6th Grade · Science · Activity · shared by Luke Morgan
Investigate why tropical orchids fail in a sterile greenhouse. A 6th Grade Science activity on plant-fungi symbiosis and nutrient uptake.
Mystery Investigation: The Case of the Fading Orchids
The Scenario: The Ultra-Clean Botany Lab has just built the most advanced greenhouse in the world. It is completely sterile, meaning every speck of dust, bacteria, and fungus was removed before the plants arrived. The scientists used filtered air, purified water, and expensive chemical fertilizers containing all the minerals plants usually need. They planted rare tropical orchids, expecting them to thrive in this "perfect" environment. However, within weeks, the orchids stopped growing. Their leaves are turning yellow, and they appear to be starving, even though they are being fed plenty of nutrients. Your team of lead investigators must find out why these plants are failing in a lab that was supposed to be perfect.
Phase 1: Initial Evidence Analysis
Read the following Evidence Logs collected by the lab technicians. Look for clues that explain how plants normally get what they need in the wild versus what is happening in the sterile greenhouse.
Evidence Source
Discovery Notes
Soil Sample 402 (Wild Jungle)
Microscopic analysis shows thousands of tiny, thin white strands called hyphae . These belong to mycorrhizal fungi . They are wrapped tightly around orchid roots and spread several feet away into the dirt.
Soil Sample 901 (Sterile Lab)
The soil is "pure." No fungi, bacteria, or other organisms were detected. The orchid roots are clean and have no attachments.
Nutrient Report
The lab soil is rich in phosphorus , but the orchid roots are too thick to reach the tiny pockets where the phosphorus is trapped. In the wild, fungi strands are thin enough to enter these tiny spaces to collect the mineral.
Plant Energy Log