8th Grade Diagnostic Test

According to an August 2011 report from a government research laboratory, the amount of carbon dioxide (in parts per million) in the Earth's atmosphere increased by almost 25% between 1958 and 2011. The graph on the left illustrates this increase as well as the yearly cycle, which is driven by the

seasons.

If a student wants to understand what has led to this increase, what is the best scientific question he or she could ask an expert?

Arctic forests exist in higher latitudes on Earth. During snowy seasons, the ground is covered with snow and is very bright. The trees are much darker in color and stand taller than the snow cover.

In computer simulations, areas with full snow coverage are 0.42°C to 0.78°C cooler than areas with substantial forests.

Which statement explains how trees influence the climate in Arctic forests?

The picture below shows a model of the Solar System.

What does the model show correctly about the Solar System?

A group of students is having an annual downhill cart race. The unpowered carts, like the one shown below, are lined up at the top of a hill.

What gives the cars their potential energy?

A pattern of stars that has been named is called a constellation. Late at night, Carolyn saw the constellation named Leo, the lion, in the eastern part of the sky. A drawing of Leo is shown on your left.

Early the next morning before sunrise, Carolyn saw the same constellation in the western part of the sky. How could she see the same constellation in a different part of the sky?

Green plants produce sugar in their leaves through the process of photosynthesis. To make this sugar, plants must acquire some materials from their environment.

Arrow 2 represents _______ that is taken up from the soil through the roots of the plant.

Mike and Joe take turns pitching a baseball, and Drew catches it. Mike can throw the ball harder than Joe can.

Which of the following statements is true?

Mr. Walters is launching a toy rocket.

The rocket experiences a force that pushes it up into the air. Which of the following statements is true?

A student is learning about gravity and falling objects on Earth. She wants to determine if the shape of an object affects the rate at which it falls due to gravity. She constructs a table with four different ideas for an experiment. The table is shown on your left.

Which experiment would best test what the student is trying to determine about objects falling due to gravity?

The colors on the map above show the locations of the major tectonic plates that make up the Earth's crust.

Which city on the map is most likely to experience a major earthquake?

A sound wave from a jackhammer travels through a section of concrete with a fixed frequency. At the

concrete's boundary is mud. The diagram below shows the path of the sound wave as it travels from the concrete into the mud.

What happens to the sound wave when it passes from the concrete into the mud?

When an object such a a stone is dropped into water, it disturbs the surface of the water. Waves form

at the surface of the water and travel outward from the point of the disturbance.

The diagram below is based on a single frame from a video of the waves that formed when a stone was dropped into water.

If a student were to measure the distance labeled as "Z," she would know the value of the _______ of the wave.

Which mineral has a non-metallic luster and a density of 2.3 g/cm3?

A student drew the diagram to the left to model the process of sexual reproduction.

Sexual reproduction results in a child that is different from its parents because

The butterflies shown below all belong to the same species, but one of them has inherited a rare mutation for blue wings rather than orange wings. The butterflies feed on nectar from orange flowers, and their color acts as camouflage while they feed.

What will most likely happen to the butterfly with blue wings?

In some animals, brown eyes (B) are dominant over blue eyes (b). Which of these genotypes will complete this Punnett square?

Suppose a population of rabbits is introduced to an environment that has hot summers and extremely cold winters. Every winter, many rabbits die because of the cold and the lack of food. The rabbits have a range of ear sizes.

Rabbits lose a lot of their body heat through their ears. Every winter, more of the large-eared rabbits die than the others. Every summer, more of the short-eared rabbits die than the others.

At first, there are an equal number of rabbits with each size of ears. After several years, what will the frequency of ear sizes in the population be like?

Holding a marshmallow near a campfire flame causes it to turn brown even if the marshmallow does not touch the flame. Why does this happen?

A model of a carbon dioxide molecule is shown in the image to your left.

Which of the following best describes the carbon dioxide molecule?

In atomic theory, new substances are formed when the atoms of other substances are rearranged. In this kind of change, the total number of atoms is conserved.

An example of this is shown in the diagram below. There are six atoms

both before and after the arrow.

Which statement below is also true of the rearrangement of atoms?

Directions: Select ALL the correct answers.

The diagram below shows the similar limb structures of a dolphin, a horse, and a bat. Similar bones are highlighted in the same colors.

Which of the following is true about these three species?