171 likes | 1.05k Views
Homeostasis, Transpiration, Tropisms, & Turgor Pressure . Ms. DeFreese 7 th Grade Science. Transpiration. G uard cells are found on each side of the stoma to help open and close the pore to prevent water loss R esponse to the amount of water available. Transpiration.
E N D
Homeostasis,Transpiration, Tropisms, & Turgor Pressure Ms. DeFreese 7th Grade Science
Transpiration • Guard cells are found on each side of the stoma to help open and close the pore to prevent water loss • Responseto the amount of water available
Transpiration • Active control the gas exchange of CO2 and H2O, between the plant and the atmosphere
Tropisms • A tropism is a growth or turning movement in response to an environmental stimulus. • Positive = towards the stimulus • Negative = away from the stimulus
Phototropism • The growth response of a plant in response to light direction.
Gravitropism • The growth response of a plant in response to gravity. • Roots exhibit positivegravitropism • Stems and leaves exhibit negative gravitropism.
Positive & Negative Gravitropism Example of negative gravitropism – this tree is growing against gravity (up).
Turgor Pressure • Pressure of the cell contents against the cell wall • High = plenty of water; pressure on cell wall enables plant to “stand up” • Low = lack of water; no pressure on cell wall makes plant wilt
Homeostasis • The state of balance in the body’s internal environment • In order to work properly the body needs to keep it’s internal conditions as constant as possible. • Even if the body is in homeostasis, changes in internal conditions do happen but within a very narrow limit
Assignment • Study these notes and your work from earlier... • Complete any “missing” assignments… • Very SHORT quiz tomorrow. If you know this material you should have an “A”…