A scientist performs an experiment to see how plants respond to acid rain. He places the water plants in water of varying pH measurements. The pH levels are 2.5, 6.0, 7.0, and 9.0. Each day, he measures the health of the plants by counting the number of leaves on the plant. The plants used in this experiment typically grow in water at a neutral pH. Why was only one variable tested in this experiment?

The scientist tested one variable to determine what caused the number of leaves to change.
It just happened that way; you can test as many variables as you want.
The scientist ran out of materials so he tested only one variable.
The scientist tested two variables.

Which of the following does not describe a physical property of iron? a iron is silvery-white or gray in color. b iron has a boiling point of about 3,000°c. c iron is a magnetic element . d iron and sulfur react to form iron sulfide.

For a to be healthy, it has to have lots of different kinds of plants and animals. all of the different types of plants and animals in an ecosystem. name four types of ecosystems from those listed in the video. b) c) d) most living things live here. all living things depend on how an ecosystem like a game of sticks? why should we build new buildings on existing land? name four extinct species from those listed in the video. b) c) d) the best way to wipe out a species is to the largest ecosystem in the world is this percent of the world is covered by water. how many of all species in the world live in the ocean? list five things you can do to increase biodiversity. b) c) d) e) how many species are we losing per hour?

Solutions to environmental problems in europe must