Problem 184 - Objective Biology for NEET

Question

The haploid plant body produces and is referred to as (a) spores, sporophyte (b) gametes, gametophyte (c) zoospores, zoosporangia (d) conidia, conidiophores

Step-by-Step Solution

Answer

(b) gametes, gametophyte

Step 1: Understand the life cycle of plants

Plants have a life cycle that includes haploid (n) and diploid (2n) phases, called alternation of generations. The haploid phase is known as the gametophyte, and the diploid phase is the sporophyte. Each phase produces specific types of cells.

Step 2: Identify the haploid phase and its products

In the haploid (n) phase, or the gametophyte phase, the plant body produces gametes, which are reproductive cells.

Step 3: Choose the correct answer

Based on our knowledge of plant life cycles, the haploid plant body, which is the gametophyte, produces gametes. This matches with option (b) in the exercise.

Key Concepts

Gametophyte

The gametophyte represents a fundamental phase in the plant life cycle, specifically characterized as the sexual phase. In this stage, the plant is haploid, meaning it carries a single set of chromosomes. As a gametophyte, the plant will produce gametes, which are the reproductive cells necessary for sexual reproduction.

These gametes come in the form of sperm and eggs in seed plants, or as antheridia (male) and archegonia (female) in non-seed plants like mosses and ferns. Fertilization, the fusion of these gametes, gives rise to the diploid phase of the plant's lifecycle, known as the sporophyte. We can perceive the gametophyte as a critical contributor to genetic diversity, as it undergoes processes such as meiosis and mitosis that shuffle and distribute genetic material in novel ways.

Haploid

The term 'haploid' is used to denote cells or organisms containing a single set of chromosomes, abbreviated as 'n'. This is in contrast to diploid cells, which contain two sets of chromosomes (2n). Haploid is an essential term within the context of the plant life cycle, as it specifically refers to the number of chromosomes within the gametes and the gametophyte stage.

During sexual reproduction, haploid gametes join to create a diploid zygote, which then develops into the sporophyte phase. Understanding 'haploid' is crucial as it relates directly to genetic content passed through generations, influencing traits and the resulting biodiversity within plant populations.

Sporophyte

The sporophyte stage is the diploid phase in the plant life cycle. Here, the plant carries two sets of chromosomes (2n), one set from each parent. The primary role of the sporophyte is to produce spores through meiosis. These spores are haploid cells that have the potential to grow into new gametophytes, thus completing the alternation of generations cycle.

Differentiating from the gametophyte, the sporophyte does not produce gametes but spores which are capable of developing into new haploid plants without fertilization. The sporophyte is often the more conspicuous and long-lived phase in the life cycle of vascular plants, such as ferns, and is the dominant stage in seed plants, including gymnosperms and angiosperms.