CBSE Class 12 Biology Sexual Reproduction In flowering Plants Notes Set B

Download CBSE Class 12 Biology Sexual Reproduction In flowering Plants Notes Set B in PDF format. All Revision notes for Class 12 Biology have been designed as per the latest syllabus and updated chapters given in your textbook for Biology in Standard 12. Our teachers have designed these concept notes for the benefit of Grade 12 students. You should use these chapter wise notes for revision on daily basis. These study notes can also be used for learning each chapter and its important and difficult topics or revision just before your exams to help you get better scores in upcoming examinations, You can also use Printable notes for Class 12 Biology for faster revision of difficult topics and get higher rank. After reading these notes also refer to MCQ questions for Class 12 Biology given our website

Sexual Reproduction In flowering Plants Class 12 Biology Revision Notes

Class 12 Biology students should refer to the following concepts and notes for Sexual Reproduction In flowering Plants in standard 12. These exam notes for Grade 12 Biology will be very useful for upcoming class tests and examinations and help you to score good marks

Sexual Reproduction In flowering Plants Notes Class 12 Biology

SEXUAL REPRODUCTION IN FLOWERING PLANTS

Topics:

Flowers

Pre- fertilization- structure and events

Pollination

Fertilization

Double fertilization

Post fertilization- events

Development of seed and fruits

Apomixes

Polyembryony

Types of fruits

Introduction

Sexual reproduction in flowering plants involves transformation of diploid sporophytic cell into haploid gametophytic cells by meiosis.Fusion of haploid gametes of opposite sex to form diploid zygote.The zygote then develops into an embryo which ultimately forms a diploid plant body. In flowering plants all these steps of sexual reproduction occur within specialized reproductive organs called the flowers.

Pre- fertilization: Structures and Events

The parts of a stamen are filament and anther.It is bilobed and dithecous. The anther is a four- lobed structure consisting of four micro sporangia located at the corner, two in each lobe. Developed micro sporangia are called pollen sacs.

 class_12-biology_concept_254  

Structure of the pollen grains or male gametophyte

1. Wall layers: the outer hard layer-exine is made up of the most resistant organic material Sporopollenin which is resistant to high temperature, pH, and enzymatic action.

2. Exine has apertures called germ pores

3. Inner wall- intine is made up of cellulose and pectin 

class_12-biology_concept_255  

CBSE Class 12 Biology - Sexual Reproduction Inflowering Plants notes

 

Structure of an ovule or megasporangium
The ovule has a stalk-funicle- Hilum is the junction between ovule and funicle- two integuments envelop the ovule except at micropyle. Opposite end is called chalazal end. It encloses mass of cells called nucellus, with an embryo sac.

Megasporogenesis:
                             Nucellus
                                   ↓
                       Megaspore mother cell
                                   ↓
                             (One cell enlarges)
                                   ↓
                                 meiosis
                                   ↓
                             4-Megaspores
           3- degenerate and one functional megaspore remains.
                                   ↓ Nucleus divides mitotically
                                   ↓
           2 - Nucleate (move to opposite poles)
                                   ↓
                          II Mitosis
                      4 -Nucleate
                                   ↓
                                  III Mitosis

CBSE Class 12 Biology - Sexual Reproduction Inflowering Plants notes

 

2) Geitonogamy
Transfer of pollen grain from the anther to the stigma of another flower in the same plant.

3) Xenogamy
Transfer of pollen grain from the anther to the stigma of a different plants.

CBSE Class 12 Biology - Sexual Reproduction Inflowering Plants notes

CBSE Class 12 Biology - Sexual Reproduction Inflowering Plants notes

Outbreeding devices
 Dichogamy – pollen release and stigma receptivity are not synchronized.
 Heterostyly – anther and stigma are placed at different positions.
 Self- incompatibility
 Production of unisexual flowers.

Pollen- pistil interaction
1) The pollen grains germinate in pollen tubes and the pollen tube passes through style, reaches ovary.
2) Enters ovule through micropyle with the help of synergids
3) Two male gametes are released.
(Artificial hybridization is achieved by emasculation and bagging techniques (removal of anther and dusting stigma with anther of desired type to prevent contaminations of its stigma with unwanted pollen)

Double fertilization
.One male gametes (n) + egg → (n) Syngamy (2n) → Zygote
Another male gamete (n) + polar nuclei (2n) → PEN(3X)
Primary endosperm nucleus develops into endosperm.

Post- fertilization events
A) Development of endosperm and embryo B) maturation of ovule into seed C) ovary into fruit.

Endosperm development
PEN undergoes repeated nuclear divisions to form into free- nuclear endosperm and if the cell wall formation occurs, forms to cellular- endosperm

Embryo development (Embryogeny)
Zygote → pro- embryo → globular embryo
                                             ↓
                                     Heart shaped embryo
                                             ↓
                                     Matured embryo

Dicot embryo consist of an embryonal axis and two cotyledons.


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Chapter 1 Reproduction in Organisms
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CBSE Class 12 Biology Reproduction in Organisms Notes
CBSE Class 12 Biology Reproduction In Organisms Notes Set A
CBSE Class 12 Biology Reproduction In Organisms Notes Set B
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Chapter 2 Sexual Reproduction In Flowering Plants
CBSE Class 12 Biology Sexual Reproduction In Flowering Plants Minds Map
CBSE Class 12 Biology Sexual Reproduction In flowering Plants Notes Set A
CBSE Class 12 Biology Sexual Reproduction In flowering Plants Notes Set B
CBSE Class 12 Biology Sexual Reproduction In flowering Plants Notes Set C
Chapter 3 Human Reproduction
CBSE Class 12 Biology Human Reproduction Minds Map
CBSE Class 12 Biology Human Reproduction Notes
CBSE Class 12 Biology Human Reproduction Study Guide
Chapter 4 Reproductive Health
CBSE Class 12 Biology Reproductive Health Notes Set A
CBSE Class 12 Biology Reproductive Health Notes Set B
CBSE Class 12 Biology Reproductive Health Study Guide
Chapter 5 Principles of Inheritance and Variation
CBSE Class 12 Biology Genetics Notes
CBSE Class 12 Biology Principles Of Inheritance And Variation Minds Map
CBSE Class 12 Biology Principles Of Inheritance And Variation Notes
CBSE Class 12 Biology Principles Of Inheritance And Variations Study Guide
Chapter 6 Molecular Basis of Inheritance
CBSE Class 12 Biology Molecular Basis Of Inheritance Minds Map
CBSE Class 12 Biology Molecular Basis Of Inheritance Notes Set A
CBSE Class 12 Biology Molecular Basis Of Inheritance Notes Set B
CBSE Class 12 Biology Molecular Basis Of Inheritance Study Guide
Chapter 7 Evolution
CBSE Class 12 Biology Evolution Minds Map
CBSE Class 12 Biology Evolution Notes Set A
CBSE Class 12 Biology Evolution Notes Set B
CBSE Class 12 Biology Evolution Study Guide
Chapter 8 Human Health and Diseases
CBSE Class 12 Biology Human Health And Disease Minds Map
CBSE Class 12 Biology Human Health And Disease Notes Set A
CBSE Class 12 Biology Human Health And Disease Notes Set B
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Chapter 9 Strategies for Enhancement In Food Production
CBSE Class 12 Biology Strategies For Enhancement Of Food Production Minds Map
CBSE Class 12 Biology Strategies For Enhancement In Food Production Notes Set A
CBSE Class 12 Biology Strategies For Enhancement In Food Production Notes Set B
CBSE Class 12 Biology Strategies For Enhancement In Food Production Study Guide
Chapter 10 Microbes In Human Welfare
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CBSE Class 12 Biology Microbes In Human Welfare Notes Set A
CBSE Class 12 Biology Microbes In Human Welfare Notes Set B
Chapter 11 Biotechnology Principles and Processes
CBSE Class 12 Biology Biotechnology Principles And Processes Notes Set A
CBSE Class 12 Biology Biotechnology Principles And Processes Notes Set B
CBSE Class 12 Biology Biotechnology Principles And Processes Study Guide
Chapter 12 Biotechnology and Its Application
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Chapter 13 Organisms and Populations
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Chapter 14 Ecosystem
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Chapter 15 Biodiversity and Conservation
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Chapter 16 Environmental Issues
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Concepts Maps
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