plant responses part2 planthormones
TRANSCRIPT
Plant Responses Part 2: Plant Hormones
8SCIENCE: Mon. Feb. 21
Review: What are plant responses?
• Called tropisms– When a plant responds to an outside stimulus
• What are some examples of plant stimuli?– Sunlight, water, carbon dioxide, temperature
• What are some types of tropisms or responses?– Gravitropism– Phototropism– Thigmotropism
Plants have hormones like other living things
• Plant hormones are chemical substances that affect GROWTH
• Two types to learn:– Auxin– Ethylene
Plant Hormones: Auxin• Auxin causes plant stems and leaves to show positive
phototropism– Plants will Grow TOWARDS the sun/light
• When light shines on a plant on one side, auxin works on the shaded side to curve it towards the light
Plant Hormones: Ethylene• Organic compound made of carbon and hydrogen• Causes different plant responses but mainly used to
RIPEN fruit• Fruits are picked when they are still green (e.g.
bananas, oranges) and during transportation to the store are exposed to ethylene gas