a1.1- water

Question 1

why is water a medium for life

Answer 1

• first cells originated in water
• where most life processes occur

Question 2

physical properties [9]

Answer 2

1. high specific heat capacity
   - takes a lot of energy to break H+ bonds
   high latent heat of vaporisation
   - the energy it would take away during evaporation- getting to the boiling point
   good coolant
   - evaporating water removes a lot of heat energy from the organism
   good solvent
   - medium for metabolic reactions
   transport medium
   - dissolves nutrients, gases and waste products
   dense
   - can support the mass of large and small organisms
   - ice is less dense: life on top and below
   buoyancy
   - float
   viscosity
   thermal conductivity
   So Lions+Vultures Can Sit Till Dawn Breaks Vith ThemCaww

Question 3

black-throated loon example [3]

Answer 3

1. oiled feathers: water has greater thermal conductivity than air
2. large wings: generate lift in less buoyant air
3. hydrodynamic- reduce drag against viscosity

Question 4

ringed seal

Answer 4

1. low density blubber: increases buoyancy
2. insulating blubber: reduce heat loss
   - higher specific heat capacity
   - temperature is more stable
3. streamlined shape: against viscosity

Question 5

why is water polar

Answer 5

• due to unequal sharing of electrons
• imbalance of charges
• hydrogen bonding due to polarity
  *bonds diagram

Question 6

cohesion of water molecules + application

Answer 6

due to hydrogen bonds
1. transport of water under tension in xylem
2. use of water surfaces as habitats- surface tension

Question 7

adhesion of water to material that are polar + application

Answer 7

1. capillary action in soil
2. plant cell walls

Question 8

solvent properties of water

Answer 8

• hydrophilic molecules dissolve in water
• most enzymes catalyse reactions in aqueous solution
• some functions of cells depend on them being hydrophobic and insoluble

Question 9

origin of water

Answer 9

• from extra-planetary objects
• ice asteroids maybe from asteroid belt
• other asteroid knocks out asteroid belt- to us
• large asteroids at least few hundred kilometers so it would still be ok after ozone

Question 10

reasons for water retention [2]

Answer 10

1. earths gravity prevents water form escaping the planet
2. temperature is cool enough to condense water

Question 11

relationship between the search for extraterrestrial life and the presence of water

Answer 11

• universal solvent
• important for transport medium within a cell

Question 12

adhesion

Answer 12

• ability of dissimilar molecules to stick together
• form intermolecular associations with polar and charged molecules

Question 13

cohesion

Answer 13

• ability of like molecules to stick together
• forms h bonds

Question 14

hydrophilic

Answer 14

• water loving
• polar
• charged

Question 15

examples of hydrophilic substances [2]

Answer 15

1. glucose
2. minerals

Question 16

hydrophobic

Answer 16

• repels water
• non-polar
• non-charged

Question 17

examples of hydrophobic substances [2]

Answer 17

1. fat
2. oil

Question 18

goldilocks zone

Answer 18

• habitable zone
• range of distance form a star with the right temperatures for water to remain liquid

Question 19

signs of water in space

Answer 19

spectroscopy
- analyses the wavelengths of light emitted or absorbed by a substance
- used to detect the presence of water molecules in space

Question 20

other factors that contribute to look for extraterrestrial life

Answer 20

1. carbon
2. nitrogen
3. suitable temperature

Question 21

phospholipid bilayer

Answer 21

hydrophilic head
- glycerol and a phosphate molecule
hydrophobic tail x2
- fatty acid (hydrocarbon) chains

Question 22

properties of the phospholipid bilayer

Answer 22

• held together by weak hydrophobic interactions between the tails
• individual phospholipids can move within the bilayer: allows fluidity and flexibility
• spontaneous breaking and reforming of membranes (endocytosis / exocytosis)

Question 23

fluid-mosiac model

Answer 23

fluid– the phospholipid bilayer is viscous and individual phospholipids can move position
mosaic– phospholipid bilayer is embedded with proteins, resulting in a mosaic of components

Question 24

osmolarity

Answer 24

measurement of solute concentration of a solution

Question 25

what property allows for the presence of ions, sugars, amino acids and proteins in sweat

Answer 25

solvent properties