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Plant Adaptations to Life on Land

Directions: Before you start listen to part of a talk in a biology class.

*Vocabulary is sometimes provided in written form when it may be unfamiliar to the student, but essential for understanding the lecture

Vocabulary
gametes
terrestrial environment
aquatic environment

TRANSCRIPT

Plant Adaptations to Life on Land

As organisms adapted to life on land, they had to contend with several challenges in the terrestrial environment. Water has been described as “the stuff of life.” The cell’s interior is a watery soup: in this medium, most small molecules dissolve, and the majority of the chemical reactions of metabolism take place. Drying out is a constant danger for an organism exposed to air. Even when parts of a plant are close to a source of water, the aerial structures are likely to dry out. Water also provides buoyancy to organisms. On land, plants need to develop structural support in a medium that does not give the same lift as water. The organism is also subject to radiation because air does not filter out ultraviolet rays of sunlight. Additionally, the male gametes, a male cell that is able to unite with the opposite sex in sexual reproduction, must reach the female gametes using new strategies, because swimming is no longer possible. The successful land plants developed strategies to deal with all of these challenges. Not all adaptations appeared at once. Some species never moved very far from the aquatic environment, whereas others went on to conquer the driest environments on Earth.

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