1295 questions and answers in this section
Explain why Roman aqueducts were so ingeniously designed to transport water over long distances.

Explain why Roman aqueducts were so ingeniously designed to transport water over long distances.

The Romans had grasped one essential thing: water always flows downhill. They designed their aqueducts with a gentle and constant slope (often between 0.1 and...

Read full answer

Explain why are forest fires necessary for some plant species?

Explain why are forest fires necessary for some plant species?

Some plants actually need fire to release their seeds or to trigger their germination. For example, the cones of certain pines like the Aleppo pine...

Read full answer

Explain why the color of the sea changes.

Explain why the color of the sea changes.

The color of the sea mainly depends on how light interacts with water. When a light ray hits the surface of the water, certain colors...

Read full answer

Explain why predators at the top of the food chain are essential for the balance of ecosystems.

Explain why predators at the top of the food chain are essential for the balance of ecosystems.

Top predators, also known as super predators, prevent certain species from becoming dominant and overly reducing the populations of other animals or plants. For example, by limiting...

Read full answer

Explain why the migration of monarch butterflies is an incredible feat of nature?

Explain why the migration of monarch butterflies is an incredible feat of nature?

Every year, monarch butterflies embark on a true aerial marathon of nearly 4,000 kilometers. Incredible but true, these fragile insects, weighing just a few grams, can fly...

Read full answer

Explain why do some beaches change color depending on the tide?

Explain why do some beaches change color depending on the tide?

The tide alters the visual aspect of the beaches by revealing or covering different sand areas. At high tide, the water covers the beach, making...

Read full answer

Explain why some cities have winding streets?

Explain why some cities have winding streets?

If you've ever noticed that some cities have streets that wind in all directions, it's often due to the natural terrain. Hills, mountains, or waterways...

Read full answer

Explain why the Mayans developed such a precise and sophisticated calendar system.

Explain why the Mayans developed such a precise and sophisticated calendar system.

For the Mayans, agriculture was primarily based on the cultivation of corn, essential for their survival. Using a hyper-accurate calendar was key to knowing exactly...

Read full answer

Explain why the presence of lichens is an indicator of air quality?

Explain why the presence of lichens is an indicator of air quality?

Lichens are organisms that are very sensitive to air quality, making them effective bio-indicators for monitoring air pollution. Since they have no roots, they absorb...

Read full answer

Explain why do jellyfish have a paralyzing effect on swimmers?

Explain why do jellyfish have a paralyzing effect on swimmers?

The venom of jellyfish is a complex cocktail mainly composed of toxic proteins. These proteins are designed to quickly paralyze prey so that the jellyfish...

Read full answer