Nature of Science
Two different scientists perform the same experiment and collect slightly different data. What is the most scientific course of action?
A. Each scientist should discard the other's results.
B. Both scientists should repeat the experiment and compare methods.
C. The scientist with the most experience should decide which data is correct.
D. They should combine their data to match the expected result.
B. Both scientists should repeat the experiment and compare methods.
🔍 Explanation: When results differ, repeating the experiment and checking procedures helps identify possible errors or variations. Collaboration and repetition are key in scientific investigations
A solid changes into a liquid at 0°C. This is an example of:
A. A chemical change
B. Condensation
C. Freezing
D. Melting
D. Melting
🔍 Explanation: Melting is the phase change from solid to liquid. For water, this occurs at 0°C. No new substance is formed, so it's a physical change, not chemical.
n the food chain: Grass → Rabbit → Fox → Wolf
What would most likely happen if all the foxes disappeared?
A. Rabbit population would decrease
B. Grass would overpopulate
C. Wolf population would increase immediately
D. Rabbit population would increase due to less predation
D. Rabbit population would increase due to less predation
🔍 Explanation: With no foxes to eat them, rabbits would increase, leading to overgrazing and eventual ecosystem imbalance. Food chains are delicate systems
What causes the Moon to appear to change shape in the night sky?
A. The Moon changes size
B. Earth’s shadow falls on the Moon
C. The Moon reflects sunlight as it orbits Earth
D. Clouds cover different parts of the Moon
C. The Moon reflects sunlight as it orbits Earth
🔍 Explanation: The Moon doesn’t emit its own light. As it orbits Earth, we see different portions of its sunlit side, creating phases.
Which subatomic particle determines the identity of an element?
A. Neutron
B. Proton
C. Electron
D. Ion
B. Proton
🔍 Explanation: The number of protons in an atom (its atomic number) defines what element it is. For example, all carbon atoms have exactly 6 protons.
Which best illustrates the difference between a scientific theory and a scientific law?
A. A theory describes how something happens, while a law explains why it happens.
B. A law is proven true, while a theory is an opinion.
C. A law describes a pattern in nature, while a theory explains the cause of the pattern.
D. A theory becomes a law after enough experiments are done.
C. A law describes a pattern in nature, while a theory explains the cause of the pattern.
🔍 Explanation: Laws describe what happens (often mathematically), while theories explain why it happens. For example, Newton’s Law of Gravity describes attraction between masses; Einstein’s theory explains how gravity works.
Which statement correctly describes the relationship between temperature and particle motion in a substance?
A. As temperature increases, particles move slower
B. As temperature decreases, particles vibrate more
C. Temperature has no effect on particle motion
D. As temperature increases, particle motion increases
D. As temperature increases, particle motion increases
🔍 Explanation: Heat gives particles energy. In solids, they vibrate more; in gases, they move faster. This relationship explains changes in states of matter and pressure.
Which of the following is not required for photosynthesis to occur?
A. Water
B. Carbon dioxide
C. Oxygen
D. Sunlight
C. Oxygen
🔍 Explanation: Oxygen is a product of photosynthesis, not a reactant. The process requires carbon dioxide, water, and sunlight to make glucose and release oxygen.
What determines the color of a star?
A. The number of planets orbiting it
B. Its distance from Earth
C. Its surface temperature
D. The gases in its core
C. Its surface temperature
🔍 Explanation: The color of a star is directly related to its temperature. Hot stars appear blue or white, while cooler stars appear red or orange.
Which two body systems work together to deliver oxygen to the body’s cells?
A. Digestive and endocrine
B. Respiratory and circulatory
C. Nervous and muscular
D. Skeletal and excretory
B. Respiratory and circulatory
🔍 Explanation: The respiratory system brings oxygen into the lungs, while the circulatory system transports that oxygen through the bloodstream to the body’s cells.
A student develops a hypothesis that increasing the amount of light will cause plants to grow faster. Which step should come next?
A. Prove the hypothesis is true
B. Publish the results immediately
C. Test the hypothesis with an experiment
D. Change the hypothesis if others disagree
C. Test the hypothesis with an experiment
🔍 Explanation: In the scientific method, a hypothesis is tested through controlled experimentation to gather evidence. Scientific conclusions are based on data, not opinions.
Endothermic reactions pull in heat from the environment, lowering the surrounding temperature. An example is photosynthesis or ice melting. Which of the following describes an endothermic reaction?
A. Heat is released, making the surroundings warmer
B. Light is produced as a byproduct
C. Heat is absorbed, making the surroundings cooler
D. Energy is converted into mass
C. Heat is absorbed, making the surroundings cooler
In an ecosystem, which organisms are responsible for returning nutrients to the soil?
A. Producers
B. Consumers
C. Decomposers
D. Herbivores
C. Decomposers
🔍 Explanation: Decomposers like fungi and bacteria break down dead organisms and waste, releasing nutrients back into the soil for plants to use.
A comet differs from an asteroid because:
A. It orbits backward
B. It has a solid metal core
C. It has a glowing tail of gas and dust
D. It remains in Earth’s atmosphere
C. It has a glowing tail of gas and dust
🔍 Explanation: Comets are made of ice and dust, and as they approach the Sun, they develop a visible tail due to solar radiation and winds. Asteroids are mostly rocky and do not have tails.
A skateboarder at the top of a ramp has what kind of energy?
A. Kinetic energy
B. Sound energy
C. Potential energy
D. Thermal energy
C. Potential energy
🔍 Explanation: At the top of the ramp, the skateboarder has gravitational potential energy stored due to height. It can be converted into kinetic energy when moving downhill.
Angie looked under a microscope and saw cells that contain a relatively large structure filled with water. She concluded she was observing a plant cell. Why did she draw that conclusion?
A She observed a central vacuole.
B She observed a chloroplast.
C She observed a lysosome.
D She observed a nucleus.
A) She observed a central vacuole.
Explanation:
Plant cells typically contain a large central vacuole, which is a membrane-bound structure filled with water and dissolved substances. This vacuole helps maintain cell structure and stores nutrients and waste products. It's much larger in plant cells than in animal cells.
Which of the following statements about atoms is correct?
A. Protons and electrons are found in the nucleus
B. Neutrons have a positive charge
C. Electrons orbit the nucleus in energy levels
D. Atoms only contain protons and electrons
C. Electrons orbit the nucleus in energy levels
🔍 Explanation: Electrons move in specific energy levels (or shells) around the nucleus, which contains protons (positive) and neutrons (neutral).
What happens to energy as it moves up the food chain?
A. It is created
B. It increases at each level
C. It remains the same
D. It decreases due to heat loss
D. It decreases due to heat loss
🔍 Explanation: Only about 10% of the energy at one trophic level is passed on to the next. The rest is lost as heat through metabolic processes.
Which object is most massive?
A. The Earth
B. The Sun
C. The Moon
D. Jupiter
B. The Sun
🔍 Explanation: The Sun contains about 99.8% of the total mass of the solar system—much more than any planet, including Jupiter.
A doctor is examining an unknown sample and concludes that it is a tissue. Which most likely explains why the doctor made that conclusion?
A The sample contained cytoplasm and organelles.
B The sample had a membrane and a nucleus.
C The sample was made of a group of similar cells. D The sample was made of two kinds of cells.
C) The sample was made of a group of similar cells.
Explanation:
A tissue is defined as a group of similar cells that work together to perform a specific function. The presence of similar, organized cells is a clear indicator that the sample is a tissue.
A scientist notices that more people are getting colds in the winter months. She hypothesizes that cold weather weakens the immune system, making people more susceptible to colds. Which of the following is a testable hypothesis?
A. Cold weather makes people miserable.
B. Cold weather weakens the immune system, causing colds.
C. Colds are more common in the winter.
D. People should stay warm to prevent colds.
B. Cold weather weakens the immune system, causing colds.
🔍 Explanation: A testable hypothesis is a statement that can be measured or tested through experimentation. The hypothesis about cold weather weakening the immune system can be tested by studying how temperature affects immune function and the frequency of colds.
Which process best describes how a gas changes to a liquid?
A. Sublimation
B. Melting
C. Condensation
D. Freezing
C. Condensation
🔍 Explanation: Condensation is the process where gas loses energy and becomes a liquid, like when water vapor turns into dew.
Mammals are complex organisms whose bodies are highly organized. Which choice lists levels of organization in mammals from least organized to most organized?
A cells → molecules → atoms
B cells → tissues → organs
C molecules → tissues → cells
D organs → tissues → cells
B) cells → tissues → organs
Explanation:
In mammals (and all multicellular organisms), the levels of biological organization from least organized to most organized are:
Cells – The basic unit of life.
Tissues – Groups of similar cells that work together to perform a specific function.
Organs – Structures made up of different tissues that work together to perform complex functions.
What causes lunar phases?
A. The Moon’s rotation on its axis
B. The Earth’s shadow falling on the Moon
C. The changing positions of the Earth, Moon, and Sun
D. Changes in the Moon’s surface
C. The changing positions of the Earth, Moon, and Sun
🔍 Explanation: As the Moon orbits Earth, the portion illuminated by the Sun changes from our point of view, causing the different phases.
Which statement best explains why we always see the same side of the Moon?
A. The Moon rotates once every 28 days, the same time it takes to orbit Earth
B. The Moon doesn’t rotate
C. Earth blocks the other side of the Moon
D. The Moon’s orbit is too small to allow different angles
A. The Moon rotates once every 28 days, the same time it takes to orbit Earth
🔍 Explanation: This synchronous rotation means the Moon turns at the same rate it revolves, so the same side always faces Earth.