BIO 80 1 EXAM

What is biology?

Biology is the scientific study of life

What is science?

Science is a body of knowledge about the natural world; a collection of unified insights about nature, the evidence of which is an array of facts.

Scientific facts

are objective and verifiable observations;

observations that have repeatedly been confirmed and

accepted as “true”. AKA theories:

Theory

A theory is a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses

• Newton’s Theory of “Universal Gravitation”

• Einstein’s Theory of Relativity

• Darwin’s Theory of Natural Selection

Scientific method

Observation, questions, hypothesis & predictions, experimentation, analysis & conclusion.

Science is cyclical

True

four other principles of science

1. Scientific inquiry is only related to natural

explanations for natural phenomena

(Any scientific hypothesis or claim must be falsifiable)

2. Every assertion regarding the natural world is

subject to challenge and revision based on

evidence

3. Science invokes the principle of parsimony

(Occam’s Razor)

4. Science doesn’t tell you how to use scientific

knowledge

Scientific Ethics

“The relationship between general moral orientations and the problems of generating and applying scientific knowledge”

Characteristics of Life

1. Energy Processing

• Living things need an outside source of materials and energy to

maintain their organization and carry on life’s activities

• Food provides nutrient molecules, which are used as building

blocks or energy sources

2. Regulation

• Living things need to keep themselves stable in temperature,

moisture level, nutrient level, salt, acidity, and other factors critical

to maintaining life

• This is called homeostasis– the process by which a cell or

organism maintains internal conditions within certain boundaries

3. Response to the environment

• Living things can sense and respond to environmental stimuli

4. Growth and development

• Life only comes from life

• Every type of living thing can reproduce in some way

• Reproduction transmits DNA from generation to

generation

• All living things grow and develop

5. Order

• Life is characterized by highly ordered structure and

organization

6. Evolutionary adaptation

• Adaptations are modifications that make organisms

suited to their way of life

The branch of biology concerned

with naming and classifying species

Taxonomy

Currently recognized domains

Bacteria, Archaea, and Eukarya

Currently recognized kingdoms

Archaea, Bacteria, Protista,

Fungi, Plantae, and Animalia

used to name each species

Binomial nomenclature: coined by Carlous Linneus

The first name designates

the species’ _____

genus: group of

closely related organisms

The second name is

specific epithet: unique for

each species within a genus

Theory of evolution

provides a framework

for understanding how the diversity of life on

Earth arose

• Central theme is gradual change over time

Three observations about life

1. Organisms are well suited (adapted)

for life in their environments

2. Life shares many unifying

characteristics

3. Life is incredibly diverse

Aristotle

384-322 BCE

Darwin challenged his idea of the scala naturae

(Species organized into a complex structure where humans are at top).

James Hutton

1795

Proposed gradualism- earths geological features can be explained by gradual mechanisms.

Darwin connection: Darwin also thought humans could relate and evolve the same way.

Charles Lyell

1795

Uniformatarianism; The same geological processes are operating today as in the past, at the same rate.

Lyell's Principles of Geology provided Darwin with the concept of deep time and gradual change, which proved essential for Darwin to formulate his theory of evolution by natural selection.

Thomas Malthus

1798

Essay on the principle of population: human growth is exponential and resource growth is linear.

Darwin applied this economic concept to the natural world. He realized that since all animals produce more offspring than limited environmental resources can support, individuals born with advantageous variations are more likely to survive, reproduce, and pass those traits to the next generation

Jean-Batiste Lamarck

1809

Jean-Baptiste Lamarck (French zoologist) hypothesized that species

evolve through use and disuse of body parts and the inheritance of

acquired characteristics:

1. Organisms become more complex over time

2. The environment applies stresses to those organisms

3. In response to those stresses, the organism develop new

parts or otherwise change to alleviate the stresses

4. Changes that occurred during the organism’s life are passed

on to its offspring

George Cuvier

1812

Proposed catastrophism: catastrophic events are responsible

for mass extinctions and formation of all landforms

Darwin adapted Cuvier’s empirical evidence of extinction and the fossil record, replacing Cuvier's "catastrophes" with natural selection

Lyell published his principles of geology in what year

1830

Darwin travels around the world on HMS beagle in what year and what was found

1831-1836

Found ocean fossils high in the Andes

While on the HMS beagle, Darwin was:

1. Reading Lyell’s Principles of Geology

2. Reading Malthus’ Principles of Population

3. Thinking about overproduction and

competition

4. Marveling in the beauty and diversity of

plankton in the open ocean

5. Appreciating the diversity of life!

Adaptions

Characteristics

of organisms that enhance

their survival and

reproduction in specific

environments

What year does Darwin write his essay on descent with modification

1844

In Origin of Species, Darwin never used the word evolution, but

described this process as____

Descent with modification

Descent

All organisms are related

through descent from an

ancestor that lived in the remote

past

What does Wallace send Darwin and what year

1858- his hypothesis of natural selection

When was the origin of species published

1859

Origin of species influenced by ___________________________

Influenced by Aristotle’s Scala naturae, gradualism in geology, Cuvier, Lamarck, voyage on the Beagle, and Wallace

Evolution, as described by Charles Darwin, is based on four central ideas:

1. Descent with modification

2. Common ancestry

3. Adaptation

4. Natural selection

Observations of Natural Selection

Observation 1: Species produce more offspring than are needed to replace the parents and maintain the population.

Observation 2: Despite producing many offspring, adult population sizes usually remain fairly constant.

Observation 3: Natural resources (food, water, space, etc.) are limited and limiting - can restrict population growth.

Observation 4: Individuals within a population vary in their traits.

Observation 5: Much of this variation is heritable, meaning offspring inherit traits from their parents.

Observation 6: Humans use artificial selection to breed organisms with preferred heritable traits.

Natural Selection Inferences

Inference 1: There must be a struggle for

existence in nature, with too many individuals

and not enough resources.

Inference 2: The struggle for existence is not

random, but selective

AKA survival of the fittest!

Inference 3: Populations change over time as

the frequency of advantageous traits

increases

Prerequisites for natural selection to occur vs prerequisites for artificial selection

When did George Mandel publish his work on the patterns of inheritance in pea plants

1866

When were chromosomes discovered

1882

When was the term genetics coined

1905

When was the first images of DNA

1951

When was the structures of dna described

1953

What is evidence for evolution?

1. Anatomical and molecular homologies

2. The fossil record

3. Biogeography

4. Experimental evidence (direct observation)

Molecular homologies

genes shared among

organisms inherited from a

common ancestor

Vestigial structures

remnants of features that served

a function in the organism’s

ancestors

Convergent evolution

is the evolution of similar, or

analogous, features in distantly related groups

Analogous traits arrise

when groups independently adapt

to similar environments in similar ways

Homologous traits share

common ancestry but (typically)

serve different functions

Biogeography

the geographic distribution of species

• Influenced by continental drift: slow movement of continents over

millions of years

• Based on evolution and continental drift, we can predict

biogeography

• We can use evolution and continental drift to explain biogeography

Allele

Form of a gene

Convergent evolution does not provide information about

Ancestry

Analogous traits serve

similar functions but evolved

independently through convergent evolution

Microevolution

change of allele frequencies within a population over time.

Microevolution can result from______

• Natural Selection

• Sexual Selection

• Genetic Drift

• Gene flow

• Mutation

Macroevolution results in the formation of

new species or large groups of living things

Genetic variation

variation in

heritable traits, is a prerequisite

for evolution by natural selection

Gene

Unit of heredity

Genotype

The combination of alleles

Heterozygote

Possessing different alleles

Homozygote

Possessing two of the same

allele

Dominance

One allele masking the other in the heterozygous condition

Phenotype

An organisms appearance; observable traits or characteristics of an organism

Discrete characters

phenotypic differences

that occur on an “either-or” basis

e.g., Mendel’s pea plants

Quantitative characters

phenotypic differences that vary along a continuum e.g., coat color in horses is influenced by multiple genes

New alleles arise by

mutation: a change in the

nucleotide sequence of an organism’s DNA

The effects of the mutations on the survival and

reproduction of organisms is the basis of____

Natural selection

Chromosome

cellular structure

containing DNA; consists of a pair of

sister chromatids

Homologous Chromosomes

pair of

chromosomes with the same genes;

one from each parent

Sexual reproduction increases genetic diversity in what ways

During meiosis, genetic diversity is generated in two ways:

○ 1: Independent assortment: the random distribution of homologous

chromosomes during meiosis.

○ 2: Crossing over: homologous chromosome exchange reciprocal

portions of themselves

● After meiosis, further genetic diversity is generated via:

○ 3: Random fertilization

species

a group of individuals that

are capable, through reproduction, of

sharing alleles with one another

Population

a group of a single species

living together in a specific area

Gene pool

all the alleles present in all

the individuals in a population

Allele frequency

how common an

allele is in the population

Conditions for hardy Weinberg equilibrium

No mutations

Random mating

No natural selection

Extremely large population in size

No gene flow

Sexual Selection

a form of natural

selection that can affect the frequency of

alleles in a gene pool.

○ Occurs when differences in

reproductive success arise because of

differential success in mating.

Intrasexual selection

direct competition

among individuals of one sex (often males) for mates of the

opposite sex

Intersexual selection

Intersexual selection (between sexes): AKA mate choice,

when individuals of one sex (usually females) are choosy in

selecting their mates

Genetic drift

Causes allele frequency to change randomly

Bottleneck effect

a sudden reduction in the number of alleles present in a population.

By chance alone, certain alleles may be more common among survivors, while others

are less common or absent.

Founder effects

: a change in allele frequencies

that occurs when a new population is established

Genetic drift Key points

Can change allele frequencies through chance variation in survival or

reproduction

Is more significant in small populations

Can cause allele frequencies to “drift” randomly

Can lead to a loss of genetic variation within populations

Can lead to the fixation of deleterious alleles

Gene flow

The movement of alleles into or out of a population

due to the movement of fertile individuals or their

gametes.

Neutral Variation

genetic variation that does not confer a selective advantage or disadvantage … yet!

Diploidy

In diploid eukaryotes, a considerable amount of genetic variation is hidden from selection in the

form of recessive allele

Balancing selection

Occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a

population