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AS Biology > Water > Flashcards

Water Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Why is water dipolar in nature?

A

because when hydrogen atoms covalently bond to an oxygen atom, hydrogens outer electrons are more attracted to oxygens atom than hydrogens atom. This is because oxygens atom is larger and therefore has more protons. This makes oxygens atom slightly negative and hydrogens atom slightly positive. Hence, there are positive and negative regions in water molecules.

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2
Q

Why are adjacent water molecules attracted to each other?

A

because of the uneven distribution of charge
(polarity)

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3
Q

What type of bonds form between water molecules?

A

Hydrogen Bonds

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4
Q

One hydrogen bond is weak but multiple hydrogen bonds are….

A

really strong

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5
Q

What happens when salt is added to water?

A

The positive sodium ions (Na+) and the negative chloride ions (Cl-) split apart

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6
Q

Why do The positive sodium ions (Na+) and the negative chloride ions (Cl-) split apart when salt is added to water?

A

Because collectively, the water molecules have a stronger attraction for the ions than they do for each other

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7
Q

What are Hydrophilic Substances?

A

Polar substances which disassociate(dissolve) in
water

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8
Q

What are hydrophobic Substances?

A

Non-polar substances which are repelled by water and group together in their presence(in the presence of water)

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9
Q

What are polar substances?

A

substances that have an uneven distribution of charge

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10
Q

What is transported in solution?

A

Essential substances for the functioning
of cells and the whole organism

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11
Q

What reactions occur in solution?

A

All metabolic reactions

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12
Q

What effects does water cause?

A

osmotic effects.

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13
Q

.

A

.

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14
Q

What is specific heat capacity?

A

The amount of heat required to raise the
temperature of 1Kg of liquid by 1oC.

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15
Q

Why does it take a lot of energy to raise the temperature of water?

A

Because water has a very high specific heat capacity

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16
Q

What is the specific heat capacity of water?

A

4200 J/Kg degrees Celsius

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17
Q

Why can water provide very constant
temperatures in aquatic environments.?

A

Because water has a very high specific heat capacity and so Provides a stable environment for enzymes
within organisms

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18
Q

What is the specific latent heat of vaporisation?

A

Amount of heat energy required to
vaporise a liquid.

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19
Q

Why is the specific latent heat of vaporisation very high in water?

A

due to hydrogen bonding.

20
Q

a lot of energy can be lost during sweating or panting with minimal…

A

water loss

21
Q

When is water at its densest ?

A

at 4 degrees celcius

22
Q

What happens to water’s density below 4 degrees?

A

It decreases

23
Q

What is the structure of ice?

A

Each molecule in ice is hydrogen bonded to 4 neighbours in a 3D crystal.

24
Q

why is ice less dense than water?

A

becauseas liquid water cools, each water molecule forms the maximum 4 hydrogen bonds. Water molecules consequently get more spaced out and form a geometrical regular structure. As there’s now less water molecules in a given space , the mass of ice decreases and so does its volume

25
Q

Why can aquatic organisms live and move in the water below?

A

because surface ice acts as an insulator and the temperature gradient within the water column causes the circulation of nutrients

26
Q

what is cohesion?

A

a force where molecules stick together.

27
Q

As a result of cohesion at the surface of a liquid, what force exists?

A

Surface tension

28
Q

What has has the highest surface tension of any liquid?

A

Water

29
Q

What allows for the ability of small organisms to skate over water?

A

Water’s surface tension

30
Q

When are aqueous solutions formed?

A

When solutes are dissolved in the solvent water

31
Q

Why can water dissolve ions and polar molecules?

A

Because it’s a polar molecule and so it can easily dissolve other ionic and polar molecules by attracting positive solutes in it negative areas and attracting negative solutes in its positive areas

32
Q

How does water dissolve ionic substances ?

A

Water molecules cluster around ions , separating them from the ionic lattice. Each ion gets surrounded and water molecules form an electrostatic attraction with these ions until they’re dissolved

33
Q

Is it true that water can act as a transport medium and a reaction medium?

A

Yes

34
Q

Even though water is a small molecule, why is it not a gas at room temperature?

A

Because the hydrogen bonds between water molecules are stronger than most intermolecular forces and require a lot of energy in order to be broken.so water is a liquid at room temperature

35
Q

Is water a liquid or a gas at room temperature?

A

A liquid , as gas has an unusually high boiling point for a small molecule

36
Q

What is waters boiling point?

A

100 degrees celcius

37
Q

Does water have a high latent heat of vaporisation?

A

Yes

38
Q

What is density?

A

A measure of how much mass a substance has in a given volume

39
Q

Why does ice float on water’s surface?

A

Because it’s less dense than water

40
Q

What is adhesion?

A

The attraction between non alike molecules

41
Q

Where does water display adhesive properties?

A

With polar substances

42
Q

What allows the surface of water to act as a habitat for insects like pond skaters?

A

Surface tension

43
Q

What is an example of an aqueous solution?

A

They cytoplasm in cells is an aqueous solution, where many chemical reactions occur

44
Q

Hydrogen bonds form between water molecules. Describe the formation of a hydrogen bond between 2 molecules of water and explain why water can form these bonds.

A

Hydrogen bonds form between the Oxygen and Hydrogen of adjacent water molecules. This is because the oxygen is slightly negative and the hydrogen is slightly positive. The water molecule is polar

45
Q

Hydrogen bonds allow water to act as a solvent. Why is the ability of water to act as a solvent important for the survival of organisms

A
  • can act as a medium for metabolic reactions
  • allows ionic compounds to separate
    -transport
    -allows organisms to take in food and mineral ions
    -able to dilute toxic substances
    -helps in transport systems, such as the xylem and the circulatory system

AS Biology (15 decks)

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