Living things have the following six characteristics that define life: they are made of cells, they use energy, they grow, they reproduce, they respond to their environment and they self-regulate. A seventh characteristic is often added to the list, which is that living things have biological organization.Know More
Single-celled organisms such as bacteria are considered living things since they possess all of the characteristics. Viruses, which are infectious agents, usually aren't considered because they don't use energy, don't grow, can't reproduce independently and are unresponsive to the environment. Multicellular beings, such as humans, often have other organisms living within their bodies.
Organisms are classified based on their shared characteristics and common descent. These classifications are divided into categories which are further divided by their subcategories. These divisions include domain, kingdom, phylum, class, order, family, genus and species.
Life on Earth is believed to have started at least 4.25 billion years ago, around 290 million years after the Earth's formation. The earliest evidence humans have found for a life form is a 3.7 billion year old biogenic graphite. While Earth is the only known planet to contain life, other life forms are hypothesized to be present within the solar system and beyond.Learn more about Biology
The six kingdoms of life are animalia, plantae, fungi, protista, archaebacteria and eubacteria. Every living organism on the planet falls into one of the six kingdoms. The placement of organisms is based on characteristics like reproduction, metabolism and cell type.Full Answer >
Biology is important to everyday life because it allows humans to better understand their bodies, their resources and potential threats in the environment. Biology is the study of all living things, so it helps people to understand every organism alive, from the smallest bacteria to California redwoods and blue whales. Professional biologists often concentrate on a small subset of living organisms, such as birds, plants or bacteria.Full Answer >
All living things have in common their genetic building blocks, which are DNA. Though each organism's DNA differs in what specific genes they carry, which account for the diversity of life, all known living things use these molecules to develop and reproduce.Full Answer >
The ultimate source of energy for all life on Earth is the sun. Every form of life on Earth is dependent upon others, and without sunlight, most life on Earth would cease to exist rather quickly.Full Answer >