Name: ______________________________________ Per. _______ Date: _______________________

AICE Marine – Unit 3 Test Question ANSWERS

1. Fig. 2.2 shows the energy flow in a marine ecosystem.The numbers are arbitrary units (a.u.)

light energy from Sun 8 million a.u.

light energy received by producers 2 million a.u.

energy lost by energy in bodies of energy lost by deathrespiration producers and decay60 850 a.u. 92 000 a.u. 21 980 a.u.

energy in bodies ofprimary consumers

Fig. 2.2

Use the information in Fig. 2.2 to answer the questions below.(a) State the number of arbitrary units of energy which are the result of primary productivity.92 000 (a.u) [1]

(b) Calculate the number of arbitrary units of energy transferred to the primary consumers. 9170 (a.u.) [1]

(c) Suggest the number of arbitrary units of energy which would pass to the secondaryconsumers.figure within range of 900 to 950 (a.u.)A allow e.c.f. as long as approx.

10% of answer to (ii) [1]

(d) State the form in which energy is lost to the environment by respiration.heat / kinetic / thermal [1]

2. Describe the similarities and differences between chemosynthesis and photosynthesis.(a) similarities

similarities1. both make organic material / glucose ;2. from inorganic substances / named, e.g. CO2 ;3. make energy / food / named organic A carried out by producersmaterial + available to / is basis of food chain ; [3]

Name: ______________________________________ Per. _______ Date: _______________________

(b) differences differences

1. chemical energy v light (energy); A solar2. ref. to use of H2S for chemosynthesis; A sulfides or sulfites3. chemosynthesis only in bacteria; A photosynthesis in plants, bacteria, and algae4. AVP (alternate valid point); e.g. photosynthesis requires chlorophyll [4]

3. Fig. 1.1 represents a food chain in the marine environment. The figures show the productivity,measured in kJ m-2 year-1, of each trophic level.

Fig. 1.1

(a) Explain what is meant by the term producer.use light (energy) / sun(light) / photosynthesis / chemical energy / chemosynthesis / reference to autotrophicnutrition;

to synthesise organic substances / named example / food / provide food for next trophic level / eq ; [2](b)

(i) Calculate the difference between the productivity of the herbivores and the productivityof the producers.

4513.4 kJ m–2 year –1 answer to include full units for mark [1]

(ii) Express your answer to (b)(i) as a percentage of the productivity of the producers.Show your working.

appropriate calculation ; = 89.8(%) correct answer, with no working shown, gains both marks allow ecf from an incorrect answer to (b)(i) [2]

(c) Suggest three reasons to account for the difference between the productivity of the herbivoresand the productivity of the producers.

1. reference to energy loss by respiration / heat ;2. not all producers eaten ;3. some parts not eaten ;4. reference to losses in undigested material / faeces / egestion ;5. reference to losses in urine / excretion ; [3]

Name: ______________________________________ Per. _______ Date: _______________________

(d) Suggest why the productivity of producers in an estuary is usually higher than it is in the openocean.idea of nutrients in estuary ; accept a named example of a nutrientdue to run-off / brought in by rivers ; [2]

4. Outline the process of photosynthesis.light energy ;to chemical (energy) ;in organic material / named ;carbon dioxide and water ; allow in equation (words or symbols)oxygen released ; [4]

5. (a) Explain what is meant by the term productivity, in marine ecosystems. any 3 of:(total) amount of biomass / carbon / organic material;produced by plants/algae/phytoplankton / producers;reference to photosynthesis / chemosynthesis;reference to / rate / timescale e.g. per day/month/year;reference to unit area; [3]

(b) List three factors which affect productivity.

any 3 of:temperature;nutrient / named e.g.;light level;concentration of carbon dioxide;pH; [3]

Fig. 5.1 shows variations in productivity with depth in the Northeast Pacific Ocean inwinter, spring and summer.

Fig. 5.1

Name: ______________________________________ Per. _______ Date: _______________________

(c) State the depth at which the difference in productivity between winter and spring isgreatest.12 metres; A 12 – 13 [1]

(d) Suggest explanations for the differences between the productivity in the NortheastPacific Ocean in the winter and the spring.productivity higher in spring / lower in winter; max. 2 for factors alonemore light / ora;more photosynthesis / ora;increased temperature / warmer / ora;increased growth rate / reproduction / ora;increased nutrient / named e.g. (availability) / ora;faster growth / reproduction; [4]

6. Fig. 2.1 shows the energy input to a marine ecosystem from the Sun, the energy within eachtrophic level and the energy lost from each trophic level.The figures are in arbitrary units.

Fig. 2.1

(a) Complete the box in Fig. 2.1 to show the total energy lost as heat. 12705; [1]

Name: ______________________________________ Per. _______ Date: _______________________

(b) Calculate the percentage of the energy from the Sun which is used by the producers.Show your working.(if answer incorrect credit 1 mark for working 15 000/1 500 000 x 100) 1 (%)

[2]

(c) This ecosystem is in the open sea.Suggest why most of the energy from the Sun is not used by the producers.any 2 of:reflected from plant / water surface;wrong wavelength;water absorbs some light / only reaches surface;not absorbed by chlorophyll / owtte;transmitted through algae / producer; [2]

(d) On the grid below draw a pyramid of energy for the food web shown in Fig. 2.1.

Name: ______________________________________ Per. _______ Date: _______________________

appropriate shape;labels;scale + suitable approximate proportions; if no scale max 2

(e) In the ecosystem in Fig. 2.1, the initial energy input is from the Sun.Explain how energy is supplied to organisms at hydrothermal vents.

any 4 of:reference to chemical energy;from dissolved minerals;example;chemosynthesis;reference to (chemosynthetic) bacteria;as producers / make food / organic material (for other organisms);reference to one named organism e.g. Tevnia / Riftia / tubeworms;reference to symbiotic relationship;

[4]

7. (a) Explain what is meant by the term productivity.

rate of accumulation of biomass/energy;per unit area/per unit volume;

[2]

Fig. 2.1 shows the energy flow in part of an aquatic ecosystem.The figures are MJ per year.

(b) Calculate the percentage of incident sunlight that becomes available as netproduction in phytoplankton.

2.2 (%); [1]

(c) Not all of the energy in the incident sunlight becomes available as net production inphytoplankton. Give an explanation for this.not all light is absorbed by phytoplankton/light passes through;ref to incorrect wavelengths/colours;some reflected;ref to losses in plant respiration;

Name: ______________________________________ Per. _______ Date: _______________________

credit NPP = GPP – R;ref to the inefficiency of photosynthesis;

[3]

(d) Using the information in Fig. 2.1, explain why food chains rarely have more than five trophic levels.ref to energy losses (between trophic levels);only 9% transferred from phytoplankton to zooplankton/between trophic levels/creditreason for loss (e.g. parts uneaten/undigested/excretion/egestion)/insufficient energyavailable to transfer (to support more than 5 trophic levels);Note: “loss of heat energy” gains both mark points

[2]

8. Fig. 2.1 shows a food web on a continental shelf.

Fig. 2.1

(a) State the number of trophic levels in this food web.four; [1]

(b) Productivity can be measured as the mass of carbon incorporated into biological molecules per unit area per unit time.

The primary productivity of the phytoplankton in this food web is 90 g of carbon per m2 per year.

The efficiency of transfer between phytoplankton and herbivores is approximately 10%.

Name: ______________________________________ Per. _______ Date: _______________________

Assuming that zooplankton and bottom-feeding herbivores eat equal quantities of phytoplankton, calculate the amount of carbon incorporated into zooplankton per m2 per year. Show your working.

correct use of value of 90 and efficiency of 10 % in calculation; (divided by 2 and ) answer 4.5; [2]

(c) Suggest why the efficiency of transfer between phytoplankton and herbivores is only 10%.allow in terms of either carbon or energy1 losses in respiration (of phytoplankton)/as heat; (assume in phytoplankton unlessotherwise stated)2 not all phytoplankton eaten;3 not all material in phytoplankton, digested/absorbed or some ingested phytoplankton lostin faeces (of herbivores); [2]

9. Fig. 1.1 shows a marine food chain.

Fig. 1.1

(a) What is the source of the energy input to the food chain?sun; [1]

(b) Suggest the type of organisms labelled Y.zooplankton/krill; [1]

(c) Calculate the percentage of the energy input that is converted into the biomass of thephytoplankton.Show your working.

18%; (1 mark for correct working) [2]

(d) Calculate how many units of energy reach the sharks.

0.072; (1 mark for correct working) [2]

(e) State two ways by which energy is lost from the food chain.

1. heat/respiration;

Name: ______________________________________ Per. _______ Date: _______________________

2. faeces/undigested food/uneaten/inedible components; [2]

(f) Describe the role of photosynthesis in the food chain.Any 2 of:captures light energy;for use by plants;ref. to converting light energy to chemical/potential energy that is then available to the rest of the food chain; [2]

Fig. 1.2 shows the changes in the biomass of phytoplankton throughout the year in atemperate ocean.

Fig. 1.2

(g) Describe and explain the shape of the graph between points X and Y on the curve.

(from X to Y) rapid increase/from 12 to 34/ in biomass;increased photosynthesis; [2]

+ 2 of:

increasing level of light;temperature increasing;increase in nutrients; [2]

Name: ______________________________________ Per. _______ Date: _______________________