Characteristics of Life

Characteristics of Living Things

• Anything that possesses all of the characteristics of life is known as an organism.

Living things share the same 7 characteristics

1. Cells and organization,

2. response to stimuli,

3. homeostasis,

4. metabolism,

5. growth and development,

6. reproduction, and

7. evolution.

Characteristics of Living Things

All living things:

• have an orderly structure

• produce offspring

• grow and develop

• adjust to changes in the environment

Living things are organized• When biologists search for signs of life, one of

the first things they look for is structure• Whether an organism is made up of one cell or

billions of cells, all of its parts function together in an orderly, living system.

–A cell is the smallest unit of an organism that can perform all life’s processes.

Living things make more living things

• One of the most obvious of all the characteristics of life is reproduction, the production of offspring.

Living things change during their lives

• Growth results in an increase in the amount of living material and the formation of new structures.

• All of the changes that take place during the life of an organism are known as its development.

Living things adjust to their surroundings

• Organisms live in a constant interface with their surroundings, or environment, which includes the air, water, weather, temperature, any other organisms in the area, and many other factors.

Living things adjust to their surroundings

• Anything in an organism’s external or internal environment that causes the organism to react is a stimulus.

• A reaction to a stimulus is a response.

• Regulation of an organism’s internal environment to maintain conditions suitable for its survival is called homeostasis.

Living things adapt and evolve• Any structure, behavior, or internal process that

enables an organism to respond to environmental factors and live to produce offspring is called an adaptation.

• Adaptations are inherited from previous generations.

• The gradual change in a species through adaptations over time is evolution.

Three Domains of Life

– The three domains of life are Bacteria, Archaea, and Eukarya.

– The six kingdoms include Archaea, Bacteria, Protista, Fungi, Plantae, and Animalia.

All living things have an orderly structure, produce offspring, grow and develop, and adjust to changes in the environment. Sometimes nonliving things have one or more of these characteristics, but unless something has all of them it is not considered to be a living thing.

Are these alive?

These plants are called Lithops from the Greek lithos, meaning “stone.” Although they don’t appear to be so, Lithops are just as alive as elephants. Both species possess all of the characteristics of life.

HomeostasisHomeostasis is the regulation of an organism's

internal environment to maintain conditions suitable for survival. An example is the adjustment an organism makes in the amount of water in its cells; without the ability to make such adjustments, organisms die.

adaptationA structure, behavior or internal process that

enables an organism to respond to environmental factors and live to reproduce is an adaptation. Evolution is the gradual change of a species over time and occurs through adaptations.

scientific methods.

• The common steps that biologists and other scientists use to gather information and answer questions are collectively known as scientific methods.

• Scientific methods usually begin with scientists identifying a problem to solve by observing the world around them.

• A hypothesis is an explanation for a question or a problem that can be formally tested.

• Eventually, the scientist may test a hypothesis by conducting an experiment.

• The results of the experiment will help the scientist draw a conclusion

about whether or not the hypothesis is correct.

Share the results

• Publishing a Paper– Scientists submit research papers to scientific

journals for publication.– In peer review, the editors of a journal will

send submitted papers out to experts in the field who anonymously read and critique the paper

– The scientific method involves making observations, asking questions, forming hypotheses, making predictions, designing experiments, analyzing data, and drawing conclusions.

What is a controlled experiment?

• Some experiments involve two groups: the control group and the experimental group.

• The control is the group in which all conditions are kept the same.

• The experimental group is the test group, in which all conditions are kept the same

except for the single condition being tested.

independent variable,

• The condition in an experiment that is changed is the independent variable,

because it is the only variable that affects the outcome of the experiment.

Independent= Xdependent= Y

Fertilizer amount

Height of plant

dependent variable,

• While changing the independent variable, the scientist observes or measures a second condition that results from the change.

• This condition is the dependent variable, because any changes in it depend on changes made to the independent variable.

theory

• A theory is an explanation of a natural phenomenon that is supported by a large body of scientific evidence obtained from many different investigations and observations.

A scientist conducts an experiment to test the effect of light on plant growth. In each experiment, three plants of the same variety are each given 10 mL of water. One plant is exposed to full sunlight for 8 hours, one is exposed to full sunlight for 4 hours, and one plant is kept in a dark room. Plant height is measured after two weeks. What is the independent variable in this experiment?

What is the independent variable

in this experiment?

The independent variable is the condition that is changed.

In this case, the amount of sunlight is changed for each plant.

Plant heights are measured results of the experiment, so plant height is the dependent variable.

Explain the difference between quantitative and qualitative information.

Quantitative information can be expressed numerically, and may also be used to generate graphs or tables in order to communicate data clearly. Qualitative information is not expressed numerically. Observational data and written descriptions of what scientists observe, are qualitative information.

Explain how ethics are part of scientific discoveries.

Ethics are a system of moral values or principles of right conduct. The knowledge gained through scientific research is not good or bad, but some applications of scientific knowledge may be considered unacceptable to some people. It is the responsibility of society as a whole to determine the ethical use of scientific discoveries.

Stem cells

• How does technology benefit a society?

Technology is the application of scientific research to society's needs and problems.

It can result in improvements in such areas as food production, waste and pollution reduction, and medical care.

While technology has provided numerous benefits, sometimes problems result as well.