Ch.1: Biology and the Tree of Life

A search for ideas and observations that unify our understanding of the diversity of life

Biological science

Organism

A life form; a living entity made up of one or more cells

5 fundamental characteristics that organisms share

Energy, cell, information, replication, and evolution

To stay alive and reproduce, organisms have ti acquire and use ____.

energy

Plants absorbing sunlight and animals ingesting food are 2 examples of _____.

energy

Organisms are made up of membrane-bound units called ___.

cells

A ______ regulates the passage of materials between exterior and interior spaces.

cell's membrane

Organisms process hereditary, or genetic, _____ encoded in units called _____.

information, genes

Organisms respond to information from the enviornment and ____ to maintain _______.

adjust, stable internal conditions

One of the great biologists of the 20th century, _________, said that the "dream of a bacterium is to become two bacteria."

Francois Jacob

Almost everything an organism does contributes to one goal:

replicating itself

Organisms are the product of ____, and their populations continue to ____.

evolution, evolve

Organisms (life forms) are considered "alive" because they....

acquire and use energy, are made up of one or more cell(s), process information, are capable of replication, and are a product of evolution

Two of the greatest unifying ideas in all of science that emerged in the mid 1800's, revolutionized the way biologists think about the world, and laid the groundwork for modern biology:

the cell theory and the theory of evolution by natural selection

What is a theory?

an explanation for a very general class of phenomena or observations that are supported by a wide body of evidence

The concepts of the cell theory and the theory of evolution by natural selection established 2 of the 5 attributes of life:

organisms are cellular, and their populations change over time

The cell theory emerged after some __ years of work.

200

In 1965, the Englishman _______ devised a crude microscope to examine the structure of cork (a bark tissue) from an oak tree, where he discovered cells (named after their resemblance to cells inhabited by monks in a monastery) for the very first time.

Robert Hooke

Soon after Hooke published his results, a Dutch scientist named ______ succeeded in developing much more powerful microscopes, come capable of magnifications up to 300x.

Anton van Leeuwenhoek

With his powerful microscopes, Leeuwenhoek inspected samples of _____ and made the first observation of a dazzling collection of _____ that he called "animalcules." (He also observed and described human blood cells and sperm cells.)

pond water, single-celled organisms

In the 1670's, an Italian researcher who was studying the leaves and stems of plants with a microscope concluded that plant tissues were composed of _____.

many individual cells

By the early 1800's, enough data had accumulated for a German biologist to claim that ______ consist of cells.

all organisms

The smallest organisms known today are _____. (barely 200 nanometers wide, or 200 billionths of a meter)

bacteria

A ____ is a highly organized compartment bound by a thin, flexible structure called a plasma membrane that contains concentrated chemicals in a watery solution.

cell

The chemical reactions that sustain life take place inside ____.

cells

Most scientific theories have 2 components:

a pattern in the natural world, and a mechanism or process that is responsible for creating that pattern

In 1858, a German scientist named _____ added the the process component by stating that all cells rise from preexisting cells.

Rudolph Virchow

What is the cell theory? What explanation did it challenge?

All organisms are made of cells, and all cells come from preexisting cells; spontaneous generation

In the mid-1800's, most biologists believed that organisms could arise ____ under certain conditions.

spontaneously

The idea that the bacteria and fungi that spoil foods such as milk and wine were thought to appear in these nutrient-rich media of their own accord - springing to life from nonliving materials, is an example of _____.

spontaneous generation

What is a hypothesis?

A testable statement to explain a phenomenon or a set of observations

Biologists usually use the _____ to refer to proposed explanations for broad patterns in nature and prefer ____ to refer to explanations for more tightly focused questions.

world theory, hypothesis

______: a coherent group of tested general propositions that can be used as principles of explanation and prediction for a class of phenomenon.

theory

An experimental ____ describes a measurable or observable result that must be correct if a hypothesis is valid.

prediction

A French scientist named ____ set out to test Virchow's cell-from-cell hypothesis when it appeared in print.

Louis Pasteur

Pasteur created two treatment groups, a _____ and a ______ to determine whether microorganisms could arise spontaneously or whether they only appear when exposed to preexisting cells.

broth that was not exposed to a source of preexisting cells and a broth that was

In Pasteur's experiment, what two items did he use to test spontaneous generation?

A straight neck flask and a swan neck flask

What were Pasteur's experimental results?

The treatment exposed to preexisting cells quickly filled up with bacteria and fungi, while the broth in the swan-necked flask remained sterile, even when left sitting for months.

If all cell's come from preexisting cells, it follows that all individuals in an isolated property of single-celled organisms are ______.

related by common ancestry

The realization made independently by the English scientists _____ and ____ was that all species - all distinct, identifiable types of organisms - are related by common ancestry.

Charles Darwin, Alfred Russel Wallace

_____ is a change in the characteristics of a population over time. It means that species are not independent and unchanging entities, but are related to one another and can change through time.

Evolution

Darwin called this process descent with modification.

The characteristics of a species can be modified from generation to generation

Species being related by common ancestry contrasted with the prevailing view in science at the time, which was that species represent entities separated by a _____.

divine being

Natural selection occurs whenever 2 conditions are met:

1. Individuals within a population vary in characteristics that are heritable.

2. In a particular environment, certain versions of the heritable traits help individuals survive/reproduce better than other versions do.

What does heritable mean?

Traits that can be passed down to offspring

A group of individuals of the same species living in the same area at the same time

population

If certain heritable traits lead to increased success in producing offspring, then those traits ______ in the population over time.

become more common

Natural selection acts on ____, but evolutionary change occurs in _____.

individuals, populations

What is changes in populations that occur when humans select certain individuals to produce the most offspring?

Artificial selection

In Biology, fitness means...

the ability of an individual to reproduce viable offspring

Individual with ___ fitness produce many surviving offspring.

high

In Biology, an adaptation is....

a trait that increases the fitness of an individual in a particular environment

The divergence process by which natural selection has caused populations of one species to diverge and form new species

speciation

What is a tree of life?

A family tree of organisms

One of the greatest breakthroughs in research on the tree of life occurred when American biologist ______ and colleagues began analyzing the chemical components of organisms as a way to understand their evolutionary relationships.

Carl Woese

Understanding the phylogeny of all organisms means understanding...

their actual genealogical relationships

The rRNA molecule is made up of sequences of ___ smaller chemical components called ______.

4, ribonucleotides

Ribonucleotides in rRNA are symbolized by the letters __, __, __, and __, and are connected linearly.

A, U, C, G

The ribonucleotide sequence in rRNA is a treat that can ___ during the course of evolution.

change

"If the theory of evolution is correct, then rRNA sequences should be very similar in _______, and less similar in organisms that are _______.

closely related organisms, less closely related

A diagram that depicts evolutionary history by describing the phylogeny of organisms is called a _______.

phylogenetic tree

Just as a family tree shows relationships between individuals, a phylogenetic tree shows ________.

relationships between species

On a phylogenetic tree, branches that share a recent common ancestor represent species that are _____; branches that don't share common ancestors represent species that are ______.

closely related, more distantly related

In a phylogenetic tree, the tree's main node is the ________ of all living organisms.

common ancestor

The tree of life implied by rRNA and other genetic data established that there are 3 fundamental groups (domains) or lineages of organisms:

the Bacteria, the Archaea, and the Eukarya

In all ______, cells have a prominent cell called the nucleus. (membrane bound)

eukaryotes

Because the vast majority of bacterial and archaeal cells lack a nucleus, they are referred to as ______.

prokaryotes

The vast majority of bacteria and archaea are ______; many eukaryotes are ______.

unicellular, multicellular

In science, the effort to name and classify organisms is called _____; any named group is called a _____.

taxonomy, taxon (plural: taxa)

Bioligists often use the term ______ to refer to major lineages within each domain.

phylum (plural: phyla)

Each phylum is considered a _____ on the tree of life.

major branch

Swedish botanist (1735) named Carolus Linnaeus established a system for naming species that is still in use today; 2 part name unique to each type of organism:

Genus, Speices

An organisms genus and species designation is called its ______.

scientific name or latin name

Scientific names are based on _____ or _____ word roots.

Latin, Greek

If the predictions are accurate, the hypothesis is _____.

supported