-by-Step Solution

Answer

The correct answer is (d) In the capsule of sporophyte.

Step 1: Understanding the key terms

First, a clear understanding of the terms is needed. In bryophytes, the gametophyte is the dominant phase, the sporophyte is the next generation, and the seta is the stalk that supports the capsule of the sporophyte.

Step 2: Relating the terms to the lifecycle of bryophytes

Now, muster the knowledge of bryophyte lifecycle. The sporophyte generation grows on the female gametophyte, and it produces spores. The seta is the stalk that supports the capsule, but it does not produce spores. The capsule of the sporophyte is where the spores are produced.

Step 3: Final selection

Since the capsule of the sporophyte is where the spores are produced, the correct answer is (d) In the capsule of sporophyte.

Key Concepts

Gametophyte

Bryophytes, like mosses and liverworts, are non-vascular plants where the life cycle is fascinating owing to its unique features. The gametophyte is the dominant and photosynthetic phase in the life cycle of bryophytes. This stage is where these plants spend most of their lifecycle. All tissues and structures that you see, like the leafy green structure in mosses, are part of the gametophyte phase.

• The gametophyte typically provides sustenance through photosynthesis, as they have chlorophyll.
• This stage is involved in sexual reproduction. Male and female gametes are produced here.
• Gametes fuse to form a zygote, which is the initial part of the sporophyte generation.

The focus on gametophyte indicates how important it is in the reproductive cycle of bryophytes. Its role as the primary phase signifies its evolution in adaptation to land environments. As it generally anchors itself to the substrate through structures called rhizoids, it ensures water absorption essential for both support and reproduction.

Sporophyte

The sporophyte is the result of the fertilization process that involves gametes produced by the gametophyte. In bryophytes, unlike in higher plants, the sporophyte is not independent but is dependent on the gametophyte for nutrition and support.

• The sporophyte is usually smaller and grows on the female gametophyte.
• This phase includes three main structures: the foot, the seta, and the capsule.
• The sporophyte is genetically different due to the combination of genetic material from both male and female gametes.

Understanding the role of the sporophyte in bryophytes underscores its function as a vessel for spore formation and dissemination, which aids in propagation and survival across generations.

Spore Production

An essential part of the bryophyte life cycle is spore production, which occurs in a specific part of the sporophyte. These cells have the crucial function of ensuring the continuity of the plant's lifecycle through dispersal and growth of new gametophytes.

• Spores are produced by meiosis within the capsule of the sporophyte.
• Meiosis results in haploid spores, which can germinate into a new gametophyte.
• The capsule often contains structures that aid in spore release, spreading them to favorable environments.

Proper spore production and distribution ensure that bryophytes can adapt and survive in diverse ecological conditions, highlighting their resilience and adaptability. Ultimately, the lifecycle of bryophytes, with its distinct alternation of generations, showcases a uniquely structured evolution, relying on both the sporophyte and gametophyte phases.