7th Grade Science Final Exam Practice

Genetic variation is important for the survival of a species because it allows for adaptation to changing environments. When a species has high genetic variation, it means that there are many different versions of genes within the population. This diversity provides the potential for individuals to possess traits that may be advantageous in certain conditions. In the face of environmental changes or new challenges, individuals with beneficial traits are more likely to survive and reproduce, passing on their advantageous genes to future generations. This genetic diversity helps maintain the overall health and resilience of the species.

Food webs are overlapping food chains that exist within an ecosystem. They represent the interconnectedness of different organisms and their feeding relationships. Unlike a food chain that shows a linear flow of energy from one organism to another, a food web shows multiple interconnected food chains, illustrating the complex interactions between different species in an ecosystem. Therefore, the correct answer is food webs.

Vaporization refers to the process in which a liquid changes into a gas. It occurs when the temperature of the liquid reaches its boiling point and the molecules gain enough energy to break free from their liquid state and form a gas. This process is commonly observed when water boils and turns into steam. Therefore, the statement that the change from a liquid to a gas is called vaporization is true.

This statement is incorrect because the temperature of a substance increases when heat energy is added to it, not when it goes down. Heat energy is the energy transferred between substances at different temperatures, and it flows from a higher temperature to a lower temperature until thermal equilibrium is reached. Therefore, as heat energy goes down, the temperature of a substance also decreases.

Fossils are found in sedimentary rock because this type of rock is formed from layers of sediment that accumulate over time. These sediments can include the remains of plants and animals, which become preserved and fossilized within the rock. Sedimentary rocks are also often found in areas where there were once bodies of water, such as lakes or oceans, which provide the ideal conditions for the preservation of fossils. Therefore, sedimentary rock is the most likely type of rock to contain fossils.

Animal waste contains harmful substances such as nitrogen and phosphorus, which can contaminate water sources when it enters rivers, lakes, or groundwater. This pollution can lead to an increase in algae growth, deplete oxygen levels in the water, and harm aquatic life. Additionally, if the animal waste is not properly managed or treated, it can seep into nearby water bodies, causing further pollution. Therefore, it is true that animal waste contributes to water pollution.

Charles Darwin proposed the theory of natural selection over 100 years ago. His groundbreaking work, "On the Origin of Species," published in 1859, outlined the concept of natural selection as the driving force behind the evolution of species. Darwin's theory revolutionized the field of biology, providing a scientific explanation for the diversity of life on Earth. His observations and evidence gathered during his voyage on the HMS Beagle led him to propose that organisms with traits beneficial for their environment are more likely to survive and reproduce, passing on those advantageous traits to future generations.

The mid-Atlantic ridge is a divergent boundary. Divergent boundaries occur when two tectonic plates move away from each other, creating a gap. In the case of the mid-Atlantic ridge, it is located in the middle of the Atlantic Ocean, where the Eurasian and North American plates are moving apart. This movement causes magma to rise from the Earth's mantle, creating new crust and causing the seafloor to spread. Therefore, the correct answer is divergent.

Light energy is also known as radiant energy because light is a form of electromagnetic radiation. Radiant energy is the energy carried by electromagnetic waves, including visible light, infrared radiation, ultraviolet radiation, and other forms of electromagnetic radiation. Light energy travels in waves and can be absorbed, reflected, or transmitted by different materials. It is responsible for our ability to see and is used in various applications such as lighting, photography, and communication.

The term "rock cycle" refers to the continuous process in which rocks are transformed and recycled over a long period of time. This process involves various geological forces such as weathering, erosion, and sedimentation, as well as heat and pressure deep within the Earth's crust. The rock cycle demonstrates how rocks can change from one type to another through processes like melting, cooling, and solidification. It highlights the dynamic nature of rocks and emphasizes their constant transformation over geologic time.

When energy transformations occur, some energy is always lost as heat. This is due to the fact that energy cannot be created or destroyed, but it can be converted from one form to another. When energy is transformed, some of it is inevitably converted into heat energy, which is a form of energy that is often dissipated and cannot be fully utilized for useful work. This loss of energy as heat is a fundamental principle in thermodynamics known as the second law of thermodynamics.

The statement is false because the arrows in a food chain always point in the direction that energy (food) is moving. In a food chain, energy flows from the producers (plants) to the primary consumers (herbivores), then to the secondary consumers (carnivores), and so on. The arrows in a food chain represent the transfer of energy from one organism to another, indicating the flow of energy in the same direction as the arrow.

As you descend deeper into the earth, the temperature and pressure of the rock and metal increase. This is because the earth's interior is heated by the residual heat from its formation and radioactive decay. The pressure also increases due to the weight of the overlying layers of rock and the gravitational pull towards the center of the earth. These increasing temperature and pressure conditions contribute to the formation of the earth's core and the movement of molten rock in the mantle.

Temperature is the measure of heat energy of particles in a substance. It indicates the average kinetic energy of the particles in a substance, which determines how hot or cold it is. Temperature is measured using various scales such as Celsius, Fahrenheit, and Kelvin. It is an important property in thermodynamics and plays a crucial role in determining the direction of heat transfer between objects.

Thermal energy flows from hot to cold until there is equilibrium or no difference in temperature because heat naturally moves from areas of higher temperature to areas of lower temperature in order to reach a balanced state. Once the temperatures are equal or there is no temperature difference, there is no longer a driving force for the thermal energy to flow, resulting in equilibrium.