Characteristics of Life

What do these pictures have in common?

6 Characteristics to Define Life Made of one or more cells Respond to stimuli in their environment Maintain a stable internal environment Reproduce Need energy to stay alive Grow The processes carried out by an organism that are necessary for life are called metabolic processes.

Made of one or more cells Cells are the basic building blocks of life. They are the smallest unit that can perform all of the metabolic processes necessary for life. One cell = single-celled organism (unicellular) Many cells = multicellular organism All cells share certain basic structures Cell membrane- separates cell from its environment and controls what enters or leaves the cell

Respond to stimuli in their environment A stimulus is a change that affects how an organism acts. Ex: chemicals, light, hunger The reaction is called a response. Many responses help keep an organism safe. https://www.youtube.com/watch?v=Rz D4skFeJ7Y

Maintain a stable internal environment Homeostasis- the act of keeping a constant environment inside an organism Living organisms need ways to maintain their internal temperature, water balance, and acidity. If homeostasis is not maintained, disease or death may occur.

https://www.youtube.com/watch?t=21&v=rSBbnHLR_cg

Reproduce Reproduction is the production of offspring. Many organisms reproduce sexually. Offspring get traits from both parents Some organisms reproduce asexually. Offspring are identical to the parent

Need energy to stay alive Most organisms get energy from food! Producers (plants) use sunlight to produce their food (sugar) through photosynthesis. Consumers eat plants or other consumers. Organisms use energy to carry out all the activities that happen inside their bodies. Energy keeps up an organism's metabolism. Metabolism- all the chemical reactions that take place in its body.

Grow Multicellular organisms increase the size and number of their cells. Single-celled organisms just grow in size and when they get too big, they just divide.

Necessities of Life Water Air Place to live Food

Necessities of Life Water Air Place to Live Cells need water to keep their inside environments stable Most chemical reactions that happen in cells need water. Air Most organisms use oxygen to help them break down food for energy. Other organisms use carbon dioxide to make food- ex: plants Place to Live All living things need a place to live that has everything they need to survive.

Necessities of Life Food All organisms need food to get energy and nutrients in order to live and grow. From food, organisms get the following molecules needed to survive: Proteins- used to build or fix parts of an organism’s body or to help reactions within a cell Nucleic acids- ex: DNA- stores instructions for the organism Lipids- a form of stored energy Ex: fats and oils Carbohydrates- provide and store energy for cells Ex: sugars and starches ATP- the molecule that carries energy and is used by cells