Water is the medium of life.
A1.1 Water
Essential idea: What is the most important molecule in the world?
Challenge: Can you justify why?
Support: think what we need to live
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Water is important because:
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2.2 Vocabulary
The cohesive nature of water gives it surface tension.
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Water is so cool
What physical and chemical properties of water make it essential for life?
What are the challenges and opportunities of water as a habitat?
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Guiding Questions
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Brain Break – what do these 5 words mean?
2.2.U2 Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water.
A1.1 Water
Brain Break – what do these 5 words mean?
2.2.U2 Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water.
A1.1 Water
Understandings, Application and Skills
A1.1 Water Syllabus Reference
Statement | Guidance |
A1.1.1—Water as the medium for life | Students should appreciate that the first cells originated in water and that water remains the medium in which most processes of life occur |
A1.1.2—Hydrogen bonds as a consequence of the polar covalent bonds within water molecules | Students should understand that polarity of covalent bonding within water molecules is due to unequal sharing of electrons and that hydrogen bonding due to this polarity occurs between water molecules. Students should be able to represent two or more water molecules and hydrogen bonds between them with the notation shown below to indicate polarity. |
A1.1.3—Cohesion of water molecules due to hydrogen bonding and consequences for organisms | Include transport of water under tension in xylem and the use of water surfaces as habitats due to the effect known as surface tension. |
A1.1.4—Adhesion of water to materials that are polar or charged and impacts for organisms | Include capillary action in soil and in plant cell walls |
A1.1.5—Solvent properties of water linked to its role as a medium for metabolism and for transport in plants and animals | Emphasize that a wide variety of hydrophilic molecules dissolve in water and that most enzymes catalyse reactions in aqueous solution. Students should also understand that the functions of some molecules in cells depend on them being hydrophobic and insoluble. |
A1.1.6—Physical properties of water and the consequences for animals in aquatic habitats | Include buoyancy, viscosity, thermal conductivity and specific heat capacity. Contrast the physical properties of water with those of air and illustrate the consequences using examples of animals that live in water and in air or on land, such as the black-throated loon (Gavia arctica) and the ringed seal (Pusa hispida) |
A1.1 Water
Understandings, Application and Skills
A1.1 Water.Syllabus Reference
A1.1.7—Extraplanetary origin of water on Earth and reasons for its retention | The abundance of water over billions of years of Earth’s history has allowed life to evolve. Limit hypotheses for the origin of water on Earth to asteroids and reasons for retention to gravity and temperatures low enough to condense water. |
A1.1.8—Relationship between the search for extraterrestrial life and the presence of water | Include the idea of the “Goldilocks zone” |
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What is water made up of?
A1.1.2—Hydrogen bonds as a consequence of the polar covalent bonds within water molecules
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A1.1.2—Hydrogen bonds as a consequence of the polar covalent bonds within water molecules
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A1.1.2—Hydrogen bonds as a consequence of the polar covalent bonds within water molecules
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Why is water dipolar?
A1.1.2—Hydrogen bonds as a consequence of the polar covalent bonds within water molecules
The hydrogen atoms have a slightly positive charge
The oxygen atom has a
slightly negative charge
Polar: The electrons are shared unequally, creating an unequal distribution of charge.
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A1.1.2—Hydrogen bonds as a consequence of the polar covalent bonds within water molecules
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A1.1.2—Hydrogen bonds as a consequence of the polar covalent bonds within water molecules
The bonds are made and broken quickly as the molecules move, however the large numbers of bonds contribute to the stability of water
Partly positive hydrogen atoms of one water molecule are attracted to the partially negative oxygen of another water molecule
Hydrogen bonding is a special type of attraction between molecules
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What is cohesion?
A1.1.3—Cohesion of water molecules due to hydrogen bonding and consequences for organisms
Hydrogen bonding between water molecules produces high cohesion
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A1.1.3—Cohesion of water molecules due to hydrogen bonding and consequences for organisms
Cohesion of water molecules along a surface produces surface tension
Fishing spiders and pond skaters rely on surface tension to move across the surface of ponds
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Brain Break – what do these 5 words mean?
Checkpoint
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Challenge:
A1.1.3—Cohesion of water molecules due to hydrogen bonding and consequences for organisms
Can you make a paperclip float?
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What is adhesion?
A1.1.4—Adhesion of water to materials that are polar or charged and impacts for organisms
Water molecules sticking to non water, polar or charged surfaces is called adhesion
Adhesion helps water climb up the thin tubes of plants to the leaves
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Adhesion and cohesion move water in plant stems
A1.1.4—Adhesion of water to materials that are polar or charged and impacts for organisms
Together they cause capillary action
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A1.1.5—Solvent properties of water linked to its role as a medium for metabolism and for transport in plants and animals
Polar Molecules Like Water
Lic
HydrophiLic
2.2 Water
This term is used to describe substances that are chemically attracted to water.
A1.1.5—Solvent properties of water linked to its role as a medium for metabolism and for transport in plants and animals
( water loving )
hydrophilic
2.2 Water
This term is used to describe substances that are insoluble in water
A1.1.5—Solvent properties of water linked to its role as a medium for metabolism and for transport in plants and animals
hydrophobic
( water fearing )
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What is a solvent?
A1.1.5—Solvent properties of water linked to its role as a medium for metabolism and for transport in plants and animals
Water is an excellent solvent
A wide range of substances dissolve in water
Water is attracted to and can surround ions or polar molecules (such as sugars and some amino acids, dissolving them
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Water as a solvent
A1.1.5—Solvent properties of water linked to its role as a medium for metabolism and for transport in plants and animals
Blood and cytoplasm are mostly water as water is an excellent transport medium
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Transport of molecules in the blood
A1.1.5—Solvent properties of water linked to its role as a medium for metabolism and for transport in plants and animals
Fats
They are carried in blood inside lipoprotein complexes (in the plasma
Cholesterol
They are carried in blood in lipoprotein complexes (in the plasma)
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2.2.A3 Modes of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water.
Sodium Chloride
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What is specific heat capacity?
A1.1.6—Physical properties of water and the consequences for animals in aquatic habitats
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Brain Break – what do these 5 words mean?
2.2.U2 Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water.
A1.1 Water
What is latent heat of vaporization?
A1.1.6—Physical properties of water and the consequences for animals in aquatic habitats
Water can evaporate below its boiling point (100C). This can be seen when we sweat.
The (thermal) energy is transferred to the gaseous state and acts as a coolant.
Water is said to have a High latent heat of vaporisation. Meaning it removes a large amount of energy to transfer it to gaseous state
Ice is unusual because it is less dense than liquid water (most substances become more dense when they solidify from a liquid).
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Why is ice special?
This is because the spacing between hydrogen and oxygen becomes fixed as it cools.
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Cool facts
Extra Information
Ponds and lakes freeze from the top down and never freeze completely to the bottom
Many plants and fish therefore are not frozen and can live underneath the ice
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Water is transparent
A1.1.6—Physical properties of water and the consequences for animals in aquatic habitats
Water is transparent simply because it does not absorb light in the visible spectrum, and all frequencies of coloured light are transmitted through.
Because water is transparent, light penetrates tissue and aquatic environments, important for photosynthesis.
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A1.1.8—Relationship between the search for extraterrestrial life and the presence of water
The "Goldilocks zone" or "habitable zone" concept is crucial in the context of the search for extraterrestrial life. It helps scientists identify regions within a planetary system where conditions might be suitable for the existence of life as we know it.
The primary criterion for the Goldilocks zone is the presence of liquid water, which is considered a key ingredient for life on Earth. While water is essential, it's important to note that the Goldilocks zone is not a guarantee of life, but rather a starting point for potential habitability.
A1.1 Water
A1.1.8—Relationship between the search for extraterrestrial life and the presence of water
Mars Temperature 20 °C to -153 °C
Venus Temperature 482 °C to 438 °C
Mars 3.72
Earth is 9.81
Venus is 8.87
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A1.1.8—Relationship between the search for extraterrestrial life and the presence of water
Mars 3.72
Earth is 9.81
Venus is 8.87
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A1.1.8—Relationship between the search for extraterrestrial life and the presence of water
The primary criterion for the Goldilocks zone is the presence of liquid water, which is considered a key ingredient for life on Earth. While water is essential, it's important to note that the Goldilocks zone is not a guarantee of life, but rather a starting point for potential habitability.
The origin of the first cells is believed to be in water, specifically in the Earth's ancient oceans. The early Earth had a primordial soup of organic molecules, and under favorable conditions, these molecules eventually formed self-replicating structures, which are considered the precursors of cells.
A1.1 Water
Water is important because:
A1.1.7—Extraplanetary origin of water on Earth and reasons for its retention
The origin of the first cells is believed to be in water, specifically in the Earth's ancient oceans. The early Earth had a primordial soup of organic molecules, and under favorable conditions, these molecules eventually formed self-replicating structures, which are considered the precursors of cells.
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Water is important because:
A1.1.7—Extraplanetary origin of water on Earth and reasons for its retention
In Pairs….
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A1.1.6—Physical properties of water and the consequences for animals in aquatic habitats
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Water Recap
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Kahoot
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Quiz
Hypertonic solution has a high solute concentration and low water concentration
Hypotonic solution has a low solute concentration and high water concentration
50% Sucrose Solution
50% ___________
5% Sucrose Solution
95% ___________
20% Sucrose Solution
80% ___________
50% Sucrose Solution
50% ___________
5% Sucrose Solution
95% ___________
20% Sucrose Solution
80% ___________