Unit 1: Diversity of Life Grade 11 AP Bio

Fact

an observation that has been repeatedly confirmed, is accepted as true, never final and may be modified or discarded

Hypothesis

a tentative statement based on observation and leads to deductions that can be tested

Provisionally corroborated hypothesis

if the deductions are verified/tested

Inference

the process of drawing conclusions based on evidence and reasoning

Theory

a comprehensive explanation that is well supported by multiple pieces of scientific evidence over time, can incorporate facts, laws, inferences, and tested hypotheses, explains why something happens

Law

A true fact that is applied universally, explains what happens

A cell

1. An area separated from the external environment

2. Maintains a fairly stable internal environment

3. Different/separated from the external environment

Prokaryotes

Has no nuclear membrane

Composed of a cell membrane + ribosomes + DNA

Capsule

a sticky outer layer that allows the cell to cling to surfaces

Cilia

hairs on the outside of the cell that help it move

Flagellum

the long tail-like structure that helps it move

Eukaryotes

1. Has a true nuclear membrane 2. Contains membrane-bound organelles

Biodiversity

The variety of life found in a given place

Species Richness

counting the number of different species

Simpson's Diversity Index

a calculation that measures the number of species and their relative abundance

Genetic Diversity

measures the variation in DNA sequences among individuals of the same species

Gene

a place in the DNA to find something written

Ecosystem Diversity

how many different types of ecosystems exist within a region

Species

A group of organisms that can interbreed with others of the same type, individuals within a species possess similar anatomical characteristics

Morphological

Physical characteristics (color, shape, form), comparing measurements and descriptions of similar organisms can be applied to both sexual & asexual organisms and fossils, commonly used for plants and insects

Advantages of morphological concept

simplicity makes it easy to use

Disadvantages

1. Deciding boundaries for variation - all populations are made up of non - identical individuals 2. Sexual dimorphism: difference in appearance of sexes of the same species 3. Cryptic speciation - A group of species that are morphologically identical but belong to different species 4. Species can look similar to imitate poisonous animals to scare off predators (monarch butterflies/viceroy butterfly, poisonous/non poisonous snake)

Biological species

A population whose members can successfully breed with one another in a natural environment and not with another species, proposed by Ernst Mayr in 1942

Biological species concept requirements

1. Members of a species can & will reproduce with one another naturally (recognize each other as mates)

2. Offspring must be fertile or viable(live without other help)

3. (optional) Must be reproductively isolated from other groups of organisms

Biological species concept limitations

1. Some organisms reproduce asexually 2. Mating may not be possible(populations are separated, fossilized species)

Ecological species

Focuses on the similarity of ecological niche and role, describes a set of organisms adapted to a particular set of resources(niche), created to address climate change

Advantages of ecological concept

considers species' role in an ecosystem

Disadvantages of ecological concept

Geographically spread out populations that don't interbreed can be considered the same species

Niches can change over development

Hard to decide boundaries since certain species can live in a wide range of ecosystems and fill different niches

Phylogenetic Species

A species is a tip on a phylogeny, when the smallest set of organisms that share an ancestor can be distinguished from other sets of organisms

Advantages of phylogenetic concept

Considers ancestry, genetic similarity, evolutionary process

Disadvantages of phylogenetic concept

doesn't consider reproductive habits, subspecies are not recognized, mutations are hard to determine

Ring species

A connected series of neighboring populations, each can interbreed with closely related populations, has two end populations that are too distantly related to interbreed

Taxonomy

the scientific discipline of naming and classifying organisms, used to distinguish organisms from one another for other uses

Importance of taxonomy

- Helps farmers separate weeds from crops

- Increase crop yields & pest resistance

- Identification of infectious organisms

- Tracing the transmission of disease & developing treatments

- Discovering new medical products (drugs, hormones),

- Looking at similar past cases/solutions

- Identifying plants before use

- Identifying evolutionary links between species

- Allows for the conservation of species

Classification

Grouping organisms based on a set of criteria that helps to organize and indicate evolutionary relationships

Hierarchical classification

arranging items at different levels in relation to other items in the group

Nested system

classifying organisms from most general to most specific

Rank

each level or category

Taxon

the classification of an organism at each rank level

Domain

the most general, contains the most species

Domain Bacteria contains

Kingdom Bacteria

Domain Archaea contains

Kingdom Archaea

Domain Eukary contains

Kingdoms Protista, Fungi, Plantae, Animalia

6 Kingdoms

Bacteria, Archaea, Protista, Fungi, Plantae, Animalia

Binomial nomenclature

a two-part naming system: The organism's scientific/species name, italicized if typed, underlined if handwritten, developed by Carolus(Carl) Linnaeus

Genus

identifies the group of closely related species it belongs to (capitalized)

Species in binomial nomenclature

specific name for the species, (not capitalized), third word indicates a subspecies

Taxonomy

the ordered division and naming of organisms

Phylogeny

the evolutionary history of a species or group of related species

Systematics

classifies organisms and determines their evolutionary relationships, uses fossil, molecular, & genetic data to infer evolutionary relationships

Evolution

the gradual change in a species over time

Modern classification

Using morphological similarities and evolutionary history to assign a species to taxa

Anatomy

the study of the structure & form of organisms, a branch of morphology, helps scientists determine evolutionary relationships among species

Homology

similarity due to shared ancestry, distinguished from analogy by comparing fossil evidence & degree of complexity, probably has a common ancestor

Reasons to assume homology

the more complex 2 similar structures are, the more likely it is that they are homologous, may or may not have the same function, develops from similar embryonic tissue

Analogy

similarity due to convergent evolution, has a different ancestor but the same function, develops from different embryonic tissue

Homoplasies

Analogous structures or molecular sequences that evolved independently

Divergent evolution

When a related common ancestor adapts into different traits

Convergent evolution

the process in which unrelated species evolve similar physical characteristics because they have similar lifestyles, occurs when similar environmental pressures & natural selection produces similar organisms from different lineage

Vestigial structures

Biological structures that may have once had a purpose, but have no current use

Exaptation

the process in which structures originally adapted for one function take on new functions through descent, with modification

Physiology

Deals with the physical and chemical functions of organisms, considers biochemistry and internal processes

DNA sequencing

comparing DNA from different species to determine relationships, similar DNA sequences = more closely related

Nucleic acids

comparison infers relatedness and traces organism's evolutionary history

DNA

codes for ribosomes change and helps investigate branching points hundreds of millions of years ago

Mitochondrial DNA

evolves rapidly, can be used to explore recent evolutionary events

Molecular clocks

Uses constant rates of evolution in genetics to estimate when species diverged, calibrated with branches whose dates are known from fossil records (must pick an gene that is not completely essential)

Neutral theory

1. States that much evolutionary change in genes and proteins has no effect on fitness - therefore not influenced by Darwinian selection 2. States that the rate of molecular change should be regular like a clock

Molecular systematics

Using DNA and other molecular data to determine evolutionary relationships, depicts evolutionary relationships in phylogenetic trees

PhyloCode

recognizes only groups that include a common ancestor and all its descendents, provides rules for phylogenetic nomenclature, tree represents a hypothesis about evolutionary relationships

Branch point

represents the divergence of two species

Sister taxa

groups that share an immediate common ancestor

Rooted tree

includes a branch to represent the last common ancestor of all taxa in the tree

Branch point (node)

the point where a branch separates

Polytomy

a branch from which more than two groups emerge

Phylogenetic bracketing

predicts features of an ancestor from features of its descendents

Advantages of a phylogenetic tree

Shows patterns of descent, shows similar characteristics in closely related species

Disadvantages of a phylogenetic tree

Doesn't indicate when species evolved or how much genetic change occurred, should not assume that a taxon evolved from the taxon

Cladistics

Grouping organisms by common descent

Clade

a group of species that includes an ancestral species and all its descendants, must be mono phyletic

Monophyletic

Consists of all ancestor species and descendants

Paraphyletic

Consists of an ancestral species and some of its descents

Polyphyletic

Clade + few extras to compare

Shared ancestral character

A characteristic that originated in an ancestor of the taxon, something the whole group has (dependent on context)

Shared derived character

An evolutionary novelty unique to a particular clade, something only some evolved to have (dependent on context)

Maximum parsimony

Assumes that the tree that requires the fewest evolutionary events is the most likely, contains the least appearances of shared derived characteristics

Maximum likelihood

If you follow rules about how DNA changes over time, a tree can be found that follows maximum parsimony

Domains of life

Bacteria, Archaea, Eukarya

Eukarya is more closely related to Archaea

Protista(Eukarya) is unicellular

Endosymbiosis

Proposes mitochondria & plastids(chloroplasts) were small prokaryotes living in larger host cells

Evidence for Endosymbiosis

- Similarities in inner membrane structure and function

- Are double membrane organelles

- Outer membrane matches the eukaryotic cell membrane

- Possesses individual DNA, different from eukaryotic

- Replicate through binary fission

- Organelles transcribe and translate their own DNA

- Ribosomes are more similar to prokaryotic than eukaryotic

Oxygen revolution

- Occurred 2.7-2.2 billion years ago

- Oxygen began to accumulate in the atmosphere

- Believed that eukaryotic chloroplasts were once cyanobacteria

Prokaryotes

- Live in extreme environments

- Most are microscopic, but have large populations

- Large genetic diversity

- Divided into Bacteria & Archaea

Prokaryotic Structure

- Most are unicellular - some form colonies

- Multicellular - cannot function without other cells

- Colonies - live together but can function individually if separated

- 0.5-5 picometers, smaller than 10-100 picometer eukaryotic cells

- DNA is organized in a single ring-shaped chromosome in the nucleoid region

Bacterial Cell Shapes & Organization(

1. Cocci (circular)

2. Bacilli (rod)

3. Spiral

Peptidoglycan

- Sugar polymers cross-linked by polypeptides

- Encloses entire bacterium\anchors other molecules that extend from its surface

Eukaryotic cell wall material

Cellulose or chitin

Bacterial cell wall material

Contains peptidoglycan

Archaea cell wall material

- Polysaccharrides & proteins

- Lacks peptidoglycan but can have pseudopeptidoglycan

Antibiotics

Targets peptidoglycan -> damages bacterial cell walls

Capsule/slime layer

- A sticky layer of polysaccharide or protein

- Adheres to substrate or other individuals

- Shields bacteria from hosts' immune system