Chapter 1

The Study of Life

• Earth is home to an incredible diversity of life.– All living things and all the places they are found

on earth make up the BIOSPHERE.• Every part of the biosphere is connected to every other

part of the biosphere, regardless of distance.– Deserts– Grasslands– Wetlands– Savannahs– Forests– Tundra

The Study of Life

• The variety of life across the biosphere is called BIODIVERSITY.

• Biodiversity is greater near the equator and more sparse near the poles.

Biodiversity

• More species are able to survive in warmer area than in colder areas.

• SPECIES can be defined as a group of living things that are genetically similar enough to interbreed and produce fertile offspring.

• There are about 2 million different species identified thus far on Earth.

All Organisms Share Characteristics

• An ORGANISM is an individual living thing and is made up of one or more CELLS.

• Cells are the basic units of life, are microscopic and may have specialty functions.– Muscle cells– Sex cells– Skin cells– Brain cells (neurons)

All Organisms share Characteristics

• All organisms need energy to survive.– Energy powers metabolic functions, or the chemical

processes required for life.• All organisms must react to their environment.– Sunlight, water, temperature, wind, food, etc. are all

external stimuli that organisms must adapt to in order to survive.

• Reproduction and development.– All organisms must be able to reproduce, either sexually

or asexually, and pass on DNA to their offspring.

All Levels of Life Are Systematic

• A SYSTEM is an organized group of related parts that interact to form a whole.

• In the living world, systems exist on all scales from cells to organisms to entire ecosystems.

• An ECOSYSTEM is a physical environment with different species that interact with one another and with nonliving things.

Structure and Function

• Each part in a system serves a specific purpose and therefore performs a specific function.

• This is true on all scales, just as with systems, from the cellular level on up.

• Examples:

Organisms Maintain Homeostasis

• HOMEOSTASIS is the maintenance of constant internal conditions in an organism.– Uses negative feedback– Examples:

Evolution

• EVOLUTION explains the unity and diversity of life.– The change is living things over time through

genetic modifications, called ADAPTATIONS.

Scientific Method Review

Variables

• Dependent Variable – observed and measured during an experiment. These are not manipulated, but affected by the independent variable.

• Independent Variable – the variable that is being manipulated. This is what you, as a scientist change.

• Constants – The conditions that remain the same during the experiment.

Data

• Quantitative Data – Deals with numbers, can be easily measured

• Examples:

• Qualitative Data – Deals with descriptions. Can be observed but not measured.

• Examples:

Biologists’ Tools and Technology

• Imaging technology provides new views of life.– Microscopes provide enlarged images of objects– In the classroom, we will be using light

microscopes often and will be able to see things as small, or even smaller, than single cells

– Electron microscopes, found at some colleges, use a beam of electrons to magnify objects• Scanning Electron Microscopes (SEM) scans the surface• Transmission Electron Microscopes (TEM) scans

through

Biologists’ Tools and Technology

• Medical Imaging– Xrays, CAT scans, MRIs, fMRIs, Ultrasounds, etc.

Complex Systems are Modeled on Computers

• Biologists have used computers and developed new software to better model living systems in order to make predictions based on observations.

• Examples:

Molecular Genetics

• GENE – segment of DNA that stores genetic information

• MOLECULAR GENETICS – study and manipulation of DNA on the molecular level (GMO food)

• GENOMICS – study and comparison of genomes both within and across species

Biology and Your Future

• Your health and the health of the environment depend on your knowledge of biology.

• Biotechnology offers great promise but also raises ethical issues.

• Biology presents many unanswered questions.

What Do You Think?

• Many medications used to treat human illnesses are based on substances found in other organisms. How might a decrease in biodiversity affect medical treatments and/or future discoveries?

• Mosquitos carry many different diseases that can sicken and kill humans. Even mosquitos that are not infectious are considered pests. However, they are also food for many species. If we had a way in which to rid the earth of mosquitos, do you think we should?