How many 2n chromosomes does a whitefish blastula have, and how many 2n does an onion root tip have?
969900
It's impossible to answer your question without knowing precisely what species of whitefish and onion your are talking about. For instance, "whitefish" can refer to dozens of different species according to http://en.wikipedia.org/wiki/Whitefish . Try reposting your question with the names of the species.
885418
D is definitely the false answer because, in Meiosis I, the homologous chromosomes are seperated. The chromosomes are divided in Meiosis II. The seperating of the two homologous chromosomes into different daughter cells cause the number of chromosomes to be halved.\n\nE is definitely correct because the daughter cells are different from each other due to cross-over and also because of the seperation of homologous chromosomes.
312139
A human parental cell (or germ cell) has 46 chromosomes or 23 pairs (2n).
582124
The fern.  I've found sites listing species that have 480 or 768 or  even 1200 chromosomes!\n\nNo humans are not the "best" and no it's not true that "Acording to evolution the more an organism evolves [whatever that means] the more chromosomes it gets."\n\nHumans aren't even in the running for most chromosomes.  Many plants, and even the lowly amoeba has us beat.  The butterfly has 380.\nOther contenders: \nWhite Ash 138 \nCarp 100\nGoldfish 94 \nSweet Potato 90 \nTurkey 82\nChicken 78 \nDog 78 \nDuck 78\nHorse 64 \nCow 60 \nSilkworm 56\nCotton 52 \nAmoeba 50 \nChimp 48\nTobacco 48 \nHuman 46
268425
Mendel's law of independent assortment basically says that each chromosome pair will separate during meiosis individually, regardless of whether the chromosome originated maternally or paternally.  So for example, if there are two pairs of chromosomes, 1 and 2, and each have a maternal and paternal copy (1M, 1P, 2M, and 2P), pairs 1 and 2 will segregate without input from the other pair.  So during meiosis, when the a haploid cell is formed with only one chromosome copy, there are many different combinations that can be formed.  The cell could contain 1M/2M, 1M/2P, 1P/2M, or 1P/2P.  It is easy to see how organisms with more chromosome pairs (humans have 23 pairs, 46 total) will produce more combinations, hence diversity among the species.  Hope that helps!
699918
Humans have 46 chromosomes, not 26. \n\n23 come from mom, 23 from dad.
279599
sex cells. they only have half the nomal number of chromosomes.
65963
During meiosis, sexually reproducing organisms choose one of the two versions of each chromosome they have (the two versions are supplied because each parent provides one copy of each chromosome) to be included in the haploid gametes. Because one copy of two possible choices has to be made for each of the 4 chromosomes (diploid number of 8 is referring to the fact there are 2 copies of each of 4 chromosomes meaning 8 total). \n\nTo figure out the number of possible combination you use a simple probability formula. \n\nThere are 2 choices for the first chromosome location x 2 possible choices for the second location x 2 possibilities for the third location x 2 possibilities for the final location\n\n2x2x2x2 = 16 possible combinations that can be made in any one gamete.\n\nOf course this is the absence of any crossing over event, which can produce an incalculable number of possible rearrangements.
756934
Meiosis consists of 2 nuclear divisions that reduce the # of chromosomes to the haploid # (n) in preparing for sexual reproduction. \n\nThe fertilization of the haploid cells, sperm and ova (gametes), is the diploid cell (zygote) which gives a 50% chance of daughter cells being maternal or paternal for each chromosome. not sure on the 1/8 chance of paternal chromosomes.\n\n# of possible combinations = 2 to the nth power (2 ^n)\nso, if 2n=6, then n=3 and there is 2 ^3 = 8 number of combinations.\n\nJust FYI, In humans with 23 pairs of chromosomes, a gamete  could have 2^23 or 8,388,604 possible combinations of chromosomes from that parent. Any couple could have 2^23 ×  2^23 or 70 trillion different possible children, based just on the number of chromosomes. \n\nIn addition, crossing-over, in which the two homologous chromosomes of a pair exchange equal segments during synapsis in Meiosis I, can add further variation to an individual’s genetic make-up.
202968
If the rest of your question was: "What is the diploid number of chromosomes after synthesis?" Than the answer is still 12 because a haploid cell won't form until mitosis. If you clarify your question, you can get better answers. I'll come back to check.
1018240
none\n\n\nyou start with one pair of homologous chromosomes in prophase I of meiosis I.  at metaphase I, these homologues line up across the metaphase plate, and at anaphase, they seperate so that one homologue goes to one pole, and the other homologue goes to the other pole.  after cytokinesis at the end of telophase I, you have one homologue in each cell...that homologue then goes through meiosis II, and at metaphase II, that homologue lines up at the metaphase plate with each sister chromatid facing each pole, and the chromosome is "pulled apart".  Anaphase II pulls the sister chromatids to each pole, and cytokinesis splits the one cell into two....two cells, each containing one sister chromatid of a homologous pair. (although in some text books this is refered to as a single homologue)
535424
a chromatid forms one part of a chromosome after it has coalesced for the process of mitosis or meiosis. during either process, the word "chromosome" indicates a pair of two exactly identical or "sister" chromatids joined at the central point of each chromatid, called the centromere.\n\na chromosome, by definition, has exactly one centromere. thus when sister chromatids are pulled apart by the mitotic spindle during anaphase - that is, when the centromere joining two sister chromatids splits into two centromeres - then each sister chromatid becomes an independent chromosome.\n\nin non-gametic, non-dividing human cells, there are 23 pairs of chromosomes and thus 46 chromatids.
1098076
A chromatid forms one part of a chromosome after it has coalesced for the process of mitosis or meiosis. During either process, the word "chromosome" indicates a pair of two exactly identical ("sister") chromatids joined at the central point of each chromatid, called the centromere.\n\nA chromosome, by definition, has exactly one centromere. Thus when sister chromatids are pulled apart by the mitotic spindle during anaphase -- that is, when the centromere joining two sister chromatids splits into two centromeres -- then each sister chromatid becomes an independent chromosome.\n\nIn non-gametic, non-dividing human cells, there are 23 pairs of chromosomes, thus 46 chromatids. When it is ready for mitotic cell division, each chromosome will replicate itself during the synthesis phase within its life cycle, making a total of 92 chromatids before dividing, producing two cells each with 46 (remember, since the term "chromosome" is redefined,but still the number of chromosomes remains 46 despite the replication).\n\nIn gametic cell division (meiosis),the cell replicates once but divides twice so that 23 chromosomes are left in each of four egg or sperm cells. (23 chromosomes are each needed from the male and female to combine and make 46 chromosomes for the zygote.)\n\nA common mistake among students is that they think that chromatids always exist; chromatids ONLY exist when a chromosome replicates itself.
643728
http://www.hr-rna.com/RNA/Spider%20pages/Green%20Lynx%20page.htm\n\nhttp://www.biosurvey.ou.edu/okwild/misc/glspider.html
166727
This may seem like a silly suggestion, but try representing the elements mentioned in your textbook (which I'm sure has some illustrations) with pieces of paper, matches, beans or something like that, so you can understand the events and the outcome. \nNow, if you _really_ want an explanation, here it comes (I've ommited the names of the phases, they'll be in your textbook).\n\nMeiosis includes 2 cell divisions with different characteristics. \nWe start with a diploid (2 n) cell, in which DNA duplication has occurred so that each DNA strand is double. These strands do not yet appear as chromosomes (condensed bodies); in fact, the chromatin strands have to be "relaxed" in order to duplicate. \n\n***Meiosis I: (in which the nº of chromosomes decreases to half)\n1. The chromatin (DNA strands) starts to condense and appears as small dense dots (the chromosomes) within the cell nucleus. These chromosomes will each have 2 "arms" (they look like an X or a V) because the DNA in each has been duplicated.\n2. Now all these chromosomes align in homologous pairs, with the aid of a transparent structure formed by tiny intracellular fibers (the spindle) that has formed and will help them to move in orderly fashion within the nucleus.\n3. While they keep condensing, each homologous chromosome contacts its "brother", and they exchange some fragments of their DNA ("crossing over"). Usually only one "arm" of each  chromosome participates in crossing over. \n4. In the meantime, the nuclear membrane is disintegrating...\n5. The pairs of homologues, still united, align at the middle (equator) of the spindle... \n6... and then each pair of homologues is divided, one chromosome of each pair goes toward each "pole" of the spindle. \n7. New nuclear membranes form around the 2 groups of chromosomes. Each of these groups will only have ONE of each pair of homologues. Essentially the information in each new nucleus is the same, BUT has some differences because, as you recall, there has been crossing over i.e. partial exchange of DNA between homologues. \n8. The original cell with the 2 nuclei divides and forms 2 cells, with half the nº of chromosomes of the original cell (haploid or n). Each of the chromosomes still has a duplicate DNA strand.\n\n... the cell takes a short break (you can take a break too!)... but the chromatin does not duplicate this time (it's already done that)\n\n***Meiosis II: (in which each double DNA strand becomes single again, this phase is similar to a normal mitosis).\n1. The chromatin condenses again, so that it appears as chromosomes.\n2. This time the spindle aligns the center of each chromosome at its equator.\n3. The central part of the chromosome is duplicated and the sister "arms" (chromatids) separate, each migrating to opposite poles.\n4. Now you have two groups of chromosomes, each group still has the haploid (n) nº of chromosomes (the same amount with which they started this 2nd meiosis) but now, each chromosome has a single DNA strand. \nA new nuclear membrane forms around each of these groups of chromosomes.\n5. The rest of the cell divides.\n\nSo, to sum up: you started with ONE diploid cell. You end with FOUR haploid cells. In animals, this process only happens during the production of gametes. \nIf we're talking about the formation of female gametes, then only ONE of the 4 resulting cells will become an ovule (and that only after more maturation), the other 3 cells form "polar bodies".\nIn contrast, when it's spermatozoids being produced, all FOUR resulting cells will become spermatozoids. \nThat's one of the reasons sperm is cheaper than ovules! There's just more of them in the entire animal kingdom.\n\nNow, what is the purpose of this extremely complicated (the above is a very simplified version) process? The result will be cells that have half the chromosomes of the normal body cells. These cells
271518
two copies of chromosomes ion the same cell
712484
I searched the ultimate source of all the stuff on net and here's what came out-\n\nhttp://scholar.google.com/scholar?q=humans%20and%20shark%20dna&hl=en&lr=&oi=scholart\nhttp://www.google.com/search?hl=en&q=humans+and+shark+dna\n\nGood luck