Biology in the 21st Century

The Study of Life

Biologists study life in all its forms

Earth is Home to an Incredible Diversity of Life!

The Biosphere

All living things and all the places they are found on earth

Biodiversity

The variety of life

Why is biodiversity greater closer to the equator? More living things are able to survive in

consistently warm temperatures than in areas that have changes in temperature

Species

A particular type of living things that can reproduce by interbreeding among themselves About 2 million species have been identified,

but biologists estimate that over 10 million remain to be discovered

Every year about 10,000 new species are identified!

Organism

Any individual

living thing

All organisms share certain characteristics

Characteristics of Life

Cells

Need for energy

Response to environment

Reproduction and development

Cells

All organisms are made up of one or more cells

A cell is the basic unit of life

Need for Energy

Energy is the ability to cause a change or to do work

The form of energy used by all living things is chemical energy

Animals get their energy by eating other organisms

Metabolism – the chemical processes that build up or break down materials

Response to Environment

Light, temperature, and touch are just a few of the physical factors to which organisms must respond.

These factors are called stimuli

Reproduction & Development

Members of a species must have the ability to produce new individuals.

In all organisms, the genetic material is DNA

The process of development allows organisms to mature and gain the ability to reproduce

Unifying Themes of Biology

All Levels of Life Have Systems of Related Parts

A system is an organized group of related parts that interact to form a whole

Two organisms that interact can also be a system

Structure & Function are Related in Biology

What something does (function) in an organism is directly related to its shape or form (structure)

Example: You bite with your sharp front teeth and chew with your molars

Organisms Must Maintain Homeostasis to Survive in Diverse Environments While environmental conditions change,

the conditions inside organisms usually stay stable

Homeostasis is usually maintained through negative feedback, a change in a system causes a response that tends to return that system to its original state

Evolution Explains the Unity and Diversity of Life

Evolution is the change in the genetic makeup of a subgroup of a species over time

It occurs through natural selection of adaptations.

Science is a way of thinking, questioning, and gathering evidence

There is no single “scientific method” but investigations tend to have common stages:

Collecting Observations

Asking Questions

Forming Hypotheses and Making Predictions

Confirming Predictions

Drawing Conclusions

Viewing Conclusions in Context

Observation

the act of noting or perceiving objects or events using the senses

Forming a Hypothesis

HYPOTHESIS – an educated guess based on what is already known

Must be backed up by fact

PREDICTION – expected outcome of a test, assuming the hypothesis is correct

EXPERIMENT – a planned procedure to test a hypothesis

CONTROL GROUP – a group in an experiment that receives no experimental treatment

EXPERIMENTAL GROUP – a group that receives experimental treatment

Control and experimental groups are identical except for one variable!

Variables in an Experiment

INDEPENDENT VARIABLE – the one factor that is changed in an experiment

DEPENDENT VARIABLE – the variable that is measured as a result of the change in the independent variable

Drawing Conclusions

• Once data are collected and analyzed, a conclusion is made as to whether the data support the hypothesis.

• The hypothesis may be supported or rejected.

• A hypothesis can be supported, but never proven because another experiment with new data and new information may alter the conclusion.

• Many experiments must be performed in order for a hypothesis to be proven correct.