Name:Phototropism and Gravitropism Fill in the Blank Notes

Main Understandings○ Explain phototropism and gravitropism as examples of control systems in plants○ Explain how our understanding of phototropism and gravitropism has changed over time.

How do plants respond to different stimuli?

● ______________________: a growth in

response to a stimuli

● Positive tropism: the plant grows

________________________ the stimuli

● ____________________________ tropism:

the plant grows AWAY from the stimuli

What is phototropism?

● When light is the _______________________that the plant responds to

● The plant has a hormone called _____________________. This hormone is found in both the roots and the top of the plant

(the shoot) and causes plant growth.

● A high concentration of auxin results in the elongation/ growth of that part of the ____________________!

How does it work? Auxin

● The auxin molecules moves ________________ from the light and result in cell elongation wherever they move.

● Light overhead: auxin moves _______________the stem causing the stem to grow

● Light to the side: the auxin moves away from the light causing that side to grow and the plant to bend ____________________ the light.

Darwin’s famous experiment

● Cut off the tip it did ______________grow

● Covering the tip, it did not bend.

● Covering the base it ________________.

● Another scientist _____________________________

studies plants after Darwin.

●

● Inserted a disk on each side of the plant. Found when it was on the shady side - phototropism was affected.

● Found when it was in the sunny side it did not affect bending.

Gravitropism

● Roots also have auxins that move based on the root’s position

● Root _________________ - the auxin moves down and the BOTTOM SIDE GROWS LESS (this is opposite of auxin in the

shoot).

● Therefore, the top side grows more and it bends _____________________.

Fill in the blank notes Turgor Pressure and RootsMain Understandings:

○ Explain osmosis; diffusion, active transport and root pressure in root hairs○ Explain transpiration in plants, cohesion and adhesion as properties of water, and turgor pressure

Recall:

● Where are sugars produced in our plant?____________________ By what process?___________________

● Transported by what?_______________

● Where does water leave our plant?_______________________

But where does water first enter our plant?!

● The _______________!

● The roots have tiny little extensions called

_______________ that help absorb water and minerals!

● Water moves into our roots via _______________

● The minerals have to be moved into the root cells against

their concentration gradient by ______________________.

Water Then…Moves up towards the leaves through the ________________!

What was the movement of water out of the leaves called again?______________________

Why else is water important → Turgor Pressure

● Water is why are stems are either firm and straight

up or wilted!

● Turgor pressure is when water moves into our plant

cell pushing the cell ___________ against the cell

____________.

● As a result, the plant is firm or ____________.

● When water moves out of our plant cell, the cell shrinks and ________!

● Water would move into the cell in a _____________ solution

● Water would move out of the cell in a ____________ solution

Turgor Pressure also affects Guard Cells:

● When the guard cells are turgid, they _____________which allows gas exchange

● When the guard cells are flaccid or wilted, they ____________ and reduce the amount of water loss and gas exchange.

Transpiration Summary:

● The process by which water leaves the plant.

○ Water enters the plant by the root and root___________cells

○ Then moves up the________________

○ When it reaches the _________________ it turns to water vapour and leaves the plant.

○ The water leaving the plant pulls on the other water molecules by ___________________

○ The adhesion of water to the xylem cells helps prevent water from going back down.

Gas Exchange in plants:

● In sunlight: ___________________

○ Carbon dioxide flows _____________the plant through the stomata to make sugars. Oxygen leaves through the_________________.

● When it is dark: Plants use ________________

○ They use the sugar they made and _____________ to produce energy. They then release __________________.

○Woody Trees/Stems have another way:

● Woody trees and stems also have tissues with pores called ___________________!

● Allows for even more gas exchange to occur.