BACKGROUND: Seeds do not usually sprout in the winter. How do they know when to germinate? Grocery stores need to have ripe, unbruised produce to sell to the public, but often this product is packed weeks ahead of time and shipped hundreds of miles to get to the store. It is often harvested before it is ripe. How does it become ripe after harvest? There are several different plant hormones that help in plant growth and development, ripening, and response to environmental stimuli.

PROCEDURE: Review the experiment shown in Model 1.

Plant Hormones

Analysis:
Consider the experiment illustrated in Model 1.

What is the stimulus in this experiment?