Biology Chapter 2: Sexual Reproduction in Plants

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Questions and Answers

What does the hilum represent in an ovule?

The basal part of the ovule

The opening of the ovule

The junction between ovule and funicle (correct)

The protective envelope of the ovule

What is the main purpose of the integuments in an ovule?

To support the funicle

To house the microspores

To provide food for the embryo sac

To encircle the nucellus (correct)

Which of the following is NOT a characteristic of the embryo sac in an angiosperm ovule?

Located within the nucellus

Formed from a megaspore

Has one or two protective envelopes (correct)

Usually contains abundant reserve food materials

How many ovules might be typically found in an ovary?

One to many, depending on the species Signup and view all the answers

What health issues are commonly associated with pollen grains?

Allergies and bronchial afflictions Signup and view all the answers

What is the process of megasporogenesis?

Formation of megaspores from the megaspore mother cell Signup and view all the answers

Which of the following statements about pollen viability is true?

Pollen viability can depend on temperature and humidity conditions. Signup and view all the answers

What is the primary function of flowers in angiosperms?

To attract pollinators for sexual reproduction Signup and view all the answers

Which of the following best describes the significance of flowers in human culture?

They convey important human emotions and are used in celebrations. Signup and view all the answers

What term describes a pistil that is composed of multiple fused parts?

Syncarpous Signup and view all the answers

What is a major use of pollen tablets in Western countries?

They serve as food supplements. Signup and view all the answers

What is the major function of the stigma in the gynoecium?

It serves as a landing platform for pollen grains. Signup and view all the answers

How are pollen grains used in the context of crop breeding programs?

They can be stored in liquid nitrogen for years. Signup and view all the answers

What characteristic of flowers contributes to the diversity of angiosperms?

Variation in inflorescence and floral structures Signup and view all the answers

In the context of sexual reproduction in flowering plants, what does 'double fertilization' refer to?

The fertilization of an ovule and the formation of endosperm Signup and view all the answers

Which of the following terms refers to the development of seeds without fertilization?

Apomixis Signup and view all the answers

In which plant family do pollen grains maintain viability for an extended period?

Rosaceae Signup and view all the answers

Which of the following statements is true about flowers?

They contribute to the process of sexual reproduction. Signup and view all the answers

What is the end product of sexual reproduction in flowering plants?

Fruits and seeds Signup and view all the answers

What is the basal bulged part of the pistil called?

Ovary Signup and view all the answers

Which of the following does NOT relate to the adaptations of flowers for sexual reproduction?

Thorns to protect from herbivores Signup and view all the answers

What is the primary characteristic of cleistogamous flowers?

They produce guaranteed seed-set without pollinators. Signup and view all the answers

What is the primary role of endosperm during seed development?

To provide nutrition to the developing embryo. Signup and view all the answers

Why are cleistogamous flowers considered autogamous?

Pollen and stigma are positioned close together and remain sealed. Signup and view all the answers

What distinguishes xenogamy from other types of pollination?

It involves the transfer of pollen from one plant to another. Signup and view all the answers

What is a disadvantage of cleistogamous flowers for plants?

They may lead to lower genetic diversity. Signup and view all the answers

Which flowers are an example of producing both cleistogamous and chasmogamous types?

Viola Signup and view all the answers

What is a fundamental difference between chasmogamous and cleistogamous flowers?

Chasmogamous flowers open to allow pollen transfer, while cleistogamous do not. Signup and view all the answers

In which scenario would cleistogamous flowers be particularly advantageous?

In isolated environments with few pollinators. Signup and view all the answers

Which of the following accurately describes geitonogamy?

Pollen is moved from one flower to another on the same plant. Signup and view all the answers

In which of the following does polyembryony occur?

In some angiosperms. Signup and view all the answers

What is the significance of apomixis in angiosperms?

It results in seed formation without fertilization. Signup and view all the answers

Which stage of embryo development follows the globular stage?

Heart-shaped stage. Signup and view all the answers

What constitutes a mature dicotyledonous embryo?

Two cotyledons and an embryonal axis. Signup and view all the answers

What is a key characteristic of chasmogamous flowers?

They can open and allow for both self and cross-pollination. Signup and view all the answers

Which cell division process occurs during microsporogenesis?

Meiosis Signup and view all the answers

What is the function of the bagging technique in plant breeding?

To prevent cross-pollination. Signup and view all the answers

Study Notes

Flower – A Fascinating Organ of Angiosperms

Flowers are crucial for sexual reproduction in flowering plants (angiosperms) and offer aesthetic, ornamental, and cultural value.
Different flowers symbolize diverse human emotions and play roles in social and religious celebrations.
Pollen can cause allergies, with Parthenium being a notable allergenic species due to its widespread presence.
Pollen grains are nutrient-rich; use as food supplements has gained popularity, particularly in Western markets, for athletic performance boosts.

Pre-fertilisation: Structures and Events

Pollen grains require landing on the stigma to maintain viability; their lifespan can range from 30 minutes to several months, depending on species and environmental conditions.
Storage of pollen in liquid nitrogen for years is possible, allowing for pollen banks analogous to seed banks in agriculture.

The Pistil, Megasporangium (Ovule), and Embryo Sac

The gynoecium is the female reproductive part, composed of one or more pistils; pistils can be monocarpellary or multicarpellary (syncarpous or apocarpous).
Each pistil includes the stigma, style, and ovary, with the ovule developing within the ovary.
Ovules vary in number from one to many within an ovary; the structure includes the funicle, hilum, integuments, micropyle, chalaza, and nucellus.
The embryo sac forms within the nucellus from a megaspore through a process called megasporogenesis.

Pollination Mechanisms

Cleistogamous flowers are self-pollinating due to their closed structure, ensuring seed set without pollinators.
Geitonogamy involves pollen transfer within the same plant, while xenogamy entails cross-pollination between different plants.

Double Fertilisation and Seed Development

Endosperm formation occurs before embryo development, progressing through various stages until maturation.
Dicotyledonous embryos contain two cotyledons, while monocotyledonous embryos have one.
After fertilisation, the ovary becomes a fruit, and ovules transform into seeds.

Apomixis and Polyembryony

Apomixis leads to seed formation without fertilisation; it is advantageous in agricultural applications.
Some angiosperms exhibit polyembryony, producing multiple embryos in a single seed.

Summary of Key Concepts

Understanding the morphology and processes of sexual reproduction in angiosperms highlights their ecological significance and contributions to biodiversity.
The versatility of reproductive strategies in flowering plants reflects their adaptations to various environments and the importance of genetic diversity.

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Description

Explore the intricate processes of sexual reproduction in flowering plants in this quiz based on Chapter 2. Learn about the fascinating structures and events involved from pre-fertilization to post-fertilization. Discover why flowering plants are essential to our ecosystem and how they attract us through their beautiful characteristics.