<p>(a)</p>
<p>The intensity of a stimulus doesn’t make an action potential any more powerful - if the individual neuron fires, it fires completely and the same way every time. We can tell the intensity of the stimulus causing neurons to fire by the frequency at which our neurons are firing.</p>
<p>Question: Explain the use of helicase, ligase, and primase in DNA replication. For brownie points, talk about telomerase too.</p>
<p>Helicase pretty much seperates the DNA strands at the replication fork. Toposiomerase works downstrand to unwind the extra winds in the strand caused by helicase. Ligase connects Okazaki fragments. DNA Primase for the leading strand is used once, while for the laggin strand is used multiple times. In both instances, it assembles a short complementery rna precursor called a primer. Telomerase adds telomeres, which are noncoding repetitive DNA sequences, to the end of strands to correct for the laggins strand not being able to replicate the entire strand (if it were not for telomerase, our chromosomes would consistently shorten and lose important genes)</p>
<p>Helicase unwinds the DNA during replication.
Ligase connects the Okazaki fragments.
Primase begins replication to initiate a new complementary strand.
Telomerase attaches to the end of the template strand and adds a short sequence of nucleotides.</p>
<p>LH: regulates oogensis and spermogenisis
FSH: Stimulates the follicle to release the egg. Also is in control of progestorone and extrogen levels.
estrogen: Builds up the lining of the uterus
progestorone: maintains the lining.</p>
<p>Nice answers, but don’t forget to post a question with your answers so other people can join in!
How about:</p>
<p>Question: Discuss the flow of energy in a food web in terms of thermodynamics. Start with producers and go on up.</p>
<p>In reference to the Chi-square question, I assumed that everybody would know that snapdragons were incompletely dominant. It should be prior knowledge, in my opinion, seeing as out of three textbooks and two review books I’ve seen, they all use snapdragons as the prominent example of incomplete dominance.</p>
<p>^ ok thanks.</p>
<p>Whooops, i forgot the question part.
What do you mean in terms of thermodynamics…?</p>
<p>Question: Which of the following would happen to a the cell of a saltwater organism when placed into distilled water?
a) it would remain unchanged
b) it would shrivel up
c) it would swell
d) it would divide
e) it would reproduce</p>
<p>^C, it would swell. This is because the cell has a high salt concentration whereas distilled water has zero salt concentration. So, salts can escape the cell to put the two in equilibrium, but this doesn’t really happen because water enters the cell much quicker through osmosis. Thus, the cell swells. This is why freshwater protists have contractile vacuoles that constantly expel water entering the cell.</p>
<p>How does an angiosperm reproduce?</p>
<p>The cells would swell up due to the change in osmolarity. Usually, however, when the marine organism is in its saltwater environment, the cells constantly expel salts and drink water to make up for the water loss that occurs because their environments are saltier than their cytosol.</p>
<p>agiosperm reproduction: pollen is produced in the anther of the stamen. through cross pollination or self-pollination, a pollen grain sticks to the stigma of the carpel and a pollen tubule moves down the style allowing sperm to enter. through double fertilization, one sperm fertilizes an embryo in an ovule and the other activates the endosperm (food supply) for the seed which is now triploid. the ovule matures to become a seed and the ovary matures to become a fruit. there is so much more I could mention, but this is completely off the top of my head and I haven’t quite started studying yet :/</p>
<p>Describe the differences between the lysogenic and the lytic cycle.</p>
<p>Beginning with the mature sporophyte, the two reproductive parts of an angiosperm are located in the flower. The female organelle is the ovary, and the male organelle is the anther. In this stage all cells are diploids. And it is the dominant stage of the angiosperm. </p>
<p>Next, the 2N anther uses meiosis to divide into 4 haploid pollen grains. Then these 4 hapliod grains use mitosis to turn into 8 haploid cells with 8 nuclei. </p>
<p>While this is going on in the anther, the ovary is also quite busy. Each ovary consists of ovules, which are diploid cells. Then the ovule goes through meiosis to produce 4 haploid cells. Out of these 4 haploid cells only one survives and it goes on to produce 8 haploid cells. The 8 N cells are in a 3-2-3 formation with 3 haploid cells on the two ends of the cell and 2 polar bodies in the middle. </p>
<p>Angiosperms do not self fertilize (i dont think?) and therefore most of them rely on animals, also known as vectors to carry the pollen grains to different flowers. When one pollen grain gets in contact with the stigma (the sticky part female part of the flower) it begins to form a pollen tube. The pollen tube is the tube that carries the sperm from the pollen grain into the ovule of the flower. In the end it produces two haploid sperm cells and when it enters the ovule something remarkable happens. Two fertilizations occur. One fertilization is between sperm and the egg nuclei. This goes on to be the zygote (2N). The second fertilization is between the second sperm and the two polar bodies. Once they fuse, it becomes a triploid cell and it will grow into the endosperm. The endosperm provides nutritents to the developing embryo. </p>
<p>i just went over this last night :D</p>
<p>One question about these frqs. Should we define the terms? like endosperm, anther etc.</p>
<p>QUESTION:
For each of the following natural selection curves, define what happens and give an example.
<p>angiosperms can both self-pollinate and cross-pollinate. there are just more advantages to cross pollination such as gaining genetic diversity so that a massive amount of plants don’t die from the same cause. this is something that say, a farmed corn-field made up of genetically identical plants lacks.</p>
<p>Lysogenic vs lytic.</p>
<p>When a virus enters a cell, there are two cycles that they can follow. Both cycles are very similar in fact, the lysogenic cycle is simply an elongated lytic cycle. In the lysogenic cycle the virus implants its DNA into the the DNA of the host. When it is inserted, it is called is now called a prophage. however it eventually becomes a part of the cells DNA. When the cell divides, the virus’s DNA also divides. This could also be called a dorminant stage. But then, if something triggers the virus’s dna it takes it self out of the cell and goes onto a different phase: the lytic phase. </p>
<p>In the lytic phase the virus the virus takes over the metabolism of the host and causes it to produce different proteins and amino acids. These amino acids assemble into new virus’s and eventually causes the cell to burst, thus allowing the sinister virus to continue to destroy cells. </p>
<p>QUESTION:
What are the major differences between Prokaryotes and Eukaryotes? (you can just list them if you want)</p>
<p>
</p>
<p>You should define terms on the test of course, but on here write whatever helps you study. I define terms just for practice, but hopefully everyone knows more or less what you are talking about at this point in the game, or will look up whatever they don’t know.</p>
<p>"QUESTION:
For each of the following natural selection curves, define what happens and give an example.
<p>Stabilizing curve is represented by a bell curve. This curve is representing animals do not have extreme traits. Animals that do not have this extreme traits are better suited for the environment, and survival. An example of stabilizing curve would be heart size. People with abnormally large hearts are at a disadvantage because there is a decreased amount of blood flowing though the arteries and veins (because the left ventricle muscle are larger and carry less blood to pump though the body.) An human with a small heart wont have enough cardiac muscle to pump blood throughout the body. (assuming that the individual has a abnormally small heart for their height). A person with a medium sized heart will survive because he or she can push more blood though the body.</p>
<p>directional curve is when a extreme trait has an advantage in a environment. A classic example of this is moths during the industrial revolution. White moths were prevalent before the time period, and dark moths did not have an advantage. During the revolution pollution caused the trees to become darker. This caused the white moths to have an disadvantage because they couldn’t camouflage as well as dark moth. In other words the dark moths (extreme trait) gained an advantage over the previously successful trait.</p>
<p>disruptive curve is represented by 2 bell curves. Disruptive curve is representing an extreme trait that can survive in two or more environments. An example is weed. Weed can grow outside on your lawn, where it block out sunlight for grass and other plants, or it can survive in an Forrest were it would quickly sprout a flower and spread spores.</p>
<p>A sexual curve is very different from the previous curves. Sex curves are when organisms reproduce with a mate with excellent traits so their offspring will survive. An example would be a peacock. The male, who is colorful, will spread out its wings and walk around. If the female believes that these traits are adequate for the survival of their children she will mate with the male.</p>
<p>Natural selection affects the frequency of a heritable trait in a population. These can be represented by curved graphs.</p>
<p>**stabilizing curve: ** cuts out extreme members of a population. For example, favoring gray animals over black and white ones.
directional curve: when natural selection favors one extreme. For example, black over white or grey.
disruptive curve: The opposite of stabilizing; cuts out the middling individuals and favors the extremes- white or black over grey.
sexual curve: The sexual characteristics of males and females is known as sexual dimorphism. One gender shows off its characteristics and advances sexual reproduction success. When one characteristic attracts more of the opposite gender, that characteristic shows up more in the following generations, differing from the original population.</p>
<p>Question: What is the endosymbiotic theory, and what is a piece of supporting evidence for the theory?</p>
<p>QUESTION:
What are the major differences between Prokaryotes and Eukaryotes? (you can just list them if you want) </p>
<p>Difference:</p>
<p>Eukaryotes:
have organelles
have closed nucleolus
have bigger ribosomes (S40 S60 S80)
Flagella/cilla are apart of the cytoskeleton
do not have operons
contain histones
come together to form tissues, organs, and organisms
replicate when damaged, or very large
communicate though demesomata, channel proteins, and tight junction
thought to have been created by multiple prokaryotes coming together in a symbiotic relationship </p>
<p>Prokaryotes
do not have organelles, however they do have various vesicles that have special functions
have open nucleus
have smaller ribosomes (S30 S30 S60?)
do not have histones
have operons
replicate when environment is perfect to do so.
cut up foreign viral DNA / RNA
flagella/cilla are not apart of the cytoskeleton
some plasma membranes contain peptidoglycans</p>
<p>Similarities
Have a plasma membrane
Replicate DNA / cell
Create proteins
have ribosomes
have genetic material
contain vesicles that preform special functions
may have cell wall
may be photosynthetic?
may be heterotrophic</p>
<p>“Question: What is the endosymbiotic theory, and what is a piece of supporting evidence for the theory?”</p>
<p>Endosymbiotic theory states that eukaryotic cells first came about as a result of a mutualistic relation between small prokaryotes and larger ones, as evidenced by chloroplasts and mitochondria, whose ancestors are supposedly prokaryotic cells. </p>
<p>Evidence for this idea includes:</p>
<p>Mitochondria and chloroplasts have their own ribosomes similar in size to prokaryotic ribosomes.
Mitochondria and chloroplasts have their own DNA.
Mitochondria and chloroplasts reproduce by a process similar to binary fission.
Mitochondria and chloroplasts have a size similar to many prokaryotic cells, which are in general smaller than eukaryotic cells.</p>
<p>What are the major differences between Prokaryotes and Eukaryotes? (you can just list them if you want) </p>
<p>Prokaryotes v. Eukaryotes
circular DNA v. DNA wrapped around histomes to chromosomes
no internal membranes v. yes
no ER, mitochondria, vacuoles v. yes
anaerobic or aerobic v. just aerobic
unicellular v. multicellular</p>