WCAS - Washington Comprehensive Assessment of Science — Questions and Answers

Question 1: A student stood quietly in a field observing a rabbit eating grass. The student moved and stepped on a twig. The twig broke, which made a loud sound, and the rabbit ran away. Choose the order that shows how a rabbit processes information after hearing a twig break. 1 - The rabbit hears a twig break. 2 - 3 - 4 - A. The rabbit acts. B. The rabbit's brain processes information. C. The rabbit's brain sends a message to act.

BAC
BCA (Correct answer)
CBA
ABC

Correct answer: BCA

Explanation: The sequence of events goes from the initial perception of the sound by the rabbit's ears, to the processing of this information by its brain, to the brain sending a signal to the muscles to act, and finally to the rabbit's physical response of running away.

Question 2: What type of rock is formed from the cooling and solidification of magma or lava?

Crystalline
Sedimentary
Metamorphic
Igneous (Correct answer)

Correct answer: Igneous

Explanation: Igneous rocks form from the cooling and solidification of magma or lava.

Question 3: An engineer is designing a new ski helmet. The primary criterion is safety, but other important criteria include low weight, comfort, and aerodynamics. The engineer finds that using a denser, thicker foam improves the safety rating significantly but also increases the helmet's weight and reduces its aerodynamic efficiency. This situation is a clear example of:

The need to make trade-offs between competing criteria. (Correct answer)
An error in the initial problem definition.
A systematic failure in the design process.
The complete satisfaction of all design constraints.

Correct answer: The need to make trade-offs between competing criteria.

This scenario perfectly illustrates the concept of a trade-off, which is central to engineering design. [13, 15] The engineer must balance the competing criteria of safety, weight, and aerodynamics. Improving one criterion (safety) has a negative impact on others (weight, aerodynamics). The final design will be a compromise that seeks to optimize the overall solution based on prioritized criteria.

Question 4: A rocket accelerates upward from a launchpad. According to Newton's Third Law of Motion, what is the 'reaction' force to the hot gases pushing downward from the rocket's engine?

The rocket pushing down on the launchpad.
The hot gases pushing up on the rocket. (Correct answer)
The force of gravity pulling the rocket down.
The air resistance pushing against the rocket.

Correct answer: The hot gases pushing up on the rocket.

Newton's Third Law states that for every action, there is an equal and opposite reaction. The 'action' force is the rocket's engine pushing the hot gases downward. The 'reaction' force is the hot gases pushing the rocket upward with an equal and opposite force, which causes the rocket to accelerate.

Question 5: A group of students designs a solar oven using a cardboard box, aluminum foil, plastic wrap, and black construction paper. The black paper is placed at the bottom of the box. What is the primary role of the black construction paper in this energy system?

To reflect sunlight away from the food.
To absorb radiant energy and convert it into thermal energy. (Correct answer)
To create a convection current inside the box.
To provide structural support for the oven.

Correct answer: To absorb radiant energy and convert it into thermal energy.

Dark-colored surfaces, especially black, are excellent absorbers of radiant energy. In the solar oven, the black paper's function is to absorb the maximum amount of incoming sunlight (radiant energy) and transform it into thermal energy (heat), which then cooks the food. The plastic wrap traps this heat inside the oven.

Question 6: According to the law of conservation of energy, which of the following statements is true?

The total amount of energy in an isolated system remains constant over time. (Correct answer)
Energy can be lost as heat, reducing the total energy in a closed system.
Energy transformations are always 100% efficient.
Energy can be created but not destroyed.

Correct answer: The total amount of energy in an isolated system remains constant over time.

The law of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another or transferred from one system to another. Therefore, in an isolated (or closed) system, the total amount of energy is always conserved.

Question 7: A student claims, "Plants require sunlight to grow." Which of the following statements provides the strongest scientific evidence to support this claim?

Plants look healthier and greener when they are outside in the sun.
It is a well-known fact that all plants need sunlight.
My friend told me that her plant died when she kept it in a dark closet.
An experiment was conducted where one plant was placed in sunlight and an identical plant was placed in a dark room; the plant in the sun grew 5 cm while the plant in the dark did not grow. (Correct answer)

Correct answer: An experiment was conducted where one plant was placed in sunlight and an identical plant was placed in a dark room; the plant in the sun grew 5 cm while the plant in the dark did not grow.

A scientific argument requires a claim supported by evidence and reasoning. The strongest evidence comes from controlled, repeatable investigations that produce measurable data. The statement describing a controlled experiment provides specific, empirical evidence that directly supports the claim that sunlight is necessary for growth, while the other options are anecdotal, assertions, or uncontrolled observations.

Question 8: A geologist studying the rock cycle finds a sample of shale, a sedimentary rock, that has been subjected to intense heat and pressure deep within the Earth's crust, transforming it into slate. Which of the following geological processes is responsible for this change?

Metamorphism (Correct answer)
Weathering
Lithification
Erosion

Correct answer: Metamorphism

Metamorphism is the process where existing rocks are altered by heat, pressure, or reactive fluids. The transformation of shale into slate is a classic example of metamorphism, where the original rock changes form without melting. [1, 3, 22, 24]

Question 9: Which statement accurately describes the relationship between genes, chromosomes, and DNA?

Chromosomes are made of genes, which are long strands of DNA.
Genes are segments of DNA, which is tightly coiled to form chromosomes. (Correct answer)
A gene is made of many chromosomes, which are composed of DNA.
DNA is a segment of a gene, which is located on a chromosome.

Correct answer: Genes are segments of DNA, which is tightly coiled to form chromosomes.

The correct hierarchical relationship is as follows: DNA is the molecule that carries genetic instructions. A gene is a specific segment of that DNA that codes for a protein or functional RNA molecule. This long strand of DNA is then tightly packaged and coiled around proteins to form a structure called a chromosome, which is located in the cell's nucleus.

Question 10: A student observes a cell under a microscope and notes the presence of a rigid cell wall, a large central vacuole, and numerous chloroplasts. Based on these observations, the student can most likely conclude that the cell is from what type of organism?

A plant (Correct answer)
A fungus
A bacterium
An animal

Correct answer: A plant

Plant cells have several distinct structures not found in animal cells, including a rigid cell wall for support, a large central vacuole to maintain turgor pressure, and chloroplasts for photosynthesis. Animal cells lack these features, and while bacteria have cell walls, they do not have membrane-bound organelles like chloroplasts or a large central vacuole.

Question 11: What term describes an inherited behavior that an organism can perform without ever learning how to do it?

Conditioning
Instinct (Correct answer)
Habituation
Adaptation

Correct answer: Instinct

Explanation: Instinct refers to inherited behaviors that organisms can perform without prior experience or learning. These behaviors are genetically programmed and often aid in survival, such as bird migration or spider web-building.

Question 12: When thermal energy is added to a pure substance in its solid state, the particles within the substance begin to vibrate more rapidly. If enough thermal energy is added, what change will most likely occur?

The substance will undergo a chemical reaction.
The substance will condense into a liquid.
The substance will melt into a liquid state. (Correct answer)
The particles will break apart into individual atoms.

Correct answer: The substance will melt into a liquid state.

Adding thermal energy increases the kinetic energy of particles in a substance. In a solid, this causes increased vibration. When the vibrations become strong enough to overcome the forces holding the particles in a fixed lattice, the solid melts and transitions into the liquid state. This is a physical change, not a chemical reaction. Condensation is the process of a gas turning into a liquid. Breaking particles into individual atoms would require a chemical reaction, not just a phase change.

Question 13: Which wave behavior allows waves to bend around the edges of obstacles or openings?

Diffraction (Correct answer)
Reflection
Absorption
Refraction

Correct answer: Diffraction

Diffraction is the spreading of waves around the edges of barriers or through openings, especially when the opening is close in size to the wavelength.

Question 14: A scientist is studying an unknown element. She observes that it has 12 protons and 12 neutrons in its nucleus. Based on the periodic table, what can be inferred about this element?

The element is a noble gas.
The element has similar properties to the element with 11 protons.
The element's atomic mass is 12.
The element's atomic number is 12. (Correct answer)

Correct answer: The element's atomic number is 12.

The atomic number of an element is defined by the number of protons in its nucleus. [6, 8] Since the unknown element has 12 protons, its atomic number is 12, which identifies it as Magnesium (Mg). The atomic mass is the sum of protons and neutrons (approximately 24 in this case). Elements are grouped by similar properties in columns, not by adjacent atomic numbers. [2, 15] Atomic number 12 is an alkaline earth metal, not a noble gas.

Question 15: Which term describes the physical or behavioral traits that develop during an organism's life in response to environmental factors?

Inherited trait
Genetic mutation
Acquired characteristic (Correct answer)
Evolutionary adaptation

Correct answer: Acquired characteristic

Explanation: Acquired characteristics are traits that an organism develops during its lifetime in response to environmental influences, rather than being inherited genetically. These traits can include skills learned through experience, changes in behavior, or physical adaptations due to environmental conditions.

Question 16: The Doppler effect describes which phenomenon?

A change in the observed frequency of a wave when the source or observer is moving (Correct answer)
The reflection of waves off smooth surfaces
The bending of waves as they pass through different media
Waves losing energy as they travel farther from the source

Correct answer: A change in the observed frequency of a wave when the source or observer is moving

The Doppler effect causes the observed frequency to increase as a wave source approaches and decrease as it moves away from the observer.

Question 17: Which of the following is NOT a type of plate boundary?

Perpendicular boundary (Correct answer)
Transform boundary
Divergent boundary
Convergent boundary

Correct answer: Perpendicular boundary

Explanation: Perpendicular boundary is not a recognized type of plate boundary.

Question 18: The heart is an organ composed of cardiac muscle tissue, connective tissue, and nervous tissue, all of which work together to pump blood. This is an example of which biological principle?

Multiple tissues combining to form a functional organ. (Correct answer)
Similar cells aggregating to form a single tissue.
Cells differentiating to perform unique roles.
Organs grouping together to form an organ system.

Correct answer: Multiple tissues combining to form a functional organ.

An organ is defined as a structure made up of two or more different types of tissues that work together to perform a specific function. In this case, the muscle, connective, and nervous tissues combine their functions to create the organ known as the heart.

Question 19: Sea otters are a crucial component of the kelp forest ecosystem. They prey on sea urchins, which in turn feed on kelp. Without sea otters, sea urchin populations explode, leading to the destruction of the kelp forests that provide habitat for numerous other species. Because of their disproportionately large effect on the ecosystem relative to their abundance, sea otters are considered a(n):

Keystone species (Correct answer)
Invasive species
Decomposer
Producer

Correct answer: Keystone species

A keystone species is an organism that has a disproportionately large effect on its environment relative to its abundance. The sea otter's role in controlling the sea urchin population is critical for the health and stability of the entire kelp forest ecosystem, making it a classic example of a keystone species.

Question 20: A student places a metal spoon in a bowl of hot soup. After a few minutes, the handle of the spoon becomes warm. Which of the following correctly describes the primary method of heat transfer that causes the spoon's handle to warm up?

Conduction, because heat energy is transferred from particle to particle along the spoon. (Correct answer)
Radiation, because the soup emits thermal energy in the form of waves.
Insulation, because the metal prevents the heat from escaping the soup.
Convection, because the heat from the soup circulates up the spoon.

Correct answer: Conduction, because heat energy is transferred from particle to particle along the spoon.

The correct answer is conduction. Conduction is the transfer of thermal energy through direct contact between particles. In this scenario, the particles of the soup with higher kinetic energy collide with the particles of the spoon, transferring that energy. This process continues up the solid metal spoon from one particle to the next, causing the handle to warm.

Question 21: A small island ecosystem can support a maximum population of 500 seabirds due to limited nesting sites and food resources. If the seabird population grows to 600 individuals, which of the following is the MOST likely outcome?

Other species will immigrate to the island to support the larger population.
The population will experience a decline due to density-dependent limiting factors. (Correct answer)
The birds will evolve to require fewer resources.
The island's carrying capacity will permanently increase to 600.

Correct answer: The population will experience a decline due to density-dependent limiting factors.

The carrying capacity is the maximum population size an environment can sustain. When a population exceeds its carrying capacity, density-dependent limiting factors like competition for food, increased disease transmission, and lack of space will lead to a decrease in the population size until it returns to a sustainable level.

Question 22: Which of the following is an example of a chemical change?

A bicycle frame rusting over time. (Correct answer)
Shredding a piece of paper into smaller pieces.
Dissolving sugar in a cup of hot tea.
Melting an ice cube into liquid water.

Correct answer: A bicycle frame rusting over time.

A chemical change results in the formation of a new substance with different properties. [1] Rusting is a chemical reaction where iron reacts with oxygen to form iron oxide (rust), a new substance. [7] Melting ice, shredding paper, and dissolving sugar are all physical changes because the chemical identity of the substance (H₂O, cellulose, sucrose) does not change. [3]

Question 23: Which celestial body is primarily responsible for causing ocean tides on Earth?

Jupiter
Venus
Moon (Correct answer)
Sun

Correct answer: Moon

Explanation: The gravitational pull of the Moon is the primary force behind ocean tides on Earth.

Question 24: In a population of rock pocket mice, most individuals have light-colored fur, which provides camouflage on sandy soil. A volcanic eruption covers the area in dark lava rock. Over many generations, the frequency of mice with dark-colored fur increases significantly in the population. This scenario is an example of:

Natural selection (Correct answer)
Genetic drift
Artificial selection
Acquired characteristics

Correct answer: Natural selection

This is a classic example of natural selection. The change in environment (dark lava rock) made dark-colored fur an advantageous trait for survival, as it provided better camouflage from predators. Mice with this heritable trait were more likely to survive and reproduce, passing the trait to their offspring, which led to an increase in its frequency in the population over time.

Question 25: A city located in a seismically active region of Washington State is updating its building codes to improve safety during an earthquake. Which engineering strategy would be most effective at mitigating damage to a new skyscraper?

Anchoring the building's foundation directly and deeply into the bedrock.
Making the building as lightweight as possible using only wood and glass.
Installing a base isolation system with lead-rubber bearings to absorb seismic energy. (Correct answer)
Using rigid, thick concrete walls to prevent any movement of the building.

Correct answer: Installing a base isolation system with lead-rubber bearings to absorb seismic energy.

Base isolation is a modern engineering technique designed to 'decouple' a building from its foundation during an earthquake. Flexible bearings, often made of lead and rubber, are installed in the foundation to absorb the seismic waves and allow the ground to move without transmitting the full force to the structure above. This significantly reduces shaking and mitigates damage.

Question 26: Which part of the electromagnetic spectrum do cell phones primarily use to send and receive signals?

Radio waves and microwaves (Correct answer)
Gamma rays
X-rays
Visible light

Correct answer: Radio waves and microwaves

Cell phones communicate using radio waves and microwaves, which can travel long distances and penetrate walls.

Question 27: In a complex multicellular organism, which organ system is primarily responsible for detecting stimuli from the environment and coordinating the body's responses?

Circulatory system
Endocrine system
Nervous system (Correct answer)
Muscular system

Correct answer: Nervous system

The nervous system, which includes the brain, spinal cord, and nerves, is specialized to detect changes (stimuli), process information, and send signals to muscles and glands (effectors) to produce a coordinated response.

Question 28: The amplitude of a wave is best described as:

The number of waves produced per second
The distance between two consecutive crests
The speed at which the wave travels
The maximum displacement of a medium from its rest position (Correct answer)

Correct answer: The maximum displacement of a medium from its rest position

Amplitude measures how far the wave displaces the medium from its equilibrium position, which relates to the wave's energy.

Question 29: The forelimbs of a human, the wing of a bat, and the flipper of a whale all have a very similar bone structure, despite performing different functions. Which of the following is the BEST explanation for this observation?

The different functions of the limbs caused the bone structures to become similar over time.
These organisms evolved in similar environmental conditions, leading to similar structures.
This is a coincidence, and the bone structures developed independently in each species.
These organisms share a common ancestor that had a similar forelimb structure. (Correct answer)

Correct answer: These organisms share a common ancestor that had a similar forelimb structure.

This is an example of homologous structures. These are structures that are similar in related organisms because they were inherited from a common ancestor. Even though the forelimbs are used for different functions (grasping, flying, swimming), the underlying similarity in bone arrangement points to a shared evolutionary history.

Question 30: How do digital communication devices encode and transmit information using waves?

By varying the temperature of the signal
By reversing the direction of wave travel
By encoding data as binary patterns in wave signals (Correct answer)
By changing the medium through which waves travel

Correct answer: By encoding data as binary patterns in wave signals

Digital devices convert information into binary code (0s and 1s) which is encoded into wave signals for transmission.

Question 31: According to multiple international scientific assessments, which human activity is the single largest driver of biodiversity loss globally?

Changes in land use, primarily for agricultural production. (Correct answer)
The introduction of invasive species into new habitats.
The spread of plastic and chemical pollution in the oceans.
The construction of large urban centers and associated sprawl.

Correct answer: Changes in land use, primarily for agricultural production.

While pollution, invasive species, and climate change are all significant threats, the primary driver of biodiversity loss to date has been land-use change, which results in habitat destruction and fragmentation. The conversion of natural habitats like forests and grasslands into farmland is the most significant form of this land-use change.

Question 32: Which of the following describes a density-independent limiting factor that could affect a population of deer in a forest?

A rise in the population of wolves, the primary predator of the deer.
An outbreak of a contagious disease that spreads quickly among the deer.
A sudden, severe forest fire that burns a large area. (Correct answer)
Increased competition for a limited supply of acorns during the winter.

Correct answer: A sudden, severe forest fire that burns a large area.

Density-independent factors affect a population regardless of its size or density. A forest fire is a catastrophic event that will impact the deer population whether it is large or small. The other options—disease, competition, and predation—are density-dependent factors, as their effects become more pronounced as the population density increases.

Question 33: Which of the following types of waves requires a medium to travel through?

Radio waves
Ultraviolet rays
Sound waves (Correct answer)
Light waves

Correct answer: Sound waves

Sound is a mechanical wave and must travel through a physical medium such as air, water, or a solid.

Question 34: From November to February, the constellation Orion is clearly visible in the night sky from Mississippi. Orion appears to rise from the east and set in the west. The stars do not actually move through the sky. They appear to change positions due to the Earth's Movement. What factor is responsible for the changes in Orion's position when viewed during the winter month?

The revolution of the moon around the Sun
The rotation of the Sun
The revolution of the Sun around the Earth
The rotation of Earth on its axis (Correct answer)

Correct answer: The rotation of Earth on its axis

Explanation: As the Earth rotates on its axis, different parts of the sky become visible from different locations on the planet. This rotation causes celestial objects, such as stars and constellations like Orion, to appear to move across the sky from east to west. So, as the Earth rotates during the night, it gives the impression that Orion rises from the east and sets in the west. This apparent motion is due to the observer's perspective from the rotating Earth, not due to the stars actually moving.

Question 35: When a wave passes from one medium into another, which wave property always remains unchanged?

Amplitude
Wavelength
Frequency (Correct answer)
Speed

Correct answer: Frequency

Frequency is determined by the source of the wave and does not change when the wave enters a new medium.

Question 36: A coastal community in Washington notices a significant increase in the frequency and size of harmful algal blooms in the nearby estuary, leading to 'dead zones' where fish cannot survive. Which human activity is the MOST likely cause of this phenomenon, known as eutrophication?

Increased carbon dioxide emissions from local industrial plants.
The construction of a new dam on a river that feeds into the estuary.
Overfishing of commercially important fish species within the estuary.
Runoff of fertilizers and animal waste from agricultural areas upstream. (Correct answer)

Correct answer: Runoff of fertilizers and animal waste from agricultural areas upstream.

Eutrophication is the process where a body of water becomes overly enriched with nutrients, leading to excessive growth of algae. When the algae die and decompose, the process consumes large amounts of dissolved oxygen, creating hypoxic 'dead zones' where aquatic life cannot survive. The primary source of these excess nutrients, particularly nitrogen and phosphorus, is agricultural runoff containing fertilizers and animal waste.

WCAS - Washington Comprehensive Assessment of Science

The Washington Comprehensive Assessment of Science (WCAS) is a state-mandated assessment aligned to the Next Generation Science Standards (NGSS), measuring student proficiency in science at grades 5, 8, and 11.

Questions

120 min

Time Limit

65%

To Pass

Checking for saved progress...

Exam Rules

You can skip questions and return to them later
Flag questions for review before submitting
No feedback shown until you submit the entire exam
Unanswered questions count as wrong — answer everything
10 pretest questions are mixed in and don't affect your score
Timer auto-submits when time runs out
Your progress is auto-saved every 30 seconds