Glossary: Sexual Reproduction in Flowering Plants | Biology for Grade 12 PDF Download

The glossary serves as your trusted companion, helping you navigate through the complex terminology and concepts that form the foundation of a chapter.  Biology might sound tough, but it's actually super interesting. This glossary is here to make it fun. It breaks down the tricky stuff into little, easy-to-understand pieces, so you can enjoy learning about how plants make new plants.

Before you dive into the details, let's understand why this glossary is so important:

1. Making Things Clear: Biology can sometimes feel like a jungle of tricky words, especially when we're talking about how plants make more plants. This glossary is like a friendly guide. It explains things in simple words so you can understand what's going on in your biology book and class.

2. Remembering things Better: Did you know that it's easier to remember things when you know what the words mean? This glossary is like a memory booster. It teaches you the words you need to know, so you remember the important stuff about plant reproduction.

3. Talking the Talk: As you become a biology whiz, you'll want to chat with your friends and teachers about all the amazing things you're learning. Knowing these terms will help you join in the conversation and ask smart questions.

Happy Glossary Learning!

Glossary: Pre-fertilisation : Structures and Events

• Microsporogenesis: The process of formation of microspores from a pollen mother cell (PMC) through meiosis is called microsporogenesis. 
• Pollen Grains: As the anthers mature and dehydrate, the microspores dissociate from each other and develop into pollen grains. The pollen grains represent the male gametophytes.
• Exine: Pollen grains are generally spherical measuring about 25-50 micrometers in diameter. It has a prominent two-layered wall. The hard outer layer called the exine is made up of sporopollenin which is one of the most resistant organic  material known.
• Germ Pore: Pollen grain exine has prominent apertures called germ pores where sporopollenin is absent.
• Intine: The inner wall of the pollen grain is called the intine. 
• Vegetative Cell: When the pollen grain is mature it contains two cells, the vegetative cell and generative cell. The vegetative cell is bigger, has abundant food reserve and a large irregularly shaped nucleus. 
• Generative Cell: The generative cell is small and floats in the cytoplasm of the vegetative cell.
• Stigma, style & ovary: The stigma serves as a landing platform for pollen grains. The style is the elongated slender part beneath the stigma. The basal bulged part of the pistil is the ovary. 
• Ovule: The ovule is a small structure attached to the placenta by means of a stalk called funicle.
• Integuments: Each ovule has one or two protective envelopes called integuments.
• Nucellus: Enclosed within the integuments is a mass of cells called the nucellus.
• Megasporogenesis: The process of formation of megaspores from the megaspore mother cell is called megasporogenesis. 
• Antipodals: Three cells are at the chalazal end and are called the antipodals.
• Pollination: Transfer of pollen grains (shed from the anther) to the stigma of a pistil is termed as pollination.
• Autogamy: In this type, pollination is achieved within the same flower. Transfer of pollen grains from the anther to the stigma of the same flower.
• Chasmogamous flowers: These are similar to flowers of other species with exposed anthers and stigma.
• Cleistogamous flowers: Cleistogamous flowers which do not open at all.
• Geitonogamy: Transfer of pollen grains from the anther to the stigma of another flower of the same plant.
• Xenogamy: Transfer of pollen grains from anther to the stigma of a different plant.
• Emasculation: If the female parent bears bisexual flowers, removal of anthers from the flower bud before the anther dehisces using a pair of forceps is necessary. This step is referred to as emasculation.
• Bagging: Emasculated flowers have to be covered with a bag of suitable size, generally made up of butter paper, to prevent contamination of its stigma with unwanted pollen. This process is called bagging.

Glossary: 

Double Fertilisation

• Zygote: Male gametes moves towards the egg cell and fuses with its nucleus thus completing the syngamy. This results in the formation of a diploid cell, the zygote.

• Double Fertilisation: Two types of fusions, syngamy and triple fusion take place in an embryo sac the phenomenon is termed double fertilisation.

Glossary: 

Post-fertilisation: Structures and Events

• Scutellum: Embryos of monocotyledons possess only one cotyledon. In the grass family the cotyledon is called scutellum.
• Non albuminous: Non albuminous seeds have no residual endosperm as it is completely consumed during embryo development.
• Albuminous seeds: Albuminous seeds retain a part of endosperm as it is not completely used up during embryo development.
• Pericarp: The wall of the ovary develops into the wall of fruit called pericarp.
• False fruits: In most plants, by the time the fruit develops from the ovary, other floral parts degenerate and fall off. However, in a few species such as apple, strawberry, cashew, etc., the thalamus also contributes to fruit formation. Such fruits are called false fruits.
• True Fruits: Most fruits however develop only from the ovary and are called true fruits. 
• Parthenocarpic fruits: In most of the species, fruits are the results of fertilisation, there are a few species in which fruits develop without fertilisation. Such fruits are called parthenocarpic fruits.

Glossary: 

Apomixis and Polyembryony

• Apomixis: A few flowering plants such as some species of Asteraceae and grasses, have evolved a special mechanism, to produce seeds without fertilisation, called apomixis.
• Polyembryony:  Occurrence of more than one embryo in a seed is referred to as polyembryony.