IB Bio HL Yr 1 Unit 2

Monozygotic twin

Identical twins

How do monozygotic twins form?

When an embryo divides into two individuals (same DNA)

Carl Linnaeus

Scientist known for morphology and the morphological species concept

The morphological species concept

The idea that organisms in a species share internal and external structure

How is the binomial system for species formatted?

Made of genus and species. Genus is capital, species lowercase. Italicized and can be abbreviated to G. species.

Biological species concept

Two organisms are part of the same species if they can produce fertile offspring

A population

A group of organisms in the same species living in the same place at the same time.

Speciation

The splitting of one species into two or more

Number of chromosomes in humans

46

Number of chromosomes in chimpanzees

48

Diploid cell

A cell with two sets of chromosomes, most body cells (48 chromosomes)

Haploid cell

A cell with one set of chromosomes, sex cells (23 chromosomes)

Karyogram

A method for viewing chromosomes digitally by dividing, staining, and photographing them.

What three characteristics are chromosomes classified by?

Banding pattern, size, and position of centromere

Genome

All the genetic information of an organism (all of it’s DNA)

Gene

A length of DNA with hundreds or thousands of base pairs

SNPs (Single-nucleotide polymorphisms)

Positions in which a more than one gene base can be present in a species (4,000 to 5,000 in humans)

How is genome size measured?

nuclear DNA content of a haploid cell (C-value), mass, or number of base pairs

Whole genome sequencing

Determining all the base sequences in an organisms genome

What is whole genome sequencing used for?

Examining evolutionary relationships and in the future personalized medicine

What organisms does the biological species concept not work for?

Asexually reproducing species and species with horizontal gene transfer

DNA barcode

A short section of DNA from one gene that is enough to identify a species by

What are DNA barcodes used for?

Species identification

Taxon

A group for classifying organisms (e.g. phylum)

Taxonomy

The act of creating groups to classify organisms and assigning them to groups

What is the order of the taxa in the traditional method of taxonomy?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Cladistics

An alternative approach to taxonomy that used unranked clades and focused on evolutionary relationships

Clade

A group of organisms that have evolved from a common ancestor including the common ancestor

How are organisms place in clades?

By examining base sequences in DNA, amino acid sequences of proteins, and morphological features

Molecular clock

Because mutations in organisms occur at a roughly constant rate, the differences in the genome of two organisms can be compared to determine approximately how long ago they diverged

Cladogram

A visual representation of clades through a tree diagram

What are the three domains?

Bacteria, Archaea (archaebacteria), and Eukarya

Lamarkism

Developed by Jean-Baptiste Lamarck, the idea that evolution occurs because of acquired traits being passed down to offspring (e.g. giraffe necks stretched to reach high branches and so their children were naturally born with long necks)

Darwinism

Evolution occurs through random mutations in the genome of an organism which gets passed down to offspring and will go under the influence of natural selection

Artificial selection

When humans have selected to breed organisms with similar traits in order to produce offspring with the desired trait.

Pentadactyl limb

The section of bones that makes up human arms, bird wings, lizard feet, whale fins, and several other animal arm-like structures that came from a common ancestor (homologous structure)

Vestigial structure

A structure passed down from an ancestor that no longer has a use (e.g. appendix)

Homologous structures

Structures with a similar structure but different function, passed from a common ancestor.

Analogous structure

Structures with the same function but different structure and evolutionary origin.

What two processed cause speciation to occur?

Reproductive isolation and differential selection

Reproductive isolation

When two populations of a species because separated reproductively due to geographical separation of behavior and temporal differences (sympatric speciation)

Differential selection

Different pressures in the environment act on the populations in different ways, causing natural selection to take place and lead to different features forming. Examples include climate, predation, and competition

Allopatric speciation

When populations in different geographic locations become different species

Sympatric speciation

When a population living in one location splits due to behavioral or temporal differences

Adaptive radiation

When species evolve to occupy different ecological roles which minimizes competition and increases biodiversity (example: Darwin’s finches)

Polyploidy

When the number of chromosomes in a cell duplicates without the cell dividing, resulting in a cell with double the amount of chromosmes

Allopolyploidy

When individuals from different species cross breed, the resulting cell undergoes polyploidy. Division is successful because there will be two homologous chromosomes of each type (two from each parent) enabling it to overcome fertility problems

What are the three types of biodiversity

Species, ecosystem, and genetic

Richness

The total number of species in an ecosystem

Evenness

How similar the populations of the species are (do they have a similar abundance?)

What caused the first five mass extinctions?

An asteroid, volcanic activity, and climate/atmospheric changes

What is causing the sixth mass extinction?

Human activity

What are the anthropogenic causes of species extinction?

overharvesting, habitat destruction, invasive species, pollution and climate change

What human activities cause ecosystem loss?

Land-use change for agricultural expansion, urbanization, overexploitation, mining and smelting, building of dames and extraction of water, drainage/diversion of water, leaching of fertilizers, climate change

IPBES (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services

Intergovernmental organization that asses biodiversity through monitoring

What does IPBES monitor?

Population size, range of a species, diversity of species in an ecosystem, richness and evenness, area occupied by ecosystem, extent of degradation, number of threatened species within a taxonomic group, genetic diversity with a species

Simpson’s Reciprocal Index

Higher value of D is more diversity

What is the overarching cause of the current biodiversity crisis?

Human population growth and overpopulation

In situ conservation

Conservation of habitats like natural parks or nature reserves that keep species in their native habitat

Management of nature reserves

Includes removal of alien species, reintroduction of species that have become locally extinct (like wolves at Yellowstone), attempts to increase/decrease population of herbivores or predators if needed, prevention of poaching, supplementary feeding, and control of human access

Rewilding

Taking an ecosystem that is very damaged and attempting to restore it to a natural state

Ex situ conservation

When organisms are taken out of the environment into a zoo or botanic garden to breed and keep endangered species safe

Storage of germ plasm in seed or tissue banks

Storing living material for long term that could be used in the future (seeds for plants and tissues, eggs, or sperm for animals)

EDGE

Evolutionarily Distinct and Globally Endangered