Likely Questions

Question 1

What was the Paleocene/Eocene Thermal Maximum? Why was it important? What is the significance for calcifying organisms?

Answer 1

A period around 55 million years ago when rates of CO2 change were comparable to now, and temperatures got to around 8 degrees warmer.

It’s important because its the best analogy for current climate change.

There was a total absence of calcareous deposits during this time, indicating the loss of calcifying organisms.

Question 2

What were some of the major bleaching events in the last 30 years and what were the approximate distributions?

Answer 2

1998 : Global - ENSO
2001 : Global - ENSO 
2006 : Caribbean and Pacific 
2010 : Mostly Pacific 
2016: Mostly Pacific

Question 3

What is the current status of temperatures and its relationship to coral bleaching?

Answer 3

Temperatures have exceeded bleaching thresholds in 3 of the last 3 years, all over the planet, with mass mortality.

Question 4

What were the earliest reefs made of and when?

Answer 4

Stromatolites, which are structures that are a mix of microorganisms, biofilms, and cyanobacteria. Earliest known from the precambrian but may have been important during the cambrian.

Question 5

When did the first coral reef system appear?

Answer 5

240 million years ago

Question 6

Approximately how old are modern reefs?

Answer 6

10,000 years

Question 7

What are nephridia?

Answer 7

An invertebrate version of a kidney, removes metabolic waste, surplus ions, hormones and toxins. Its a ciliated funnel into the body cavity

Question 8

How does solubility of calcium carbonate organisms change with water temperature?

Answer 8

Solubility goes up when temperature goes down

Question 9

What kind of skeletons would you expect to see given climate change? Why?

Answer 9

Calcitic, bicarbonate ions go up, carbonates go down, aragonite saturation goes down.

Question 10

What are the key features of Cnidarian movement?

Answer 10

Siphonoglyph - a ciliated groove at one or both ends of the mouth of sea anemones and some corals. The siphonoglyph extends into a pharynx and is used to create currents of water into the pharynx. These water currents are important for respiration and maintenance of internal pressure.

Cilia - help create water currents

Muscles - use jet propulsion by expanding and contracting muscles and pushing water out.

Question 11

What is Halimeda and why is it important?

Answer 11

A calcareous algae, major contributor to calcification.

Question 12

What are some other reef builders?

Answer 12

Microbilites thought to be important - they deposit calcium carbonate in spaces deeper in the structure in areas that are generally anoxic.

Question 13

What is the calcification significance of the Bahamas Banks?

Answer 13

Seagrasses cause spontaneous precipitation of calcium carbonate by dropping carbon dioxide down.

Question 14

What are some limitations associated with not having a circulatory system?

Answer 14

You can’t get very big because transporting nutrients and oxygen becomes more difficult, likely would make metabolic activity less efficient

Question 15

When were sponges important reef builders?

Answer 15

In the Paleozoic

Question 16

How do zooxanthellae help corals calcify?

Answer 16

By providing energy, and also because they provide the conditions for bicarbonate to disassociate into carbonates so the corals don’t need to pull carbonates straight from the water column.

Question 17

What are organisms besides corals that have zooxanthellae?

Answer 17

Forams, anemones, Tridacna clams, some sponges.

Question 18

What are some of the groups and representatives of bioeroders?

Answer 18

Microborers: algae, fungi or bacteria
Epilithic and Endolithic, mostly depending on light requirements

Macro (surface): grazing molluscs and fishes, excavating parrotfish and urchins
Macro (deep): boring bivalves, sponges, urchins, polychaetes, etc.

Question 19

How does bioerosion happen?

Answer 19

Mechanical methods like rasping, chemicals that dissolve the calcium carbonate.

Question 20

Describe forams.

Answer 20

A protist cell is divided into granular endoplasm and transparent ectoplasm from which a pseudopodial net may emerge through a single opening or through many perforations in the test. Individual pseudopods characteristically have small granules streaming in both directions. The pseudopods are used for locomotion, anchoring, and in capturing food, which consists of small organisms such as diatoms or bacteria.

The foraminiferal life-cycle involves an alternation between haploid and diploid generations, although they are mostly similar in form. The haploid or gamont initially has a single nucleus, and divides to produce numerous gametes, which typically have two flagella. The diploid or schizont is multinucleate, and after meiosis divides to produce new gamonts. Multiple rounds of asexual reproduction between sexual generations are not uncommon in benthic forms.

Question 21

Describe alternation of generations.

Answer 21

A multicellular gametophyte, which is haploid with n chromosomes, alternates with a multicellular sporophyte, which is diploid with 2n chromosomes, made up of n pairs. A mature sporophyte produces spores by meiosis, a process which reduces the number of chromosomes to half, from 2n to n.

Question 22

What is the difference between mitosis and meiosis?

Answer 22

Mitosis: cell division with 2 daughter cells, same number of chromosomes as parent nucleus, normal tissue growth

Meiosis: cell division with four daughter cells, each with half the number of chromosomes of the parent cell. e.g. the production of gametes and plant spores

Question 23

What is Crustose Coralline Algae and why is it important?

Answer 23

Algae that has a calcareous skeleton. Important reef builder, binder, lures babies to settle on it, can grow into algal ridges. Has a broader distribution than corals.

Question 24

Why does having closed systems facilitate the transition to land?

Answer 24

Conservation of water, rapid flow rates accelerate transport of O2 to particular tissues and removal of CO2 (especially in larger organisms)

Question 25

How will a change in ocean chemistry affect the distribution and abundance of algae? Seagrasses? Corals?

Answer 25

Algae: likely to increase proportionally due to increased CO2 with similar distribution

Seagrasses: Same as algae

Corals: likely to reduce in diversity and abundance, migrate to colder waters. I’d predict an increase in disease prevalence due to metabolic stress of increased calcification. Skeletons likely to be weaker and less robust to physical damage.

Question 26

Describe coral respiration/digestion.

Answer 26

There are no respiratory organs, and both cell layers absorb oxygen from and expel carbon dioxide into the surrounding water. When the water in the digestive cavity becomes stale it must be replaced, and nutrients that have not been absorbed will be expelled with it. Some Anthozoa have ciliated grooves on their tentacles, allowing them to pump water out of and into the digestive cavity without opening the mouth. This improves respiration after feeding and allows these animals, which use the cavity as a hydrostatic skeleton, to control the water pressure in the cavity without expelling undigested food.

Question 27

How do major reef inverts cope with changing salinity?

Answer 27

Sponges and corals: water flows out with ammonia and waste products

Worms, molluscs and arthropods: excretory glands or nephridia

Echinoderms: nitrogenous waste diffuses out respiratory surfaces

Verts: kidneys

Question 28

How does water reach leaves on a tree?

Answer 28

Through the negative water potential established by evaporating water from the surface of the leaves.

Question 29

What wavelengths do chlorophylls absorb? Carotenoids?

Answer 29

Chlorophyll a/b: 430nm/453nm (blue) and 662nm/642nm (red) - reflects green

Carotenoids: 460 nm and 550 nm (green) - reflects reds

Question 30

How are elements and nutrients acquired by plants?

Answer 30

They enter the plant through the epidermis of the roots, cross the root cortex, and then pass into the vascular cylinder by way of the selectively permeable cells of the endodermis. From the vascular cylinder, the xylem sap is transported long distances by bulk flow to the veins that branch throughout each leaf.

Question 31

What is the tension-cohesion model?

Answer 31

Movement of xylem sap is driven by a water potential diffference created at the leaf end of the xylem by the evaporation of water from leaf cells. Evaporation lowers the water potential at the air-water interface, thereby generating the negative pressure that pulls water through the xylem.