Sc 7 N 3 2

Keesha did an experiment to study the rate of photosynthesis in the water plant Elodea,. She placed a piece of Elodea in a beaker of water and set the beaker 10cm from a light source. Keesha counted the bubbles released from the plant every minute for five minutes. She repeated the process two more times. First, she moved the light to 20 cm from the beaker, and then she moved the light to 30cm from the beaker. Keesha's setup and data are shown above.

What is the outcome variable (dependent variable) in this experiment?

• the number of bubbles produced

• the type of plant placed in the beaker

• the amount of time the bubbles were counted

• the distance of the light source from the plant

The following statements were taken from procedures of four different investigations. The statement from which investigation is an example of repetition?

• Investigation 1

• Investigation 2

• Investigation 3

• Investigation 4

Two types of models can be used to show detail of the structures of cells are shown in the picture. Which of the following describes a limitation of the drawing but NOT the clay model?

• It does not represent the main parts of a cell.

• It does not contain the correct number of nuclei.

• It cannot represent a living cell, since a true cell is three-dimensional.

• It cannot represent a living cell, since the cytoplasm should be in constant motion.

A timeline of some models of atoms throughout history is shown above. These models have contributed to the formation of the atomic theory. Which statement BEST summarizes the development of the atomic theory over time?

• The discovery of new evidence resulted in changes to the atomic theory.

• Advancements in atomic models proved the atomic theory was accurate.

• The atomic theory was modified with the discovery of every new element.

• Changes in atomic models showed that the atomic theory was based on opinion.

Deforestation occurs when large areas of trees are cut down. Which of the following impacts on the environment would result from deforestation?

• increased erosion

• colder temperatures

• decreased carbon dioxide

• greater oxygen production

The oldest rock formation identified on Earth is found on the shoreline of Hudson Bay in Canada. This rock formed 4.2 billion years ago. Which information does a scientist need to most accurately determine the age of a rock?

• the percentage of each mineral that makes up the rock

• the thickness of younger rock layers that cover the rock

• the amount of each radioactive element present in the rock

• the amount of weathering present on the surface of the rock

Interactions between layers of Earth cause convection currents to move crustal plates. The diagram above shows four layers of Earth. In which layer of Earth are the convection currents that directly result in tectonic plate motion found?

• 1

• 2

• 3

• 4

The arrows in the picture above show several ways heat is transferred from the Sun as it strikes sand on the surface of a beach. Which arrow shows convection?

• 1

• 2

• 3

• 4

Sunlight is composed of energy that is visible to humans and energy that is not visible to humans. Which statement describes how the visible energy from the Sun is different from the nonvisible energy?

• It travels at a different speed through space

• It travels a different distance through space

• It has different wavelengths

• It has different amplitudes

The diagram above demonstrates how a magnifying lens can make a penny appear larger. What property of the magnifying lens is most responsible for allowing it to magnify the penny?

• It can reflect light

• It can refract light

• It can increase the intensity of light

• It can increase the wavelength of light