The net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane.

What is solute potential?

The component of water potential due to the dissolved solute, which is always negative.

What is pressure potential?

The component of water potential due to the pressure of the cell contents against the wall, which is usually positive in a plant cell.

Eduqas A-Level Biology A400QS

Biological Molecules

Topic overview Inorganic ions and the properties of water Monosaccharides and disaccharides Polysaccharides, storage and structure Lipids, triglycerides and phospholipids Amino acids and protein structure Condensation, hydrolysis and the food tests

Cell Structure and Organisation

Topic overview The nucleus and the endomembrane system Mitochondria, chloroplasts and other organelles Prokaryotic cells and viruses Cell theory, microscopy and measuring cells Comparing cells and the levels of organisation

Cell Membranes and Transport

Topic overview The fluid-mosaic model Factors affecting membrane permeability Diffusion and facilitated diffusion Osmosis and water potential Active transport and bulk transport Determining water potential in practice

Enzymes

Topic overview Enzymes as biological catalysts The active site and induced fit Temperature, pH and buffers Substrate and enzyme concentration Inhibition and immobilised enzymes

Nucleic Acids and Their Functions

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Importance of ATP

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Photosynthesis

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Respiration

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Microbiology

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Mitosis and Meiosis

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Sexual Reproduction in Humans

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Sexual Reproduction in Plants

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Inheritance

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Variation and Evolution

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Application of Reproduction and Genetics

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Adaptations for Gas Exchange

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Adaptations for Transport

Topic overview Vascular systems compared across animal groups The mammalian heart and blood vessels The cardiac cycle and its control Blood, haemoglobin and dissociation curves The Bohr effect, chloride shift and tissue fluid The root and the uptake of water The endodermis and the entry to the xylem Xylem, transpiration and cohesion-tension The potometer and xerophytes and hydrophytes Phloem and translocation

Adaptations for Nutrition

Topic overview Modes of nutrition Saprotrophic nutrition Holozoic nutrition and the unicellular gut From a sac-like gut to a tube gut The human gut and the effect of diet Herbivores, carnivores and parasites

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Immunology and Disease: Disease and Its TransmissionImmunology

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Immunology and Disease: The Immune ResponseImmunology

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Human Musculoskeletal Anatomy: Skeletal TissuesMusculoskeletal

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Human Musculoskeletal Anatomy: Structure and Function of the SkeletonMusculoskeletal

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Human Musculoskeletal Anatomy: JointsMusculoskeletal

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Neurobiology and Behaviour: The BrainNeurobiology

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Neurobiology and Behaviour: NeuroscienceNeurobiology

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Neurobiology and Behaviour: BehaviourNeurobiology

Topic overview Innate behaviour: escape reflexes, kineses and taxes Habituation and imprinting Classical and operant conditioning Primate societies and the costs and benefits of group living Insect castes, dominance hierarchies, territory and courtship

Cell Membranes and Transport

Osmosis and water potential

3 things to know
Component 1

Overview

Water potential, solute potential and pressure potential.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What is water potential?

Key term

What is the water potential of pure water?

Key term

Why is the water potential of a solution always negative?

Questions from this subtopic

Each one with the model answer underneath.

1
Define osmosis.
Model answer
The net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane.
2
What is water potential?
Model answer
The tendency of water to move out of a solution, measured in kilopascals.
3
What is the water potential of pure water?
Model answer
Zero, which is the highest value water potential can take.
4
Why is the water potential of a solution always negative?
Model answer
Dissolved solute lowers the tendency of water to leave, so adding any solute takes the value below zero.
5
What is solute potential?
Model answer
The component of water potential due to the dissolved solute, which is always negative.
6
What is pressure potential?
Model answer
The component of water potential due to the pressure of the cell contents against the wall, which is usually positive in a plant cell.

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Osmosis and water potential

Overview

What you need to know

What is water potential?

What is the water potential of pure water?

Why is the water potential of a solution always negative?

Questions from this subtopic

Define osmosis.

What is water potential?

What is the water potential of pure water?

Why is the water potential of a solution always negative?

What is solute potential?

What is pressure potential?

Other ways to work this

What is inside Levo

The 3-step method, run for you

Cram a whole paper in one sitting

Blank Blitz makes facts automatic

Build It gets the exam shape right

Test It catches misconceptions

Brain Breaks between sessions

Every question in Cell Membranes and Transport, on a schedule.