IB bio A3.1 diversity of organisms

what is the initial way of categorizing organisms

morphology

what are the categories that organisms are divided into called

taxa

what is taxonomy

the science and skill of categorizing life

what is continuous vs discontinuous variation

continuous means it can be placed into distinct categories

discontinuous means there is a wide range of possibilities

what did Carl Linneaus do?

designed the idea of a universal system to categorize living organisms

what did Linneaus base his classification system on

morphological classification

what is the binomial nomenclature system

genus and species

each organism has a unique name

universally understood

stability so you cannot change the name with no reason

what definition of a species is now preferred

biological species concept

what is the biological species concept

individuals must be able to breed together and produce fertile offspring to be classified as a species

what is the problem with the biological species concept?

some organisms reproduce asexually

hybrids are not always infertile

cannot be applied to extinct animals

what are some other things taken into account when deciding on a species

ecological niche

genetics

types of molecules it can produce

lineage

define speciation

the process by which a population is seperated into two groups that can no longer reproduce together due to selection pressures

is it easy to say when speciation occurred

no because it is arbitrary

how many chromosomes do humans and chimpanzees have

46, 48

what is a karyogram

representation of the chromosomes found in a cell arranged according to a standard format which is used to determine a karyotype

how are chromosomes placed in order

according to their size and shape which is dependent on thee position of the centromere

what is a karyotype

the specific number and appearance of the chromosomes in a cell

gorillas and chimpanzees evolved from the same common ancestor as humans. what are the two explanations for the different chromosome numbers simply

a complete chromosome disappeared in humans

two chromosomes from an earlier ancestor fused to become one

is it likely that a complete chromosome disappeared

no, because removing a chromosome would cause a threat to the viability of the species

how can we test the hypothesis that two chromosomes fused to become one

chromosome 12 and 13 from a shared ancestor likely fused and became chromosome 2 because it has a similar shape and length and banding pattern

what refutes the idea that two chromosomes became one

the telomeres are present where there is overlap

there is overlap which makes the banding pattern slightly different but after overlapping them the banding pattern looks similar

where do our genetic differences come from

although there are the same genes shared across a species, each organism has their own allele. these reveal genetic differences and are often caused due to a mutation passed from generation to the next.

there is more variation within or between species

between

what is one major difference between genomes

the size of the quantity of DNA in the nucleus

how can sequencing data help with ecology

differences within a genome can be seen in the base pairs of each genome. sequencing technology can help compare the genome of organisms with others all around the world

what is the connection between an organism’s complexity and their genome size

the more complex they are, the larger their genome

why is genome sequencing important

allows them to identify species and compare them to evolutionary relationships and see how closely related they are

what is phylogenetics

a technique in which they use genome sequencing to study how closely related two organisms are

organisms that share similar genomes tend to be

more closely related

how is genetic sequencing advancing

it is now using more powerful techniques and software to increase speed and lower costs which make it possible for many more people to sequence their own genomes.

what is a potential use of genome sequencing

personalized medicine wherein they can use a person’s genetic makeup to prescribe individual treatments. Patterns can be used by sequencing test subject’s DNA to understand the connection between certain compounds/ drugs and their genome. this can be used to treat dynamic diseases

how can you use genome sequencing to produce medication

find beneficial molecules that are produced naturally

find out which gene controls that molecule’s synthesis

copy that gene and use it to instruct synthesis of the molecule in a lab

distribute the protein as a medical treatment

why is it difficult to apply the biological species concept to plants that undergo parthenogenesis

they continue for many generations without needing sexual reproduction.

how is it difficult to apply the biological species concept to asexually (binary fission) reproducing organisms

they do not reproduce sexually by breeding so no gametes are produced. the cells formed are identical to the parent cell and it cannot be tested whether they can produce fertile offspring because they reproduce asexually

what is the problem with applying the biological species concept to horizontal gene transfer organisms

in horizontal gene transfer means they can exchange genetic material within their lifetime.

this means they mix lineages and it makes it harder to identify the bacteria’s genes and genes from other species that may have gotten inside the bacteria

it can also occur between bacteria and archea and viruses and eukaryotes and so on

why do interspecific hybrids tend to be infertile

they end up with a chromosome number that is neither that of the mother nor the father’s species which makes it hard to reproduce with either as the pairs cannot match up during meiosis

what are two ways to identify species

dichotomous key

barcodes

how are bar codes used to identify species

a Barcode identification number (BIN) is given to a genetic sequence obtained from an organism

it is matched with database of sequences of other organisms that are named and identified

if there is a strong match, then it is known that, with high confidence, the species name is correct for that organism

allow people to rapidly identify various species present in an ecosystem by taking samples

what is an indicator species

a species that is sensitive to certain types of pollution so their presence indicates a lack of pollution