(1.1) Which groups of people were the main contributors to pre-Renaissance knowledge of oceans and marine biology?
Ancient Pacific Islanders had detailed knowledge of marine life, which their descendants still retain. The Phoenicians were the first accomplished Western navigators. The ancient Greeks had considerable knowledge of nearshore organisms in the Mediterranean region. The Greek philosopher Aristotle is considered by many to be the first marine biologist. During the Dark Ages, people in the Far East and the Pacific continued to explore and learn about the sea.
(1.1) What contributions to marine science did the voyage of the HMS Challenger from 1872-1876 yield?
The expedition set new standards for ocean research. For the first time, scientists began to get a coherent picture of what the ocean was like. They also learned about the enormous variety of marine life, for Challenger brought back thousands of previously unknown species. Thus, the Challenger expedition laid the foundations of modern marine science.
(1.1) What modern technology is used by marine scientists to gather data about oceans?
Sonar, satellites, surface buoys, ROVs, AUVs, aircraft, and gliders.
(1.2) What are the general steps of the scientific method?
Making observations, forming hypotheses, testing hypotheses through controlled experiments multiple times, drawing conclusions
(1.2) How does a hypothesis develop into a scientific theory?
A hypothesis develops into a scientific theory when alternatives have been ruled out and it has passed every possible test.
(1.2) What are some limitations of the scientific method and science?
Scientists are never completely free of bias.
(1) All of the following are examples of remote sensing except...
(1) Factors that may affect variables are called...
Which is true about a valid scientific hypothesis?
a. It is the same as a scientific theory.
b. It is a testable statement.
c. It can be scientifically proved to be true.
d. It is never rejected.
b. (It is a testable statement. )
(1) What role do marine laboratories play in the field of marine science?
Today labs dot coastlines around the world and are used by an international community of scientists. Some are equipped with the most up-to-date facilities available.
(1) Compare and contrast induction and deduction.
In induction, one uses observations to arrive at general principles. Reasoning from general principles to specific conclusions is deduction.
(1) Most of the major advances in marine biology have come in the last 200 years. What do you think are the reasons for this?
Reasons include increased mobility due to advances in the means of transportation (faster ships, planes), methodology (sampling equipment, microscopes, scuba, satellites, etc.), developments and discoveries in biology and other fields of science that have stimulated further research in the marine environment (theories of evolution, plate tectonics, etc.), and improved educational opportunities and facilities.
(1) Recall that the statement "There are mermaids in the ocean" is not a valid scientific hypothesis. Can the same be said of the statement "There are no mermaids in the ocean?" Why?
Yes, it is a valid scientific hypothesis because it can be falsified if a mermaid is found. No scientific hypothesis can be proven so this does not mean it is not a scientific hypothesis. So far all attempts to falsify this hypothesis have failed: no one has found a mermaid. Thus, the hypothesis is accepted as true, though not proven.
(1) Imagine you are a marine scientist and you notice that a certain type of crab tends to be larger in a local bay than in the waters outside the bay. What hypotheses might account for this difference? How would you go about testing these hypotheses?
One possible hypothesis: "Crabs outside the bay are smaller because wave action outside the bay is stronger than inside the bay." We can reject it if some of these smaller crabs are moved inside the bay, placed in a cage that allows food to move in, and all are checked and their size compared after a reasonable period of time.
(2.1) What are the characteristics of each layer of Earth?
The core consists mostly of iron. The inner core is solid and the outer core is liquid. The temperature of the core is estimated to be over 4000°C. Most of the mantle is solid, but very hot. The crust is extremely thin, like a rigid skin floating on top of the mantle.
(2.1) What are the similarities and differences between oceanic crust and continental crust?
Both are part of Earth's crust and both are less dense than the underlying mantle. Oceanic crust, which makes up the sea floor, consists of basalt that has a dark color. Oceanic crust is denser than continental crust. Ocean crust is also much thinner than continental crust.
(2.2) How does seafloor spreading occur?
Huge slabs of oceanic crust are separated at the mid-ocean ridges, creating cracks in the crust called rifts. When a rift occurs it releases some of the pressure on the underlying mantle. The reduced pressure allows hot mantle material to melt and rise up through the rift. The ascending magma pushes up the oceanic crust around the rift to form the mid-ocean ridge. When this molten material reaches the earth's surface, it cools and solidifies to form new oceanic crust. The process repeats itself as the sea floor continues to move away from the mid-ocean ridge.
(2.2) Why are subduction zones important?
As new lithosphere is created, old lithosphere is destroyed at subduction zones. If this did not occur, the earth would have to expand constantly to make room for the new lithosphere.
(2.2) What is the difference between lithogenous sediment and biogenous sediment?
Lithogenous sediment is derived from the physical and chemical breakdown of rocks, mostly on the continents. Fine red clay found on the open ocean floor is an example of lithogenous sediment. Biogenous sediment consists of the skeletons and shells of marine organisms. Biogenous sediment is made mostly of calcium carbonate or silica.
(2.3) What are the characteristics of the continental shelf, the continental slope, and the continental rise?
The continental shelf is the shallowest part of the continental margin and is almost flat. The shelf is composed of continental crust and is part of the continent that presently happens to be under water. The continental slope begins at the shelf break and descends down to the deep-sea floor. The continental slope is the actual edge of a continent and is relatively steep. The continental rise consists of a thick layer of sediment piled up on the sea floor.
(2.3) How do hydrothermal vents form?
At the center of a mid-ocean ridge, the plates are pulling apart. This leaves a gap or depression known as the central rift valley. Seawater seeps down through these cracks until it gets heated to very high temperatures by the hot mantle material. The heated water then forces its way back up through the crust and emerges in hydrothermal vents, or deep-sea hot springs.
(2) Which hypothesis explains what makes Earth's plates move?
a. continental drift
c. slab pull
a. (continental drift )
(2) Which statement about Earth is true?
a. Earth is presently in an ice age.
b. Earth is presently in an interglacial period.
c. Sea levels on Earth are falling.
d. Climate has remained the same through much of Earth's history.
b. (Earth is presently in an interglacial period. )
(2) Which is the deepest and largest ocean?
(2) Why are continents higher than oceanic crust?
The continents can be thought of as thick blocks of relatively warm, light crust floating on the mantle, much as icebergs float in water. Oceanic crust floats on the mantle, too, but because it is denser it does not float as high. That is why the continents lie high and dry above sea level and oceanic crust lies below sea level, covered with water.
(2) Compare and contrast a collision of an oceanic plate and an oceanic plate and a collision of an oceanic plate and a continental plate?
When two oceanic plates collide, one of the plates dips beneath the other to form the trench. The trench is associated with earthquakes and volcanoes. When an oceanic plate collides with a continent, it is always the oceanic plate that descends into the mantle. This is because the continental block is less dense than the oceanic plate and floats on top. A trench also forms. When oceanic and continental plates collide, continental volcanoes develop behind the trench.
(2) What are the differences between active and passive margins?
Active continental margins have narrow shelves, steep slopes, and little or no continental rise. Passive margins have wide shelves, relatively gentle slopes, and a well-developed rise.
(2) Why are most oceanic trenches found in the Pacific Ocean?
Due to the collision of a continental plate and an oceanic plate or two oceanic plates in the Pacific Ocean, one plate is forced below the other. At these collision sites, trenches form.
(2) Scientists who study forms of marine life that lived more than 200 million years ago usually obtain fossils not from the sea floor, but from areas that were once undersea and have been uplifted onto the continents. Why?
Due to changing sea level over geologic history, along with uplifting caused by plate tectonics, these fossils are now located above sea level.
(2) What are some of the major pieces of evidence for the theory of plate tectonics? How does the theory explain these observations?
Scientist Alfred Wegner was the first to propose that the continents we know today were once joined into a single supercontinent he called Pangaea. He noted that the edges of the continents fit together much like puzzle pieces. Since he could not explain how these continents traveled away from one another to their current positions, his work was not supported at that time. Since that time, however, evidence to support his theory has continued to accumulate. One of the major pieces of evidence for his theory is the discovery of mid-ocean ridge system in the ocean basins. These ridges are a continuous chain of submarine volcanoes and geologic activity is concentrated around these areas. At these ridges, oceanic crust is separating as molten rock flows from the Earth's interior. New rock is formed in this way and older rock is pushed further from the ridges. Sediments are deeper on ocean floor located away from the ridge, demonstrating that this area has had more time to accumulate these sediments. Rocks are also known to be older moving away from the ridges. Perhaps the strongest piece of evidence to support the activities at the mid-ocean ridges is the discovery of bands, or stripes, on sea-floor rocks known as magnetic anomalies. These anomalies occur because as molten rock cools, magnetic particles in the rocks point towards a magnetic point on the Earth. At different times during geologic history, this magnetic point is magnetic north as it is today. At other times, the field has reversed to create a magnetic south instead. These magnetic anomalies show the direction of this magnetic field at the time they were formed. Therefore, these bands show that the seafloor was not formed all at once, but in stages over geologic time. As new sea floor is created, seafloor in other areas is destroyed as some plates are forced together by this movement. In these areas, trenches are formed. Evidence includes: the fitting together of the coasts of the continents on the opposite sides of the Atlantic Ocean, the similarity of geologic formations and fossils found on the opposite sides, a geologically active mid-ocean ridge running along the central Atlantic between the opposite coasts, bottom sediments that get thicker the farther one travels from the ridge, and rocks on the sea floor on one side of the ridge show magnetic bands that are mirror images of rocks found on the opposite side of the ridge. All of these observations are explained by sea-floor spreading from the mid-ocean ridge.
(2) Which processes affected the formation and concentration of minerals on Earth?
Geological processes, biological processes, and atmospheric processes.
(2) Which evidence supports the statement that, on Earth, "Most minerals owe their existence to life."?
Photosynthetic organisms released oxygen into the atmosphere. This caused iron in Earth's basalt crust to oxide and led to the formation of more than half of Earth's minerals.
(3) The difference between temperature and heat.
Temperature reflects the average kinetic energy (energy of motion) of the particles. The higher the average kinetic energy, the faster the particles move, the higher the temperature. Heat, on the other hand, is the total kinetic energy of all the particles in a substance or object. It is measured in calories, with one calorie equaling the amount of heat necessary to raise the temperature of 1 gram of water from 1 °C.
(3) Three ways in which hydrogen bonds give water its unique chemical properties.
Water freezes when the molecules move so slowly that the hydrogen bonds take over, locking the molecules into a fixed, three-dimensional pattern known as a crystal. In ice crystals the molecules are farther apart than in liquid water, so water expands as it freezes. Because the same mass of water occupies more volume as ice than as liquid water, ice is less dense and floats. The amount of heat needed to raise a substance's temperature by a given amount, or its heat capacity, reflects how much heat the substance can store. Water has one of the highest heat capacities of any naturally occurring substance due to hydrogen bonds. Hydrogen bonds are constantly forming and breaking between water molecules in the liquid state. These bonds cause water molecules to stick together. Because water contains a large number of hydrogen bonds at any given moment, water has more cohesion than other liquids. Cohesion is the sticking together of particles of the same substance. The cohesive property of water lends to a high degree of surface tension, which is the measure of the elastic tendency of liquids.
(3) Which is denser, ocean water at the Equator or ocean water at the North Pole? Explain your reasoning.
Ocean water is denser at the North Pole because as the temperature of liquid water decreases, density increases.
(3) How far down into the ocean can light penetrate in clear water?
About 1,000 m
(3) What are the two most common ions found in seawater?
Chloride (Cl-) and sodium (Na+)
(3) Three ways in which gases can enter the ocean.
Gas exchange between the ocean and the atmosphere, oxygen is released through photosynthesis, carbon dioxide is released through cellular respiration
(3) Why is the high heat capacity of water important to marine organisms?
Water's high heat capacity means that most marine organisms are not subjected to the rapid and sometimes drastic temperature changes that occur on land.
(3) What is salinity? How is it measured and expressed?
Salinity is defined as the total amount of salt dissolved in seawater. Salinity is typically measured using electronic instruments. Because of their electrical charges, ions are good electrical conductors. The conductivity of seawater therefore reflects the salinity. Oceanographers express salinity determined from conductivity measurements in practical salinity units (psu) rather than parts per thousand, but the two units are numerically the same: 35 psu is equivalent to 35%.
(3) In unusually cold winters the northern Black Sea sometimes freezes, while the nearby Adriatic Sea usually does not, even though it is just as cold. Freshwater runoff gives the surface of the Black Sea a low salinity of about 18‰. What would you guess about the salinity of the Adriatic?
The Adriatic Sea has a higher salinity 35 ppt and therefor a lower freezing point.
(3) Will ocean acidification affect organisms with silica skeletons?
Directly, no, but indirectly yes through the removal/ reduction in competition from calcareous organisms which will be directly affected by ocean acidification.
How does a Tsunami form?
They form when a earth quake happens and one plate slides under the other in subduction.
Theory of Plate Tectonics
Formation of the sea floor and its features through sea floor spreading and the colliding of plates.
Formed by sedimentation are composed of the biologically rich continental shelves that then gradually drop and slope into the sea floor, comprising the boundary between continental and oceanic plates.
As the solar winds came by they strip mars atmosphere. As a result liquid water is not possible on the surface of water.
Chain of islands in Alaska where volcanoes are formed due to subduction.