Science Free Sample | TruePath Academics

Ecosystem Population Change

Which statement best describes ecological succession?

Choose your answer

A Succession can help a community move toward a more stable balance after change

B Succession has no relationship to community recovery

C Succession and equilibrium mean exactly the same thing

D Succession prevents any ecosystem from becoming stable

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The science behind this question

Succession describes community change over time after a disturbance or on a new surface.

Secondary succession begins where soil remains, such as after many fires or floods.

study image showing ecosystem recovery stages from disturbed ground to pioneer plants, shrubs, young trees, and returning animals, with a bare-rock lichen inset. — **Disturbance and Succession Recovery** After disturbance, populations and biodiversity may recover in stages as habitat resources return and succession proceeds.

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In a food web, hawks eat snakes and snakes eat mice. If mice decrease, what indirect effect may occur?

A. Hawks become producers immediately.
B. Snakes no longer need energy.
C. Hawks may decrease after snakes have less food.
D. Mice decrease cannot affect hawks.

A decrease in mice can reduce snakes, which can later affect hawks.

Answer to this example only: Hawks may decrease after snakes have less food.

Chemical Formulas and Atomic Models

An atom contains 6 protons and 8 neutrons. What is its mass number?

Choose your answer

A 48

B 8

C 6

D 14

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The science behind this question

Mass number equals protons plus neutrons, so neutrons equal mass number minus atomic number.

Isotopes are atoms of the same element with different numbers of neutrons, so their mass numbers differ while their proton counts stay the same.

study image showing alpha particles passing through, deflecting, or bouncing back from gold foil, plus a nuclear atom model with a tiny dense positive nucleus. — **Rutherford Evidence** Gold foil evidence supported a small dense positive nucleus and mostly empty space in atoms.

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Which particle has no electric charge?

A. Neutron
B. Electron
C. Nucleus
D. Proton

A neutron has no electric charge. Protons are positive, and electrons are negative.

Answer to this example only: Neutron

Friction and Air Resistance

Which action would reduce friction?

Choose your answer

A Increasing surface grip

B Adding sand

C Lubricating surfaces

D Roughening surfaces

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The science behind this question

Smoother surfaces, wheels, bearings, and lubricants often reduce friction by helping surfaces move past each other more easily.

Rolling friction acts when a wheel, ball, or roller moves across a surface.

study image comparing static friction, sliding friction, rolling friction, rough surfaces, and smooth or lubricated surfaces with correct opposing force arrows. — **Friction Types and Surface Effects** Friction opposes motion or attempted motion. Static, sliding, and rolling friction appear in different situations, and surface condition changes how much friction acts.

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Which conclusion is best for static friction?

A. It is the same as gravity.
B. It exists only in outer space.
C. It acts only after surfaces are sliding quickly.
D. It can prevent an object from starting to move.

Static friction acts before sliding begins.

Answer to this example only: It can prevent an object from starting to move.

Rocks, Minerals, and the Rock Cycle

A student applies the concept. Fossils are most often preserved in which rock type?

Choose your answer

A Sedimentary rock

B Melted magma

C Fresh lava

D Inner core metal

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The science behind this question

Fossils are most commonly preserved in sedimentary rocks because organisms or traces can be buried gently before the sediment hardens.

Sedimentary rocks often have layers, rounded grains, ripple marks, mud cracks, and fossils.

study image showing weathering, erosion, deposition, compaction, cementation, layers, fossils, and a final sedimentary rock sample. — **Sedimentary Rock Formation Sequence** Sedimentary rock forms when sediment is deposited, buried, compacted, and cemented; fossils are possible in those layers.

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Heat and pressure can change existing rock into which rock type?

A. Fossil fuel
B. Metamorphic
C. Igneous
D. Sedimentary

Metamorphic rock forms when existing rock is changed by heat and pressure.

Answer to this example only: Metamorphic

Galaxies and the Universe

Which statement best compares elliptical and irregular galaxies?

Choose your answer

A Both contain no stars.

B Ellipticals are smooth and organized; irregulars lack a clear shape.

C Both have spiral arms.

D Both are planets.

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The science behind this question

Irregular = no clear spiral or elliptical shape.

A question may ask which type has arms, which looks smooth, which lacks a regular shape, which tends to have more gas and dust, or which may have more active star formation.

no-text study image showing a spiral galaxy, a smooth elliptical galaxy, and a patchy irregular galaxy side by side. — **Galaxy Types Comparison Study** Galaxy shape is a major classification clue: spiral galaxies have arms, elliptical galaxies look smooth, and irregular galaxies lack a regular shape.

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Which description best matches an elliptical galaxy?

A. Smooth oval-shaped collection of mostly older stars
B. Flat disk with arms
C. Ring structure
D. Chaotic cloud

The correct answer is A: Smooth oval-shaped collection of mostly older stars. Elliptical galaxies are smooth round or oval systems that often contain older stars and less gas and dust than spirals.

Answer to this example only: Smooth oval-shaped collection of mostly older stars

Science

Which statement best describes ecological succession?

The science behind this question

An atom contains 6 protons and 8 neutrons. What is its mass number?

The science behind this question

Which action would reduce friction?

The science behind this question

A student applies the concept. Fossils are most often preserved in which rock type?

The science behind this question

Which statement best compares elliptical and irregular galaxies?

The science behind this question

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