Reproduction in Angiosperms

Topic 9.3

9.3.1: Dicotyledonous animal-pollinated flower

Angiosperms are flowering plants, which form seeds inside a protective chamber called an ovary. The figure below is a label diagram of an animal-pollinated flower.

Animal-pollinated flower

9.3.2: Pollination, fertilization, and seed dispersal

The figure below shows the process of pollination, which is the delivery of pollen from the anther to the stigma. The transfer of pollen can occur from the anther to the stigma on the same plant or between different plants. Placing the mouse pointer on the figure will produce a new figure outlining fertilization and seed dispersal.

Picture of human lungs

9.3.3 & 9.3.4: Seed structure and germination

The internal and external structure of a non-endospermic seed (e.g., bean) is shown below. The conditions for seed germination are explained for a typical seed. Note that seeds vary in their oxygen, water, and temperature requirements.

Seed Germination

9.3.4: Metabolic activities of a germinating starchy seed

The figure outlines the metabolic processes carried out by a germinating starchy seed. The process starts with the absorption of water and the formation of gibberellin in the embryo's cotyledons. this stimulates the production of amylase, which catalyzes the breakdown of starch to maltose. The maltose diffuses to the embryo for energy and growth.

Seed Metabolism

9.3.6: Control of flowering

Flowering is controlled a long-day and short-day plants by the use of cytochromes and the hormone florigen. It is all based on the conversion of Pr (red absorbing) to Pfr (far-red absorbing) in red and white light and the conversion of Pfr to Pr in darkness. The action of Pfr promotes flowering in long-day plants and inhibits flowering in short-day plants.

flowering link flowering animation
Florigen and Flowering
Back to top of page

Valid XHTML 1.0 Strict Valid CSS!