Paul Andersen explains how the behavior of various organisms is shaped by natural selection. The action of phototropism and the timing of photoperiodism have both been shaped by the relative availability of light. Courtship in the...

Paul Andersen explains how organisms regulate timing and control. Phototropism and Photoperiodism allow plants to respond to light throughout the day and year. Circadian rhythms are used in all organisms (including animals) as an...

Photoperiodism is a plant's ability to respond to the length of day and night, regulating processes like flowering based on a critical day length. Plants are classified as long day, short day, or day-neutral based on how they respond to...

Plant Physiology and Chemistry Set: 8. This clip shows how the relative length of light and darkness affects flowering in plants.

Plant Reproduction Set: 6. This clip offers a very simple introduction to the role of flowers in the sexual reproduction of angiosperm plants.

Genetic Expression Set: 7. This clip shows how external factors such as light and temperature can affect gene expression.

From fertilization, to germination, to growth, to death, this series of videos explores the life cycles of plants. The means by which plants respond to their environment is also highlighted. Specific attention is paid to development of...