Unit 5 Flashcards
Definition - Positive Tropism
Growth towards the stimulus.
Definition - Negative Tropism
Growth away from the stimulus.
Most roots are positively geotropic, most shoots are positively phototropic and negatively geotropic.
Roots grow towards gravity; shoots grow towards light, except when it’s coming from an angle.
What is auxin responsible for in plants?
Auxin is responsible for differential growth towards light and was discovered in the 1920s.
Definition - Phytohormones
Plant hormones that control growth, development, and responses to stimuli in plants.
What are the functions of plant hormones?
They can promote or inhibit growth, development, and responses to stimuli in plants.
What hormone promotes fruit ripening?
Ethylene promotes ripening in fruits.
What hormone promotes stem growth in plants like wheat?
Gibberellins promote stem growth. Wheat has been bred to be less responsive to gibberellins for shorter stems.
What triggers the secretion of enzymes in a Venus Fly Trap for insect digestion?
Jasmonic acid, a phytohormone, triggers enzyme secretion.
What adaptations do cell walls have in plants?
They provide strength for roots to push through soil and make shoots resilient to wind and gravity.
What are microfibrils made of in plant cell walls?
Microfibrils are bundles of cellulose.
What is the role of auxin in plant cell growth?
Auxin promotes cell wall expansion by promoting proton pumps that transport hydrogen ions.
Where is auxin produced and transported within plants?
Auxin is produced in shoots and transported to roots.
What is transpiration in plants?
Transpiration is the loss of water vapor from plant leaves to the atmosphere.
What are guard cells and what do they do?
Guard cells are cells that control the opening and closing of stomata, regulating gas exchange and water loss.
