2.) Why are most oceanic trenches found in the Pacific Ocean?-->An oceanic trench is a linear depression of the sea floor caused by the subduction of one plate under another. These trenches are associated with earthquakes and volcanoes. They are generally parallel to a volcanic island arc. Examples include are the Mariana Islands which are located in the Pacific Ocean. Oceanic trenches typically extend 3 to 4 km below the level of the surrounding oceanic floor. The deepest ocean depth to be sounded is in the Challenger Deep of the Mariana Trench at a depth of 10,911 m (35,798 ft) below sea level.earthquake.usgs.gov/learning/glossary.php?term=oceanic%20trenchen.wikipedia.org/wiki/Mariana_Trench
1.) During the day, algae carry out both photosynthesis and respiration, but at night, whent here is no light, they can only perform respiration. Small, isolated tide pools on rocky shores are often inhabited by thick growths of seaweeds, which are algae. Would you expect the amount of oxygen in the water to differ between night and day? How?
-->Yes, I would expect the amount of oxygen in the water to lessen at night. With no solar energy, autotrophs (plants, algae, and seaweed) don't produce oxygen.
1.) Scientists use the particular structure of nucleic acids and other chemical differences to separate the archaea from the bacteria. Can you think of other characteristics that could be used to distinguish not only between these two domains but also between them and Protists?
-->The two prokaryotic domains, Bacteria and Archaea, have important differences, including the chemistry of their cell walls and plasma membranes, and the cellular machinery that manufactures proteins. They are the simpliest and most primitive form of life that we know. Protists are mostly aquatic primary producers that lack the specialized tissues of plants. They range in size and compllexity from single cells to large multicellular seaweeds.
2.) Only very few flowering plants have invaded the oceans, but those that have are very successful. What are some possible reasons for the small number of marine flowering plants? How do those that have taken the step manage to thrive in some environments?
-->There are only a few species of flowering plants that live in the ocean. An example is the Seagrass flowers, whose closest relatives seem to be members of the lily family, which shows that seagrasses evolved from land plants. But they have very well adapted to life in the marine environment. Instead of attracting insect for pollination, the pollen is carried by the water currents. Tiny seeds result from successful fertilization. These seeds are dispersed by water currents and perhaps in the feces of the fish and other animals that browse on the plants.
1.) Hagfishes and lampreys are the only living representatives of a very ancient group. Why do you suppose there are still some of these jawless fishes around? --> Jawless fishes are know to be the most primitive fishes living today. I suppose they have exsited this long due to their feeding habits. They feed mostly on dead or dying fishes. This resource is simply impossible to run out off.2.) A deep-water shark, new to science, is collected for the first time. The specimen is studied in detail, but its stomach is empty. How could you get a rough idea of its feeding habits? The specimen is a female, and its reproductive tract is found to contain 20 eggs. Can you tell the type of developement characteristic of this species?--> In order to determine the feeding habits of this new specimen, you can study the jaws. Not all of the nearly 350 living species of sharks conform the same body plan, but the majority are known to contain rows of numerous sharp, often triangular teeth. This feature helps since sharks are known to be adapted for predatory feeding. Also to keep in mind, that there are sharks (whale sharks) that are filter feeders. This is could very well help explain an empty stomach. Because this specimen is yet to be unknown, it is hard to study the type of developement characteristic of the 20 eggs found. There are two different types of sharks that may very well affect the developement. One is oviparous and the other is viviparous. In an oviparous shark, the yolk is needed to provide energy for at least several months of development. Without this amount of time, the eggs won't be fully developed. And in a vivparous shark, nutrition is provided by direct contact with the reproductive tract of the female.3.) Individuals of some species of bony fishes change sex, some to maintain more males than females, others more females than males. What are the advantages and disadvantages of each situation? Are there any advantages and disadvantages in having an equal number of males and females?-->One advantage of maintaining more males than females is that there will be more chances of having a dominant male. Since a dominant male is needed to triger these changes (protandry and protogyny). A disadvantage of this situation will be that with less female, there will be less chances of reproduction. Whereas, this would be an advantage of having more females than males. And as for having an equal number of males and females, I think that there will be no advantages or disadvantages, since everything will turn out to be average.
1.) What factors might account for the fact that the vast majority of atolls occur in the Indian and Pacific oceans and that atolls are rare in the Atlantic?-->One main factor that accounts for the fact that the vast majority of atolls occur in the Indo-West Pacific region, is that the trade winds, which is the steadiest winds on earth, blow from latitudes of about 30 degrees toward the equator. Atolls are strongly influenced by these winds. They are also usually found far from land, rising up from depths of thousands of meters or more. The Pacific Ocean is the world's deepest ocean. And it is known to have alot of volcanic activity which atolls gets its start when a deep-sea volcano erupts to build a volcanic island. Reef corals also require warm water. And there are more warm surface currents in the Indian and Pacific Ocean than in the Atlantic Ocean.2.) Scientists predict that the ocean will get warmer and the sea level will rise as a result of an intensified greenhouse effect. How might this affect coral reefs?-->Yes, our planet Earth is in fact warming up, an effect known as global warming. It is predicted that the ocean currents may change. This change will affect the already stressed ecosystems such as mangrove forests and estuaries will be flooded; coral reefs may not grow fast enough to keep up with the rising sea levels.3.) There are only a few reefs off the northeast coast of Brazil, even though it lies in the tropics. How would you explain this?-->The northeast coast of Brazil lies in tropics, which is common for reef-building corals. But there are only a few reefs located in this area. There is also the Amazon River which is known to be the largest river in the world. Most corals do not do well near river mouths. This is not only because of the lowered salinity but also because rivers bring in a lot of silty sediment, which is generally unfavorable to corals.