Blog #7

Blog #7: Compare and contrast two biomes. Describe them in detail; include pictures of plants and animals you are likely to see.

          The Freshwater Biome accounts for one fifth of Earth and provides half of the drinking water, one third of the water used for irrigation, and nearly ninety percent of the world's bathwater. The biome consists of inland lakes, streams, brooks, creeks, rivers, ditches, sloughs, gutters, puddles and canals. Leeches and catfish are a few of the many animals that the Freshwater Biome supports. 
Source: http://www.idiotica.com/cranium/encyclopedia/content/Freshwater.htm
          
          The Marine Biome are consisted of marine regions, coral reefs, estuaries, and oceans. This is similar to Freshwater Biomes because they both contain bodies of water, but Marine Biomes cover more of Earth's area, about 3/4 of Earth's surface, opposed to Freshwater Biomes which cover only 1/5 of Earth's area.
Source: http://www.ucmp.berkeley.edu/exhibits/biomes/marine.php

 

Blog #6

Blog #6 Which level of the food pyramid is the most important? Support your answer.


In my opinion, fruits and vegetables are the most important  level of the food pyramid. Although people can argue that proteins is the most important, fruits and vegetables can't make you overweight or unhealthy if you eat more than the recommended portion. When the new food pyramid wasn't created yet, people were going by the old food pyramid, which had proteins as the biggest and most important part of the food pyramid. That led many Americans to obesity, which is why the new food pyramid was created: to help people better understand how many servings of each level they should be eating. Fruits and vegetables are most important because they contain carotenes, which enhance our immune systems and helps against diseases. Fruits and vegetables also provide fiber, nutrients, minerals and vitamins, such as Vitamin A, which is good for eyesight and growth, and Vitamin C, which is good for protection against viruses and bacteria and healing wounds.


Sources: http://www.netdoctor.co.uk/health_advice/facts/vitamins_which.htm
http://pediatrics.about.com/od/foodpyramid/a/05_food_pyramid.htm

Blog #5

There have been 5 major extinction events throughout history, are humans impacting the 6th? Why or why not?

I do believe that humans are impacting extinction. Many animals are constantly in danger of being extinct, because of many reasons which include hunting animals for food, and destroying natural habitats. One website even says that a biodiversity expert has warned us that "humans are driving animals and plants to extinction faster than new species can evolve." If this is true, wildlife is in anger, and humans are the cause. Also, it is becoming increasingly difficult for animals to survive in the climate changes and habitat loss. Unfortunately, almost 17,300 species are considered under threat and a lot would have to be done to stop these species from future extinction. 

Source:  http://www.guardian.co.uk/environment/2010/mar/07/extinction-species-evolve

Blog #4

Describe the three types of selection: directional, stabilizing and disruptive and give an example of each in your own words.

          Directional selection is a type of natural selection where it favors a single phenotype. It occurs in population when there is a shift towards an extreme version of the good trait. An example would be like creating new breeds of dogs over generations. For example, scientists who want dogs who can run fast will look for and select breeds who can run fast, and select the fastest runners from their offspring. Over time, after continuing the process they can produce a dog in a future generation who can run extremely fast.  
          Stabilizing selection is a type of selection where genetic diversity decreases as the population settles on a certain trait. Stabilizing selection favors the normal traits in a population. An example of stabilizing selection is choosing something in the middle, an average point. For example, animals must have certain traits to survive in an environment, so stabilizing selection chooses an average, normal trait for that animal so there are no extremes. The size of an animal would be an example, because in certain habitats, that animal cannot be too big or too small, so stabilizing selection chooses a medium size for that animal.
          Disruptive selection is pretty similar to directional selection; it favors the extreme traits in a population. It is like the opposite of stabilizing selection. It is different from directional selection though, because sudden environmental changes cause sudden forces favoring a particular extreme. Disruptive selection occurs quickly. An example of this would be like the color of an animal. If a mouse had black fur and another had white fur, the offspring could have gray fur. However, the environment they are in may give an advantage to the black and white mice, therefore causing the mouse with gray fur to stand out. As a consequence of the selective environmental pressures the mice population would be disruptively selected for extreme values of the black and white mice, but not the gray mice.
 

Blog # 3

Blog #3 Explain what micro evolution is. What are the three ways that variation occurs?


Micro evolution is a change in gene frequency within a population caused by mutations, natural and artificial selection, genetic drift and gene flow. Micro evolution is basically evolution resulting from genetic changes which may lead to new sub-species. An easier way to describe micro evolution is this: When someone with specific traits successfully reproduces, the next generation will have more copies of that certain trait; If the trend continues then that trait will become so common in a population causing the population profile (a chart which shows the number of people as a function of their ages)  to change.


Firstly, genetic variation is the variety of genes in a population. The first and ultimate way that genetic variation can occur is through mutations. This is because mutations change the order of nucleotide bases of DNA. The second way that variation occurs is from independent assortment, which is the recombination of chromosomes during reproduction. Lastly, the third way in which variation happens is from crossing over during meiosis. Crossing over may result in the production or new combinations of genes.

 

Blog #2

Why is fossil record hard to interpret?

The fossil record is basically a a collection or fossilized artifacts from all over the world. Many scientists hope to find more fossils to fill the missing "pieces" in the fossil record, which could help them greatly in discovering more of our past. However, this is difficult because only a very small fraction of the world's organisms have been fossilized, which makes it hard to study the fossil record. Organisms can only be fossilized in specific conditions, thus making fossilization very rare.

Furthermore, it is extremely challenging to interpret the fossil record, because often, the fossil can just be a blob that can not really be studied. Also, fossils from the same species are not guaranteed to survive equally well. Larger, lighter bones deteriorate quicker, while smaller more fragile bones are easily crushed, which makes it hard to even have a fossil to study at all. The different way the organism is preserved depends on the conditions it was in, therefore making it hard to interpret.

Sources:
http://www.wisegeek.com/what-is-the-fossil-record.htm
http://anthro.palomar.edu/time/time_1.htm

Sem. 2 Blog #1 Evolution

Why is evolution a theory and not a law?


Evolution is a theory because in order for it to become a law, it would have to be widely accepted and a supported, firmly held belief. Although evolution is supported by a lot of evidence, it isn't enough to make it into a law, which is unchangeable. Theories can be changed and tested and are beliefs that has been generally accepted from experiments and observations unlike laws, which are so firmly established that they often never change. Evolution cannot be a law, because some scientists don't agree with it and there has been much debate. For the theory of evolution to become a law, it must be accepted by all and have enough facts to go by.