What is the percentage of nitrogen in the air?
78%
What is the importance of the water cycle?
Because water is needed by all living things. It moves nutrient, pathogens and sediment in and out of aquatic ecosystems.
What is a source of carbon dioxide entering the atmosphere?
Fossil fuel use. Land use changes. Industrial processes.
True or false: The larger a star, the longer it takes to use all its fuel?
False
Name an animal that Sheldon is scared of.
Birds. Dogs. Chickens.
How do animals obtain nitrogen?
By eating plants, or eating animals that eat plants.
How does cow fart play a role in climate change?
It is a major source of the greenhouse gas methane. We mass produce beef and therefore this produces a lot of methane, contributing to the enhanced greenhouse effect and rising global temperatures.
List the 3 major greenhouse gases.
Carbon dioxide, methane, Chloroflurocarbons, Ozone, Nitrous Oxide.
Describe what a black holes is.
A collapsed star from which not even light can escape.
According to the big bang theory, how old is the universe?
13.7 billion years old
What forms of nitrogen can plants absorb?
Nitrates
Explain the meaning of Biosphere, atmosphere, lithosphere and hydrosphere.
Biosphere: Regions of the surface and atmosphere of the Earth occupied by living organisms.
Atmosphere: Envelope of gases surrounding the Earth.
Lithosphere: The rigid outer part of the Earth, consisting of the crust and upper mantle.
Hydrosphere: All the waters on the Earth's surface.
List 3 major sources of greenhouse gases.
Electricity, agriculture and industry.
What is the difference between apparent magnitude and absolute magnitude?
Apparent magnitude is the brightness of stars as observed from Earth. Absolute magnitude is the actual brightness of stars.
What is the name of Sheldon's sister?
Missy
What is the role of lightning in the nitrogen cycle?
Lightning breaks nitrogen molecules into nitrogen atoms. Nitrogen atoms combine with oxygen to form nitrogen oxides.
What was the period in time where greenhouse gases started to be emitted in much higher amounts by humans?
Industrial revolution and after.
Explain the greenhouse effect using a diagram.

In this H-R diagram, which stars are cool and bright?

Red giants and supergiants.
Explain Cosmic Background radiation.
The universe has a uniform background radiation emitted after the big bang. The afterglow is called cosmic background microwave radiation.
Why is nitrogen important for living things?
Nitrogen is essential for all living things because it is a major part of amino acids which are building blocks of proteins and of nucleic acids such as DNA.
Draw a labelled diagram of the water cycle.

What is global warming and why should we be concerned?
Global warming is driven but human emissions of greenhouse gases, and is resulting in large-scale shifts in weather patterns. Global temperature rise, warming oceans, shrinking ice sheets and glacial retreats are evidence of global warming.
From this life cycle of a star what are the two possible fates of a massive star?

To become a neutron star or a black hole.
Explain Red-shift.
Astronomers observed that stars are all red-shifted therefore they are moving away from each other. This phenomena shows that the universe is expanding.