5.0 - What is Life? - islandschoolhistory

Lesson Purpose

With the appearance of the first planets, the Universe became much more complex. Planets, which formed from clouds of chemicals created during the death of stars, are more chemically diverse than the stars from which they came. Planets also differ from stars because they don't generate huge amounts of energy at their centres. As a result, their surface temperatures are much cooler. This combination of diverse chemical ingredients and less violent conditions enabled planets to become the setting for life. When life emerged on Earth, it had characteristics that made it very different from non-living things. Many people will tell you they 'know' the difference between living and non-living things. However, biologists - the experts - have struggled to agree on a single definition of life, even though many of the proposed definitions share similarities. In this lesson, we'll focus on understanding the characteristics all livings things share.

The outcomes of this lesson are: 1.) To describe the conditions that made it possible for life to emerge on Earth; 2.) To explain the differences between life and nonlife.

Activity 1 - The Driving Question Notebook

Activity Objectives
This activity presents the driving question for Unit 5. It’s meant to help you stay focused on this question as you learn new material.

Activity Tasks

Download this latest DQ Notebook worksheet for the question: 'How does extinction drive evolution?'
Complete the first column by jotting down some notes and reflections on the question.

Activity 2 - A Big History of Everything H2

Activity Objectives
This video introduces you to the emergence of life on Earth. Understanding how life emerged from nonlife can be confusing, and this video gives one explanation of how this process occurred, and what happened as life evolved.

Activity Tasks

Watch the video and try to answer the following questions:
1. What do most people believe is the reason for the emergence of life on Earth?
2. What is the biological blueprint for everything that exists?
3. What is the earliest form of life?
4. Why is the egg a critical development?
5. What did the extinction of the dinosaurs clear the way for?
6. What did humans ultimately evolve from?
7. How did primates take the first step toward being human?
8. Based on what you learned from the video, do certain things need to happen for new species to evolve? If so, what are those things?

The emergence of life on Earth is a truly amazing development in the history of the Universe. And the fact that a chemical reaction in the oceans eventually resulted in something as complex as ourselves is nearly mind-boggling. It’s no wonder that life is one of Big History’s thresholds of increasing complexity!

Activity 3 - How Closely Related Are We?

Activity Objectives
This activity helps you gain an understanding of the relationship between different species, and see how we (humans) are related to other species. The evolution of life from bacteria to humans is pretty hard for people to wrap their minds around, and showing connections among different species will help increase your understanding.

Activity Tasks

Download this worksheet. Draw lines to match the list of organisms to the percentage of DNA shared with humans.

Activity 4 - The Origin of Life: Crash Course

Activity Objectives
It’s not always easy to see the close connections humans share with other species. Sometimes, the connections are detectable only at the genetic level; but the connections are there, nonetheless. What is it that connects humans with other species? DNA is one important ingredient – after all, DNA is something that all living things share. There are other key characteristics that most living things share with each other and these are what make living organisms different from non-living.

Activity Tasks

Watch the video and try to answer the following questions:
1. 0:20 What is one of the biggest puzzles about life that we still have yet to figure out?
2. 2:55 Hank talks about the definition of life at least three times. So, what is life?
3. 3:33 How was Friedrich Wohler’s chemistry experiment important in the discovery of where life originated?
4. 5:07 What forms of life dominated Earth for the vast majority of its existence?
5. 6:19 How can oxygen be harmful and how did it change life?
6. 8:03 What makes eukaryotes more complex?
7. 10:16 What makes DNA such an important molecule, and where did it originate?

DNA is the most important characteristic of all living things. It is essential to the story of life. Understanding the complexities of it are not essential to the Big History story; however, understanding its importance to life, is. Try not to get too bogged down in the details, especially since scientists are still trying to work out how this molecule became the master blueprint of all life on Earth.

Activity 5 - "Life and Purpose"

Activity Objectives
You will get an introduction to another way of defining what it means to be living. As you have already learned in the course, different scholars, especially those from different disciplines, may approach the same subject from a different angle, or use different words to describe the same thing. This is a great example of that process.

Activity Tasks

Download and read this article on 'Life and Purpose' and answer the following questions:
1. What does Goodenough mean by self-generation?
2. What does Goodenough mean by self-maintenance? Is this the same as the process Hank calls metabolism?
3. What does Goodenough mean when she says, “Every organism is instructed”? Is this the same as the process Hank calls reproduction?
4. What does Goodenough mean when she says, “Every organism evolves”? Is this the same as the process Hank calls adaptation?
5. In the article, Goodenough talks about how “the most interesting single generalization is that organisms are purposive whereas nonlife is not.” What do you think she means by this?

Activity 6 - Claim Testing: What is Life?

Activity Objectives
You will use claim testers to firm up your understanding of the differences between life and nonlife. More and more research and writing is coming up in the course, and your claim-testing skills need to be well-developed so you’re ready for the upcoming work.

Activity Tasks

Download this worksheet and look at page 1. Decide whether each claim is true or false - but make sure you explain what claim tester you used to support that claim.
Remember, the four claim testers are:
1. Intuition - Does your gut reaction tell you the claim is reliable? Do you feel that the claim is true?
2. Authority - Does the person stating the claim have experience in that field? Are they trustworthy?
3. Logic - Does the claim make sense to you? Does it follow a clear line of reasoning?
4. Evidence - Do you have facts that others can 'see' that support the claim?

Challenge Yourself! - Optional Activities

1. Humans and chimpanzees are close cousins; we diverged from a common ancestor that lived around 7 million years ago.
2. “The most reliable joy is to be out of doors, to be a creature among other creatures. I find it very restful."
-Ursula Goodenough

TAKE THE QUIZ!

5.0 - what is life?