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Chapter Analysis
Advanced25 pages • EnglishQuick Summary
The chapter 'Sexual Reproduction in Flowering Plants' explores the fascinating process of sexual reproduction in angiosperms, highlighting the critical roles played by flowers. It describes the pre-fertilisation stages, including structures and events leading to fertilisation, and elaborates on double fertilisation, a unique feature of flowering plants. The chapter also covers post-fertilisation structures and events, along with interesting concepts like apomixis and polyembryony, which have significant implications in plant breeding and agriculture.
Key Topics
- •Flower structure and function
- •Pre-fertilisation events
- •Double fertilisation
- •Post-fertilisation events
- •Apomixis
- •Polyembryony
- •Pollination mechanisms
- •Seed and fruit development
Learning Objectives
- ✓Understand the structure and function of flowers in the context of reproduction.
- ✓Differentiate between microsporogenesis and megasporogenesis.
- ✓Explain the events leading to double fertilisation in angiosperms.
- ✓Learn about apomixis and its role in plant breeding.
- ✓Identify strategies to prevent self-pollination in flowering plants.
- ✓Comprehend the mechanisms and significance of seed dispersal.
Questions in Chapter
Name the parts of an angiosperm flower in which development of male and female gametophyte take place.
Page 24
Differentiate between microsporogenesis and megasporogenesis. Which type of cell division occurs during these events? Name the structures formed at the end of these two events.
Page 24
Arrange the following terms in the correct developmental sequence: Pollen grain, sporogenous tissue, microspore tetrad, pollen mother cell, male gametes.
Page 24
With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.
Page 24
What is meant by monosporic development of female gametophyte?
Page 24
With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte.
Page 25
What are chasmogamous flowers? Can cross-pollination occur in cleistogamous flowers? Give reasons for your answer.
Page 25
Mention two strategies evolved to prevent self-pollination in flowers.
Page 25
What is self-incompatibility? Why does self-pollination not lead to seed formation in self-incompatible species?
Page 25
What is bagging technique? How is it useful in a plant breeding programme?
Page 25
What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion.
Page 25
Why do you think the zygote is dormant for sometime in a fertilised ovule?
Page 25
Differentiate between (a) hypocotyl and epicotyl; (b) coleoptile and coleorrhiza; (c) integument and testa; (d) perisperm and pericarp.
Page 25
Why is apple called a false fruit? Which part(s) of the flower forms the fruit?
Page 25
What is meant by emasculation? When and why does a plant breeder employ this technique?
Page 25
If one can induce parthenocarpy through the application of growth substances, which fruits would you select to induce parthenocarpy and why?
Page 25
Explain the role of tapetum in the formation of pollen-grain wall.
Page 25
What is apomixis and what is its importance?
Page 25
Additional Practice Questions
What are the major differences between sexual and asexual reproduction in flowering plants?
mediumAnswer: Sexual reproduction involves the fusion of male and female gametes, leading to genetic variations in offspring. In contrast, asexual reproduction does not involve gametes, and offspring are usually genetically identical to the parent.
Explain the structure and function of a typical flower in flowering plants.
mediumAnswer: A typical flower consists of reproductive organs, stamens (male) and pistils (female). The stamen includes an anther and filament, while the pistil comprises stigma, style, and ovary. Flowers facilitate pollination and fertilization, resulting in seed and fruit production.
How does pollination differ from fertilization in flowering plants?
mediumAnswer: Pollination involves the transfer of pollen from anther to stigma, while fertilization refers to the actual fusion of male and female gametes following successful pollination.
Discuss the significance of double fertilization in angiosperms.
hardAnswer: Double fertilization is a unique process in angiosperms where one sperm fertilizes the egg forming a zygote, and the other fuses with two polar nuclei to form the triploid endosperm, which nourishes the developing embryo.
What adaptations do flowers have for biotic pollination?
easyAnswer: Flowers adapted for biotic pollination often exhibit bright colors, appealing scents, and nectar production to attract pollinators like insects, birds, or bats.
How does seed dispersal benefit flowering plants?
mediumAnswer: Seed dispersal allows flowering plants to spread offspring across a wider area, reducing competition with the parent plant and increasing colonization opportunities in new environments.
Describe the process and importance of apomixis in agriculture.
hardAnswer: Apomixis is a form of asexual reproduction that enables seed formation without fertilization. It's important in agriculture as it allows the perpetuation of desirable traits in crops without genetic variation, thus maintaining consistent quality.
Explain polyembryony and its implications in plant breeding.
hardAnswer: Polyembryony is the phenomenon where multiple embryos develop from a single fertilized egg or ovule. It can result in increased yield and uniformity in certain crop species, benefiting plant breeding programs.
Why do some fruits develop without fertilization, and what is this process called?
easyAnswer: Some fruits develop without fertilization through a process called parthenocarpy, which can be natural or induced through growth hormones, resulting in seedless fruits.
What are the challenges and benefits of hybrid seed production in agriculture?
hardAnswer: Hybrid seed production is challenged by its cost and the need for controlled pollination. However, it offers benefits such as increased yield and disease resistance, contributing to agricultural productivity.