Why is geitonogamy functionally cross-pollination but genetically autogamy?

Geitonogamy involves the transfer of pollen grains from the anther of one flower to the stigma of another flower on the same plant. Because it requires a pollinating agent (wind, insects, water), it is functionally cross-pollination. However, because both flowers belong to the same parent plant, they share identical genetic information, rendering the event genetically equivalent to autogamy ($100\%$ genetic identity).

What is the key difference between perisperm and endosperm in mature seeds?

Perisperm is persistent, unconsumed diploid ($2n$) residual nucellus (maternal tissue) found in seeds like black pepper and beet. Endosperm is a triploid ($3n$) nutritive tissue formed after double fertilization via triple fusion ($2n_{\text{polar nuclei}} + 1n_{\text{male gamete}}$).

How should I solve ploidy level questions systematically in NEET?

Always trace origin: Vegetative maternal tissues (integuments, nucellus, funicle, pericarp) equal female parent ploidy ($2n$). Male/female gametes equal half their parent ploidy ($1n$). Zygote/embryo equals $1 n_{\text{female}} + 1 n_{\text{male}}$. Endosperm equals $2 n_{\text{female}} + 1 n_{\text{male}}$.

Sexual Reproduction in Flowering Plants Notes, Formulas, Traps & PYQs | ExamiFly

Beta

Please wait while we prepare everything for you

Sexual Reproduction in Flowering Plants Notes, Formulas, Traps & PYQs | ExamiFly | Examifly

Solved High-Yield Sample Questions

Practice Mode

Question #1NEET 2023

How many minimum meiotic divisions are required to produce $200$ seeds in a typical angiospermic plant?

Solution Locked

Step-by-Step Solution & Concept

Step 1

To produce $200$ viable seeds, we require $200$ functional zygotes, which need $200$ functional female gametes (eggs) and $200$ functional male gametes (pollen grains).

Step 2

Each megaspore mother cell ( $2n$ ) undergoes $1$ meiotic division to yield $1$ functional megaspore ( $1n$ ). Thus, $200$ functional eggs require $200$ meiotic divisions.

Step 3

Each microspore mother cell ( $2n$ ) undergoes $1$ meiotic division to yield $4$ functional pollen grains ( $1n$ ). Thus, $200$ pollen grains require $\frac{200}{4} = 50$ meiotic divisions. Total minimum meiotic divisions = $200 + 50 = 250$ .

Select an option & click Check Answer to reveal solution

Question #2NEET 2022

If a tetraploid female plant ( $4n$ ) is crossed with a diploid male plant ( $2n$ ), what will be the respective ploidy levels of the zygote, endosperm, and seed coat?

Solution Locked

Step-by-Step Solution & Concept

Step 1

Determine the ploidy of gametes: Female plant ( $4n$ ) produces female gametes ( $n_{\text{female}}$ ) with $2n$ chromosomes. Polar nuclei in central cell are $2n + 2n = 4n$ . Male plant ( $2n$ ) produces male gametes ( $n_{\text{male}}$ ) with $1n$ chromosomes.

Step 2

Zygote ploidy = $n_{\text{female}} + n_{\text{male}} = 2n + 1n = 3n$ . Endosperm ploidy = Polar nuclei ploidy + Male gamete ploidy = $4n + 1n = 5n$ .

Step 3

The seed coat develops from integuments, which are maternal sporophytic tissue, thus retaining maternal ploidy of $4n$ . Therefore, the answer is $3n$ , $5n$ , and $4n$ .

Select an option & click Check Answer to reveal solution

If you want to explore more chapters of Biology then:

Click Here

Mastering Sexual Reproduction in Flowering Plants: Ratios, Traps & Exam Strategy | ExamiFly

Chapter Overview

Core Subtopics & Syllabus Breakdown

Key Formulas & High-Yield Equations

Minimum Meiotic Divisions for N Seeds

Microspore Mother Cells (MMC) Required

Megaspore Mother Cells Required

Variable Endosperm Ploidy Formula

Polygonum Embryo Sac Nuclear-Cellular Configuration

Common Mistakes & Traps to Avoid

Past Year Question (PYQ) Trends

Solved High-Yield Sample Questions

Frequently Asked Questions

Master Sexual Reproduction in Flowering Plants with 250+ Curated NEET & AI Error-Correction Drills