Plant Transpiration Lab

Describe the process of transpiration in vascular plants:

Some of the water absorbed by a plant's roots is used for photosynthesis, but much is lost to the environment through the process called transpiration. During photosynthesis, tiny pores on the surface of the leaves, called stomata, open to permit the intake of carbon dioxide and the release of oxygen. Because the stomata must remain open for the exchange of gases, large amounts of water are lost to the environment through evaporation. During transpiration, water that evaporates from the leaves is continually replaced with water that is absorbed through the roots.

Controls: The amount of time set, and testing the plant with no lamp or heater or fan.

What environmental factors that you tested increased the rate of transpiration? Was the rate of transpiration increased for all plants tested?:
Almost every single environmental factor increased the rate of transpiration, except the lamp for the weeping fig, and zebra plant.


Did any of the environmental factors (heat, light, or wind) increase the transpiration rate more than the others? Why?
The fan increased it the most. Wind will increase the transpiration and water loss through the leaves of the plant. It gives the water molecules a kick start for evaporation.

Which species of plants that you tested had the highest transpiration rates? Why do you think different species of plants transpire at different rates?:
The rubber plant had the highest transpiration rate. It depends on where they are geographically (soil), and how big they are.


Suppose you coated the leaves of a plant with petroleum jelly. How would the plant's rate of transpiration be affected?:
The jelly would would block the water from evaporating. It would definitely slow down the transpiration rate.

Of what value to a plant is the ability to lose water through transpiration?

Transpiration causes water to be pulled up from the roots to the leaves, and minerals accompany the water to the leaf. Transpiration also helps with photosynthesis and cooling the leaf down. 

5/8 Plant Hormones

1. Auxins
Produced in the stamp tip that promotes cell elongation. Auxin moves to the darker side of the plant, causing the cells there to grow larger than the cells on the lighter side. This makes the plant curve towards the light, a plant movement called phototropism.

2. Abscisic Acid
Plays a role in how plants respond to weather stresses, like cold and drought. It slows seed germination. When this acid lowers in the plant, the hormone can no longer prevent germination, and the seeds sprout. But sometimes the plant would be better off if they were delayed. It depends on how the plant would be effected by its outside environment.

3. Ethylene
Stimulates root growth, flower opening, fruit ripening
Most frequently used to ripen fruit that is harvested green and shipped to the consumer. Ripening fruit produces ethylene, and one ripe fruit can trigger the ripening of a whole basket of fruit.