Characteristics of Life

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

b. There are two general categories of cells: 1)prokaryotic—no organized nucleus nor membrane bound organelles (bacteria) 2)Eukaryotic—Have an organized nucleus and membrane-bound organelles. (plant, animals)

2.Living things reproduce. 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 contain 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)Multi-cellular organisms also go through development, where cells divide and differentiate (blood cells, bone cells, nerve cells)

5.Living things obtain and use materials and energy. Metabolism: The combination of chemical reactions through which an organism builds up or breaks down materials as it carries out its life processes. a) Autotrophs (PRODUCERS) Obtain their energy directly from the sun through photosynthesis.

b) Heterotrophs (CONSUMERS) 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—obtain energy from the remains of organisms that have died (bacteria and fungi)

6.Living things respond to their environment. a)A stimulus- Signal to which an organism responds. b)External stimuli Ex: temperature and light. a)Internal stimuli Ex: blood sugar level or feeling thirsty.

7.Living things maintain a stable internal environment. a)Homeostasis: Maintaining a stable internal environment even when external environment changes. b)Examples?

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

1.Cell 2.Tissue 3.Organ 4.Organ system 5.Organism 6.Population 7.Community 8.Ecosystem