Unit 1: Human Body Systems - Cells

Cells are important to study because… They are the _____________________ They are the ________________ of all living organisms – including humans They act much like a small living organism –Cells carry out their own ________________ necessary for survival –Including: ____________________________

Cell Theory: Cells are so important that there is an entire __________ dedicated specifically to them Theory: an explanation of something that has been _________________ _________________

Three (3) Parts to the Cell Theory: 1) ________________ ________________ ________________

Three (3) Parts to the Cell Theory: 2) ________________ ________________ ________________ ________________ ________________ ________________

Three (3) Parts to the Cell Theory: 3) ________________ ________________ ________________

Characteristics of Life All living things have certain characteristics and activities in common. ______________________________ ___________________We will examine ___________________ that all organisms possess.

1. ________________________ ________________________. Cells are the common unit of life paramecium human bodyMay be one cell like a paramecium (unicellular) or cells like the human body (multicellular) The cell is a complex structure made of many smaller parts The parts of a cell must work together in an organized way if the entire cell is to function smoothly Cells use much of the energy they get from food to maintain the organization of all their parts Cells are produced only by organisms and are never organized by non-living material Characteristics of Life

2. _________________________________ All living things are highly organized at both molecular and cellular levels. Organisms take in substances from the environment and organize them in complex ways. Specific cell structures carry out particular functions. Cells and groups of cells are organized by function. Characteristics of Life

3. Organisms Use Energy (Metabolism) Life is a state of constant chemical activity and therefore organisms need a constant supply of energy (growth and maintenance) The sun is a source of energy for almost all organisms because it supplies the energy from which plants make food When living things take energy from food, they release waste energy (heat) If a cell runs out of energy it dies Characteristics of Life

4. ________________________________ ____________________________ Every living thing ever studied requires water to stay alive. All organisms contain certain kinds of chemicals that are not naturally produced anywhere else – organic chemicals. Organic chemicals are complex and highly organized. Organic chemicals can be made in test tubes, but only living things produce them under natural conditions. Characteristics of Life

5. _____________________________________ ____________________________________ 5. _____________________________________ ____________________________________ Multicellular organisms usually have more than one system carrying out balance To achieve balance, organisms must ADAPT. An adaptation is a structure or behavior that allows survival in a particular environment. This enables species to survive in changing environments. Can be passed on to offspring by parents.

6. ________________________________________ Living things grow and develop when they increase in size. Organisms develop when they change shape or form. All living things grow at some time in their lives. This depends on genetics, nutrition, and metabolism. Living things don’t simply gather more of their own material, they organize it. As the organism matures, visible growth (getting larger) stops, but the organism is always replacing material. Organisms grow by adding living cells inside their bodies or by increasing the size of individual cells. Characteristics of Life

6. _________________________________ » _________________ All organisms have a fairly definite period of life called the life span. There are five stages of the life span; beginning, growth, maturity, decline, death. The length of the stages varies with species and individuals. Life cycles are not found in non-living things.

7. _______________________________ Reproduction is the process by which organisms produce offspring that are similar to themselves. “like produces like” Can be an exact duplicate of parent or some variation. Although it is not necessary for each organism to reproduce, reproduction is necessary for the survival of the species. Characteristics of Life

While a non- living thing may have one or a few of the characteristics of life, only living things have a aa all of them