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.Continue Reading
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
Living things reproduce, grow, adapt to the environment, respond to stimuli and metabolize. They also undergo homeostasis, collect and convert nutrients, and use energy. Living things are organized into one or more cells. The five groups of living things are the animal, plant, monera, protista and fungi kingdoms.Full Answer >
Living things differ from non living things because they are made of cells and contain DNA, transform and metabolize energy, and reproduce. They also grow and develop, respond and react to internal and external influences, and can evolve and adapt.Full Answer >
All living things require a source of energy, nutrients, water, space to grow and reproduce, and a relatively stable environment that allows homeostasis. Many organisms also require oxygen, but this is not a universal requirement, and oxygen is actually deadly to certain organisms. Indeed, beyond these basic categories of needs, the requirements of organisms vary vastly from species to species.Full Answer >
Adenosine triphosphate, or ATP, is the energy currency of life, the way that individual cells store and use chemical energy. Any food or other source of energy a cell takes in is converted to ATP, in which form the mechanisms of the cell can easily use it. It does this by shedding a phosphate group, becoming adenosine diphosphate, or ADP, a highly energetic reaction that powers all of a cell's molecular machinery.Full Answer >