5.2 - How do Earth and Life Interact?

Lesson Purpose

The biosphere is an amazing place, serving as home for humans and many other species. The atmosphere provides the air we need to breathe, but the atmosphere also helps to protect us from the Sun's radiation. The water, plants, and animals of the biosphere provide humans with many of the resources we need for survival. But as amazing the biosphere is in creating a 'comfort zone' for humans, it can also be quite fragile, and from time to time has been subject to significant threats from various astronomical, geological, and biological forces. Changes in these forces can result in both mild and extreme impacts on the biosphere.

The outcomes of this lesson are: 1.) To describe the major events in the development of life on Earth and explain what is meant by the term biosphere.

Activity 1 - Living in the Extremes of the Biosphere

Activity Objectives
You will describe what it might be like for humans to live in the extremes of the biosphere. This activity will allow you to think about the challenges associated with living either underwater or in the upper atmosphere. It will also get you thinking about what humans might have to endure if the biosphere of Earth becomes inhospitable.

Activity Tasks

Download this worksheet and look closely at the infographic on page 3. Pay attention to what it tells you about the highest and lowest points on Earth and what these extreme locations are.
As quickly as you can, make a list of 10 challenges that humans would face if they lived in these extremes of the biosphere. Now share your ideas with the class.

Activity 2 - 'What is the Biosphere?'

Activity Objectives
This article will introduce you to the biosphere and the reasons why this concept is important to life on Earth. The study of the biosphere is an interdisciplinary one that brings together a variety of scholars to understand its meaning and importance.

Activity Tasks

Read this article on What is the Biosphere? After reading, try to answer the following questions:
1. What does the word biosphere mean and when was it first used?
2. Why was the word invented?
3. How is an ecosystem different from the biosphere?
4. Discuss - What types of natural phenomena (astronomical, geological, and biological) can affect life in the biosphere?

Activity 3- How Do Earth and Life Interact?

Activity Objectives
You have already learned that the biosphere is a relatively fragile area of the Earth, but this video will provide more detail about the factors that can affect the animals and organisms living here. In fact, there are some threats to life in the biosphere that you might be shocked to learn, including information about how the “wobble” of the Earth in its orbit can affect human existence.

Activity Tasks

Watch the video and try to answer these questions:
1. 2:00 What makes the biosphere vulnerable to sudden changes?
2. 4:07 How do the Earth’s orbit, axis, speed, and size impact the planet’s surface temperature?
3. 7:10 How can the configuration of the continents impact the biosphere?
4. 7:42 What were the conditions that led to “snowball Earth”?
5. 8:50 What is the impact on the biosphere of the burying of carbon in the shells of dead sea animals?

The biosphere is a unique place. Under normal circumstances, conditions in the biosphere allow an incredible diversity of species to live and thrive, including humans. But astronomical, geological, and biological forces can change conditions in the biosphere, and scientists have recorded many examples of these changes over the Earth’s history. In some cases, these changes can be traumatic, devastating a large number of species and turning the biosphere from a very friendly to a very unfriendly place.

Activity 4 - A Year in the Life of a Species

Activity Objectives
Next you will be able to delve deeper into life on Earth by investigating the habitat and lifeways of a particular species. It’s important to understand that even though life on Earth is closely connected, there are some important factors that distinguish species from one another.

Activity Tasks

Think about an animal species that you are interested in or is native to Hong Kong or China. Download and complete this worksheet by researching (using the internet) the following aspects of that species life over a year:
1. Habitat
2. Migration Patterns
3. Food Sources
4. Reproductive Process/Rearing of Young
5. Environmental and Human Challenges to Species
Once you have finished, present your findings to the class.
What patterns do you see across species that really distinguish them from one another?

Activity 5 - How we Proved an Asteroid Wiped Out the Dinosaurs

Activity Objectives
You will watch this video to learn about the evidence gathered by a team of geologists who proved an asteroid was responsible for wiping out the dinosaurs, and their guide will be one of the lead geologists who made this discovery! If the asteroid had been less than an hour earlier or later, humans might never have existed.

Activity Tasks

Watch the video and try to answer these questions:
1. 2:55 When Alvarez explored the clay between the Cretaceous and Tertiary rocks, what clue did the clay provide, and why were members of his team surprised by what they found?
2. 4:03 What did Alvarez think about the energy of the asteroid impact and the effect it might have had on the biosphere?
3. 4:24 Why was the claim that the dinosaurs became extinct because of an asteroid impact initially met with skepticism by some?
4. 4:38 What was the second set of clues discovered by scientists to support the claim that an asteroid impact destroyed the dinosaurs?
5. 6:29 What was the third clue found to support the claim that an asteroid impact destroyed the dinosaurs?
6. 7:15 How is the development of the story of the asteroid impact that killed the dinosaurs an example of the scientific method at work?
7. Discuss - How likely do you think it is that another astronomical event might impact life on Earth?

Five major extinction events have been identified in the history of the Earth. The asteroid impact that led to the extinction of the dinosaurs was not the greatest of these disasters, but it’s probably the best known. The claim that an asteroid made the dinosaurs extinct is a fascinating idea, but how do scientists prove a claim like this? In this video, Walter Alvarez, one of the key figures in the development of this evidence, tells how pieces of evidence were accumulated over the years to support this claim.

The story of how scientists accumulated different types of evidence to prove the claim that the extinction of the dinosaurs resulted from an asteroid impact is a fascinating one. Extinctions like this one have happened throughout the Earth’s history, and have been the result of a variety of astronomical, geological, and biological forces. Many scholars believe that the Earth is currently in the midst of a sixth extinction event.

Challenge Yourself! - Optional Activities

1. An extremophile is a microbe that thrives in crazy-dangerous conditions that would kill most other life forms.
2. Scientists think of Earth in terms of spheres: lithosphere, the solid surface; atmosphere, the layer of air; hydrosphere, the water on, in, and around our planet. The biosphere overlaps all these spheres.
3. Will you boil, burn or explode in space without a spacesuit?
4. Tardigrades are the only animal capable of surviving in outer space.
5. In one second, a 10-km-wide, 13 km deep crater was blown into the Yucatán Peninsula in Mexico 65 million years ago. The impact created an explosion equal to that caused by 100 million megatons of TNT.

TAKE THE QUIZ!