Lecture 4 Air water and chemicals

Question 1

gas must be in ____ to reach cells

Answer 1

solution

Question 2

moisture availability linked to

Answer 2

temperature

Question 3

e.g. plans and animals very sensitive to moisture loss

Answer 3

amphibia …

Question 4

Relative humidity

Answer 4

1. Air contains moisture as water vapour
2. For a given temp the air can hold only a fixed amount of water vapour
3. Higher temp, higher moisture content
4. Max moisture content for a given temperature = saturation humidity

Question 5

4 Adaptations to reduce water loss

Answer 5

1. Morphological [form and structure]
2. Physiological [way body functions]
3. Biochemical
4. Behavioural

Question 6

Adaptations to reduce water loss
e.g. mosquito (Drosophila subobscura)
3 points

Answer 6

1. Loses water from respiratory surfaces when spiracles open - during activity
2. Largely confined to woodland - high relative humidity (high humidity)
3. Active when temperature lowest [temp low = low maximum humidity. Water leaves mosquito less because temp cant hold any more moisture]

Question 7

Water uptake in plants

3 points

Answer 7

1. Availability of water from soil affected by pore size
2. Solutes in water add osmotic forces
3. Soil dries extraction of water more difficult

Question 8

plants and pH

3 points

Answer 8

1. pH of soil is mediated by soil water
2. pH of soil affects soil fauna (animals of habitat)
3. pH of water affects many organisms

Question 9

gas balance

5 points

Answer 9

1. Affects species in water CO2 not usually limiting
2. Oxygen may be limiting
3. Diffusion and solubility of oxygen in water are low
4. Interaction with temperature and turbulence
5. Oxygen limiting in aquatic and waterlogged env

Question 10

oxygen aquatic animals

Answer 10

must maintain continual flow of water over respiratory surfaces (gills)

OR have large SA relative to volume

Question 11

Gas and water balance in mosquito

2 points

Answer 11

1. Loses water from respiratory surfaces when spiracles open - during activity
2. Needs spiracles open to obtain sufficient oxygen for flight muscles

Question 12

Gas and water balance in plants

3 points

Answer 12

1. Lose water from cell surfaces
2. Need stomata open to obtain CO2 for photosynthesis
3. Strategies for dealing with this - C4 plants have higher water use efficiency

Question 13

Organisms in soil

2 points

Answer 13

1. Require film of soil water for water balance which allows oxygen to diffuse
2. Deep film = anaerobic conditions

Question 14

Substrate/Soil structure

4 points

Answer 14

1. Affects species on land and in water
2. Substrate type and particle size affects aquatic plant and animal distribution
3. Affects sessile and sedentary aquatic organisms.
4. Greatest affect on terrestrial species that inhabit soil:
   Soil animals
   Seed and roots

Question 15

Chemical resources
Autotroph resources (plants need)

4 points

Answer 15

1. Light
2. CO2
3. H2O
4. Mineral resources

Must obtain from atmosphere or soil

Question 16

Essential chemical resources for plants from water and air

3 points

Answer 16

1. Hydrogen
2. Oxygen
3. Carbon

Question 17

Essential chemical resources for plants from soil

9 points

Answer 17

1. Hydrogen
2. Nitrogen
3. Phosphorous
4. Potassium
5. Sulphur
6. Iron
7. Trace elements / micronutrients

Question 18

Chemical resources
Each element has its own characteristic properties

5 points

Answer 18

1. Absorption in soil
2. Diffusion in soil water
3. Affect accessibility
4. Different plant species = different proportions of mineral resources
5. Plants differ in composition

Question 19

Mineral availability may

Answer 19

limit plants to particular soil types e.g. Oak prefer heavy fertile soil

Question 20

Nitrogen

3 points

Answer 20

1. Essential resource for all plants
2. Any adaptation that allows a plant to succeed in soil with low mineral nitrogen availability = advantage
3. Legumes [pea family] can access free nitrogen from air because of mutualistic association with nitrogen fixing bacteria

Question 21

Heterotroph resources - essential chemical resources for animals

2 points

Answer 21

1. Most of chemicals also essential for animals but also need:
   Sodium
   Chlorine
2. Commonly in organic form in food

Question 22

salinity

4 points

Answer 22

1. Plants and animals suffer osmotic stress
2. Freshwater habitats = water moves in
3. Marine habitats many species isotonic but some hypotonic = water loss
4. Salinity of soil-water can affect plants and animals
5. Greatest stress in env where salinity fluctuates - salt marshes and estuaries

Question 23

Current flow

4 points

Answer 23

1. Affects species in air and water
2. Aquatic animals and plants show morphological specialisation
3. Affects sessile and sedentary aquatic organisms
4. Can affect dispersal

Question 24

Substrate attachment

5 points

Answer 24

1. Sessile, sedentary and mobile animals
2. Plants
3. Depends on substrate grain size and stability
4. Flow rate in freshwater habitats
5. Tides and wave action in intertidal habitats

Question 25

attachment mechanisms

4 points

Answer 25

1. Sheltering under rocks or in burrows
2. Flat/streamlined body shape
3. Modified appendages:
   Suction
   Mucus
4. Glue