Which of the following best describes a chemical reaction?
A) A process where atoms in the original substances rearrange to form new molecules with different properties.
B) A process where atoms are destroyed and created anew.
C) A change that alters only the physical form of a substance, not its chemical identity.
D) A reaction that occurs without changing the properties of the original substances.
Correct Answer: A) A process where atoms in the original substances rearrange to form new molecules with different properties.
Explanation: In a chemical reaction, the atoms of the starting substances (reactants) rearrange to form new substances (products) with different physical and chemical properties.
What role do decomposers play in an ecosystem?
A) They convert sunlight into chemical energy.
B) They consume other organisms for energy.
C) They recycle nutrients from dead matter back to the ecosystem.
D) They produce oxygen through the process of photosynthesis.
Correct Answer: C) They recycle nutrients from dead matter back to the ecosystem.
Explanation: Decomposers, like bacteria and fungi, break down dead organisms and waste materials into simpler substances, recycling nutrients back into the ecosystem. This is crucial for nutrient cycling, supporting the growth of plants and, by extension, the entire food web.
What drives the water cycle on Earth?
A) The rotation of the Earth around its axis.
B) The movement of Earth's tectonic plates.
C) Energy from the sun and gravity.
D) The magnetic field of the Earth.
Correct Answer: C) Energy from the sun and gravity.
Explanation: The water cycle is powered by the sun's energy, which causes evaporation, and gravity, which drives precipitation and the flow of water on and beneath the Earth's surface. This continuous movement of water between the atmosphere, land, oceans, and living things is a fundamental Earth process.
How do human activities contribute to the greenhouse effect?
A) By planting trees and other vegetation.
B) Through the release of gases that trap heat in the atmosphere.
C) By constructing buildings that reflect sunlight.
D) Through the use of renewable energy sources like wind and solar power.
Correct Answer: B) Through the release of gases that trap heat in the atmosphere.
Explanation: Human activities, such as burning fossil fuels and deforestation, release greenhouse gases like carbon dioxide and methane into the atmosphere. These gases trap heat from the sun, contributing to the greenhouse effect and global warming.
What is the first step in the engineering design process?
A) Building a prototype.
B) Testing the design.
C) Defining the problem with criteria and constraints.
D) Choosing the best solution.
Correct Answer: C) Defining the problem with criteria and constraints.
Explanation: The first step in the engineering design process involves clearly defining the problem to be solved, including the requirements (criteria) the solution must meet and any limitations (constraints) that must be considered. This foundational step guides all subsequent design activities.
What happens to matter during a chemical reaction?
A) It is destroyed.
B) It changes form, but the total mass remains the same.
C) It increases in mass.
D) It decreases in mass.
Correct Answer: B) It changes form, but the total mass remains the same.
Explanation: According to the law of conservation of mass, matter is neither created nor destroyed in a chemical reaction. Although the reactants change form to become products, the total mass of the system remains constant.
What can cause a species to become endangered?
A) An increase in biodiversity.
B) A decrease in natural resources.
C) Human activities that alter their habitat.
D) Natural disasters that occur frequently.
Correct Answer: C) Human activities that alter their habitat.
Explanation: Species become endangered primarily due to habitat loss or degradation caused by human activities such as deforestation, urban development, and pollution. These changes can severely limit the resources available for the species to survive and reproduce.
Why are models used to study Earth's systems?
A) To make Earth's systems more complex.
B) Because Earth's systems cannot be studied directly.
C) To predict and understand phenomena that are too large or too small.
D) To demonstrate Earth's systems in real-time.
Correct Answer: C) To predict and understand phenomena that are too large or too small.
Explanation: Models are essential tools in Earth sciences because they allow scientists to simulate and study complex processes that cannot be observed directly due to their scale, complexity, or both. Models help in making predictions and understanding the dynamics of Earth's systems.
How does plate tectonics contribute to the formation of mountains?
A) By the accumulation of sediment in ocean basins.
B) Through the cooling and solidification of magma beneath Earth's surface.
C) By the movement and collision of Earth's lithospheric plates.
D) Through the evaporation of large bodies of water.
Correct Answer: C) By the movement and collision of Earth's lithospheric plates.
Explanation: Mountain ranges are often formed by the movement and collision of lithospheric plates. When two plates collide, the crust can be pushed upwards to form mountains. This process is a fundamental aspect of plate tectonics, illustrating the dynamic nature of Earth's surface.
Why do some substances dissolve in water while others do not?
A) Substances that are heavier than water cannot dissolve.
B) Only substances that react chemically with water can dissolve.
C) The ability to dissolve depends on the molecular structure and the forces between the water molecules and the substance.
D) Substances dissolve in water based on their color.
Correct Answer: C) The ability to dissolve depends on the molecular structure and the forces between the water molecules and the substance.
Explanation: The solubility of a substance in water depends on its molecular structure and the type of forces that exist between the substance's molecules and water molecules. Polar substances and those that can form hydrogen bonds with water are generally soluble, while non-polar substances are less likely to dissolve.
