Biodiversity Exam

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Eukaryotic cells transitioned from prokaryotic cell many years ago probably billion of years ago. The many fossils that have been found tend to suggest that eukaryotes diverged from prokaryotes about 2 billion years ago. The eukaryotes are generally known as protists while the bacteria and archaea are known to be prokaryotes. In order for the bacteria to tolerate and increase their territory, they had to modify their structure and thus changed into newer species with many forms. Evolution of the Eukaryote from prokaryotes ancestors is seen from the many differences between the two cells. There are a number of theories to explain the transiton from prokaryote to eukaryotes. Molecular analysis of the sequences shows that some eukaryotic genes are closely related to the Archaea and the bacteria. The prokaryotes are unicellular while the eukaryotes are multicellular.

Some scientists proposed that some eukaryotic cell organelles e.g. the mitochondria originated from bacteria through endosymbiosis thus providing evidence for the evolution. Endosymbiosis was proposed in order to explain the origin of Mitochodria and chloroplasts from prokaryotes where a larger prokaryote engulfed a smaller one million of years ago. The two entered into symbiosis where both benefited. The larger prokaryote gained excess ATP provided by the smaller prokaryote’s mitochondria and excess sugar from chloroplast. In turn it provides a stable environment and raw materials. Chloroplasts and mitochondria have a diversity of structure and their own DNA that supports the idea of endosymbiosis. The rapid evolution of prokaryotes was due to massive horizontal gene transfers as a group of genes. These prokaryotes acquired pathways with time which are more complex in eukaryotes.

Eukaryotes are heterotrophs, autotrophs while some can vary their mode of nutrition depending on the environment where they are. They can live in salt water, fresh water, or in soil thus showing their diversity.prokaryotes are believed to be the first life forms that performed the process of photosynthesis. The oxygen produced from the process contaminated the atmosphere selecting against anaerobic metabolic pathways. This in turn caused a large extinction of some of the prokaryotes. There are suggestions that the first life forms were heterotrophs that after some time exhausted their food supply therefore the autorophs replaced them and thus become dominant.

Eukaryotes exhibit diversity of form. They have variation in their lifecycles where they alternate between diploid and haploid phases similar to alternation of generations found in higher plants. This diversity of form and life cycles suggests that they evolved from prokaryotes. Prokaryotes are found everywhere on the earth wherever life seems to exist. Thus they outnumber the eukaryotes but both require each other for survival.

Zonation is the creation of zones each with different characteristics. There are five general zones in the marine environment and these include intertidal zone, neritic zone, oceanic pelagic zone, oceanic pelagic zone, benthic and abyssal zone.

The winds on the surface of the earth will be bundled up along the equator of the earth thus introducing abundant moisture into the earth. In that case, clouds will be abundant in this area and thus it rains heavily. In between 20-37 degrees latitude, the warm and dry air that come down result into no clouds in the sky. In the polar front the air that is going up will result into formation of cloud and rain. The water capacity is nearly 3 times that of air. Since water undergoes evaporation and condensation, it is cycled in the atmosphere. Water evaporates from the surface and condenses to form clouds which are blown by the winds. These clouds then return back to the earth as precipitation what evaporates the water is the heat from the sun. The air circulation will determine the type of climate in an area. Tide is a general name for the rise and fall of sea level on land. In other words tides are the rise and fall of large amounts of water in the oceans. Tides are there because the earth and moon are attracted to each other like magnets. The moon pulls the water since water is constantly moving. These tides are found in oceans where there exists high to low tides. When the moon travels around the earth, both of then travel around the sun so the gravitational forces between the three cause the rise and fall in the oceans.

There are certain types of animal that are found in the tidal zone. These animals face a number of harsh conditions such as extreme temperatures and desiccation so they have adapted to the environment in order to cope. Crustaceans compensate for losses through evaporation by drinking water. They have adapted a number of behavioural adaptations like kinetic responses to humidity, rolling into a ball or aggregating together.  Tiny animals that live in the splash zone avoid desiccation by tightly closing their shells, some like crabs have a hard outer cover, sea stars hold on to rocks to avoid being washed away while others house in crevices and fish are covered and fed by marine plants in the low intertidal level. The tide pool animals are adapted to the environment in various ways. Some snails can sell approaching predator thus move away, some tides secrete mucus to stick in rocks during tides and some fish can breath air at the surface of the ocean thus able to survive in oceans poor in oxygen.

North America has higher latitudes so further away from the sun. Higher latitudes lead to lower temperatures and this affect plant life. Plants have developed strategies to maximize daylight for photosynthesis and night to respire. The leaning of the northern hemisphere towards the sun causes changes in the seasons i.e. changes to summer. This seasonal change causes change in temperature and this causes plants to adapt to this temperature variation.

Plants in North America live in higher altitudes and therefore have to adapt to colder temperatures. Preventing water loss in plants that live in higher altitudes is hard since higher altitudes have lower humidity levels, are characterized by wind, and less rainfall. This therefore means that plants will lose great amounts of water but some plants are well adapted to this environment and are successful.

Temperature which is largely influenced by altitude, latitude and geographic positioning will largely determine what type of vegetative community is found in North America region. The higher up one goes the lower temperatures are and rain increase so in North America grasslands might be found.

Vertebrates are animals with backbone. The evolution of vertebrates involves a transition from water to land where they occupy diverse habitats. The first vertebrates lived in water and they were the fish which later evolved by adapting to the environment through developing some structures like jaws and fins. Amphibians later evolved from fish which gave rise to reptiles and later birds and mammals.The adaptations that made the transformation possible include;

Possession of jaws: The earlier like the hagfish and lamprey fish did not have jaws so they sucked flesh. The subsequent fish that evolved e.g. sharks possessed jaws thus they could swallow, capture or feed on prey.

Lungs and limbs: Vertebrates had to develop lungs and limbs in order to survive on land. They had to be able to breathe and walk on land. The primitive lungfish first possess this adaptation since it has both the lungs and gills, the fins are supported by bone and they can also walk in water. The amphibian evolved from fish through this adaptation.

Watertight skin and eggs: This is an adaptation that led to the evolution of vertebrates in order for them to prevent water loss through their skins. This feature is seen in reptiles that also have amniote egg which contain a supply of water and protected by a hard shell. Birds evolved from reptiles and also have amniote egg and feathers.

Endothermy: This adaptation is possessed by mammals and birds and is what makes them to be warm blooded. Body temperature is regulated internally by use of heat from burning of food. Birds have further evolved to possess different ways of feeding, reproducing and avoiding predators.

Biodiversity is the variety of living things which includes plant and animal life in a particular area.

It also be defined as the variation of living things within a given species, ecosystem or planet.

Genetic biodiversity is the variation of genes that are found within an organism.

Species biodiversity is the total number of species that live in an area.

Ecological biodiversity is the different forms of ecosystems, natural communities and habitat.

In terms of climate, biodiversity can be defined as the variation of weather patterns or the climate in a given area.

The principles of measuring biodiversity include: the number of entities i.e. species, people, and different habitats, the extent of differences between the items of study, how rare is the species is also a basis for measuring biodiversity. How species complement each other is also a principle of measuring biodiversity. Species diversity indices measure diversity at the species level from the aspect of number of species and the frequency of that species.

Methods of measuring biodiversity are canopy fogging-little insecticide is sprayed on top of a tree making the insect to fall which is collected in a funnel screen. Quadrant sampling-different species are counted within a quadrant and counting is repeated. Using nets to capture birds, bats and fish and transect sampling where a rope is marked at set intervals and the species at every interval are recorded. Any method is used depending on the type of species that is being studied.

In canopy fogging, more insecticide can be used thus killing the insects but it’s relatively a simple procedure. In Quadrant method there might be mistakes in counting but when done efficiently, it can give good results. Using nets to capture birds if a tiresome method but inexpensive.

Individual species area relationship (ISAR) method facilitates the identification of a particular key species in order to measure biodiversity. It involves investigating species numbers in relation to the area of study and then adding some complicated statistical methods to explain the role of individual species in relation to their effect on biodiversity.

Genetic diversity can be measured by looking at the genes and chromosomes directly or by indirectly looking at the physical features of the particular species and making an assumption that they have a genetic base. Genetic code is used in measuring genetic diversity. Indicator species can be used as a method of measuring biodiversity

. The advantages of measuring biodiversity in terms of species number are that;

  • It is applicable practically.
  • Some information on the number of species already exists
  • It acts as a surrogate measure for other types of biodiversity
  • This method can be applied widely by many people and applications

The disadvantages include:

  • As long as their are no agreements about the definition of a species, this method of measurement is at a disadvantage
  • There are different types of diversity thus posing a limitation to this method


Harley, Christopher & Helsmith, Brian. Oceanography. American Society of Limnology and Oceanography (2003). Retrieved on 5th May 2012 from

Klappenbach, Laura Basis of vertebrate evolution from jawless fish to mammals. (2012). Retrieved on 5th May 2012 from

Anthoni, Floor. Oceanography-currents circulation. (2003). Retrieved on 5th May 2012 from

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