UPCAT General Science (Extended) — Universe, Solar System & EarthFlash Cards

What is the Big Bang Theory and when did it occur?

The Big Bang Theory explains that the universe began as a singularity - an infinitely hot, dense point just millimeters in size - that exploded 13.8 billion years ago. This explosion created energy, space, time, and matter, leading to the expanding universe we observe today.

Why do we see red-shifted light from distant galaxies?

Red-shifted light occurs because distant galaxies are moving away from us due to universal expansion. As galaxies recede, their light waves stretch to longer (redder) wavelengths - like how an ambulance siren sounds lower as it moves away from you.

What are the three most abundant elements in the universe?

Hydrogen (most abundant), Helium, and Lithium. These light elements were formed during the first few minutes after the Big Bang when the universe was hot enough for nuclear fusion but cool enough for nuclei to remain stable.

During which epoch of the Radiation Era were protons and neutrons first formed?

Hadron Epoch (10⁻⁶ seconds after Big Bang, temperature 10¹⁰ K). The universe cooled enough for quarks to bind together, forming the first protons and neutrons - the building blocks of atomic nuclei.

How did our solar system form 4.6 billion years ago?

A star in our region exploded, dispersing matter. Gravitational forces collected this matter into clumps that cooled and formed the Sun, planets, and asteroid belt. Heavy elements sank to planet cores while lighter materials formed crusts and atmospheres.

Why are inner planets rocky while outer planets are gas giants?

Distance from the Sun determines composition. Close to the Sun, only materials with high melting points (silicates, iron, nickel) could condense, forming rocky planets. Far from the Sun, gases and ices could condense, creating massive gas giants with thick atmospheres.

How did Earth get its Moon?

A Mars-sized planet called Theia collided with early Earth, scraping away a large portion of Earth's surface. The debris trapped by Earth's gravity eventually coalesced to form the Moon. This impact also helped tilt Earth's axis.

What are the four main layers of Earth's structure?

From outside to inside: Crust (solid outer shell), Mantle (hot, semi-fluid rock), Outer Core (liquid iron and nickel), Inner Core (solid iron and nickel). Temperature and pressure increase with depth.

What evidence did Alfred Wegener use to support Continental Drift Theory?

Four key evidences: 1) Continents fit like puzzle pieces, 2) Similar fossils on separated continents (like Mesosaurus), 3) Matching rock formations across oceans, 4) Glacial striations in now-tropical regions showing past ice ages.

How does seafloor spreading work at mid-ocean ridges?

Hot magma rises from the mantle between oceanic plates, filling gaps and pushing plates apart. New oceanic crust forms as magma cools. Older crust moves away from the ridge and eventually subducts under continental crust.

What happens when two continental plates collide?

Neither plate subducts because both have similar density. Instead, the collision crumples and uplifts the crust, forming mountain ranges like the Himalayas. This is called continental-continental convergent boundary.

Why do earthquakes occur along transform faults like the San Andreas Fault?

Plates slide past each other horizontally, creating friction that causes them to stick. Pressure builds up over time until the plates suddenly jerk apart, releasing stored energy as seismic waves - causing earthquakes.

What is the difference between P-waves and S-waves in earthquakes?

P-waves (Primary): Compress and stretch rock like sound waves, travel through solids and liquids, arrive first. S-waves (Secondary): Move rock sideways perpendicular to direction, only travel through solids, arrive second and cause more damage.

How do composite volcanoes differ from shield volcanoes?

Composite: Steep, cone-shaped with explosive eruptions from thick, viscous lava (like Mount Mayon). Shield: Broad, gentle slopes with fluid lava flows from multiple vents (like Hawaiian volcanoes). Different magma composition creates different eruption styles.

What is the rock cycle and how do the three rock types transform?

Continuous process where rocks change types: Igneous rocks (from cooling magma/lava) → Sedimentary rocks (from weathering/deposition) → Metamorphic rocks (from heat/pressure) → back to igneous when melted. Any rock can become any other type.

Why does granite have large crystals while obsidian looks like black glass?

Granite: Intrusive igneous rock that cooled slowly underground, allowing large crystals to form. Obsidian: Extrusive igneous rock that cooled rapidly on surface, preventing crystal formation and creating a glassy texture.

What processes turn loose sediments into solid sedimentary rock?

Three main processes: 1) Compaction - weight of overlying sediments squeezes particles together, 2) Cementation - minerals precipitate from water and glue particles, 3) Lithification - overall hardening process creating solid rock from loose materials.

How does chemical weathering differ from physical weathering?

Physical weathering: Breaks rocks into smaller pieces without changing composition (like freeze-thaw cycles). Chemical weathering: Changes rock composition through reactions (like limestone dissolving in acid rain to form caves).

What makes Earth habitable compared to Venus and Mars?

Earth is in the 'Goldilocks Zone' - perfect distance from Sun for liquid water. Venus is too hot (runaway greenhouse effect), Mars is too cold (thin atmosphere). Earth also has protective magnetic field, stable rotation, and ozone layer blocking harmful radiation.

What are Earth's four spheres and how do they interact?

Lithosphere (solid Earth), Hydrosphere (all water), Atmosphere (gas layer), Biosphere (all life). They constantly interact: water cycle connects hydro-atmosphere, weathering links litho-hydrosphere, life depends on all spheres and modifies them.