Block 1

Question 1

What does the environmental oxygen depend on? (2)

Answer 1

1. O2 supply

2. O2 consumption

Question 2

How is oxygen (3)

Answer 2

Photosynthesis
Diffusion
Convection

Question 3

What does oxygen consumption depend on? (3)

Answer 3

Number of respiring organisms
Temperature (how this Impacts metabolic rate)
Concentration of organic matter

Question 4

How are the oxygen levels of aquatic habitats varied from terrestrial? Why?

Answer 4

Aquatic oxygen is much more varied than terrestrial.

Terrestrial habitats have air flow which regulated oxygen. Aquatic differences in water temp make anoxic conditions.

Question 5

What changes the density in aquatic environments?

Answer 5

Temperature. Lower temperatures mean higher density except below 4°C where the density decreases again

Question 6

Normoxia

Answer 6

Normal levels of oxygen (up to 21KpaPO2)

Question 7

Anoxia

Answer 7

No oxygen

Question 8

Hypoxia

Answer 8

Partial lack of oxygen

Question 9

Hyperopia

Answer 9

Excess levels of oxygen (greater than 21Kpa)

Question 10

How is thermal stratification caused?

Answer 10

Thermal stratification is due to a difference in the temperature of the water which causes different densities. This means that water separates, Coldwater stays at the bottom and is heavier.

Question 11

Thermocline

Answer 11

Rapid temperature change in water. The two bodies of water cannot come together

Question 12

Pycnocline

Answer 12

A layer in an ocean or the body of water in which water density increases rapidly with depth

Question 13

What can thermal stratification cause?

Answer 13

It can lead to anoxic bottom layers in marine habitats

Question 14

In what seasons are you most likely to find anoxic bottom layers in marine habitats and why?

Answer 14

Summer and winter because the top water temperature is different from the one below

Summer is above 4°C and winter is below

Question 15

Why are you less likely to find oxygen minimum zones in deeper oceans?

Answer 15

Because currents in the deepest oceans can transport oxygen

Question 16

Explain how oxygen deficient or anoxic areas are formed in water? (5)

Answer 16

1. phytoplankton are at the top of the water and produce oxygen via photosynthesis
2. Phytoplankton are eaten by zooplankton et cetera
3. Oxygen also diffuses across from the air
4. As organisms and larger predators die they sink to the bottom and are eaten by Decomposes this will cause oxygen to be used up.
5. oxygen is not replenished and this leads to anoxic conditions

Question 17

What can upWelling lead to?

Answer 17

Dead zones

Question 18

State the difference in the north Atlantic Ocean and the south Atlantic Ocean

Answer 18

North Atlantic Ocean: Stable oxygen percentages with no stratification or oxygen minimum zones

South Atlantic Ocean: distinct oxygen minimum later