Osmosis
Übersicht
Leave a limp stick of celery in water and it turns crisp again; soak a potato chip in salty water and it goes floppy. Both are caused by osmosis, the movement of water across a partially permeable membrane. It is how plants stand upright, how roots drink, and how every cell keeps its water balance.
In this lesson you will learn the role of water in organisms, what osmosis is, how to investigate it, and how solutions of different strengths change plant and animal cells. At Extended level you will use water potential and the terms turgid, flaccid and plasmolysis to explain what you see.
Ziele
- Describe the role of water as a solvent in organisms with reference to digestion, excretion and transport
- State that water diffuses through partially permeable membranes by osmosis
- State that water moves into and out of cells by osmosis through the cell membrane
- Investigate osmosis using materials such as dialysis tubing
- Investigate and describe the effects on plant tissues of immersing them in solutions of different concentrations
- State that plants are supported by the pressure of water inside the cells pressing outwards on the cell wall
- [Supplement] Describe osmosis as the net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane
- [Supplement] Explain the effects on plant cells of immersing them in solutions of different concentrations by using the terms: turgid, turgor pressure, plasmolysis, flaccid
- [Supplement] Explain the importance of water potential and osmosis in the uptake and loss of water by organisms
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Unterrichtsbewertung
Herzlichen Glückwunsch zum Abschluss der Lektion über Osmosis. Jetzt, da Sie die wichtigsten Konzepte und Ideen erkundet haben,
Sie werden auf eine Mischung verschiedener Fragetypen stoßen, darunter Multiple-Choice-Fragen, Kurzantwortfragen und Aufsatzfragen. Jede Frage ist sorgfältig ausgearbeitet, um verschiedene Aspekte Ihres Wissens und Ihrer kritischen Denkfähigkeiten zu bewerten.
Nutzen Sie diesen Bewertungsteil als Gelegenheit, Ihr Verständnis des Themas zu festigen und Bereiche zu identifizieren, in denen Sie möglicherweise zusätzlichen Lernbedarf haben.
- Osmosis is the movement of: A. any particles down a gradient B. water across a partially permeable membrane C. ions using energy D. sugar into a cell Answer: B
- Water moves by osmosis from a region of: A. low to high water potential B. high to low water potential C. equal water potential D. low to low water potential Answer: B
- A potato cylinder has initial mass 4.0 g and final mass 3.6 g. The percentage change is: A. +10% B. -10% C. -4% D. +4% Answer: B
- A plant cell that has taken in water and is firm is described as: A. flaccid B. plasmolysed C. turgid D. lysed Answer: C
- A red blood cell placed in pure water will: A. become turgid B. shrink C. burst D. stay the same Answer: C
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Empfohlene Bücher
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Lehrbuchabschnitt
Passive Transport
Explain why and how passive transport occurs
"Biology: Passive Transport" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/biology/pages/5-2-passive-transport. Access for free at https://openstax.org/books/biology/pages/1-introduction
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Lehrbuchabschnitt
Transport of Water and Solutes in Plants
Define water potential and explain how it is influenced by solutes, pressure, gravity, and the matric potential
"Biology: Transport of Water and Solutes in Plants" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/biology/pages/30-5-transport-of-water-and-solutes-in-plants. Access for free at https://openstax.org/books/biology/pages/1-introduction
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