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IB BIOLOGY > A1.1 Water > Flashcards

A1.1 Water Flashcards

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1
Q

where did the first cells originate?

A

the first cells originated in WATER

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2
Q

why is water a substance on which life depends? (4 points)

A
  • Water helps organisms regulate their temperature​
  • water is a solvent, so it can transport substances around the body​ + things can dissolve in it
  • Water is a habitat for a lot of living organisms​
  • Many reactions in living organisms require water​
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3
Q

what was water required for in regard to the first living organisms? (3 points)

A
  • in a liquid state, molecules can move around and interact, allowing the processes of life to happen
  • it was required for the effective interaction of the naturally formed molecules of life, allowing growth and copying of these molecules
  • it was required for the formation of compartments, which allowed the development of internal chemistry different from the surrounding environment.​
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4
Q

water is the solvent that? (5 points)

A
  • makes up the cytoplasm​
  • makes up the fluid inside all organelles​
  • permits transport of substances in and out of cells​
  • is an essential component of blood and other bodily fluids​
  • Provides habitats for many organisms in the form of rivers, oceans etc.​
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5
Q

describe the structure of an atom

A
  • An atom is composed of a nucleus containing protons and neutrons, surrounded by electrons in energy levels
  • It is made up of three types of subatomic particles: protons, neutrons, and electrons
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6
Q

what bonds exist in water molecules?

A

there are covalent bonds between oxygen and hydrogen atoms

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7
Q

what is special about the sharing of electrons in the covalent bonds of water molecules?

A

the sharing of electrons in these covalent bonds between oxygen and hydrogen atoms are UNEQUAL, making them POLAR COVALENT BONDS

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8
Q

why are electrons not shared evenly between the Oxygen and the Hydrogen atoms?

A

Because the oxygen’s nucleus is more electronegative

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9
Q

what is electronegativity?
what can it be influenced by?

A
  • Electronegativity is the ability of an atom to attract a shared pair of electrons

IT CAN BE INFLUENCED BY:

  • The number of protons in the nucleus:

The positive protons in the nucleus attract the electrons in the shells.​

  • The number of orbital shells:

The greater the number of shells between the outer electrons and the nucleus, the lower the electronegativity.​

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10
Q

what is unique about the sharing of electrons in a polar covalent bond?

A

the electrons are NOT shared equally

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11
Q

describe the polarity of water

A

Because Oxygen is more electronegative than Hydrogen, it attracts the shared pair of electrons greater. This uneven distribution of electrons results in the oxygen atom being slightly negative (δ-), whilst the hydrogen atoms are slightly positive (δ+).​

This polarity of water gives it many of its unique properties.​

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12
Q

outline the formation of ionic bonds between atoms

A

An ionic bond is an attraction between a positively charged ion and an negatively charged ion.

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13
Q

outline the formation of covalent bonds between atoms

A

In a covalent bond, two atoms share one or more pair of electrons.

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14
Q

Explain the sharing of electrons between ATOMS in a polar covalent bond (describe it generally, not just for water)

A
  • In a polar covalent bond, the nucleus of one atom has more pull on the shared electrons than the other atom.
  • As a result, it has a bigger electron cloud surrounding it.
  • Because electrons have a negative charge and there are MORE ELECTRONS around this nucleus, there is a slight negative charge (ઠ-) on this nucleus.
  • Because there are LESS ELECTRONS around the second atom’s nucleus, there is a slight positive charge (ઠ+) on this nucleus
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15
Q

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

A

There are two polar covalent bonds within a water molecule; one between the oxygen atom and each hydrogen atom

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16
Q

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

A
  • A water molecule consists of 2 hydrogen and 1 oxygen atom (H20)
  • WITHIN a water molecule, electrons are shared through polar covalent bonding between the atoms
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17
Q

what bonds exist BETWEEN water molecules?
how do they form?

A
  • hydrogen bonds
  • they form when a slightly negatively charged part of a molecule (oxygen) comes close to a slightly positively charged hydrogen molecule in the same or another molecule
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18
Q

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

what do they look like? (draw)

A

The partially positive hydrogen atoms of one water molecule are attracted to the partially negative oxygen atom of a different water molecule, forming a hydrogen bond

  • hydrogen bonds are WEAK, so they are drawn with a dashed/dotted line, NOT a solid line
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19
Q

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

A
  • Water’s ability to make hydrogen bonds with itself and other charged molecules grants it a number of emergent properties such as:
  • cohesion
  • adhesion
  • solvency
  • a high specific heat

**Collectively these properties make water the primary medium of life

**hydrogen bonds between water molecules are weak, but because there are so many of them, collectively they give water these properties

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20
Q

how far apart (in terms of angle) are the hydrogen atoms in a water molecule?

why?

A

The hydrogen atoms are 105 degrees apart.

This is due to the repulsion between the electrons in the hydrogen atoms.​

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21
Q

Draw the hydrogen bonds between multiple water molecules

A
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22
Q

atoms do not have __

A

atoms do not have an overall charge

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23
Q

Draw the structure of hydrogen and oxygen atoms

A
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24
Q

Draw the structure of water molecules including how the electrons are arranged

A
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25
Q

Define cohesion

A
  • Cohesion = the property of water in which it makes hydrogen bonds with itself, causing water molecules to stick together

OR (class PPT):

It is a property of water in which water molecules are attracted to each other by hydrogen bonding, allowing the molecules to move together

*you need energy to break these bonds

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26
Q

Describe how water moves through the xylem of a vascular plant

A
  1. Transpiration (evaporation) occurs through stomata of a leaf. As transpiration occurs, it creates negative pressure
  2. The tension created by transpiration “pulls” water in the plant xylem, drawing the water upward
  3. Cohesion pulls up water molecules in a chain as the top-most water is pulled up and out of the stomata.
27
Q

Outline the cause of surface tension

A

The molecules on the surface are more attracted to other molecules of the liquid than to molecules in the surrounding air.

The net effect is an inward force that causes water to behave as if its surface were covered with a stretched elastic membrane.

*on the surface of water, there are relatively strong cohesive forces between water molecules which need to be overcome.​

28
Q

State a benefit to living things that results from surface tension

A

Surface tension allows organisms like water striders to “walk on water” and provides a stable environment for other organisms that live on or near the surface of water.

To break through the surface of the water, enough force must be applied to break many hydrogen bonds simultaneously.

29
Q

define tension

A

Tension: A force that tends to stretch something

29
Q

Define adhesion

A

The attraction of water to other polar or charged molecules

OR (class PPT):

A property of water in which water molecules are attracted to surfaces such as walls of the cells, vessels or tubes via hydrogen bonds

30
Q

Define polar

A

Polar means there is unequal sharing of electrons in a covalent bond between two atoms

31
Q

Define ion

A

An ion is an atom with different (unequal) numbers of electrons and protons, meaning it is an atom with a charge

32
Q

Compare cation and anion

A
  • A cation has a positive charge because it has more protons than electrons
    (ex. Na+)
  • An anion has a negative charge because it has more electrons than protons
    (ex. Cl-)
33
Q

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

A
  • The slight negative charge (δ-) of water oxygen atom is attracted to the [slight] positive charge of molecules that are polar or charged.
  • The slight positive charge (δ+) of water hydrogen atom is attracted to the [slight] negative charge of molecules that are polar or charged.
34
Q

Outline the cause of capillary action

A

Capillary action is the movement of water in through a narrow space, often in opposition to external forces like gravity

Adhesion of water to the walls of a vessel will cause an upward force on the liquid

35
Q

Describe capillary action in plant tissue

A

Capillary action helps bring water from the roots all the way up to the branches and leaves.

Adhesion of water to the xylem walls will cause an upward force on the water.

36
Q

Outline the cause and effect of capillary action in soil

A

Capillary action in soil the primary force that enables the soil to retain water.

In the same way that water moves upwards through a tube against the force of gravity; water moves upwards through soil pores, or the spaces between soil particles.

37
Q

Identify solvent and solutes of a solution

A
  • Solvent: the liquid in which a solute dissolves
  • Solute: the substance that dissolves in a solvent
38
Q

Define solvation

A

Solvation is the interaction of a solvent with the dissolved solute

39
Q

Explain why water is able to dissolve charged molecules

A
  • Water is electrostatically attracted to ions
  • The slight positive charge (δ+) of water’s hydrogen atom is attracted to the negative charge of an anion
  • The slight negative charge (δ-) of of water oxygen atom is attracted to the positive charge of a cation
40
Q

Explain why water is able to dissolve polar molecules

A
  • Polar molecules can form hydrogen bonds with water
  • The slight positive charge (δ+) of water’s hydrogen atom is attracted to the negatively charged region of the solute
  • The slight negative charge (δ-) of water’s oxygen atom is attracted to the positively charged region of the solute
41
Q

Outline the solvation of hydrophilic and hydrophobic substances

A
  • Hydrophobic means water fearing. Because they are not polar or charged, hydrophobic molecules will not dissolve in water. They are insoluble.
  • Hydrophilic means water loving. Because they are polar or charged, hydrophilic molecules will dissolve in water. They are soluble.
42
Q

State an example of the function of a molecule depending on it being HYDROPHILIC and SOLUBLE

A

Because they have hydrophillic amino acids, enzymes can dissolve in cytoplasm where they are used to catalyze chemical reactions in the cell

other examples in nature:
- Glucose​
- Ions​
- Amino acids​
- Proteins e.g. enzymes​

​*This ensures they can be transported easily. Making water an excellent transport medium.​

43
Q

Outline the role of water as a medium for metabolism

A

Water is incredibly important for many metabolic reactions. For examples the cytoplasm contains a huge number of dissolved substances. The cytoplasm is largely formed of water, and how these molecules interact with water can impact their actions.​

For example:​

The presence of water within enzymes can enable them to maintain their shape to be able to catalyse reactions.​

*Cytosol is the liquid part of the cytoplasm, a structure common to all cells. It is composed of about 80 percent water and also contains lots of dissolved substances. These substances must be dissolved in water in order to carry out the metabolic processes required to keep the cell alive.

43
Q

State an example of the function of a molecule depending on it being HYDROPHOBIC and INSOLUBLE

A

Because of their hydrophobic tail, phospholipids will form bilayers in water, with the tails not exposed to water

other examples in nature:
- Steroid hormones​
- Plasma membrane and nuclear membrane​
- Certain part of proteins​

*Because steroids are hydrophobic, they can pass straight through the nuclear membrane and interact with DNA-​

44
Q

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

A
  • Water is used to transport molecules through the body of vascular plants.
  • Dissolved mineral ions are transported in the xylem from roots to leaves
  • Dissolved sugars produced in photosynthesis are transported in the phloem from source to sink
45
Q

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

A

Water is used to transport molecules through the body within the blood of animals. Blood plasma transports:
- Salt ions
- Amino acids
- Proteins
- Glucose
- Waste products of metabolism
- A small amount of dissolved gasses

46
Q

Define physical property

A

A physical property is a measurable behavior or characteristic of matter that exists without the matter reacting or interacting with other things

47
Q

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

A
  • Buoyancy
  • Viscosity
  • Thermal conductivity
  • Specific heat capacity
48
Q

Outline the cause and effect of buoyancy

A

Cause:
an upward force applied to an object that is immersed in a fluid.

Effect:
If the buoyant force of the fluid is greater than the object’s weight, the object will float.

49
Q

Outline the cause and effect of viscosity

A

Cause:
Viscosity is due to the amount of friction the molecules of a liquid experience as they flow over each other.

Effect:
A thick fluid is more viscous and a thin fluid is less viscous.

50
Q

Compare viscosity of air to water to blood

A

Air, < Water, < Blood

  • Molecules in air have little friction as they flow over each other, so air is not viscous.
  • Molecules in water can form hydrogen bonds with each other, increasing the friction and viscosity.
  • Cells and dissolved solutes in blood cause even more friction as the blood flows, increasing viscosity.
51
Q

Define thermal conductivity

A

Thermal conductivity is a measure of a material’s ability to move heat across a temperature gradient.

*OR (ppt): Thermal conductivity is the ability of a substance to transfer heat when there is a temperature difference.

52
Q

Compare less conductive to more conductive materials

A

Less Conductive:
- Heat slowly moves through the material.
- Better at insulation and preventing heat loss.

More Conductive:
- Heat rapidly moves through the material.
- Better for absorbing and transferring heat.

53
Q

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

A

Organisms that are warm blooded will lose heat quicker in water compared to the air. Therefore, they will need mechanisms to overcome this such as blubber.​

*Water has a high thermal conductivity compared with other liquids (except liquid metals). Air has a much lower thermal conductivity than water.​

54
Q

Define specific heat capacity

A

Specific heat capacity is the quantity of heat needed to raise the temperature of a chemical per unit mass

55
Q

Describe why water has a high specific heat capacity

A

Water’s high heat capacity is caused by its numerous hydrogen bonds.

Each individual “bond” is weak, but there are so many of them that collectively a lot of energy must be added to break them all.

56
Q

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

A

As a result of its high specific heat capacity, water heats up or cools down very slowly. (water doesn’t experience rapid changes in temperature)

This provides for a stable internal environment and habitat of living things

57
Q

Outline a benefit to life of water’s high specific heat capacity

A

Because living body’s contain a lot of water, body temperature is slow to fluctuate when environmental temperatures change.

Water’s high specific heat capacity helps body temperature rise and fall slowly when external temperatures becomes very hot or cold

58
Q

High latent heat of evaporation:

  1. How does evaporation of water help to cool us down?​
  2. Why does this make water the perfect molecule to cool us down?​
A
  1. Sweat evaporates from the surface of our skin and helps to cool us down.

*Hydrogen bonds require energy for the bonds to be broken. For sweat to evaporate these bonds must be broken.

  1. A lot of energy (heat) is required from the surface of our skin to break this bonds. Therefore, it cools the organism very quickly
59
Q

Compare the physical properties of water to those of air

A

Water:
- greater buoyant force
- greater viscosity
- greater thermal conduction
- greater specific heat capacity

Air:
- lower buoyant force
- lower viscosity
- lower thermal conduction
- lower specific heat capacity

60
Q

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

A

It has hydrodynamic shapes for swimming. The loon uses a layer of dry air and downy feathers for insulation.

  • Buoyancy in water allows the bird to stay afloat without expending a lot of energy, however when flying through air the bird must expend energy to stay aloft.
  • Air is not viscous, so the loon can easily move through it when flying. The loon doesn’t lose as much body heat to the air because air has low thermal conductivity.
  • However, because the air has a low specific heat, its temperature changes as rapidly.
61
Q

Describe how the ringed seal (Pusa hispida) interacts with the physical properties of water in their habitat.

A

It has hydrodynamic shapes for swimming. The ringed seal has blubber for insulation.

  • Buoyancy in water allows the seal to stay afloat without expending a lot of energy.
  • However, the water is viscous, so the seal has adaptations for streamlining as it swims through it.
  • Water has a greater thermal conductivity than air, so the seal needs to insulate itself with blubber to maintain body temperatures.
  • However, because the water has a high specific heat, the temperature of the water does not change as rapidly as the air around it, providing habitat stability for the seal.

IB BIOLOGY (8 decks)

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