Junior Cycle 3rd-Year Science Notes: Strand Two — Earth and Space

*Water Cycle Processes*

Evaporation, Condensation, Precipitation, Runoff, Infiltration.

*Water Cycle Importance*

Distributes water, supports ecosystems, and regulates Earth's climate.

*Carbon Cycle: Photosynthesis*

Plants take in CO₂ and convert it into glucose using sunlight.

*Carbon Cycle: Respiration*

Animals and plants release CO₂ back into the atmosphere by breaking down glucose for energy.

*Carbon Cycle: Decomposition*

Dead organisms are broken down by decomposers, releasing CO₂ and methane into the atmosphere.

*Carbon Cycle: Combustion*

Burning fossil fuels and biomass releases stored carbon as CO₂.

*Carbon Cycle: Ocean Uptake*

Oceans absorb CO₂, where it forms carbonates used by marine organisms or remains dissolved.

*Carbon Cycle Importance*

Regulates Earth's temperature, supports life, and balances carbon between the atmosphere, oceans, and biosphere.

*Nitrogen Cycle: Fixation*

Atmospheric nitrogen (N₂) is converted into ammonia (NH₃) by bacteria or lightning.

*Nitrogen Cycle: Nitrification*

Ammonia is converted into nitrites (NO₂⁻) and then nitrates (NO₃⁻) by soil bacteria.

*Nitrogen Cycle: Assimilation*

Plants absorb nitrates and use them to build proteins and DNA.

*Nitrogen Cycle: Ammonification*

Decomposers convert organic nitrogen from dead organisms back into ammonia.

*Nitrogen Cycle: Denitrification*

Bacteria convert nitrates back into atmospheric nitrogen (N₂).

*Nitrogen Cycle Importance*

Provides essential nutrients for plants, supports food chains, and recycles nitrogen through ecosystems.

*Types of Energy*

Kinetic, Potential, Thermal, Chemical, Electrical, Nuclear.

*Law of Conservation of Energy*

Energy cannot be created or destroyed, only transferred or transformed.

*Renewable Energy Sources*

Solar, wind, hydropower.

**Non

renewable Energy Sources** - Fossil fuels (coal, oil, gas).

*Climate Change Causes: Natural*

Volcanic eruptions, solar variations.

*Climate Change Causes: Human*

Burning fossil fuels, deforestation, industrial emissions.

*Climate Change Effects*

Rising global temperatures, melting ice caps, sea-level rise, extreme weather events.

*Climate Change Solutions*

Reducing emissions, renewable energy use, reforestation, sustainable practices.

*Food Chain Definition*

A sequence showing how energy and nutrients flow through an ecosystem.

*Example Food Chain*

Grass → Rabbit → Fox.

Producers*

Plants and algae that make their own food through photosynthesis.

*Primary Consumers*

Herbivores that eat producers.

*Secondary Consumers*

Carnivores that eat herbivores.

* Tertiary Consumers*

Top predators that eat other carnivores.

* Decomposers*

Break down dead material, returning nutrients to the soil.

*Food Chain Importance*

Shows energy flow, maintains ecosystem balance, and highlights interdependence among organisms.

*Galaxies Types*

Spiral (e.g., Milky Way), Elliptical, irregular

*Star Life Cycle*

Nebula → Protostar → Main Sequence → Red Giant/Supergiant → White Dwarf/Neutron Star/Black Hole.

*Solar System Components*

Sun, 8 planets, moons, asteroids, comets, meteoroids.

*Celestial Objects*

Includes planets, stars, asteroids, comets, and moons.

*Big Bang Definition*

Theory that the universe began as a single, dense point around 13.8 billion years ago and has been expanding ever since.

*Big Bang Evidence: Cosmic Microwave Background Radiation*

Leftover heat from the Big Bang, detected as faint radiation in the universe.

*Big Bang Evidence: Redshift of Galaxies*

Light from distant galaxies shifts toward the red end of the spectrum, indicating they are moving away.

*Big Bang Evidence: Abundance of Light Elements*

Predicted proportions of hydrogen and helium match observations.

*Big Bang Importance*

Explains the origin of the universe and sets the foundation for understanding cosmic evolution.

*Solar Eclipse*

Moon blocks the Sun (occurs during a New Moon).

*Lunar Eclipse*

Earth blocks sunlight from reaching the Moon (occurs during a Full Moon).

*Comparing Planetary Data*

Characteristics include size, mass, distance from the Sun, composition, number of moons, and atmospheric conditions.

*Space Technology*

Satellites, telescopes, space probes, rovers.

*Space Travel Achievements*

Moon landings, Mars rovers, International Space Station.

*Space Travel Hazards*

Microgravity effects, cosmic radiation, psychological challenges, spacecraft malfunctions.

**Media

Based Arguments** - Check sources, scientific evidence, and bias.

*Earth's Rotation and Revolution*

Causes day/night and seasons.

*Moon's Orbit*

Takes ~27.3 days to orbit Earth.

*Lunar Phases*

New Moon, Crescent, First Quarter, Gibbous, Full Moon, Last Quarter.

*Tides: Spring Tides*

Occur during Full and New Moons.

*Tides: Neap Tides*

Occur during Quarter Moons.