Science flash cards

What is a moon?

A natural satellite that orbits a planet.

What is a star?

A large ball of hot gases that produces light and heat through nuclear fusion.

What is a planet?

A large object that orbits a star and does not produce its own light.

What is the order of the electromagnetic spectrum?

Radio → Microwave → Infrared → Visible Light → Ultraviolet → X-rays → Gamma Rays.

How do wavelength, frequency, and energy change across the EM spectrum?

As wavelength decreases, frequency and energy increase.

What is a light-year?

The distance light travels in one year (about 9.46 trillion km).

What is nuclear fusion?

The joining of small nuclei to form larger nuclei, releasing energy.

How are forces balanced in a star?

Gravity pulls inward while pressure from nuclear fusion pushes outward.

What is the Doppler Effect?

The change in wavelength or frequency due to the movement of an object.

What is red shift?

When light from an object moving away is stretched to longer wavelengths.

How does red shift support the Big Bang Theory?

It shows galaxies are moving away from us, meaning the universe is expanding.

What is Cosmic Microwave Background Radiation (CMBR)?

Leftover radiation from the Big Bang found throughout the universe.

How old is the universe according to the Big Bang Theory?

About 13.8 billion years old.

What is the atmosphere?

The layer of gases surrounding Earth.

What is the hydrosphere?

All water on Earth.

What is the geosphere?

Earth's rocks, soil, and landforms.

What is the biosphere?

All living things on Earth.

What are the four main greenhouse gases?

Carbon dioxide, methane, water vapour, and nitrous oxide.

What is the greenhouse effect?

Natural warming of Earth as greenhouse gases trap heat.

What is the enhanced greenhouse effect?

Extra warming caused by increased greenhouse gases from human activities.

What is albedo?

A measure of how much sunlight a surface reflects.

Why does ice have high albedo?

It reflects a large amount of sunlight back into space.

What happens when ice melts and albedo decreases?

More heat is absorbed, increasing warming.

What is a species?

A group of organisms that can breed and produce fertile offspring.

What is variation?

Differences between individuals in a population.

What is genetic variation?

Variation inherited through genes.

Give an example of genetic variation.

Eye colour.

What is acquired variation?

Variation gained during life and not inherited.

Give an example of acquired variation.

A scar.

What is biodiversity?

The variety of living organisms in an ecosystem.

Why is biodiversity important?

It keeps ecosystems healthy and stable.

How are humans decreasing biodiversity?

Habitat destruction, pollution, climate change, and overhunting.

How can biodiversity be conserved?

Protected areas, breeding programs, and reducing pollution.

What are the four steps of natural selection?

Variation → Competition → Survival → Reproduction.

How did giraffes evolve long necks?

Longer-necked giraffes could reach more food, survived better, and passed on their genes.

What are the three steps of speciation?

Isolation → Different selection pressures → Reproductive isolation.

What is artificial selection?

Humans choosing which organisms reproduce.

How do farmers use artificial selection?

Breeding plants or animals with desirable traits.

What is a problem with artificial selection?

Reduced genetic diversity.

What are the five pieces of evidence for evolution?

Fossils, comparative anatomy, embryology, DNA evidence, and biogeography.

What is a scalar quantity?

A quantity with magnitude only.

Give an example of a scalar quantity.

Speed.

What is a vector quantity?

A quantity with magnitude and direction.

Give an example of a vector quantity.

Velocity.

What is distance?

The total path travelled.

What is displacement?

The straight-line change in position from start to finish.

What is the formula for speed?

Speed = Distance ÷ Time.

What is velocity?

Speed in a given direction.

What is acceleration?

The rate of change of velocity.

What is the formula for acceleration?

Acceleration = Change in Velocity ÷ Time.

What do displacement-time graphs show?

How an object's position changes over time.

What does the slope of a displacement-time graph represent?

Velocity.

What do velocity-time graphs show?

How velocity changes over time.

What does the slope of a velocity-time graph represent?

Acceleration.

What is Newton's First Law?

An object stays at rest or moves at constant velocity unless acted on by an unbalanced force.

What is inertia?

The tendency of an object to resist changes in motion.

What is Newton's Second Law?

Force = Mass × Acceleration (F = ma).

What is Newton's Third Law?

For every action force, there is an equal and opposite reaction force.

Give a sporting example of Newton's Third Law.

A runner pushes backward on the ground, and the ground pushes the runner forward.

Why does a heavier object have more inertia?

Because greater mass makes it harder to change its motion.