<p>LOL, You are ALL googling. This may work in class, but not in my turf.</p>
<p>I'm not googling.</p>
<p>Yeah this is pointless if you use wiki.</p>
<p>Progressing toward the top of the plant evolutionary ladder, there is a trend in a reduced gametophyte. However in the highest order plants, angiosperms (phylum anthophyta), the plants still contain gametophytes. What is the purpose of conserving the gametophyte by not completely elminating it?</p>
<p>To answer Boridi's question:</p>
<p>habituation: a type of learning in which the individual loses responsiveness to stimuli that convey little to no information. An example is the hydra, which will contract when disturbed from a slight touch, but will stop reacting if it is repeatedly disturbed by the stimulus. Habituation allows organisms to pay closest attention to stimuli that signal food, mates, and danger, rather than wasting time/energy on neutral, irrelevant stimuli.</p>
<p>imprinting: a type of learning that happens only during a certain time period in an animal's life and is irreversable. A famous example invovles graylag geese. A scientist, Konrad Lorenz, divided a set of eggs into two groups. One group stayed with the mother, was born, and matured normally, and the other group of eggs rested in an incubator. when the second group was born, they spent the the first critical hours of their lives (know as the sensitive period) with Lorenz instead of their mother. these geese began to follow Lorenz around and did not show recognition of their own mother. as the grew older, they would prefer the company of humans, and did not identify with other geese.</p>
<p>classical conditioning: a type of associative learning made famous by Ivan Pavlov. Classical conditioning means that the animal learns to associate an arbitrary stimulus with a reward or punishment. In Pavlov's case, he trained dogs to salivate upon hearing the sound of a bell. In the beginning, he would ring a bell before spraying powdered meat into the dogs' mouths, causing them to salivate. eventually, the mere sound of the bell was enough to trigger salivation.</p>
<p>operant conditioning: also called trial-and-error learning. In this type, an animal learns to associate one of its behaviors with a reward or punishment, then repeats or avoids that behavior accordingly. An example involves scientist BF Skinner, who put mice in a box in which they could only get food by pressing a lever.</p>
<p>I don't have it in me to tackle il bandito's question, so I'll defer that to the next person...</p>
<p>(And by the way, NONE of that was from google/wikipedia/the internet.) I'd do a works cited for my Bio textbook if I had more initiative.</p>
<p>Oh this is just a curiosity I had always never found out: Where exactly are phytochromes located in the plant cell? Is it in the thylakoid membranes?</p>
<p>since phytochrome is a photoreceptor, I'm guessing that it is in the thylakoid...</p>
<p>I'm not sure - too lazy to look it up.</p>
<p>Next question: Describe the sodium-pottasium pump from a cell's polarized state to action potential, and back to repolarization.</p>
<p>Eh...Na+/K+ ATPase doesn't really change. It's whole purpose is to keep the voltage of the cell at ~70mV. However, what does change during impulse propogation is the gated ion channels. First, usually a chemical binds to a chemically gated ion channel causing an EPSP. When summation of IPSP's and EPSP's is able to raise the voltage of the cell to around -30mV (threshold), then voltage gated Na+ channels open, allowing Na+ to stream in from out of the cell. The activation gate of this protein channel opens fast while the deactivation gate slowly closes. As the deactivation gate is closed, the K+ voltage gated ion channel's activation gate is open, allowing for the mass emigration of K+ ions following their electrochemical gradient, thus repolarizing then hyperpolarizing the cell. The open K+ channel activation gate and closed Na+ channel deactivation gate causes the refractory period. </p>
<p>The Na+/K+ ATPase just restores the resting potential of the neuron by restoring the proper electrochemical gradients of the two ions. It dephosphorylates one ATP to ADP + P<em>i and binds the P</em>i, causing it to change its conformation. It pumps 2 Na+ to the outside while pumping in 3 K+.</p>
<p>nice, that's pretty detailed. </p>
<p>you can post the next question if you want.</p>
<p>What is the complementary system and how does it work in concert with the humoral response in fighting antigens and other foreign invaders to the body?</p>
<p>Bonus: Explain the difference between the classical pathway and the alternative pathway.</p>
<p>The complement system (which is what I think you are talking about) is a group of proteins that wander around in our blood system. They function as part of the humoral response because they respond to antigens or bacteria or other invading substances in the blood. They work in the domino effect and ultimately causes the invader to lyse.</p>
<p>Classical pathway is part of the specific defense system. The proteins work "in complement" with antibodies which mark a specific pathogen for the proteins to initiate destruction.</p>
<p>Alternative pathway is nonspecific defense, so there are no antibodies involved. THe proteins basically just attack whatever foreign substances they find floating in the blood (I think special molecular marks of the invader triggers this). </p>
<p>Next question: Describe the movement of water in a plant from the roots to the leaves, and any mechanisms which allow for this to happen.</p>
<p>Use: symplastic/apoplastic pathway, casparian strip, water potential, osmosis, capillary action, and cohesion-adhesion theory.</p>
<p>Roots have lower water potential due to concentration of ions and other intercellular elements. The water thus flows from the higher potential of the soil to the lower of the roots. Nutrients such as minerals and ions can be uptaken by proton motive forces generated by proton pumps along the root cell's p-membrane. Also protons can free cations from the negatively charged soil particles. Water and minerals can either travel through symplastic, through cells, or apoplastic (through extracellular space along cell walls). Casparian strip of waxy suberin is a dead end of the apoplastic route forcing all water/minerals to enter via symplast, the guard cells in this case. They thus act as a regulator of what enters/stays out. The absorbed material enters the vessel tubes. Capillary action due to cohesion and adhesion of water causes water to move up gradually. However, transpiration induces low water pressure in the leaves and the rope of water molecules hydogen bonded travels up toward the leaves, into the low water potential area. This is cohesion-adhesion theory.</p>
<p>Name the transport/excretory and structural adaptation of annelids and describe their evolutionary significance/value.</p>