State one process that results in the loss of carbon dioxide from a marine organism such as a crustacean or a jellyfish.

The crustacean and the jellyfish obtain carbon compounds by feeding. State one source of carbon for marine organisms, other than feeding.

Explain how energy enters, flows through and is lost from marine food chains.

Deduce whether jellyfish or crustacea are a richer source of carbon in a food chain.

Suggest with a reason whether having a large body mass is an advantage or disadvantage for jellyfish.

a. (aerobic/cellular) respiration ✔

b. gas exchange / diffusion ✔

Do not accept photosynthesis.

Do not accept breathing

Organism is taken to be a living thing.

a. photosynthesis ✔

b. absorption of (dissolved) carbon dioxide / (hydrogen)carbonate directly from the oceans ✔

Accept reference to carbonate or hydrogencarbonate ions.

a. light energy is converted to chemical energy (in carbon compounds/sugars) by photosynthesis ✔

b. (chemical) energy (in carbon compounds) flows by means of feeding/through food chains/webs ✔

c. only (approximately) 10 % of energy is passed to the next trophic level ✔

d. energy released as heat (by respiration) ✔

e. energy is not recycled ✔

f. after death, energy may remain trapped as undigested detritus/fossils/fossil fuels ✔

crustacean as they have more carbon per unit volume
OR
crustacean as jellyfish has little carbon per total body size ✔

OWTTE.

The conclusion must be supported from the information given.

a. advantage of large size is ability to eat /catch large prey ✔

b. (advantage as) lower rates of predation of large jellyfish ✔

c. (advantage as) can produce more reproductive cells ✔

d. (disadvantage as) can move slower to escape from predators/capture prey ✔

e. (disadvantage as) needs more energy/nutrients to maintain structure/move/grow ✔

f. (disadvantage as) low surface area to volume ratio and thus possibly difficulty with materials/gas/nutrient exchange ✔

g. (disadvantage as) more prone to mechanical damage during storms ✔

Accept other reasonable answer.

Must say advantage or disadvantage.

In 4(a) most were able to state 'respiration' as the answer. 4(b) proved more difficult with fewer stating photosynthesis or absorption of dissolved CO₂ or HCO₃ from the seawater. Vague answers such as 'carbon in the water' were not credited. In 4(c) most knew that energy enters with sunlight, but did not state photosynthesis. They knew that it was transferred by feeding through the trophic levels and lost as heat due to respiration. A surprising number incorrectly stated that the energy was recycled and some drew diagrams of the energy flow showing this. In 4(d)(i) most were able to state that the crustacean was a richer source of carbon. An explanation using the data from the diagram was expected. In 4(d)(ii) most were able to present an argument for advantage or disadvantage.

In 4(a) most were able to state 'respiration' as the answer. 4(b) proved more difficult with fewer stating photosynthesis or absorption of dissolved CO₂ or HCO₃ from the seawater. Vague answers such as 'carbon in the water' were not credited. In 4(c) most knew that energy enters with sunlight, but did not state photosynthesis. They knew that it was transferred by feeding through the trophic levels and lost as heat due to respiration. A surprising number incorrectly stated that the energy was recycled and some drew diagrams of the energy flow showing this. In 4(d)(i) most were able to state that the crustacean was a richer source of carbon. An explanation using the data from the diagram was expected. In 4(d)(ii) most were able to present an argument for advantage or disadvantage.

In 4(a) most were able to state 'respiration' as the answer. 4(b) proved more difficult with fewer stating photosynthesis or absorption of dissolved CO₂ or HCO₃ from the seawater. Vague answers such as 'carbon in the water' were not credited. In 4(c) most knew that energy enters with sunlight, but did not state photosynthesis. They knew that it was transferred by feeding through the trophic levels and lost as heat due to respiration. A surprising number incorrectly stated that the energy was recycled and some drew diagrams of the energy flow showing this. In 4(d)(i) most were able to state that the crustacean was a richer source of carbon. An explanation using the data from the diagram was expected. In 4(d)(ii) most were able to present an argument for advantage or disadvantage.

In 4(a) most were able to state 'respiration' as the answer. 4(b) proved more difficult with fewer stating photosynthesis or absorption of dissolved CO₂ or HCO₃ from the seawater. Vague answers such as 'carbon in the water' were not credited. In 4(c) most knew that energy enters with sunlight, but did not state photosynthesis. They knew that it was transferred by feeding through the trophic levels and lost as heat due to respiration. A surprising number incorrectly stated that the energy was recycled and some drew diagrams of the energy flow showing this. In 4(d)(i) most were able to state that the crustacean was a richer source of carbon. An explanation using the data from the diagram was expected. In 4(d)(ii) most were able to present an argument for advantage or disadvantage.

In 4(a) most were able to state 'respiration' as the answer. 4(b) proved more difficult with fewer stating photosynthesis or absorption of dissolved CO₂ or HCO₃ from the seawater. Vague answers such as 'carbon in the water' were not credited. In 4(c) most knew that energy enters with sunlight, but did not state photosynthesis. They knew that it was transferred by feeding through the trophic levels and lost as heat due to respiration. A surprising number incorrectly stated that the energy was recycled and some drew diagrams of the energy flow showing this. In 4(d)(i) most were able to state that the crustacean was a richer source of carbon. An explanation using the data from the diagram was expected. In 4(d)(ii) most were able to present an argument for advantage or disadvantage.