Big Idea 1 · evolution

Week 3

Over the weekend, we were assigned to read Chapter 19, Descent with Modification, and complete a worksheet of questions on different philosophers, terms and concepts. The chapter pretty much expanded on a lot of concepts we had previously covered in class, like homozygous dominant and heterozygous, things like that, but also went much further into depth and talked a lot more on natural selection and how populations evolve, not just individuals. (Still on Big Idea 1). I actually really found reading this chapter to be a lot of fun to read and it was actually interesting.

A lot of the chapter was centered around the history behind evolution and how we got to where we are now. There were many scientists and philosophers like Charles Darwin, and even the Bible, mentioned. The chapter discussed their different ideas and views, and continued to explain, that as every philosopher was following similar concepts, that Charles Darwin was the most accurate. Darwin’s four observations that drive changes in species over time are that variations in traits exist, these variations are heritable, species overproduce, and there is competition for sources. Below are images of Darwin’s theory of evolution (left), and natural selection (right).

As homework for Monday night we watched videos on Punnett Squares and the Hardy-Weinburg equilibrium. Punnett Squares are basically just a diagram that is used to predict an outcome of a particular cross or breeding experiment. Punnett Squares and the terms homozygous recessive, homozygous dominant, and heterozygous go hand in hand, because we use homozygous recessive (rr), homozygous dominant (RR), and heterozygous (Rr) to predict the outcome. Hardy-Weinburg equilibrium is the principle that states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.

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