How Organisms Shape Habitats

Question 1

Which of the following shows how an animal can change its environment to meet its needs?

Accepted Answer

A beaver builds a dam in a stream.

Answer

A butterfly rests on a flower.

Answer

A rabbit hops across a meadow.

Answer

A fish swims in the water.

Question 2

Which example shows a plant or animal changing its environment to meet its needs?

Accepted Answer

A beaver builds a dam in a stream to make a pond where it can find food and stay safe.

Answer

A squirrel climbs a tree to pick nuts that are already on the branches.

Answer

A sunflower turns its leaves toward the sun each morning.

Answer

A child puts on a raincoat when it starts to rain.

Question 3

Fossil and geochemical evidence indicates that cyanobacteria began producing large amounts of oxygen about 2.4 billion years ago, leading to the Great Oxidation Event. The increase in atmospheric O₂ allowed ozone (O₃) to form in the upper atmosphere, which blocks harmful ultraviolet (UV) radiation. Which argument best explains how these observations illustrate the simultaneous coevolution of Earth’s atmosphere and early life?

Accepted Answer

The emergence of oxygen‑producing cyanobacteria increased atmospheric O₂, which formed an ozone layer that reduced UV radiation; this new protective layer allowed more complex, photosynthetic organisms to evolve and colonize shallow waters and land, showing how biological activity altered the atmosphere and the altered atmosphere created new evolutionary opportunities.

Answer

Increased volcanic activity released oxygen into the atmosphere, which built the ozone layer and led to the evolution of multicellular life, showing that geological processes, not biology, drove atmospheric changes.

Answer

The rise in atmospheric oxygen directly caused the extinction of all anaerobic microbes, which then allowed the ozone layer to form, demonstrating that life was eliminated before the atmosphere changed.

Answer

The formation of the ozone layer caused cyanobacteria to evolve the ability to photosynthesize, indicating that atmospheric changes drove the origin of photosynthesis.

Try three questions

Which of the following shows how an animal can change its environment to meet its needs?

Which example shows a plant or animal changing its environment to meet its needs?

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