Puerto Rico CRECE Science — Grade 4

Which form of energy is stored in a battery and converted into electrical energy when connected to a circuit?

• AChemical energy
• BSound energy
• CLight energy
• DThermal energy

What happens when a light ray hits a smooth, shiny surface like a polished mirror?

• AIt bounces off the surface in a straight direction (reflection).
• BIt bends as it passes completely through the surface (refraction).
• CIt is completely absorbed and turned into sound energy.
• DIt slows down and stops moving entirely.

Which component is necessary in a simple electric circuit to open or close the path for electrical current?

• ASwitch
• BInsulator
• CPlastic casing
• DGlass tube

A student pushes a heavy box across a wooden floor. What force opposes the motion of the box and causes it to slow down?

• AFriction
• BGravity
• CMagnetism
• DStatic electricity

Which state of matter has a definite volume but takes the shape of its container?

• ALiquid
• BSolid
• CGas
• DPlasma

Which material is attracted to a magnet?

• AIron nail
• BPlastic spoon
• CWooden block
• DAluminum foil

When water boils on a stove and changes from a liquid to water vapor, what process is occurring?

• AEvaporation
• BCondensation
• CFreezing
• DDeposition

Which device transforms electrical energy into thermal energy and light energy?

• AIncandescent light bulb
• BHand-held mirror
• CWooden pencil
• DPlastic ruler

Sound energy travels through air as vibrations. What is required for sound to travel from a drum to a listener's ear?

• AA medium made of matter (such as air)
• BA complete electrical circuit
• CDirect sunlight rays
• DA magnetic field

Which material is a good electrical conductor that allows electric current to flow easily?

• ACopper wire
• BRubber band
• CGlass cup
• DDry wooden stick

Which plant part absorbs water and mineral nutrients from the soil while anchoring the plant in the ground?

• ARoots
• BLeaves
• CFlowers
• DStems

What is the primary role of green leaves on a plant?

• ATo produce food (sugar) using sunlight through photosynthesis
• BTo absorb water directly from deep underground rocks
• CTo produce pollen for reproduction
• DTo store underground tubers during winter

An organism that eats only plants for energy is classified as a:

• AHerbivore
• BCarnivore
• COmnivore
• DDecomposer

In a simple food chain, what role do green plants play?

• AProducers
• BConsumers
• CDecomposers
• DPredators

Which sensory organ allows animals to process light signals from their surroundings and form visual images?

• AEyes
• BEars
• CNose
• DSkin

Why do some insects have coloration and patterns that blend in with plant leaves or tree bark?

• ATo camouflage and hide from predators
• BTo produce more solar heat energy
• CTo attract direct sunlight for photosynthesis
• DTo make their exoskeleton heavier

The Puerto Rican Coquí (Eleutherodactylus) is famous for its distinctive call. What type of animal is the coquí frog?

• AAmphibian
• BReptile
• CMammal
• DBird

Which human body system includes the heart, blood, and blood vessels to transport oxygen and nutrients?

• ACirculatory system
• BDigestive system
• CRespiratory system
• DSkeletal system

What do decomposers like mushrooms and bacteria do in an ecosystem?

• ABreak down dead plant and animal matter, returning nutrients to the soil
• BCapture sunlight to create new sugars for herbivores
• CHunt live animals for food energy
• DPrevent rain from falling in forest biomes

Which animal adaptation helps a hawk locate small mice running in grass from far above in the sky?

• AKeen sharp eyesight
• BWebbed swimming feet
• CThick insulating blubber layer
• DGills for underwater breathing

What Earth process breaks down solid rocks into smaller fragments over time due to wind, water, and ice?

• AWeathering
• BVolcanism
• CEvaporation
• DCondensation

Which soil layer usually contains the highest concentration of organic humus, plant roots, and rich nutrients?

• ATopsoil
• BBedrock
• CSubsoil
• DSolid granite rock layer

Which of the following is a renewable natural energy resource available in Puerto Rico?

• ASolar energy from the sun
• BCoal mined from Earth
• CPetroleum oil
• DNatural gas

Why does the Sun appear to move across the sky from east to west each day?

• ABecause Earth rotates on its axis from west to east
• BBecause the Sun orbits around the Earth every 24 hours
• CBecause the Moon pushes the Sun across space
• DBecause Earth stops spinning during daytime

What causes day and night on planet Earth?

• AEarth's rotation on its axis
• BEarth's revolution around the Sun
• CThe Moon passing in front of the Sun
• DSeasonal temperature changes

Water vapor in clouds cools down and condenses to form liquid droplets that fall to Earth as rain. This process is part of:

• AThe water cycle
• BThe rock cycle
• CThe oxygen cycle
• DThe nitrogen cycle

Which instrument measures atmospheric temperature in degrees Celsius (°C) or Fahrenheit (°F)?

• AThermometer
• BBarometer
• CAnemometer
• DRain gauge

Rocks formed from cooling molten magma or lava are classified as:

• AIgneous rocks
• BSedimentary rocks
• CMetamorphic rocks
• DFossil rocks

What shadow length is observed at solar noon when the Sun is at its highest point in the sky?

• AThe shortest shadow of the day
• BThe longest shadow of the day
• CNo shadow at all anywhere on Earth
• DA shadow pointing directly east

Why are mangrove trees along the coasts of Puerto Rico important for coastal protection?

• ATheir dense root systems trap sediment and reduce coastal erosion from ocean waves
• BThey absorb all sunlight and prevent ocean tides from rising
• CThey produce salt crystals that solidify beach sand
• DThey attract volcanic eruptions to build new land

A solar-powered outdoor light charges during the daytime and glows at night. Which energy transformation occurs when the light turns on at night?

• AStored chemical energy in the battery -> Electrical energy -> Light and thermal energy
• BLight energy -> Nuclear energy -> Sound energy
• CSound energy -> Mechanical energy -> Electrical energy
• DThermal energy -> Gravitational energy -> Chemical energy

A student plucks a tight rubber band and then plucks a loose rubber band of the same length. How does tightening the rubber band affect the sound produced?

• AThe tighter rubber band vibrates faster and produces a higher pitch sound.
• BThe tighter rubber band vibrates slower and produces a lower pitch sound.
• CThe tighter rubber band stops vibrating and makes no sound.
• DThe tighter rubber band changes color while maintaining identical vibrations.

When a pencil is placed in a clear glass half-filled with water, the pencil looks broken or bent at the water surface. What optical phenomenon causes this appearance?

• ARefraction (bending of light as it passes between air and water)
• BReflection (bouncing of light off a silver mirror)
• CAbsorption (blocking of all light energy)
• DDiffraction around solid barriers

In a series circuit containing a battery, two light bulbs, and copper wires, what happens if one light bulb burns out and breaks its filament?

• AThe circuit opens and the second light bulb turns off immediately.
• BThe second light bulb becomes twice as bright.
• CThe battery reverses its electrical polarity.
• DElectric current increases through the remaining wires.

Why are electrical copper wires wrapped in flexible plastic coating?

• APlastic is an insulator that prevents electric current from shocking people or causing sh…
• BPlastic is a conductor that accelerates the flow of electric current.
• CPlastic generates electrical energy for the wire.
• DPlastic transforms electricity into magnetic forces.

Two students pull on opposite ends of a rope with equal force (50 Newtons each). What will happen to the rope?

• AThe forces are balanced, so the rope will remain stationary.
• BThe rope will accelerate rapidly toward the left student.
• CThe rope will accelerate rapidly toward the right student.
• DThe forces will double the length of the rope instantly.

Which action demonstrates a chemical change creating a new substance?

• ABaking a cake batter until it turns into a fluffy cake
• BMelting an ice cube into liquid water
• CChopping a wooden log into smaller kindling sticks
• DTearing a sheet of notebook paper into tiny pieces

A student measures 50 milliliters of water in a graduated cylinder and freezes it in a freezer. What physical property stays the same before and after freezing?

• ATotal mass of the water sample
• BState of matter
• CTemperature
• DFlexibility of the water

Why does a marble roll farther across a smooth glass tabletop than across a thick wool carpet when pushed with the same force?

• AThe smooth glass surface generates less friction force opposing the marble.
• BThe carpet exerts a stronger gravitational pull on the marble.
• CThe glass tabletop creates a magnetic force pulling the marble forward.
• DThe marble loses all its mass while rolling on glass.

Which mixture can be separated easily using a magnet?

• AIron filings mixed with yellow beach sand
• BTable salt dissolved completely in warm water
• CWhite sugar mixed with powdered baking soda
• DRed sand mixed with brown soil

How do internal lungs work together with the circulatory system during animal respiration?

• ALungs take in oxygen gas from air, which is then absorbed into blood vessels and pumped b…
• BLungs produce glucose sugars that the heart converts directly into light energy.
• CLungs store solid calcium to build stronger limb bones.
• DLungs filter liquid water into digestive bile.

When a dog hears a sudden loud thunder sound, sound waves enter its ears and signal the brain. What is the dog's immediate behavioral response likely driven by?

• ASensory processing by the nervous system triggering a defensive or shelter-seeking respon…
• BPhotosynthesis activation in muscle cells
• CImmediate shedding of winter fur coat
• DDigestive enzyme release in stomach glands

Consider this food chain: Sun -> Phytoplankton -> Small Fish -> Puerto Rican Pelican. What happens to the pelican population if small fish numbers decline drastically due to overfishing?

• APelican numbers may decrease because their primary food energy source is scarce.
• BPelican numbers will instantly double because they eat phytoplankton instead.
• CPhytoplankton numbers will drop to zero immediately.
• DPelicans will begin producing energy through photosynthesis.

In the tropical rainforest understory of El Yunque in Puerto Rico, plants often have large, wide leaves. What adaptation advantage does this provide?

• AWide leaves capture maximum sunlight available beneath the dense forest canopy.
• BWide leaves reflect all rainwater away so roots stay dry.
• CWide leaves prevent insects from crawling on plant stems.
• DWide leaves absorb oxygen gas directly from deep soil rocks.

Which sequence correctly represents the stages of complete metamorphosis in a butterfly life cycle?

• AEgg -> Larva (Caterpillar) -> Pupa (Chrysalis) -> Adult butterfly
• BAdult -> Pupa -> Larva -> Egg
• CEgg -> Adult -> Pupa -> Nymph
• DNymph -> Larva -> Chrysalis -> Egg

Why do seeds of dandelion plants have light, feathery structure attachments?

• ATo allow the wind to carry seeds far away to new growing areas
• BTo attract large predatory birds to eat the seeds
• CTo sink deep into ocean waters for underwater germination
• DTo store heavy minerals inside the seed coating

Scientists discover fossils of ancient ocean clam shells embedded in rock layers high on a mountain in interior Puerto Rico. What does this evidence indicate about the mountain's geological past?

• AThe land area was once submerged underwater beneath an ancient ocean.
• BAncient humans carried millions of clam shells up the mountain for fun.
• COcean clams learned to climb mountains to lay eggs millions of years ago.
• DThe rock layers were formed yesterday by strong rainfall.

The Puerto Rican Parrot (Amazona vittata) is an endangered bird species native to Puerto Rico. Which factor has contributed most to its population decrease in the wild?

• AHabitat destruction from deforestation and severe hurricane damage
• BOverabundance of nesting trees in rainforest reserves
• CExcessive rainfall nourishing tropical fruit trees
• DInability of adult birds to fly