unit 2 pt 2

• an example of convergent evolution is fins of a fish and fins of a whale (mammal)
• the reason for using an outgroup in a phylogenetic tree is to decide which form of a trait is ancestral versus derived
• by definition homologous traits are traits derived from the same ancestral trait
• a derived trait is one that differs from its form in ancestor of a lineage
• to study evolutionary relationships between widely divergent organisms such as pro and euk, genes for specific ribosome subunits would be best to use
• pencillin is an important antibiotic that kills bacteria with very few side effects on human cells because it inhibits formation of peptidoglycan
• nitrogen fixation is a chemical process that is important for organisms because it is the essential first step to get atmospheric N2 into a compound like NH3
• quorum sensing response in bacteria is when cells only respond when receptors detect many inducer signals
• eukaryotic nuclear rRNA genes are closest to archaeal rRNA genes
• mitochondrial rRNA is closest to bacterial rRNA genes
• mitochondria came before chloroplasts
• an example of lateral gene transfer would be genes from bacteria that were the ancestors of mitochondria becoming part of the mitochondria genome in eukaryotes
• there is fitness advantage of asexual reproduction in a stable, favorable environment
• there is a fitness advantage of sexual reproduction in a changing, harsher environment
• self-fertilization is not the same as asexual reproduction because it involves meiosis and fertilization
• the equivalent of plants "alternation of generations" in animals is haploid sperm products of meiosis undergo-mitosis to form multicellular haploid sperm
• an evolved, distinctive characteristic of all members of complex multicellular groups like animal kingdom is an organism consisting of differentiated cells in specialized tissue types
• two advantages of having a multicellular body over a single-celled is that cells can be specialized for efficient division of labor and with a larger body it can evade predators more easily
• limitations of multicellularity:
• a major function of hox genes is to determine major body structures
• all hox genes are homologous because they have evolved from the same ancestral gene
• this set of taxa (vertebrate classes) have amniotic eggs: birds, mammals, and reptiles
• embryos with differentiated germ layers that give rise to all tissues is a distinctive of all members of the animal kingdom but not true for the others
• the advantage of the amniotic egg over the eggs of fish and frogs is that it allows gas exchange (diffusion of co2 and o2)
• dikaryon cells (n+n) differ from haploid an diploid cells because it is two separate nuclei in each cell
• an anti fungal treatment can harm fungal parasites but not humans because it inhibits chitin cell wall formation
• a defining trait of members of the plant kingdom , that distinguishes them from the protistan ancestors is that they have multicellular embryos that develop on parent
• an advantage for the earliest plants to live on land was that it was easier for chlorophyll to absorb light energy
• a match of a challenge living on land with a plant adaptation to solve that challenge is that when there is too much waterloss, waxy cuticle
• the challenge of competing for light can have the adaptation of growing taller
• the main organ for photosynthesis is the leaf
• the organ that anchors the plant in the soil is the root
• the function of a leaf is : co2 uptake from surrounding air
• the function of a stem is : transporting materials from root to leaf
• in which way do plants grow at meristem regions?

  by mitosis and cytokinesis
• phototropism: plant shoot grows towards the light
• hypothesis: phototropism response requires bluelight 


  null : blue light has no effect on phototropism
• when the hypothesis is that phototropism response requires blue light, what is important to control is the angle/position of the light and the brightness/intensity of the light
• besides light energy, the substances that is used up in photosynthesis is co2 and h2o
• the main source of o2 for aerobic respiration in underground root cells is o2 diffusing in from air pockets in the soil