Download BI 3061 Exam December 2010

EXAMINATION IN BI 3061, Biological Oceanography
Scienctific contact: Egil Sakshaug
Telephone 73917423
Date of examination: 2010-12-01:
Number of hours: 4
Size of subject: 7.5 pts
Number of pages in English: 8
Grades to be announced: 2010-12-22
Permitted aids: None
ONLY ONE ANSWER IS CORRECT FOR EACH QUESTION
ALL QUESTIONS COUNT AS EQUAL
PLEASE SUBMIT ALL ANSWERS ON A SEPARATE SHEET
1. What statement about molecular diffusion is true?
A. It is an efficient way of distributing molecules over long distances
B. The rate of spreading is the same for water, temperature and nutrients
C. Fick’s first law deals with the dispersion rate for oil in water
D. Fick’s first law describes the net transport rate of molecules across a fluid as a function of
the concentration gradient of the molecules across the liquid and the distance across
the fluid
E. Fick’s first law states that the transport across a layer of water is faster the thicker the layer
2. What statement about viscosity is NOT true?
A. Viscosity describes the “stickiness” of a fluid
B. Viscosity is higher in honey than in water
C. A much used unit for absolute viscosity is Poise
D. The kinematic viscosity is absolute viscosity divided by the density of the fluid
E. The viscosity of water is higher at high than at low temperature
3. What statement about the Reynolds number is NOT true?
A. Reynolds numbers have the units Pa h–1
B. Re>1 means that inertial forces are stronger than viscous forces
C. Re is dependent on the swimming rate and the length of the organisms
D. Zooplankton in the 50-500 µm size range can experience Re both above and below 1
E. A swimming person has Re far higher than 1
4. What statement about sinking rates is true?
A. The ultimate sinking rate of spheres is described by Stokes law
B. Large cells of phytoplankton sink slower than small phytoplankton cells
C. Gas vacuoles in Cyanobacteria help the cells sink faster
D. Fat-filled vacuoles in dinoflagellates help the cells sink faster
E. Healthy phytoplankton cells sink faster than non-healthy cells
5. What statement about light is NOT true?
A. Light does not reveal both its wave and particle mode in the same experiment
B. Irradiance is the intensity of the light source
C. Scalar irradiance is the irradiance hitting a small spherical surface
D. PAR means Photosynthetically Active Radiation
E. The shorter the wavelength, the more energy per photon
6. What statement about light is true?
A. The sky is blue because of reflection from the blue sea surface
B. Light is attenuated linearly with increasing depth in a homogeneous water column
C. Pure water has blue colour because red light is strongly back-radiated
D. Pure water has blue colour because of strong absorption of red light
E. Case I seawater is rich in cDOM
7. What statement about photosynthesis is NOT true?
A. Photosynthesis was “invented” by Cyanobacteria ~2.3 Ga ago
B. Photosynthesis has 2 photosystems, and a light and a dark reaction
C. Oxygen is produced only in PS II
D. The photosynthetic response to light is described by a P vs E function
E. The light reaction is primarily regulated by temperature
8. What statement about photoacclimation is NOT true?
A. Photoacclimation affects the P vs E parameters
B. Photoacclimation minimises the growth rate variation in a changing environment
C. Photoacclimation yields high chlorophyll content in cells grown in strong light
D. Photoacclimation yields higher Ek with increasing irradiance
E. Photoacclimation is not instantaneous but requires a certain amount of time
9. What statement about estuaries is true?
A. Fjords are estuaries and all estuaries are fjords
B. A majority of fjords is situated in areas that were not exposed to ice ages
C. Estuarine circulation implies a surface flow in and a subsurface flow out
D. Estuarine circulation in fjords can be reversed in very dry periods
E. The longest of all fjords is found in New Zealand
10. What definition is NOT true?
A. An isopleth is a plot of a measurement variable against depth and time
B. A station curve is a plot of one or more measurement variables against depth at a given
time
C. Density of water is a non-linear function of temperature
D. Rossby waves and planetary waves are the same thing
E. Earth rotates westwards
11. What statement related to growth regulation is true?
A. There are more brackish-water species than freshwater species of phytoplankton
B. A species that tolerates a wide salinity interval is called eurytherm
C. Scandinavian freshwater is typically richer in phosphate than non-polluted Nordic seawater
D. The Redfield N:P ratio for seawater is typically ~5 (mol scale)
E. The original Michaelis-Menten kinetics applies to the uptake rate of glucose as a function
of the glucose concentration in the medium
12. What statement about nutrients is NOT true?
A. With few exceptions, nutrient concentrations are higher in deep water than in surface
water
B. Ammonia does not behave according to statement A
C. The highest nutrient concentrations are found in the North Pacific deep water
D. The highest surface nitrate concentrations in winter are found in the Nordic Seas
E. The species most likely to be found in oligotrophic seawater exhibit high affinity for the
limiting nutrient
13. What statement about DIC in seawater is true?
A. pH is determined mainly by the concentration of carbonic acid and free CO2
B. There is less DIC in deep water than in surface water
C. Photosynthesis lowers pH while respiration makes it higher
D. Free CO2 represents the largest DIC pool on earth
E. Exchange of gases between the surface layer and the atmosphere is highest in calm
weather
14. What statement about alkalinity is NOT true?
A. Alkalinity expresses the charge difference between cations and non-volatile anions
B. The charge difference is neutralised mainly by bicarbonate and carbonate ions
C. Alkalinity increases during decalcification
D. Alkalinity in the sea decreases because of long-term erosion of calcareous rock
E. Alkalinity decreases with increasing salinity
15. What statement about calcification is true?
A. Spontaneous calcification is common in seawater
B. Calcification produces CO2 as a by-product
C. Calcium carbonate is produced from the carbonate pool in seawater
D. Calcite and aragonite are equally soluble in seawater
E. The carbon compensation depth (CCD) is the depth below which calcium carbonate is
precipitated from the seawater
16. What statement about the Coriolis Effect is NOT true?
A. It causes deflection to the right in the northern hemisphere and to the left in the southern
hemisphere
B. It is a secondary force dependent on the earth’s rotation
C. It is stronger the higher the speed of the object
D. It is conveniently studied in kitchen sinks and water fountains
E. It is zero at the equator, increasing toward the poles
17. What statement about Coriolis-related phenomenta is true?
A. Cyclones rotate clockwise in the northern hemisphere and anti-clockwise in the southern
hemisphere
B. The Ekman spiral is generated by wind and modified by the Coriolis Effect
C. Integrated down to the counter-current, the resultant or average Ekman current is deflected
25° relative to the wind direction
D. A bottle thrown into the sea at the coast outside Bergen in northerly wind will, because of
the Coriolis Effect drift into coastal waters
E. The eddy diffusion constant has units different from that of the molecular diffusion
constant
18. What statement about Thermohaline Circulation (THC) is NOT true?
A. THC is a global system of horizontal and vertical currents
B. Surface currents in the North Pacific participate little in THC
C. The surface currents are in the main driven by wind and partly by deep-water production
D. Western boundary currents are wide and slow
E. The Gulf Stream is an example of a Western boundary current
19. What statement about THC is NOT true?
A. The bottom water that flows from the Nordic Seas into the North Atlantic is known as
North Atlantic Deep Water (NADW)
B. Bottom water is produced in the western part of the Equatorial Pacific
C. Tidal waves are important for bottom water to reach the surface again
D. Antarctic Bottom Water (AABW) reaches north of equator
E. In the Southern Ocean, NADW reaches the surface
20. What statement about NAO is true?
A. The NAO index is the normalised surface-pressure difference between the Azores (or
Lisboa) and Iceland
B. Negative NAO is associated with mild winters in western Norway and dry winters in Spain
C. NAO+ winters are associated with poor fish recruitment in the Barents Sea
D. NAO+ winters are associated with good fish recruitment in Greenland and Canada
E. NAO has a strong impact in the Bering Sea
21. What statement about ENSO is NOT true?
A. The Southern Oscillation Index (SO) is the normalised surface-pressure difference between
Tahiti and Darwin (tropical Australia)
B. SO-related variation in trade winds has impact in the whole Pacific Ocean
C. ENSO and SO are identical terms
D. Negative SO increases the probability of an El Niño
E. Also, positive PDO increases the probability of an El Nino
22. What statement about ENSO variations is true?
A. The food chain along the coasts of Ecuador and Peru is short, with anchoveta as the key
species
B. El Niño typically occurs during the southern winter
C. El Niño brings abnormal droughts to Pacific South American deserts
D. El Niño implies abnormally large primary production off the coasts of Ecuador and Peru
E. El Niño typically brings droughts to Australia and Southeast Asia
23. What statement about dissolved organic carbon (DOC) is NOT true?
A. DOC is the largest pool of organic carbon in the ocean
B. DOC constitutes a carbon reservoir equal in magnitude to atmospheric CO2
C. It is possible to measure changes in the DOC pool on biologically relevant time scales
D. DOC constitutes a larger fraction of dissolved carbon in water than DIC
E Most larger sized-organic matter is more reactive than most smaller-sized organic matter
24. What statement about dissolved organic carbon (DOC) is NOT true?
A. Nutrient limitation of heterotrophic bacteria can lead to accumulation of degradable DOC
because of reduced consumption rates
B. DOC has a central role in the microbial loop
C. Refractory DOC is made susceptible to microbial remineralisation by photo-oxidation
D. Phytoplankton are the most important producers of refractory DOC
E. Metazoans (rotifers, copepods etc.) are producers of DOC
25. What statement about dissolved organic carbon (DOC) is true?
A. Bacterial degradation of DOC leads to gel formation
B. Some marine phytoplankton species secrete microscopic gels
C. Organic material passing through a 0.45 µm filter cannot be colloidal
D. TEP stands for “Transparent Extracellular Proteins”
E. Oceanic DOC concentration is in the magnitude of 100 mg carbon per liter
26. What statement about dissolved organic carbon (DOC) is true?
A. Protozoans have a very low excretion rate (that is, < 1% of the primary production turns
into DOC when only protozoans are predators)
B. Terrestrial organic matter in rivers is the most important source for oceanic DOC
C. The concentration of deep ocean DOC is highest in the North Atlantic Ocean and lowest in
the North Pacific Ocean
D. Eukaryotic microorganisms are the most important DOC consumers
E. Heterotrophic bacteria can consume only high-molecular weight DOC
27. What statement contains ALL the main assumptions behind the critical depth
model?
A. The photosynthetic rate increases exponentially with light and nutrients, light is
exponentially attenuated with depth and there are no grazers present
B. The photosynthetic rate is linearly related to light and light is exponentially attenuated with
depth
C. The photosynthetic rate is linearly related to light, light is exponentially
attenuated with increasing depth, grazing pressure is constant throughout the spring
bloom and there is no nutrient limitation
D. The photosynthetic rate is linearly related to light, light is exponentially
attenuated with increasing depth, the respiration rate represents the loss rate of
phytoplankton, and there is no nutrient limitation
E. Photosynthesis starts when irradiance reaches a critical level and the mixing depth is lower
than a critical depth
28. What statement about Atlantic oceanic phytoplankton is true?
A. The SMS National expedition in 1889 proved that the oceanic equatorial regions of the
Atlantic were highly productive, though biomass was kept low by grazing
B. Primary productivity in the North Atlantic and sub-polar seas is relatively low, but the low
temperature keeps grazing activity down, allowing for accumulation of biomass
C. The SMS National expedition in 1889 showed that for the whole growth season, nutrients
are limiting for phytoplankton only in the equatorial regions, where irradiance is high
D. The spring bloom phenomenon is observed in the whole Atlantic Ocean north of equator
(0° N and northwards)
E. Prior to 1889 it was widely believed that the tropical region of the Atlantic Ocean was as
lush and productive in terms of phytoplankton as the rainforests were at the same
latitudes
29. What definition is NOT correct?
A. Oxygen compensation depth: Depth where light bottle oxygen evolution (photosynthesis)
equals dark bottle oxygen consumption (respiration)
B. Photosynthetically Active Radiation (PAR): Light with wavelengths from 400-700 nm.
d ln Ed ( z ,  )
C. The diffuse attenuation coefficient (Kd): K d ( z ,  )  
dz
D. Primary production: Fixation of organic matter from another organic source that is made
available to the next trophic level
E. Euphotic zone: The depth to where net photosynthesis is positive, normally taken to be the
1% light depth
30. What statement about tropical oceanic gyres is NOT true?
A. Primary production is high
B. Grazing pressure is strong
C. The nutrient supply is small
D. The thickness of the euphotic layer is approximately 100-150 m much of the year
E. Phytoplankton biomass is relatively low
31. What process does NOT contribute to efficient vertical transport of nutrients?
A. Shear between currents of different mass
B. Turbulence in deep layers due to above-lying currents passing over underwater
topography (bank effect)
C. Melting of sea ice establishing a brackish surface layer and a pycnocline
D. Upwelling
E. Entrainment caused by estuarine circulation
32. What statement about dissolved organic carbon (DOC) and the microbial food web
is NOT true?
A. Predators can modify the relationship between algae and bacteria through biomass removal
and nutrient regeneration
B. Bacteria and the smallest eukaryote plankton organisms have a higher surface to volume
ratio than larger phytoplankton and are therefore superior competitors for mineral
nutrients in a diffusion-limited system
C. Protozoans have very low nutrient regeneration rate and can therefore induce nutrient
limitation in both algae and bacteria
D. Mineral nutrient limitation of the growth of heterotrophic bacteria can inhibit DOC
consumption
E. Selective bacterial predators can control bacterial biomass and enable simultaneous
nutrient limitation of both phytoplankton and bacteria
33. What statement about trace metals is true?
A. Trace metals are generally so abundant that they never limit phytoplankton growth
B. Phytoplankton have no need for magnesium
C. Iron is not needed in the enzymes that reduce nitrate to nitrite
D. Iron is needed in the enzymes that reduce nitrate to nitrite
E. Fixation of N2 in Cyanobacteria does not need iron
34. What statement about trace metals is NOT true?
A. HNLC waters are poor in nitrate and rich in chlorophyll a
B. Iron limitation is typical for the deep-sea part of the Southern Ocean
C. The concentration of dissolved iron in deep water is not very different from one ocean to
the other
D. Phytoplankton prefer Fe II and have problems taking up Fe III
E. Fe II oxidises rapidly into Fe III
35. What statement about the planktonic food web is NOT correct?
A. Plankton can be grouped based on taxonomy or size of the organisms
B. The biomass development of plankton is a result of growth and loss processes
C. Some plankton organisms have swimming capabilities, but they are still not able to swim
against water currents
D. The size of the pico-cyanobacteria is 2-4 µm
E. The predation of planktonic animals on high trophic levels may affect the biomass of
planktonic animals on lower levels
36. What statement about planktonic activity is correct?
A. Ciliates normally exert full control of the biomass of heterotrophic nano-flagellates (HNF)
B. Plots of prey versus predator biomass can give vulnerable information on the predation
pressure from the predator on the prey
C. Copepods feed mainly on ciliates
D. Nutrient addition to planktonic ecosystems affects phytoplankton biomass more than their
rate of production (primary production)
E. Micro-algae are the main food source for micro-zooplankton
37. What statement on the plankton community in Norwegian coastal waters is NOT
correct?
A. Heterotrophic micro-plankton is made up mainly by ciliates
B. Appendicularia are relatively large zooplankton but are, because of their feeding habits
assigned to the group of heterotrophic nano-plankton that are in the size class 2-20 µm
C. Meroplankton are temporary plankton with highly diverse species composition
D. Detritus is dead organic matter
E. Krill, amphipods and jellyfish are always carnivorous
38. What Coriolis-related statement is NOT true?
A. Sverdrup transport is a horizontal deep transport of water typical for subtropical gyres such
as the Sargasso Sea
B. An ideal geostrophic current is a current in which gravitation exactly balances the Coriolis
Effect
C. In deep water there is no friction
D. The currents surrounding subtropical gyres are deflected to the right in the northern
hemisphere and to the left in the southern hemisphere
E. The Atlantic Current is a mixture of Gulf Stream water, local water and Mediterranean
water
39. What statement about marine climate is true?
A. More than 80% of the solar radiation hitting earth is absorbed by the oceans
B. Snow on top of sea ice absorbs solar radiation strongly
C. The difference between incoming solar radiation and backradiation is known as albedo
D. Sea surface height caused by thermal expansion can differ by more than 40 m globally
E. The climate difference between Greenland and Scandinavia can be explained by the ocean
current pattern in the Indian Ocean
40. What of the following statements is NOT true?
A. An aeroplane stalls because the wing loses lift
B. A shear force is a force that developes between flows of different velocity
C. In small non-motile cells the surrounding microlayer of water can impede nutrient uptake
D. The drag coefficient is independent on the shape of an organism
E. In the real world, a laminar flow inevitably evolves into a turbulent flow