Carbon and Water: Ingredients for Life Quiz

If life needs a strong material to build its body and a liquid to move nutrients around, and if carbon provides the structure while water provides the liquid, then these are the two most essential ingredients.

If a living cell needs to eat, the food must be small enough to pass through its skin; if water breaks down (dissolves) food into tiny pieces, then it is vital for helping life get the energy it needs.

If building complex things like DNA requires an atom that can connect to many other atoms in different directions, and if carbon can form four connections (bonds) at the same time, then it is the best "Lego brick" for building life.

If we look at the atoms that make up 96% of a human body, and if we find that carbon, hydrogen, oxygen, and nitrogen are the main parts of our cells, then they are the chemical basis of all life we know.

If life needs large, complicated molecules to function, and if you need an atom that can stick to itself to make long strings, then carbon is the primary ingredient used for that structure.

If life depends on chemical reactions happening quickly, and if molecules are stuck in place in solid ice but can move freely in a liquid, then liquid water is required to let the "chemistry of life" happen.

If all living things on Earth evolved from the same start, and if they all use DNA and proteins made of the same atoms, then the basic chemical ingredients remain the same regardless of the size of the animal.

If a material is needed to build life everywhere, and if that material must be easy to find, then the fact that carbon is one of the most common elements in space explains why it is used so much.

If water can absorb a lot of heat without changing its own temperature very much, and if a living thing is mostly made of water, then that water helps protect the organism from getting too hot or too cold too fast.

If life needs to grow and change, it requires complex molecules (shapes), a way to process food (energy), and a liquid (solvent) like water to hold everything together.

If carbon could only stick to one thing, it could not make the millions of different shapes found in our bodies; if it can actually stick to many different elements, then that flexibility is what makes it special.

If a plant needs minerals from the ground to grow, and if those minerals cannot move on their own, then water must carry them through the plant's veins to reach the leaves.

If the ingredients for life are atoms, and if those atoms must connect to build things like sugar or fat, then a group of atoms that are stuck together is called a molecule.

If we know that liquid water is essential for life, and if we find a place in space that has a huge hidden ocean, then that place has one of the most important ingredients we are looking for.

If carbon is the only element that can easily build the huge, stable chains needed for the instructions of life (DNA), and if it were gone, then those instructions could not be built by other elements.

If a liquid must be safe for a cell to touch and must stay liquid even when the weather changes, then water is the best choice because it is safe and stays liquid across a wide range of temperatures.

If the definition of an "organic" molecule is one that contains carbon atoms, and if all life is made of these molecules, then carbon is the reason we use that word.

If life needs to take in building blocks and energy, and if those things are outside the body, then the body must eat or absorb them; if they are then moved around by blood or sap, they are being transported by water.

If life needs to be flexible and strong, carbon's ability to make multiple types of bonds is better; if silicon turns into a solid like sand (SiO2) when it reacts with oxygen, it would be much harder for a living thing to breathe it out.

If you have a car but no gasoline, it will not move; if life has all its chemical parts but no energy from the Sun or chemicals to power it, then it cannot stay alive or grow.