The levels of classification, from largest to smallest, are: kingdom, phylum, class, order, family, genus, species. Thus, a genus is a group that contains related species.
Electrons orbit the nucleus of an atom.
As a human inhales, the incoming air first passes through the nasal cavity, where it is both warmed and filtered.
A tertiary consumer is an animal that consumes secondary consumers, or other carnivores. Coyotes are the tertiary consumer in this food chain. They feed on foxes, which in turn feed on rabbits. Dandelions represent the producers in the food chain.
The process by which a solid becomes a gas is sublimation. Boiling, (A), is the process by which a liquid becomes gas. Melting, (C), is the process by which a solid becomes a liquid. Diffusion, (D), describes the process by which a gas or liquid intermingles with another.
The gravitational force the Moon exerts on the Earth is the same as the gravitational force the Earth exerts on the Moon. According to Newton’s third law, for every force exerted on object A by object B, object B experiences an equal and opposite force from object A. Thus, when the Earth exerts its gravitational force on an object, such as the Moon, the Moon exerts an equal and opposite force on the Earth.
Fungi are decomposers (also known as saprophytes), returning the organic material from dead matter such as leaves, trees, and animal remains back into the environment. Producers, (A), make their own food. Consumers, (C), must eat other organisms in order to gain energy. Mutualism, (D), is a type of symbiosis whereby both organisms benefit.
The freezing point of water on the Kelvin scale occurs at 273 K. Kelvin and Celsius share a similar scale (i.e., a change of one Kelvin is the same as a change of one degree Celsius). However, they differ by 273 units. To convert Celsius to Kelvin, add 273. To convert Kelvin to Celsius, subtract 273. Since water freezes at 0 degrees Celsius, this is equivalent to 0 + 273 = 273 K.
Tough elastic tissues found in the joints that connect bones to bones are called ligaments. Tendons are connective tissues that unite a muscle with some other part, such as a bone. Cartilage is a somewhat elastic tissue (unlike bone). In adults it is found in joints (where it helps reduce friction between bones), in respiratory passages, and in the external ear. Although cartilage appears in joints where bones meet, its role is not to hold them together, but to keep them apart, acting as a buffer to prevent rubbing and wear. Finally, muscles are body tissue consisting of long cells that contract when stimulated to produce motion.
Stress, a poor diet, cigarette smoking, and heredity are all factors that are linked to high blood pressure.
Cirrus clouds are the thin, wispy clouds that occur very high in the atmosphere, at elevations of 20,000 feet or more. Stratus and cumulus clouds are both low-forming. Stratocumulus clouds contain clumps of clouds and are not thin or wispy.
Fossils are most likely to be found in sedimentary rock such as shale, which is rock formed by the sedimentation of clay, mud, or silt. Sedimentary rock is composed of minerals and other matter, such as animal remains.
Animals that consume only plants are called herbivores. Carnivores, (C), consume meat. Omnivores, (D), consume both meat and plants. Saprophytes, (A), gain their nutrients through dead organisms.
The Sun is a fairly young star and therefore has lower temperature and luminosity, resulting in its yellow color. The Sun is also fairly small as stars go and falls under the “dwarf” category.
A population is a group of organisms of the same species living in the same region. Biomes, ecosystems, and communities all encompass more than one type of species.
The four planets beyond Mars—Jupiter, Saturn, Uranus, and Neptune, are referred to as the outer planets. Earth is one of the four planets closest to the Sun and is thus considered an inner planet.
A boulder that begins to roll down a hill is an example of an energy conversion from potential energy to kinetic energy. The boulder has maximum potential energy at the top of the hill, and this energy is converted into kinetic energy as the boulder rolls down the hill and picks up speed. At the foot of the hill, all potential energy has been converted into kinetic energy.
The lowest layer of the Earth’s atmosphere is called the troposphere. This layer extends from the surface to the bottom of the stratosphere. Most weather changes occur here and the temperature generally decreases rapidly with altitude.
According to the law of conservation of energy, energy can neither be created nor destroyed. Instead, it changes from one form to another.
As an ambulance approaches, the sound waves from its siren are compressed toward the observer. The intervals between waves diminish, which translates into an increase in frequency or pitch. As the ambulance recedes, the sound waves are stretched relative to the observer, causing the siren’s pitch to decrease. By the change in pitch of the siren, one can determine if the ambulance is coming nearer or speeding away. This perceived change in pitch is known as the Doppler effect.
A concave lens—one that is thicker on the edges than it is in the middle—is also known as a diverging lens because it diverges the light waves that pass through it.
A molecule is the smallest particle of an element or compound that can exist in a free state and still retain the characteristics of the element or compound. In elements whose atoms form covalent bonds, the molecules consist of two or more similar atoms (e.g., N2). (Note that atoms of some elements form metallic bonds, and these groups of atoms are not molecules; for example, pure copper (Cu) is made up of atoms that do not form molecules.) The molecules of covalent compounds consist of two or more different atoms (e.g., H2O). Protons and quarks are subatomic particles; atoms are the building blocks of molecules.
The orbit of the Moon around the Earth, which exerts a gravitational pull on the ocean’s waters, is the phenomenon most responsible for oceanic tides.
The elements in a column on the Periodic Table are referred to as a group; each member of a group has the same number of electrons in its outer shell. Each row on the Periodic Table is referred to as a period.
When molecules undergo a chemical change, the process is called a chemical reaction. The molecules that enter the reaction are called reactants and the molecules that result from the reaction are called products.