Bioknowledgy
questioning, investigating and understanding
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  • IB Biology
    • Syllabus
    • General Resources
    • Practical scheme of work >
      • Practical activities (Labs)
      • Individual investigation
      • IB Write
  • Core
    • 1. Cell biology >
      • 1.1 Introduction to cells
      • 1.2 Ultrastructure of cells
      • 1.3 Membrane structure
      • 1.4 Membrane transport
      • 1.5 The origin of cells
      • 1.6 Cell division
    • 2. Molecular biology >
      • 2.1 Molecules to metabolism
      • 2.2 Water
      • 2.3 Carbohydrates and lipids
      • 2.4 Proteins
      • 2.5 Enzymes
      • 2.6 Structure of DNA and RNA
      • 2.7 DNA replication, transcription and translation
      • 2.8 Cell respiration
      • 2.9 Photosynthesis
    • 3. Genetics >
      • 3.1 Genes
      • 3.2 Chromosomes
      • 3.3 Meiosis
      • 3.4 Inheritance
      • 3.5 Genetic modification and biotechnology
    • 4. Ecology >
      • 4.1 Species, communities and ecosystems
      • 4.2 Energy flow
      • 4.3 Carbon cycling
      • 4.4 Climate change
    • 5. Evolution and biodiversity >
      • 5.1 Evidence for evolution
      • 5.2 Natural selection
      • 5.3 Classification of biodiversity
      • 5.4 Cladistics
    • 6. Human physiology >
      • 6.1 Digestion and absorption
      • 6.2 The blood system
      • 6.3 Defence against infectious disease
      • 6.4 Gas exchange
      • 6.5 Neurons and synapses
      • 6.6 Hormones, homeostasis and reproduction
  • Additional higher level (AHL)
    • 7. Nucleic acids >
      • 7.1 DNA structure and replication
      • 7.2 Transcription and gene expression
      • 7.3 Translation
    • 8. Metabolism, cell respiration and photosynthesis >
      • 8.1 Metabolism
      • 8.2 Cell respiration
      • 8.3 Photosynthesis
    • 9. Plant biology >
      • 9.1 Transport in the xylem of plants
      • 9.2 Transport in the phloem of plants
      • 9.3 Growth in plants
      • 9.4 Reproduction in plants
    • 10. Genetics and evolution >
      • 10.1 Meiosis
      • 10.2 Inheritance
      • 10.3 Gene pools and speciation
    • 11. Animal physiology >
      • 11.1 Antibody production and vaccination
      • 11.2 Movement
      • 11.3 The kidney and osmoregulation
      • 11.4 Sexual reproduction
  • Options
    • A. Neurobiology and behaviour >
      • A.1 Neural development
      • A.2 The human brain
      • A.3 Perception of stimuli
      • A.4 Innate and learned behaviour (AHL)
      • A.5 Neuropharmacology (AHL)
      • A.6 Ethology (AHL)
    • B. Biotechnology and bioinformatics
    • C. Ecology and conservation >
      • C.1 Species and communities
      • C.2 Communities and ecosystems
      • C.3 Impacts of humans on ecosystems
      • C.4 Conservation of biodiversity
      • C.5 Population ecology (AHL)
      • C.6 Nitrogen and phosphorus cycles (AHL)
    • D. Human physiology
  • Giving back - BioKQQAnswers

Essential idea: Water is the medium of life.

The cohesive nature of nature gives it surface tension. The surface tension in turn allows organisms such as pond skaters (above) to move across the surface. For pond skaters the surface of water is their habitat. The surface tension transmits vibrations from fallen invertebrates - this allows pond skaters to detect and locate their prey.

Understandings, applications and skills:

2.2.U1 Water molecules are polar and hydrogen bonds form between them.
2.2.U2 Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water. [Students should know at least one example of a benefit to living organisms of each property of water. Transparency of water and maximum density at 4°C do not need to be included.]
2.2.U3 Substances can be hydrophilic or hydrophobic.
2.2.A1 Comparison of the thermal properties of water with those of methane. [Comparison of the thermal properties of water and methane assists in the understanding of the significance of hydrogen bonding in water.]
2.2.A2 Use of water as a coolant in sweat.
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.
[Text in square brackets indicates guidance notes]

Starter

A rapid fire introduction from Hank Green
Learn by discovery

Investigate to find about the properties of water by Tom Edwards

Drawing and annotating hydrogen bonding in water molecules
Use the video to both learn and test yourself


Presentation and notes

The presentation is designed to help your understanding. The notes outline is intended to be used as a framework for the development of student notes to aid revision.
Download presentation

Vocabulary

Correct use of terminology is a key skill in Biology. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary.
Below are the notes for this topic. Alternatively the 2.2 Water bottom line template can be used as a note construction template in itself or as a checklist if you are using your own or another template such as the Cornell style template.
Download notes


Labs

An Investigation into Leaf Surface Temperature by SAPS is good insight into the importance of water function as a coolant in plant leaves.


Quick quiz

Quick quiz Use the BioK Quick Quiz on 2.2 Water (as directed) to check your understanding of the topic.

Weblinks

Hydrogen bonding
H-bonds in water, from Northland College
The temporary nature of hydrogen bonds in water by St Olaf College
Drawing the structure of water molecules by Stephanie Castle
Polarity of water by Click4Biology

Properties of water
Properties of water by Sunamas Inc.
Properties of water, from Northland College
Molecule polarity simulation from PhET Labs (allow Java to run)
Solubility in water simulation from PhET Labs (allow Java to run)
_The thermal, cohesive and solvent properties of water by Stephanie Castle
The relationship between the properties of water and it's uses by Stephanie Castle
Cohesion in water by Click4Biology
Thermal properties of water by Click4Biology

Solubility and transport by water
Water as a solvent by Click4Biology

Dissolving
, from Northland College
Dissolving NaCl from PreparatoryChemistry
PhET Labs: Salts and Solubility and also Dissolving Sugars and Salts


The surface tension of water demonstrated on the ISS

Nature of science:

Use theories to explain natural phenomena—the theory that hydrogen bonds form between water molecules explains the properties of water. (2.2)

Theory of knowledge:

Claims about the “memory of water” have been categorized as pseudoscientific. What are the criteria that can be used to distinguish scientific claims from pseudoscientific claims?


This BBC article discusses
could water really have a memory?

Below is a humorous look at Homeopathy by Mitchell and Webb
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