exam 3 answers Flashcards
explain what accounts for the differences among the strains in the figure below
spacer seq (each column) of bacterial strains (rows) are shown in the diagram. the CAS system adds the spacers chronologically starting at the leader sequence, thus the order of attack by phages is preserved in the sequence of spacer sequences. The diagram shows not all bacteria were attacked by all phages. the bacterial strains are not the same because they’ve been attacked by different phages or the same phages but in a different order.
what is the primary dispersal stage or stages for the following groups
a) ferns - spores
b) plants - seeds, pollen, fruit
under what environmental conditions is lung breathing important for lung fish
they live in revers that periodically dry up - they breathe through gills when there’s lots of water but switch to lung breathing when the river dries up and they burrow under the mud
hagfish and lampreys are in the phylum chordata because of what morphological characteristics
notochord, pharyngeal gill slits
what evidence suggests that the association among plants and mycorrhizal fungi was more important for invasion by land plants, than the association of nitrogen fixing bacteria and plants
the association of mycorrhizal fungi and plants is found in the roots of the terrestrial plant fossils from the period just as plants colonized land (over 400 mya) whereas the association of n-fixing bacteria and plants originated more recently (100 mya). this suggests n fixing bacteria relationship was =not critical fro plants to live on land since they lived in land for 300 mya without the n fixing bacteria.
name 2 other species of homo that were extant when homo sapiens first originated
homo erectus, homo neandrethalisis, denosivans, homo floriensis
the transpiration cohesion tension theory was proposed to explain how plant circulation works
a) explain the tension part of the theory
b) how does the structure of the xylem tubes reflect an adaptation to tension
a) water molecules have a high affinity for each other and when the water transpires from the stomata, the column of water in the xylem is sucked up through the tube by of tension. water evaporating from the leaf pulls the water up the xylem tube because there is tension when the water is pulled up.
b) xylem have thick walls to resist collapse from tension and cavitation
the data below are salmonella density in the colon of mice that were either treated with streptomycin or not. discuss how these data relate to the role of the gut microbiome in immunity.
these data show that mice that didn’t get streptomycin had salmonella in their colon but the density was much lower than the ones with the anitbiotic. antibiotics affect a;; bacteria (good and bad). the increase in salmonella after the antibiotic treatment is consistent with the hypothesis that an intact gut microbiome is important in the immune sys because it keeps bad bacteria in check.
compare/contrast constitutive and gene for gene immune response
constitutive: generalized defense that’s always on
gene for gene: generalized defense that is triggered by the AVR gene of a fungus or bacteria
dif: gene for gene response is only on after being triggered; conctitutive responses are always on
compare/contrast neotony vs heterochrony
neotony: retention of juvenile/larval traits in the adult stage
heterochrony: variation in timing and rates of growth among different body parts
dif: heterochrony is more general - refers to any dif in development of dif body parts but neotony refers to a condition where adult features develop slowly so juv features are present in the adult stage
compare/contrast oviparity vs ovoviviparity
oviparity: organisms that lay eggs way before embryo is finished developing
ovoviviparity: organisms that keep the egg in the adult until right before they hatch. the offspring emerge from the adult as juveniles
dif: less parental care with oviparity. more parental care with ovoviviparity
compare/contrast arbuscle and mycelium
arbuscle: specialized structure of hyphae in mycorrhizal fungi that’s in contact w/ the plants’ inner cell membranes. transfer of materials pass through the arbuecle from plant to fungus not fungus to plant.
mycelium: collection of hyphae that form into reproductive structure
dif: mycelium are above ground structures fro reproduction. arbuscles are underground and have to do with nutrients and roots
the figure below shows changes in an insect between 1) summer, (2,3) fall and 4) midwinter in the northern hemisphere. the dots are ice nucleating agents and size of the dots indicates ice mass
a) is this figure an example of freeze tolerance or freeze avoidance
b) explain where in the insect body these changes occur and how these changes enable the insect to survive subzero temps over winter
a) tolerance
b) in the summer the fluids are in the tissues and the hemocoel. when fall comes, the ice nucleating agents are moved into the hemolymph so ice crystals grow in the hemocoel away from cells to prevent cell puncturing. in winter, the hemolymph freezes, so ice grows away from the cells.
what’s the only organ not present in a fetal homo sapien that develops in adults
placenta
a) during the day, what;s the primary factor that limits sugar producrtion by plants that use c3 photosynthesis and are well watered?
b) during the day what’s the primary factor limiting sugar production by a plant using c3 photosynthesis and has closed stomata
a) rubisco
b) CO2
The figure below shows a classic U shaped curve for homeotherms. explain two changes in physiological mechanisms that occur at temps below and two changes that occur in physiological mechanisms above the thermoneutral zone
1) below: increase metabolic rate, vasoconstriction, shivering
2) above: decrease metabolic rate, sweating, vasodilation
