Month: September 2018

Week 2 Reflective Response- Evolution

Image result for evolution tree

This week in AP Biology we learned more about evolution, and also some theories of how life started.

Evolution was first theorized by Charles Darwin while he was on board the HMS Beagle. As he circumnavigated the globe he collected specimens and other evidence to prove his ideas (1.A.4). After he went home, it took him 20 years to publish his theory of evolution. I thought this was an absurd amount of time to wait, but in that time period many people did not believe him, so he wanted to be sure he could prove it.

Image result for charles darwin on the origin of species

Image result for hms beagle

 

 

 

 

 

 

 

 

We also read some theories on how life was created on earth. One of them was the Replication-First (or Gene-First) Hypothesis, which explains how RNA most likely created the original form of life on Earth. When I read this, I wondered how the RNA could be created in the first place. I then learned that this hypothesis is dependent on the idea that organic molecules formed on Earth, including the nucleobases in RNA. RNA can store information, as well as carry out functions, something that DNA cannot do. Then the RNA bonds with random amino acids, and the good combinations survive to pass on their order of acids. They eventually form lipid layers around the RNA, creating the first cell, then DNA and proteins replace the RNA to carry out more complex functions of life. This relates to one of our big ideas, 1.D.1, which says “There are several hypotheses about the natural origin of life on earth, each with supporting evidence.”

Image result for RNA

This article helped me understand Darwin’s theory:

https://www.livescience.com/474-controversy-evolution-works.html

Here is a video that helped me understand the Replication-First Hypothesis:

 

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Week 1 Reflective Response

This week in AP Biology we learned about standard deviation and standard error, which help describe statistics or graphs. We also learned about how natural selection and mutation can change populations rapidly.

Standard Deviation and Standard Error

Standard deviation expresses the spread of the data from the mean. This picture shows how standard deviation can be used to find certain percentages of the data, and also helped me understand how standard deviation works.

Image result for standard deviation

Standard error might sound the same, but it is completely different. It deals with how accurate the data is, or what the standard deviation of a large population should be. It can also be used to find what the mean could be if the experiment was done again.

Image result for standard error

Natural Selection and Mutation

We learned about the Galapagos finches, which are a perfect example of natural selection(1.A.1). Peter and Rosemary Grant studied the finches from 1973 to 1977. They found that when a drought came to the islands, there were only big seeds left by the end, and only finches with wider beaks survived. They saw in the next population that the mean beak depth was higher, indicating that natural selection had occurred.

Image result for galapagos finches

Mutation is another important mechanic of evolution. Mutation occurs in the DNA of an organism. We studied mice in New Mexico that lived on black rocks. Originally they were all colored like the sand, but when one mutated to have dark fur like the rocks, it survived better because predators could not see it. Then through natural selection the population changed over time to have more and more dark mice. The interesting thing about the mice is that there were different mice in different regions that got the same dark fur, but through different genes changing. I was very surprised by this; I thought it would be one gene that controlled the color of mouse fur. Mutations are also important because they diversify the gene pool, which helps populations survive an adapt.

Image result for rock pocket mouse black vs white

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Xerophyte

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This is a picture of a succulent. Succulents are examples of xerophytes. Xerophytes are plants that need very little amounts of water. Succulents only need small amounts of water to survive.

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Pollen

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This is a picture of a dandelion flower. Dandelion flowers are examples of flowers with pollen. Pollen is a fine powder that is made from the male flower parts. It fertilizes the seeds when they come in contact. This flower has fine yellow powder on it.

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Stem – Herbaceous

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This is a picture of the stem of a plant. Plant stems are examples of herbaceous stems. Herbaceous stems are soft (contrasted to woody stems) and come out of the ground. This stem is soft and comes out of the ground.

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Pine Cone – Female

IMG_6243

This is a picture of a pine cone. Most pine cones are an example of female pine cones. A female pine cone is bigger than male cones, they have seeds and more room between each scale. This pine cone is bigger than others, and has seeds.

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Lichen

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This is a picture of lichen. Lichen is an example of lichen. Lichen is a slow growing crusty plant that grows on trees and rocks.

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Heartwood

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This is a picture of a pine tree. Pine trees are an example of a plant with heartwood. Heartwood is the hard inner part of the tree, usually the best wood for timber. This is a tree, so it has heartwood, and you can see the lighter wood in the middle of the picture.

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Fruit – Fleshy With Seed

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This is a picture of a blueberry. Blueberries are examples of a fleshy fruit with seed. Fleshy fruits with seeds have fleshy insides when they are fully grown, and seeds usually near the center of the fruit. Blueberries have fleshy insides and seeds in the middle.

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Frond

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This is a picture of a fern. A fern is an example of a plant with fronds. Fronds are leaves of ferns, palm trees, and other similar plants. Ferns have fronds.

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