What biological principle is illustrated by the Heike crabs?
Selection by humans
Sagan says that if artificial selection can produce vast changes in a short period of time, then what must nature be able to do, given the age of the ear (4.5 billion years or so)? Don't just quote the video here. Explain what he means!
Nature must be able to produce and create.
What are the basic “steps” in natural selection as Sagan describes them? What questions does he raise for you?
Natural Selection happens when human’s changes have created other changes without humans directly deciding to do so.
Sagan describes the basic steps as there are more creatures then can survive. Less adapted have a ...view middle of the document...
(microbenet) Each is different based of what organism. Should a mutation occur it is going against the genetic plan. Thus, some mutation can harm the next generation. Others can assist the genetic plan and assist in evolution. We all have very close DNA that breaks down proteins to support functions of our cells.
Explain the purpose of the “cosmic calendar analogy” as you understand it. Roughly how long have humans been on the calendar? 2.5 Mya
What does that make you think about the relative newness of our species?
The cosmic calendar analogy was created to explain how much time has passed since the Big Bang explosion which created the universe. Sagan calendar is based on one-year. January 1 is Big Band and the following January 1 is today. Based off this scale, “there are 438 years per second, 1.58 million years per hour, and 37.8 million years per day”(Kardas). Looking at the calendar and the existence of the universe our years of life are diminutive. Makes me feel that we are pretty small compared to what is out there.
What do we learn when Sagan visits the Royal Gardens at Kew about the relationship between plants and animals on earth? Which is more “important” – us or them; why?
Plants use carbohydrates to produce energy. We use the carbohydrates from plants to fuel us with energy. When carbohydrates and oxygen meet we use this to breath. We use energy and exhale carbon dioxide. Plants use the carbon dioxide to make carbohydrates. The cycle repeats. Carbon dioxide would still exist without animals/us. Thus, our need for plants is higher than the plants need for us.