BIOLOGY

THE STUDY OF LIFE

Chapter 1

WE LIVE IN THE BIOSPHERE

• THIN LAYER OF AIR, LAND AND WATER

• HOME TO ALL LIVING THINGS ON EARTH

• MAKES UP <1% OF EARTH’S MASS

WHAT IS AN ORGANISM?

• Any living thing

• Which of these are alive?

Do organisms arise by Spontaneous Generation?

• Spontaneous generation (SG) is life from nonlife. • Francesco Redi disproved SG of

maggots on meat in 1668.

• Louis Pasteur later disproved SG of bacteria in the late 1800’s.

Biogenesis

• Life from life

• Except for the first cells, all cells and living things came from pre-existing cells.

HOW DO WE KNOW THAT SOMETHING IS ALIVE?

• Organization

• Use energy

• Grow

• Develop

• Reproduce

• Respond to environment

• Adaptation

Organization

• Unicellular or multicellular

• Specialized structures

• Cell is basic unit of structure and function

Energy

• Energy exists in many forms – chemical, light, sound, heat

• Organisms use light energy to make food, to see, for warmth

• All energy for living things is traced back to the sun

• Plants use sunlight to make food• Other organisms eat the plants to get energy

Growth and Development

• Growth – increase in size

• Development – change in form or shape

• Amount of growth varies in different organisms

• Nature of development varies from species to species

Reproduction

• Process by which new living things are produced

• Makes new cells

• Necessary for the survival of the species

• Offspring can be duplicates of the parent or can be different from parent(s)

Response and Adaptation

• Response = reaction to a stimulus in environment

• Adaptation occurs within the entire population of organisms – responses to long-term changes in the environment; passed on to future generations.

Cells

• Smallest unit of life that exhibits all the characteristics of living things

• Within cells are organelles – specialized structures

Levels of Organization

• Atom• Cell• Tissue• Organ• Organ system• Organism• Population and

community• Ecosystem• Biopshere

(Ecosphere)

Adaptation and Interdependence

• Long-term changes

• Charles Darwin – Theory of Evolution by Natural Selection – explained how organisms could change and could pass those traits on to their offspring.

Interconnections between organisms

• Complex relationships occur between organisms living in same habitat

• Predator-prey

• Symbiosis– Mutualism– Commensalism

• parasitism

• Even a small change to one type of organism can affect the other organisms in an environment– Can cause other organisms to change– Organisms that can’t adapt fast enough might

become extinct

Role of humans in the web of life

• Look around – name the objects you see that are living, made from living things, or made from products of living things.

• Food

• Medicine

• Clothing

• resources

Scientists use careful observation and controlled experiments to study the natural world

• Careful observations – include smell, sound, sight, measurements, and careful recording

• Scientific Method – Make predictions – hypothesis– Design experiment– Carefully observe that experiment– Interpret the results – Draw conclusions

Observations

• Use human eye

• Use tools to aid the eye – ex – microscope, Geiger counter, etc.

• Measurements are in metric system – never use inches and other English units to report your results!

Hypothesis

• Possible explanation for an event or set of observations

• Proposed before the experiment is carried out.

• Educated guess

Experiment

• Focuses directly on problem being studied

• Needs hypothesis at start

• One variable

• Two or more groups – one control, others with a variation of the test subject (these are called experimental groups).

• Results must be accurately reported

Theory

• Hypothesis that is supported by many experiments done over a period of time

• Not facts, but are probable explanations for events that are supported by a wide range of evidence.

• New evidence can disprove a theory

Issues in Biology – Science in Society

• Ethics and values cannot be tested scientifically

• Experimental results must be made public so that they can be verified – Peer Review

• Public policy often relies on scientific data.

• Much experimentation is funded by public money – supported by tax dollars.

Design a scientific investigation

• Do seeds need light to germinate (sprout)?– Propose a hypothesis – always written as a

statement, not a question. Ex – seeds need light to germinate. OR seeds do not need light to germinate

– Use materials provided to perform an experiment

– Record results– Report data (must be measurable)

Write a Lab Report

• Introduction – give some background on the subject being studied – look up in your book what seeds need to germinate

• Purpose – state why this experiment is being done

• Hypothesis – predict what you think is going to happen

• Materials – list in columns, not a paragraph

• Procedure – Number each step (like in a cookbook)– Give specific instruction about what has to be

done to duplicate this experiment (pretend you are writing this for a really dumb biology teacher)

– Never use “I”, “You”, “Your”, etc.– Don’t include such things as:

• Gather the equipment

• Use pencil and paper to record results

• Results – these always go after the procedure, never at

the end of the lab report.– These should include observations and

measurements (never in paragraph form) – use columns, tables, etc.

– Use a ruler or the computer – do not hand draw lines for columns or tables

– Graphs should be traditional, not 3-D or hard to read computer-generated graphs

• Conclusions – Explain how the results supported or did not

support hypothesis– If no hypothesis, explain what you learned by

performing this lab– If there are any analysis questions, these go

after your conclusions.

The End