Signals, Sugar and Water: teacher key

How Plants Grow, grade 10 edition, written for 10th grade. How plants sense light and gravity, move water, trade with fungi and wait for the right moment, and how scientists worked it out.

Read the book. Print this page for the key.

Questions and answers

1. What did Went find causes a plant to bend toward light?
   • Root pressure
   • An uneven spread of auxin (answer)
   • Stomata closing
2. What did Ingen-Housz show about the dark?
   • A plant in the dark in a sealed chamber uses up oxygen (answer)
   • Plants make more sugar at night
   • Roots give off oxygen
3. Why would closing stomata on a hot, dry day help a plant?
   • It lets more sugar escape
   • It conserves water (answer)
   • It attracts pollinators
4. What do fungi give trees in the trade?
   • Sugars
   • Light
   • Nitrogen, phosphorus and minerals (answer)
5. What must happen for giant sequoia seeds to sprout?
   • They must fall on bare mineral soil left by fire (answer)
   • They must sit on a shelf for decades
   • They must float on water

Words

• gravitropism: growing with gravity
• transpire: lose water vapor
• endosperm: seed food store
• stomata: tiny leaf openings