Blog #4

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

• Directional Selection: Directional selection is selecting the individual with the most extreme variations in traits in a population. An example is choosing the fastest greyhound dog among a group of them. Then you pick the fastest one from their offspring. When you continue this, you end up with a really fast greyhound.
• Stabilizing Selection: Stabilizing selection is selecting the individual with the common, average traits in a population. An example is a Siberian Husky. If a Siberian Husky had heavy muscles, it would sink in the snow but if it had lighter muscles, it wouldn't be able to pull the sled. So choosing a medium Siberian Husky would be able to move through the snow and pull the sled.
• Disruptive Selection: Disruptive Selection is selecting the extreme traits in a population that would survive a sudden change in the environment. For example, when the Earth was hit by a meteor, there were large tidal waves,  increasing number of earthquakes, inadequate supply of food, and little oxygen. Larger animals would not have survived in this because they needed a lot of food and oxygen, but evidence shows that disruptive selection actually picked the traits that would help the animals in these conditions, thus making them survive.

Blog #4

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

• Directional Selection: Directional selection is selecting the individual with the most extreme variations in traits in a population. An example is choosing the fastest greyhound dog among a group of them. Then you pick the fastest one from their offspring. When you continue this, you end up with a really fast greyhound.
• Stabilizing Selection: Stabilizing selection is selecting the individual with the common, average traits in a population. An example is a Siberian Husky. If a Siberian Husky had heavy muscles, it would sink in the snow but if it had lighter muscles, it wouldn't be able to pull the sled. So choosing a medium Siberian Husky would be able to move through the snow and pull the sled.
• Disruptive Selection: Disruptive Selection is selecting the extreme traits in a population that would survive a sudden change in the environment. For example, when the Earth was hit by a meteor, there were large tidal waves,  increasing number of earthquakes, inadequate supply of food, and little oxygen. Larger animals would not have survived in this because they needed a lot of food and oxygen, but evidence shows that disruptive selection actually picked the traits that would help the animals in these conditions, thus making them survive.

Blog #3

Blog #3 Explain what microevolution is? What are the three ways that variation occurs?


Microevolution is small-scale genetic changes that lead to new subspecies. Microevolution ocurs from mutation, migration, and selection. Mutation is when there are random changes in the organism's composition or number of DNA molecules in their cell. Selection is when "weak alleles" that hurt the chances of an organism's survival are eliminated from the gene pool and the adaptive alleles that help an organism's survival are passed to a larger proportion of the gene pool. Lastly, migration is when organisms move into or out of a population and it effects the gene pool when the organisms carry a different genotype different from the population because the effect is greater on allele frequencies than if these organisms carry a similar genotype. 

Blog #2

Blog # 2 Why is fossil record hard to interpret?


Fossil records can be hard to interpret because sometimes the older fossils that are about more than three billion years old becomes fragmentary. Also some fossil records that are in mountainous areas are eroded by wind or water,  destroying the fossil. Fossils are also unreliable because not all bones of the same animal survive equally the same such as larger lightweight bones deteriorate more quickly and aren't that fossilized but small, delicate bones are crushed and carried away. Other fossils may only have a bone or two, making it hard to interpret what kind of organism it came from.

Blog #1

Evolution is a theory not a law because it has yet to be proven and supported with evidence. The definition of a scientific law is that it is a phenomenon of nature that has been proven while the definition of a theory is that it is an explanation of scientific observations. Evolution fits the definition of a scientific theory because it is an explanation of what has been observed and tested over thousands of years. There's also not a lot of information to prove evolution since it can't be repeated.

Blog #14

Favorite Topic: My favorite topic of this semester was viruses and bacterias because we got to see how they work and how they affect us. The book we read and the movie was also really interesting because it showed how deadly viruses and bacterias are. This topic relates to us, especially me because I get sick easily so it shows us what to do and how it happens.

Least Favorite Topic: My least favorite topic of this year was photosynthesis and the photosystem because it was really confusing. I didn't really understand how the plants work. I also didn't understand how the calvin cycle and light dependent cycles came into the topic because I didn't really get what they do.

If I could change one thing, I think it would be on how we take notes. The assignment is simple and I'm glad we are able to take notes from the screen but it kind of goes too fast so I don't get to write it all down. Also I'm not able to listen to the teacher because I'm too busy writing down all the notes so I can't understand what I'm writing. I just hoped that we could've slowed down a bit so we are able to take in what we just wrote down.

Blog #13

DNA changed the way we investigate crimes by giving us an idea of who the suspect is and concluding the case. By using the DNA found at the crime scene, we are able to narrow down who committed the crime. The two main types of tests are PCR and RFLP. PCR (polymerase chain reaction test) isn't very accurate but it is quick to process, usually a week. Also the DNA evidence doesn't have to be recent. It could be years after the crime and you are able to still use the DNA sample. RFLP (restriction fragment length polymorphism) is considered more accurate than PCR testing. It involves DNA fingerprinting or profiling and requires the DNA cells to be fresh, undamaged, and recently dead. Also, you would need large amounts of the samples, such as several strands of hair and large splatters of blood. Although this test is very conclusive and finalizing, it takes a long time to complete, about three weeks to three months.