Biology Concepts

1.1 What is life?

What is life? Living things vs. nonliving objects:

Comprised of the same chemical elements Obey the same physical and chemical laws

The cell is the smallest, most basic unit of all life Familiar organisms are multicellular Some cells independent – single-celled organisms

What are emergent properties? Levels range from

extreme micro to global

Each level up: More complex than

preceding level Properties:

A superset of preceding level’s properties

Emerge from interactions between components

What are the basic requirements of all living things? Three requirements

Materials and Energy Reproduction and Development Adaptations and Natural Selection

Energy - the capacity to do work The sun:

Ultimate source of energy for nearly all life on Earth

Drives photosynthesis Metabolism - all the chemical reactions

in a cell Homeostasis - Maintenance of internal

conditions within certain boundaries Acquiring nutrients

What are the basic requirements of all living things? Living things detect changes in

environment Response often involves

movement Vulture can detect and find carrion

a mile away Monarch butterfly senses fall and

migrates south Microroganisms follow light or

chemicals Even leaves of plants follow sun

Responses collectively constitute behavior

What are the basic requirements of all living things? Organisms live and die Must reproduce to

maintain population Multicellular organisms:

Begins with union of sperm and egg

Developmental instructions encoded in genes Composed of DNA Long spiral molecule in

chromosomes

What are the basic requirements of all living things? Adaptation

Any modification that makes an organism more suited to its way of life

Organisms, become modified over time

However, organisms very similar at basic level Suggests living things descended

from same ancestor Descent with modification -

Evolution Caused by natural selection

Biological Concepts

1.2 Taxonomy and Systematics

What is taxonomy? The rules for identifying and classifying organisms Hierarchical levels (taxa) based on hypothesized evolutionary relationships Levels are, from least inclusive to most inclusive:

Species, genus, family, order, class, phylum, kingdom, and domain A level usually includes more species than the level below it, and fewer species

than the one above it

How are organisms classified?

What are the three domains? Bacteria

Microscopic unicellular prokaryotes Archaea

Bacteria-like unicellular prokaryotes Extreme aquatic environments

Eukarya Eukaryotes – Familiar organisms

What are the kingdoms? Archaea –

Kingdoms still being worked out

Bacteria – Kingdoms still being

worked out Eukarya

Kingdom Protista Kingdom Fungi Kingdom Plantae Kingdom Animalia

What are scientific names? Binomial nomenclature (two-word

names) Universal Latin-based

First word represents genus of organism

Second word is specific epithet of a species within the genus

Always Italicized as Genus species (Homo sapiens)

Genus may occur alone (Homo), but not specific epithet

Biological Concepts

1.3 Scientific method

What is the scientific method? Begins with observation

Scientists use their five senses

Instruments can extend the range of senses

Hypothesis A tentative explanation

for what was observed Developed through

inductively reasoning from specific to general

What is the scientific method? Experimentation

Purpose is to challenge the hypothesis

Designed through deductively reasoning from general to specific

Often divides subjects into a control group and an experimental group

Predicts how groups should differ if hypothesis is valid

If prediction happens, hypothesis is unchallenged

If not, hypothesis is unsupportable

What is the scientific method? Results

Observable, objective results from an experiment

Strength of the data expressed in probabilities

The probability that random variation could have caused the results Low probability (less than

5%) is good Higher probabilities make it

difficult to dismiss random chance as the sole cause of the results

What is the scientific method? The results are analyzed

and interpreted Conclusions are what the

scientist thinks caused the results

Findings must be reported in scientific journals

Peers review the findings and the conclusions

Other scientists then attempt to duplicate or dismiss the published findings

What is a scientific theory? Scientific Theory:

Joins together two or more related hypotheses

Supported by broad range of observations, experiments, and data

Scientific Principle / Law: Widely accepted set of

theories No serious challenges to

validity

What types of experimental variables are there? Experimental

(Independent) variable Applied one way to

experimental group Applied a different way

to control group Response (dependent)

variable Variable that is

measured to generate data

Expected to yield different results in control versus experimental groups