We all have these in common. 8 Characteristics of Life

Living things share 8 characteristics: 1.Living things are made up of units called cells. a.Every organism is composed of at least one cell. 1.) single-celled or unicellular 2.) many-celled or multicellular

b. There are two broad categories of cells: 1)prokaryotic—no organized nucleus nor membrane bound organelles; found in bacteria and cyanobacteria 2)eukaryotic—do have an organized nucleus and membrane-bound organelles such as Golgi apparatus and mitochondria. All other organisms such as plants and animals have this kind of cell.

2.Living things reproduce. There are two basic kinds of reproduction: a)Asexual—only one parent and all offspring are identical; for example, binary fission of bacteria or amoebas. b)Sexual—two cells from different parents unite to produce the first cell of a new organism.

3.Living things are based on a universal genetic code (DNA). a)The directions for inheritance are found in deoxyribonucleic acid or DNA. b)The genetic code is basically the same for all organisms on Earth.

4.Living things grow and develop. a)For single-celled organisms, growth is mostly an increase in size. b)Multicellular organisms go through a process called development, where cells divide and differentiate into different kinds of cells.

5.Living things obtain and use materials and energy. a)The combination of chemical reactions through which an organism builds up or breaks down materials as it carries out its life processes is called metabolism. b)Autotrophs (also called producers)—plants, most algae, and some bacteria obtain their energy directly from the sun through photosynthesis.

c) Heterotrophs (also called consumers)—most other organisms, rely on the energy stored during photosynthesis. 1.Herbivores—eat plants and other photosynthesizing organisms 2.Carnivores—eat the herbivores or other carnivores 3.Omnivores—eat both plants and animals 4.Decomposers—such as bacteria and fungi; obtain energy from the remains of organisms that have died

6.Living things respond to their environment. a)Organisms detect and respond to stimuli from their environment. b)A stimulus is a signal to which an organism responds. c)External stimuli include temperature and light. d)Internal stimuli come from within, such as blood sugar level or feeling thirsty.

7.Living things maintain a stable internal environment. a)Even though external environmental conditions may vary widely, most organisms must keep internal conditions, such as temperature and water content, fairly constant. b)Maintaining a stable internal environment is called homeostasis (Greek, same condition).

8.Taken as a group, living things change over time (living things evolve). a)Plants have adapted to living in dry and hot deserts. b)Fossils of ancient organisms can be used to show how organisms have changed over time.