Questions for ‘Life on Earth is mostly green’


When most people think about life on Earth, they imagine animals. But animals are only a small part of the planet’s life, at least as measured by mass. Overall, green plants dominate.


To accompany feature “Life on Earth is mostly green


Before Reading

1.   As quickly as you can, list 15 different species, or types of living things.

2.   Take a look at your list. How many of the species that you listed are animals? How many are plants, fungi or microbes?

During Reading

1.   What percent of life on Earth is plants, by mass (weight)?

2.   What two-syllable term do scientists use for characterizing life by its mass?

3.   When you weigh yourself on a scale, the result is in pounds or kilograms. But scientists measure biomass as the mass of what chemical element? Why do they do that?

4.   What’s the total mass of life on Earth, according to the estimate by Ron Milo and Yinon Bar-On?

5.   How did the researchers estimate that mass for places where no one had conducted detailed surveys of species?

6.   What percentage of the mass of Earth’s mammals is wildlife? What makes up the majority of the collective mass of all mammals?

7.   What is the deep biosphere? What types of organisms live there?

8.   What are two reasons for uncertainty when scientists estimate the mass of Earth’s microbes?

9.   How do Milo and Bar-On estimate that Earth’s mass of animals has changed since humans first appeared? What about the mass of all plants?

10.  How many people might live on Earth by the year 2050?

After Reading

1.   What did Milo and Bar-On’s study find about the biomass of farmed animals (both mammals and birds) compared to wild ones? Did this surprise you? Explain your answer.

2.   Take a look at your list from the first question. How does it compare to the balance of life forms on Earth?