A small lead sphere is encased in insulating plastic andsuspended vertically from an ideal spring (spring constantk = 126 N/m) as in Fig. 21-71. The total mass of the coatedsphere is 0.650 kg, and its center lies 15.0 cm above a tabletopwhen in equilibrium. The sphere is pulled down 5.00 cmbelow equilibrium, an electriccharge Q = -3.00 X 10-6 C isdeposited on it, and then it isreleased. Using what you knowabout harmonic oscillation, writean expression for the electric fieldstrength as a function of time thatwould be measured at the point onthe tabletop (P) directly below thesphere.
Ento 2010 Weel 11 Notes March 28, 2016 o Order: Siphonaptera Siphon=tube Aptera=wingless Common name: fleas Species=1,800 o Siphonaptera Complete metamorphosis Piercing/sucking mouthparts No wings Adults of both sexes are blood-sucking parasites Good jumpers and runners Narrow body Many are disease vectors o Fleas: Female needs blood for eggs Female eats 15 times her weight/day Female lays 2000 eggs Eggs hatch in 1-10 days Larvae feed on adult feces Larva spins a sticky cocoon Cocoon is well camouflaged Life cycle is 12-174 days Environment (temperature and humidity) is very important o Fleas are attracted to: Heat Carbon dioxide Light Movement o Fleas: Can jump 200 times their length Resilin: a protein in the back legs of fleas that works like a rubber band o Miriam Rothschild is a world flea expert She showed that female flea reacts to sex hormones of a pregnant female host Female flea adjusts her reproductive cycle to match that of her host Lays her eggs on babies of host o Bubonic Plague Vector: fleas Disease: bacteria Yersinia pestis Antibiotic treatment is effective Found in Russia, Middle East, and Western U.S. Major outbreak in India o Bubonic plague: Reservoir=rodents Bacteria enter flea with blood meal Bacteria multiply in flea gut Bacteria break entry to gut Flea seeks new host Flea feeds on new host Regurgitates blood with bacteria Host is infected o Elephantiasis Vector: mosquitoes Disease organism: roundworms Causes swollen appendages 300 million people in Southeast Asia have Elephantiasis o River Blindness Vector: black flies Disease: roundworms West Africa 20 million people infected o Possible use of insects in war Modify plague bacteria Destroy crops War on drugs March 30, 2016 Mimicry : Resemblance of an organism to some other organism/object Natural Selection : change in the frequency of genetic traits in a population through differential survival of individuals bearing those traits Natural selection: Blue jay (a predator) eats moths 50 years ago most moths were pale pale moths were hard to see on trees pollution darkened trees today most moths are dark dark moths are now harder to catch Batesian mimicry: resemblance of an edible species (mimic) to an unpalatable species (model) to deceive predators Batesian mimicry: Viceroy looks like monarch butterfly Monarch larva eats toxic milkweed Viceroy larva eats non-toxic willow Monarch adult is toxic=model Viceroy adult is non-toxic=mimic Blue jay “learns” to avoid mimic Mullerian mimicry: mutual resemblance of 2 or more unpalatable species to enhance predator avoidance Crypsis : resemblance of an organism to its background Dead Leaf Butterfly Outer wings look like leaf Inner wings have bright color o Wing edge of moth/butterfly may mimic caterpillar or snake o Nemoria arizonaria Spring Caterpillar eats oak flowers: mimics flowers Summer Caterpillar eats oak leaves: mimics twigs Passion vine & butterfly interaction: Passion vine leaves have toxins to deter insects Some butterfly species can eat only 1 passion vine species Passion vine leaves mimic each other to confuse butterfly Female butterfly lays one egg per leaf, because larvae are cannibals! Passion vine makes “mimic eggs” on leaf Butterfly avoids passion vine leaves with “mimic eggs” April 1, 2016 o Exam 2