Knowledge & Theories, Variables, & Energy From the Sun

Modern scientists are conducting new experiments to answer questions that were considered unanswerable only a century ago.  Why are modern scientists able to investigate problems that scientists were unable to address in the past?

• Scientists of today can build on previous scientific works to expand knowledge.

• The universe has evolved to make new problems accessible to today’s scientists.

• The average intelligence of humans has increased in the past 100 years.

• Scientists have disproved most of the theories that existed 100 years ago.

Many early doctors believed that diseases were caused by evil spirits. Researchers who supported the germ theory of disease were often ridiculed during these early times. Scientists had to be convinced germ theory was correct before the medical practices were stopped.  Which of the following best describes what this story illustrates?

• Society is to blame for medical errors.

• Evil spirits correctly explained the illnesses.

• Early doctors did not care about the patient.

• Changes in theories come with scientific support.

Early nuclear reactors required a person to shut it down if something happened.  Today, newly designed nuclear plants do not need such operators.  Which of the following best describes why the design has changed?

• Scientists who design reactors did not use earlier designs.

• Scientists who developed the first power plants did not care about safety.

• Scientists working on the first power plants did not know how nuclear fission worked.

• Scientists have applied what they learned from early nuclear plants to create better designs.

Randy’s science teacher is giving a demonstration to show how a metal reacts with different acids.  He places a small piece of the metal in each of the three beakers containing a solution of a different acid.  He adds a piece of the metal to a fourth beaker that contains only water.  What is the purpose of the fourth beaker?

• It ensures that the hypothesis will be correct.

• It provides more data to include in a lab report.

• It adds an independent variable to the experiment.

• It is the control and serves as the basis for comparison.

Colleen waters the plants in her greenhouse once every day.  She wants to find out if the plants will grow more leaves if they are watered more often.  She counts the number of leaves on each plant before she starts.  She then continues to water half of each type of plant once daily, but she waters the other half of each type twice a day.  What is the dependent variable in Colleen’s experiment?

• The type of plant being grown.

• The number of leaves the plants grow.

• The amount of light the plants receive.

• The number of times the plants are watered.

Katarina’s class was studying worm systems.  They had two separate, identical worm bins with 1,000 worms in each bin.  They wanted to determine how to best feed the worms.  They fed chunks of fruit to the worms in bin 1 and mashed fruit to the worms in bin 2.  After a month, bin 1 had 947 worms and bin 2 had 1,249 worms.  Why did Katarina’s class include two methods of feeding in their experiment?

• To create a variable to test.

• To include a constant for the other variables.

• To offer more explanations for the differences.

• To ensure at least some of the worms survived.

The sun’s energy causes water to evaporate from Earth’s surface and become water vapor.  What is the most likely result when water vapor condenses into clouds?

• Heat from the water is released, causing the clouds to produce snow.

• Heat from the water retained, causing the surrounding air to deflate.

• Heat from the water is released, causing the surrounding air to expand.

• Heat from the water is retained, causing the clouds to move higher in the atmosphere.

When energy from the sun heats Earth’s land and oceans, what is the most likely result?

• The oceans will store the same amount of heat as the land.

• The oceans will store heat, and the land will not.

• The oceans will store more heat than the land.

• The oceans will store less heat than the land.

When air that is heated at Earth’s equator rises, the heated air spreads north and south toward the poles.  What is most likely to happen to most of the air that reaches the poles?

• It will cool, rise and return to the poles.

• It will cool, sink and flow back to the equator.

• It will freeze into ice and remain at the poles.

• It will become rain and later evaporate into the atmosphere.

What method of energy transfer is primarily responsible for moving energy from the sun to the Earth?

• Conduction

• Convection

• Vaporization

• Radiation