Difference Between Self Pollination And Cross-Pollination: Mechanism, & Facts
Self-pollination and cross-pollination are two major modes of pollen transfer in flowering plants. Self-pollination occurs within the same plant, producing genetically uniform offspring, while cross-pollination involves different plants and increases genetic diversity. Understanding their differences is essential for NEET, plant reproduction, and pollination biology.
This Story also Contains
- Introduction To Self-Pollination And Cross-Pollination
- What Is Self-Pollination?
- What Is Cross-Pollination?
- Differences Between Self-Pollination And Cross-Pollination
- Advantages and Disadvantages
- Self-pollination vs Cross-pollination NEET MCQs (With Answers & Explanations)
Introduction To Self-Pollination And Cross-Pollination
Self-pollination and cross-pollination are two of the elementary mechanisms of pollination in plants. Differences between these share prime importance when talking about plant reproduction and what that means for resulting genetic diversity.
What Is Self-Pollination?
Self-pollination is the transfer of pollen grains from the anther to the stigma of the same flower or another flower of the same plant. This allows fertilization to take place without any external pollinating agent.
Characteristics Of Self-Pollination
Same Plant: The pollen is transferred within the same flower or between flowers of the same plant.
Genetic Uniformity: Self-pollination leads to offspring almost entirely like the parent plant and hence is less genetically diverse.
No Pollinators Required: The process does not require any external agent for pollen transfer.
Examples: Common examples of plants exhibiting self-pollination are peas, wheat, sunflowers, etc.
What Is Cross-Pollination?
Cross-pollination is when the pollen grains are transferred from the anther of one plant to the stigma of another plant, usually different. This process increases the possibility of greater genetic diversity and adaptability in plant populations. It has the following features:
Characteristics Of Cross-Pollination
Different Plants: Pollen is transferred between different plants or flowers, promoting genetic variation.
Genetic Diversity: Cross-pollination results in high genetic diversity in the offspring and hence adaptability to a changing environment.
Pollinators involved: This has to be helped out by external agents, like insects, wind, or water, which carry the pollen.
Examples: Apple, strawberry plants, and most flowering plants have cross-pollination.
Differences Between Self-Pollination And Cross-Pollination
The differences between self-pollination and cross-pollination is included in the table below:
Characteristic | Self-Pollination | Cross-Pollination |
Definition | Transfer of pollen from the anther to the stigma of the same flower or another flower on the same plant | Transfer of pollen from the anther of one plant to the stigma of another plant |
Pollen Source | Pollen comes from the same flower or plant | Pollen comes from different plants |
Genetic Variation | Results in low genetic diversity; offspring are genetically similar to the parent | Results in high genetic diversity; offspring are genetically varied |
Pollinator Requirement | No external pollinators needed | Usually requires external agents (insects, wind, etc.) for pollen transfer |
Occurrence | Can occur in closed flowers | Requires open flowers for pollen transfer |
Examples of Plants | Peas, wheat, sunflowers | Apples, strawberries, most flowering plants |
Genetic Uniformity | Leads to genetic uniformity in progeny | Increases genetic variation in progeny |
Maturation Timing | Both anther and stigma mature simultaneously | Anther and stigma may mature at different times |
Pollen Production | Produces limited amounts of pollen | Produces large amounts of pollen |
Inbreeding vs. Outbreeding | Causes inbreeding, reducing the gene pool | Causes outbreeding, maintaining genetic diversity |
Advantages and Disadvantages
The advantages and disadvantages of self pollination and cross pollination are:
Advantages of Self-Pollination
Maintains pure lines
Reproduction without pollinators
Less energy needed for pollination
Disadvantages of Self-Pollination
Causes inbreeding depression
Less adaptability
Accumulation of harmful genes
Advantages of Cross-Pollination
Produces genetically diverse offsprings
Increases hybrid strength
Higher adaptability and evolution
Disadvantages of Cross-Pollination
Requires pollinators
Uses more resources
Failure possible if number of pollinators decreases
Self-pollination vs Cross-pollination NEET MCQs (With Answers & Explanations)
Important topics for NEET are:
Types of pollination
Self-pollination vs Cross pollination
Practice Questions for NEET
Q1. Even in the absence of pollinating agents seed setting is assured in
Commelina
Zostera
Salvia
Fig
Correct answer: 1) Commenlina
Explanation:
The plant known as Commelina develops chasmogamous and cleistogamous blooms. The stigma and anther of chasmogamous flowers are visible as they open. Cleistogamous flowers have completely closed blooms. These blooms pollinate themselves.
The final answer is Even in the absence of pollinating agents, the seed setting is assured in Commelina.
Hence, the correct answer is option 1) Commelina
Q2. Transfer of pollen grains to the stigma is relatively easy as anthers and stigma are located close to each other , pollen grains soon after they shed, come in contact with stigma
Given statement is correct for :
Pea
Date palm
Papaya
None of these
Correct answer: 1) Pea
Explanation:
Gamete Transfer in bisexual seed plants - In bisexual, self‐fertilising plants, transfer of pollen grains to the stigma is relatively easy as anthers and stigma are located close to each other; pollen grains soon after they are shed, come in contact with the stigma. Eg., peas. In bisexual self-fertilizing plants, the proximity of anthers and stigma ensures efficient pollen transfer, minimizing the need for external pollinating agents. This mechanism enhances reproductive success, especially under stable environmental conditions. Cross-pollination, however, may occasionally occur to promote genetic diversity. Self-fertilization in plants like peas ensures consistency in traits across generations while reducing reliance on pollinators.
Hence, the correct answer is option 1) Pea.
Q3. Which one of the following may require pollinators, but is genetically similar to autogamy ?
Apogamy
Cleistogamy
Geitonogamy
Xenogamy
Correct answer: 3) Geitonogamy
Explanation:
Geitonogamy - Transfer of pollen grains from the anther to the stigma of another flower of the same plant. Although geitonogamy is functionally cross-pollination involving a pollinating agent, genetically it is similar to autogamy since the pollen grains come from the same plant. Geitonogamy involves pollination and is genetically similar to autogamy. Geitonogamy is the transfer of pollen grains from the anther to the stigma of another flower on the same plant. Although functionally it involves cross-pollination with the help of a pollinating agent, genetically, it is similar to autogamy since the pollen comes from the same plant. Geitonogamy occurs in plants that produce multiple flowers, ensuring fertilization even in the absence of cross-pollination. It is common in species that rely on external pollinators like wind, insects, or birds for pollen transfer. While it promotes reproduction, geitonogamy may reduce genetic variation compared to true cross-pollination (xenogamy).
Hence, the correct answer is option 3) Geitonogamy.
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Frequently Asked Questions (FAQs)
The transfer of pollen from an anther to the stigma of the same flower or another flower of the same plant.
The transfer of pollen from the anther of one flower to the stigma of another flower—usually of another plant.
Generally, self-pollination leads to low genetic diversity since the offspring will be genetically identical to the parent plant.
Some examples include peas, wheat, and sunflower.
Cross-pollination increases the diversity of genes among offspring, hence increasing adaptability to changing environments.