1. Astronomy
   Chemistry
2. Biology
   Physics

In addition to classification of animals and plants, a biologist will also study the evolution of organisms and the interaction of organisms with one another.

1. Chlorine
   Chlorophyll
2. Chloroform
   Chloroplasts

In addition to providing the green pigment to plants, chlorophyll has a very big responsibility. It helps aid in photosynthesis, the process by which plants get their food from light and convert carbon dioxide to oxygen.

1. A stamen protects the reproductive organs from damage.
   A stamen produces the scent of the flower.
2. A stamen contains the ovules which eventually becomes seeds after fertilization.
   A stamen produces pollen, which is used in fertilization.

The stamen has three basic parts: the anther, which brushes against the pistil to start pollination, pollen sacs that create and hold the pollen, and filaments, the small stalks that help support the stamen.

1. An aerobic organism
   An anaerobic organism
2. A carbon dioxide-breathing organism
   A chloroplast

In the world of fitness, there are a few workouts that are considered anaerobic: sprinting, heavy weight training and jumping. All of these exercises have one thing in common: They all have short bursts of energy, making it a high-intensity workout.

1. The hub
   The nucleus
2. Protons
   Neutrons

The center of a nucleus has two types of particles: positively charged particles (protons) and uncharged particles (neutrons). Regardless of the number of neutrons in a cell, the protons will make every nucleus positively charged.

1. Electron
   Neutron
2. Proton
   Nucleus

When an atom has more electrons than protons, it is called a negative ion. Contrary to its name, negative ions are actually good to have around: They absorb free radicals and remove pollution in the air, purifying it.

1. The periodic table
   The gas table
2. The family table
   The elemental table

Every element is grouped into a family, where there is one thing that they all have in common. A couple of families listed are the transition metals (which include silver and gold) and the non-metal family (which includes oxygen and carbon).

1. Combo
   Compound
2. Formula
   Neutron

When a compound is written, it usually has a combination of letters and numbers. For example, if you take one hydrogen atom and add two oxygen atoms, you get water. The way it is written is H2O.

1. Melting
   Photosynthesis
2. Evaporation
   Condensation

Steam, evaporated water, is used in many different ways. In the world of cosmetology, a facial usually uses steam to help loosen pores, and steaming is also a method of preparing vegetables.

1. A center
   A pivot
2. A fulcrum
   A tilt

When it comes to illustrating how a lever works to children, oftentimes a teeter totter is used with one child sitting on the ground the other in the air.

1. Noble gases
   Non-metals
2. Transition metals
   Halogens

Balloons float because of a noble gas: Helium has the atomic number of two and is the second lowest element on the periodic table. Another element, neon, helps illuminate neon signs.

1. Conductive metals
   Transitioned metals
2. Smelted metals
   Alloy

Alloys are usually made to strengthen the two originating metals as well as protect it from corrosion. Two examples of an alloy are bronze, which is a mixture of copper and tin, and brass, which is a mixture of copper and zinc.

1. A mirror
   A prism
2. A glass
   A crystal

Ever wonder why you can only see a rainbow during a light rain? That's because light is hitting some of the water droplets, creating a natural prism.

1. Conduit
   Transmitter
2. Electrode
   Conductor

One of the reasons why wires have a plastic coating on them is to help protect them, the other is to help contain the energy they are transmitting.

1. Conductor
   Constellation
2. Contraption
   Cluster

In addition to Orion's Belt, all the signs of the zodiac are in the stars. How do you know what sign you are? If you look to the stars on your birthday, your zodiac's constellation will be visible.

1. A round
   An orbit
2. A rotation
   A race

When the Earth rotates around the sun, it is tilted. This tilt is known as an axis.

1. An organism that is known for having scales
   An organism that can live on both land and in water
2. An organism with fur
   An organism that lives in water

Some examples of amphibians include frogs, toads and salamanders. During its lifespan, an amphibian will have both gills and nostrils.

1. A warm-blooded organism with fur
   A cold-blooded organism that lives in water
2. A cold-blooded organism that has scales
   A warm-blooded animal that has feathers

Even though the dolphin is considered a mammal, an adult is actually hairless. This is because shortly after birth, the dolphin will shed its hair, leaving little pores in the skin where the hair used to be.

1. A warm-blooded organism with fur
   A warm-blooded animal that has feathers
2. A cold-blooded organism that lives in water
   A cold-blooded organism that has scales

Unlike chicken eggs, most reptiles lay soft eggs. Their shells are made of keratin. The exception to this rule are some turtle and tortoises.

1. An organism with eight legs and exoskeleton
   An organism with scales and lives in water
2. An organism with six legs and exoskeleton
   An organism with feathers and usually flies

Some examples of an arachnid are spiders and scorpions. In order to protect its young from the elements and predators, scorpions will carry their babies on their backs.

1. A heterogeneous rock
   A homogenous rock
2. A geode
   A prism

A typical geode starts out with liquid filling and forms a valve. As the liquid evaporates, crystals form.

1. A homogenous rock
   A heterogeneous rock
2. A prism
   A geode

A good example of a homogeneous rock are lava rocks. Unlike a heterogeneous rock, the bond between the two elements is so tight that it is very difficult to separate.

1. A geode
   A heterogeneous rock
2. A homogenous rock
   A prism

A good example of a heterogeneous rock is granite. Unlike a homogeneous rock, the bond between the two elements is pretty loose, so it is very easy to separate.

1. An exoskeleton
   A carapace
2. A coat
   Scales

Carapaces are usually made of bone or chitin. Other animals that have carapaces include scorpions, spiders, crabs and shrimp.

1. Binoculars
   A periscope
2. A telescope
   A microscope

One distinct difference between a group of plant cells and a group of animal cells is that plant cells have a tight wall-like structure, where animal cells are loose.

1. A slide
   A Petri dish
2. A glass
   A sampler

In order to protect the specimen from damage, a small piece of plastic (called a coverslip) is placed on top of it, compressing it, making it easier to view. This method of slide mounting is called wet mounting.

1. A bowl
   A mixer
2. A graduated cylinder
   A test tube

Depending on the size of a cylinder, you could also use it for creating mixtures. Because the size of the cylinder can vary, the amount of liquid that is measured can be greater from one cylinder to the next.

1. A coverslip
   A slide
2. A Petri dish
   A growing bowl

Petri dishes are usually lined with gelatin, which help feed the bacteria, encouraging growth. In order to protect the specimen, each dish comes with a lid.

1. An anaerobic organism
   An aerobic organism
2. A cell
   A proton

With the exception of some single-celled organisms, most of the creatures on our planet need oxygen to function. In the world of fitness, aerobics classes are designed to help strengthen the lungs through vigorous exercise.

1. A vertebrate
   An invertebrate
2. Insects
   Arachnids

A majority of the creatures that live on the earth are considered vertebrates. The creatures without spines are usually protected by an exoskeleton.

1. A mammal
   An invertebrate
2. A vertebrate
   A reptile

Many of the invertebrates that live on Earth are protected by an exoskeleton. Some examples of invertebrates are starfish, mollusks, arachnids and insects.

1. The lower crust
   The upper crust
2. The outer core
   Magma

Fracking, a drilling method to get oil, causes quite a bit of damage to the Earth's upper crust. When you remove minerals from the Earth without digging, it could cause earthquakes.

1. Cirrus clouds
   Cumulonimbus clouds
2. Stratus clouds
   Stratocumulus clouds

Made of water vapor, a cumulonimbus cloud is an easy way for the atmosphere to transfer water from one part of the planet to another. They occupy low to medium altitudes.

1. Kinetic energy
   Chemical energy
2. Solar energy
   Thermal energy

Did you ever wonder why victims of car accidents are flung forward even though the car has come to a stop? That's because even though the vehicle has come to a stop, the body is still moving at the same speed.

1. The mantle
   The inner core
2. The outer core
   The crust

Surrounded by liquid, first from the outer core, then from the magma from the mantle, the inner core is actually a solid composed of nickel and iron.