PTE

number of study units or observations included in a sample

to investigate how, where, or when something began by following evidence backward through time

to take a substance into a living organism or its tissues

the members of one species living within a particular area

to produce new organisms of the same biological kind

to grow, develop, or reproduce very successfully because conditions are suitable

connected with growing crops, raising farm animals, or the systems that support farming

the activity of growing crops and raising animals to supply food and other useful products

the condition of the air in relation to the pollutants it contains and their effects

the total greenhouse gas emissions associated with a person, product, organization, or activity, usually expressed as carbon dioxide equivalents

a lasting change in average weather patterns or their variability over decades or longer

the protection and careful management of natural resources, landscapes, and living things

to protect a resource by using it carefully and avoiding unnecessary loss or waste

the long-term loss of forest through conversion to another land use or failure of forest cover to recover

an extended period of unusually low rainfall or other water shortage that affects a region

to release gases or particles into the surrounding environment

the practice of reducing energy use and avoiding waste

to leave a dangerous place or move people from it to a safer location

a material added to soil or plants to provide nutrients needed for growth

the treatment of raw food materials to make them suitable for eating, storage, or sale

a condition in which people can reliably obtain enough safe, nutritious food to meet their needs and preferences for an active, healthy life

food that is discarded or left uneaten instead of being used for consumption

a fuel such as coal, oil, or natural gas formed from ancient organic material over geological time

the long-term rise in Earth's average surface temperature

a gas that absorbs and emits infrared radiation and therefore contributes to atmospheric warming

to gather a crop when it is ready to be used or sold

a period of unusually hot weather lasting several days or longer in a particular area

the organized supply of water to land or crops to support plant growth

a material or feature occurring in nature that people use to support life or economic activities