Problem 99 - Objective Biology for NEET

Question

Gemmae in liverworts are formed during (a) Sexual reproduction (b) Asexual reproduction (c) Spore formation (d) Adverse conduction

Step-by-Step Solution

Answer

Gemmae in liverworts are formed during asexual reproduction (option b).

Step 1: Understanding the Biological Concept

Gemmae are small, multicellular bodies that are created within structures known as gemmae cups, prominently found on the thallus - the vegetative tissue - of liverworts. They are responsible for a type of vegetative reproduction.

Step 2: Identifying the Type of Reproduction

Gemmae are not formed by sexual reproduction or spore formation but rather by a process that does not involve the fusion of gametes. They are formed during asexual reproduction when conditions are favorable.

Step 3: Discarding Irrelevant Choices

Since we have established that gemmae are formed during asexual reproduction, we can easily discard the rest of the choices which are not aligning, namely sexual reproduction, spore formation, and adverse conduction.

Key Concepts

Gemmae

Gemmae are fascinating structures found in many liverworts. They are small, multicellular bodies that play an important role in reproduction. The gemmae are housed in special structures known as gemmae cups, which rest on the surface of the liverwort thallus.
A key characteristic of gemmae is their ability to detach from the parent plant when conditions are right. Once detached, they can grow into a new, independent liverwort. This allows liverworts to spread quickly and efficiently across their environment, optimizing their chances of survival.

• Gemmae are essential for liverwort propagation.
• They allow liverworts to reproduce without needing seeds or flowers.
• These structures are specially adapted for quick dispersal and growth.

Asexual reproduction

Asexual reproduction is a fascinating process used by liverworts, among other organisms, allowing them to reproduce without the involvement of gametes. This form of reproduction does not require the fusion of an egg and sperm. Instead, liverworts rely on structures like gemmae to reproduce asexually. Asexual reproduction has several advantages:

• It allows plants to reproduce quickly and efficiently.
• Plants can reproduce even when pollinators are not available.
• It decreases genetic variation, which can be beneficial in stable environments.

The ability to reproduce asexually means liverworts can colonize new areas rapidly, maximizing their ecological niche.

Vegetative reproduction

Vegetative reproduction is a specific type of asexual reproduction. This method involves the growth of a new plant from a fragment of the parent plant, such as the thallus or specialized structures like gemmae.
For liverworts, vegetative reproduction is a vital way of ensuring survival and propagation. The gemmae detach from the parent and, under suitable conditions, develop into a new plant. This means that, although they are independent plants, they are genetically identical to the parent plant.

• It leads to the quick spread in favorable environments.
• No need for seeds or spores, allowing flexibility.
• Genetic clones preserve successful traits in similar environments.

Thallus

The thallus is a simple, undifferentiated plant body, often seen in liverworts. Unlike higher plants, which have roots, stems, and leaves, the thallus serves all these functions. In liverworts, the thallus is crucial for survival. It provides the structure from which all vital processes occur, including photosynthesis, nutrient absorption, and reproduction. This vegetative tissue houses gemmae cups, where gemmae develop.

• The thallus supports the plant in diverse habitats.
• It enables vegetative reproduction via gemmae.
• Serves as a primary site for photosynthesis and growth.

Understanding the thallus gives insight into how liverworts manage to thrive in humid environments.