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Biology > A1.1: Water > Flashcards

A1.1: Water Flashcards

1
Q

State where the first cells originated

A

In water

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2
Q

​List reasons why water is a substance on which life depends​

A
  • it is a metabolite (chemicals involved in metabolism)
  • it maintains biological structures
  • it is a temperature buffer (absorbs heat due to its high shc)
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3
Q

Describe the structure of an atom.

A
  • Protons (+vely charged) and Neutrons (no charge) within the nucleus (called Neucleons together)
  • Electrons (-vely charged)
  • Atoms that have a deficit or a surplus of electrons are called ions
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4
Q

Outline the formation of ionic and covalent bonds between atoms.

A

Covalent bonds:
- Electrostatic attraction between shared pair of electrons between the nuclei of two atoms

Ionic bond:
- Electrostatic attraction between oppositely charged ions (+vely charged is cation, -vely charged is anion)

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5
Q

Explain the sharing of electrons between atoms in a polar covalent bond.

A
  • Polar covalent (share electrons unequally)
  • Slight positive charge (delta +) due to fewer electrons around that nucleus. VV for delta -
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6
Q

State the location of the polar covalent bond within a water molecule.

A

Can occur in amino acid R groups which impact the tertiary structure of a protein

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7
Q

Explain the partial charges of the oxygen and hydrogen atoms within a water molecule.

A

As the O2 atom has more protons, it attracts the shared e- more often thus creating an unequal distribution of charge
- Delta - is Oxygen
- Delta + is Hydrogen

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8
Q

Draw a water molecule, including notation to depict the partial charges of the atoms.

A

Dotted line connects H atom and O atom
- O2 has Delta - charge
- H2 has Delta + charge

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9
Q

Outline the cause of the formation of hydrogen bonds between water molecules.

A
  • Partially positive H atoms of one water molecule are attracted to the partially negative O2 atom of a different water molecule forming a hydrogen bond.
  • Each H2O can form up to 4 Hydrogen bonds with 4 other H2O molecules
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10
Q

Outline the consequences of the collective strength of hydrogen bonds between water molecules.​

A

Allows it several emergent properties:
- Adhesion
- Cohesion
- Solvency
- High specific heat capacity

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11
Q

Define cohesion.

A

When water molecules stick together and form H bonds between different water molecules

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12
Q

Describe how water moves through the xylem of a vascular plant.

A
  • Transpiration occurs due to stomata being open to allow gas exchange for photosynthesis which causes tension
  • Tension pulls water in the xylem drawing water up
  • Cohesion pulls water molecules up and out of the stomata in a column due to the H bonds between water molecules
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13
Q

Outline the cause of surface tension.

A

There are H bonds between the water molecules as water molecules are more attracted to one another than to air molecules

  • This allows them to resist an external force thus, the cohesive nature of water allows it to have high surface tension
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14
Q

State 2 benefits to living things that result from surface tension.

A
  • Allows organisms like water striders to live on the surface of water
  • Allows some seeds to disperse away from the parent plant
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15
Q

Define adhesion.

A
  • The attraction of water molecules to other polar molecules allowing plants to move water using capillary action
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16
Q

Define polar.

A

Unequal sharing of electrons between atoms within the molecules

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17
Q

Define ion.

A

Formed when ions have different number of electrons and protons

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18
Q

Compare cation and anion.

A

Cations have positive charges as it has more protons than electrons

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19
Q

Explain why water is attracted to molecules that are polar or charged.

A

Anions have negative charges as it has more electrons than protons

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20
Q

Outline the cause of capillary action.

A
  • Adhesion of water to the walls causes an upward force on the liquid causing
  • Cohesion between Water molecules
21
Q

Describe capillary action in plant tissue.

A
  • Movement of water in a tube in opposition to the external forces of gravity
  • H bonds betw. water molecules and cellulose in xylem cell wall help this movement from the roots to the leaves -
22
Q

Outline the cause and effect of capillary action in soil.

A

Cause:
- Water adheres to surface of soil particles and plants absorb the water via osmosis

Effect:
- Water moves upwards through soil pores and the height water rises to is dependent on the soil type

23
Q

Identify solvent and solutes of a solution.

A

Solvent:
- Liquid in which a solute dissolves

Solute:
- Substance that dissolves in the solvent

24
Q

Define solvation.

A

The interaction of a solvent with the dissolved solute

25
Q

Explain why water is able to dissolve charged and polar molecules.

A
  • Water is a solvent
  • When solutes dissolve in water, each molecule gets surrounded by the water molecules
  • the water forms H bonds with the solute thus, forming a hydration shell around the solute
26
Q

Outline the solvation of hydrophilic and hydrophobic substances.

A

Solvation of Hydrophilic substances:
- partially positive charge of water’s H atom is attracted to the negative charge of an anion. VV for a partially negative charge of water’s O2 atom

Solvation of Hydrophobic substances:
- Hydrophobic molecules are non-polar and don’t have charged atoms thus, they are attracted to other hydrophobic molecules and are insoluble in water

27
Q

State an example of the function of a molecule depending on its being hydrophobic and insoluble.

A

Phospholipids have hydrophobic tails made of fatty acids which form bilayers in water with the tails being tucked away from water

28
Q

State an example of the function of a molecule depending on it being hydrophilic and soluble.

A

Dissolved substances in the cytosol are required for metabolic processes to keep the cell alive

29
Q

Outline the role of water as a medium for metabolism.

A

Water is needed for cellular metabolism as it:
- dissolves the reactants and enzymes for reactions
- catabolic reactions break down larger molecules into smaller molecules
- anabolic reactions build larger molecules from smaller molecules

30
Q

Describe the role of water as a medium for transport in vascular plants.

A
  • Dissolved minerals are transported in the xylem from the roots to the leaves
  • Dissolved sugars produced in photosynthesis are transported in the phloem from the source to sink
31
Q

Describe the role of water as a medium for transport in animal blood.

A

Water dissolves substances in solution around the body of an organism:
- Proteins like antibodies
- Glucose which is used in cellular respiration
- Waste products of metabolism like urea which is removed from the blood at the kidney

As lipids are hydrophobic, they can’t be transported in solution
- In order to be transported in blood, fat droplets are coated in proteins and phospholipids forming Lipoproteins

32
Q

Define physical property.

A

A measurable behaviour of matter that exists without the matter interacting with other things

33
Q

List physical properties of water that are consequential for animals in aquatic habitats.

A
  • Buoyancy
  • Viscosity
  • Thermal Conductivity
  • highest specific heat capacity of any liquid
34
Q

Outline the cause and effect of buoyancy.

A

Cause:
- Upward force applied to an object that is immersed in a fluid

Effect:
- Depends on the density of the object and not mass; If the density of the object is lower than the density of the fluid, the buoyant force will be greater than the force due to gravity and the object will float. VV

35
Q

Outline the cause and effect of viscosity.

A

Cause:
- Due to the amount fo friction the molecules of a liquid experience as they flow over each other. A thick fluid is more viscous and a thin fluid is less viscous

Effect:
- Water is more viscous than some other substances as it can form H bonds with itself that increase the friction and reduce water’s tendency to flow.

36
Q

Compare the viscosity of air to water to blood.

A
  • Blood is more viscous than pure watermas cells and dissolved solutes increase viscosity however, blood is more viscous than air
37
Q

Define thermal conductivity.

A

A measure of a material’s ability to move heat across a temperature gradient determined by how easily energy transfers through the material

38
Q

Compare less conductive to more conductive materials.

A

Less conductive materials (styrofoam, air):
- Heat slowly moves through the material
- Better at insulation and preventing heat loss

More conductive materials (fat, water):
- Heat rapidly moves through the material
- Better for absorbing and transferring heat

39
Q

Outline a consequence to the life of the thermal conductivity of air and water.

A

Water:
- Thick later of fat provides insulation from cold ocean temperatures in marine mammals

Air:
- A person will more quickly become hypothermic in cold water than in cold air as the water rapidly conducts body heat away from the body

40
Q

Define specific heat capacity.

A

The quantity of heat needed to raise the temperature of a chemical per unit mass (water heats up very slowly)

41
Q

Describe why water has the highest specific heat capacity of any liquid

A
  • Caused by its numerous H bonds where each bond is weak but there are so many of them that collectively, a lot of energy must be required to break them all
42
Q

State two benefits to life of the high specific heat capacity of water.

A
  • Helps body temperature rise and fall slowly when eternal temperatures become very hot or cold
  • Temperature of aquatic habitats rise and fall slowly when surrounding air temperatures become very hot or cold
43
Q

Compare the physical properties of water to those of air.

A

The physical properties of water are much higher than air

44
Q

Describe how the black-throated loon (Gavia arctica) interacts with the physical properties of water in their habitat.

A

Black-Throated Loon:
- Buoyancy allows the seal to stay afloat without expending lots of energy
- Water’s viscosity allows the seal to swim streamlined
- Water’’s great thermal conductivity allows the seal to insulate itself with blabber to maintain body temperature
- Water’s high SHC allows habitat stability for the seal

45
Q

Explain the hypothesis that asteroids are responsible for the origin of water on Earth.

A

Extraplanetary objects like asteroids contain large amounts of water and plummeted into the earth

46
Q

State two reasons why water was retained on early Earth.​

A
  1. The distance of the Earth from the Sun maintains a temperature on Earth to stay in liquid form as a result of the cohesion of water molecules via H bonds
  2. Earth’s gravity keeps water from escaping the planet
47
Q

Explain why the presence of water is considered fundamental to the search for extraterrestrial life.

A

The presence of water is precedent to the search for extraterrestrial life

48
Q

Define “Goldilocks zone” in relation to the search for extraterrestrial life.

A

Just the right distance from a star for water to remain at least periodically in liquid form on the surface

Biology (20 decks)

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