Homologous chromosomes in Meiosis?
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Each chromosome in your body has an "identical pair"- there are two chromosomes that code for the same functions- one from your mother and one from your father.\n\nBecause they come from two sources, they are coding for the same functions, but may code differently for them (ie blue eyes as opposed to brown eyes).\n\nDuring prophase one, each chromosome duplicates into two sister chromatids joined by a centromere, and then the double stranded chromosome finds it's partner which is coding for the same thing (just came from the opposite parent), and is also double stranded.  Now you have a 4 stranded tetrad.\n\nGenetic variability comes from crossing over.  This is where the two chromatids closest together in the tetrad exchange some genetic information.\n\nFor example, two of the chromatids code for blue eyes, brown hair and shortsightedness.\nThe other two chromatids code for brown eyes, red hair and normal vision.\n\nDuring crossing over one chromatid from each pair forming the tetrad literally have ends "crossing over" and bits of information are exchanged.\n\nAfter crossing over, you have 4 chromatids with unique codings.  Using the example above, we may now have:\n-blue eyes, brown hair, shortsightedness\n-blue eyes, red hair, normal vision\n-brown eyes, brown hair, shortsightedness\n-brown eyes, red hair, normal vision\n\nWe now have genetic variability in each gamete produced from this meiotic division.
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Meiosis:  \nprocess of cell division which occurs in the maturation of sex cells (Biology).\n\nMitosis:\nprocess of cell division resulting in two daughter cells which are identical to the original nucleus (Biology).
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two cell divisions.... one for meiosis 1 and one for meiosis 2
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First, note the word "true-breeding".  That indicates each plant is homozygous for all those traits, which means that you don't have to worry about that plant being het for any of those genes.  And it means that they only make a single kind of gamete with regard to thsoe 4 genes.\n\nTechnically, these loci might all be linked to each other, you would need F2 data to know for sure.  But you are supposed to assume that four traits are controlled by 4 genes.\n\nNow, since the parents were homozygous for all their genotypes, the offspring will all be identical, they will all be het for those genotypes.  And which ever phenotype they are, that's the dominant one for that trait.  So purple, green, terminal, and yellow are the dominant phenotypes.\n\nAnd there are 16 different gametes to be made, because there are 4 genes (presumably) and each is het in the F1.\n\nThe only way for an F2 to show all 4 recessive phenotypes would be for it to get a gamete from each parent taht also had all four recessive alleles.  So 1 in16 gametes will fit the bill, so the odds of getting that gamete from on parent is 1 in 16, the odds of getting it from the other parent is 1/16, so the odds of getting it from both is 1/256.
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In metaphase, the cell would have 8 chromosomes lined up in the middle, each made up of 2 sister chromatids. The microtubules are attached to the kinetochores and each sister chromatid is facing in the opposite direction of it's pair and towards one end of the cell.\n\nThe daughter cells would all have 8 chromosomes because it's mitosis, not meiosis.
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2 cell divisions\nMeiosis I and Meiosis II
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crossing over during meiosis.  this is when differnet alleles in the chromosomes switch places, and therefore allow a variation in the product.
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Humans have 23 unique chromosomes (called the haploid number) Each one of the chromosome is different from the all the others (unique). \nHowever we have two copies of each type of chromosome hence making 2x23=46 chromosomes called the diploid number).\nHomologous chromosome or homologs as you refer to them are the pair of chromosomes which are of the same type, and in normal humans there are always TWO of each type. Therefore the number of homologs or pairs of same chromosomes is the same as the haploid number of chromosomes i.e. 23 in normal human beings.\nAn autosome is any chromosome that is not a sex chromosome (i.e. neither a Y nor an X chromosome)
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>meiosis (mīŏ'sĭs) , process of nuclear division in a living cell by which the number of chromosomes is reduced to half the original number. Meiosis occurs only in the process of gametogenesis, i.e., when the gametes, or sex cells (ovum and sperm), are being formed. Because fertilization consists of the fusion of two separate nuclei, one from each of the sex cells, meiosis is necessary to prevent the doubling of the chromosome number in each successive generation. An ordinary body cell is diploid; i.e., it contains two of each type of chromosome. The members of each pair are known as homologous chromosomes. An ovum or sperm is haploid; i.e., it contains only a single chromosome of each type and, therefore, half the number of chromosomes of the diploid cell. When the two haploid cells fuse, the diploid number is restored, and the plant or animal growing from the fertilized egg (zygote) has the usual diploid number of chromosomes in its cells. Just before meiosis each chromosome replicates to form two identical copies in the form of strands called chromatids joined together at a point called the centromere. In the first stage of meiosis, called the reduction division, the members of each pair of homologous chromosomes lie side by side and crossing over occurs. Each member of the pair then moves away from the other toward opposite ends of the dividing cell, and two nuclei, each with the haploid number of double-stringed chromosomes, are formed. Thus at the beginning of the second meiotic sequence, called the equational division, each cell nucleus contains one chromosome from each homologous pair and each chromosome is of two strands that are identical (except where crossing over has occurred). Then the chromosomes separate into their single strands which move toward opposite ends of the dividing nucleus. The result of meiotic division is four cells, each haploid, with one chromosome of each pair.\n\n>meiosis (meye-oh-sis) \nDivision of cells in which four “daughter” cells are produced from one “parent” cell, each with half the genes of the parent. Meiosis is a key process in sexual reproduction. In the ovaries and testes, meiosis produces a great variety of sex cells (sperm and ova), because the genes of the parent cell can be split in many different ways. The sex cells combine in fertilization to produce a new individual with the full number of genes — half from each parent. Because the sex cells come in such variety, and come from two parents, there is an enormous number of possible forms for the offspring. (See chromosomes, genetics, and mitosis.) \n\n>mei·o·sis (mī-ō'sĭs)\nn., pl. -ses (-sēz').\nThe special process of cell division in sexually reproducing organisms that results in the formation of gametes, consisting of two nuclear divisions in rapid succession that in turn result in the formation of four gametocytes, each containing half the number of chromosomes that is found in somatic cells.\n\n>meiosis: \nIn biology, meiosis is the process that transforms one diploid cell into four haploid cells in eukaryotes in order to redistribute the diploid's cell's genome.\n\nMeiosis forms the basis of sexual reproduction and can only occur in eukaryotes. In meiosis, the diploid cell's genome, which is composed of ordered structures of coiled DNA called chromosomes, is replicated once and separated twice, producing four sets of haploid cells each containing half of the original cell's chromosomes. These resultant haploid cells will fertilize with other haploid cells of the opposite gender to form a diploid cell again. The cyclical process of separation by meiosis and genetic recombination through fertilization is called the life cycle. The result is that the offspring produced during germination after meiosis will have a slightly different blueprint which has instructions for the cells to work, contained in the DNA. This allows sexual reproduction to occur.\n\nBiochemically
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1.synapsis occur only in meiosis. \n2.mitosis divide once, where meiosis divide twice. \n3.mitosis produce two daughter cells that are genetically identical to the parent cell, where meiosis produce four daughter cells that have only half of the chromosomes the mater cell had. \n4.meiosis have their homologous chromosomes separate!! but mitosis don't.
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the chromosomes group together.
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Well, you have definitions for two different concepts: homologous genes and homologous chromosomes.\nHomologous chromosomes are essentially the ones that become paired during meiosis. They code for the same proteins and each has one version  (=allele) of the protein code. Simply put, the dominant allele will be the one that is expressed (i.e. actually codes for the protein) while the other will be inactive. Of course, there are alternative situations such as codominance in which both alleles are expressed, etc.\nThe DNA strands of the two homologous chromosomes are extremely similar, because they have the same genes, either exactly the same sequence (same alleles) or a slightly different one (different alleles). \n\nHomologous genes are those genes that occur in different species but have a hypothetical common origin. For example, some mutations result in duplicate segments of a chromosome. If the mutation is not lethal, there will be segment of DNA strand with "extra" copies of one or more genes, which are able to evolve separately and sometimes acquire a new function. \nThe researchers have to compare the DNA sequences from different species, and align them (this can be done manually or with the aid of computer algorithms) by finding characteristic DNA regions. These strands are not "identical" but rather have these comparable regions in different taxa. In addition, many homologous genes have similar functions in different species.\nFor instance, the aminoacid sequences of a protein involved in eye development are the same in humans, mice, and zebrafish, and only differ by 6 aminoacids from the same protein in the fruit fly. Therefore the codon sequence will be almost the same for this homologous gene in all these species.\nThere are entire "gene families" that presumably arose from duplication events during the evolutionary history of vertebrates.
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Meiosis is specialized cell division (similar to mitosis). Mitosis results in 2 identical daughter cells from a single cell. Meiosis results in 4 daughter cells (which may not be identical) but each daughter cell only has one set of chromosomes, instead of the 2 sets of chromosomes present in the original cell. Each of these daughter cells is called a gamete. In sexual reproduction a male gamete and a female gamete (sperm and egg) fuse. Each contributes a single set of chromosomes so the resulting fused cell (zygote) has two sets like the cells that originally formed the gametes.
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Mitosis is the cell division that takes place in most type of cells. In this division the entire DNA of the cell is replicated. The original cell divides into two daughter cells. Mitosis gives rise to almost all the cells in the body. \nA different type of cell division called meiosis gives rise to sperm and eggs. Here the daughter cells have only half the number of homologous chromosomes. This is because on fertilization the sperm and oveum will combine to form the zygote which will develop into the baby. Meiosis reduces the number of chromosomes by half, so in humans each sperm and each egg has only 23 chromosomes, including one chromosome from each pair of homologous chromosomes.
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"A" is the answer.  It happens in prophase of meiosis 1 and it does exactly what choice "A" states.  The rest of the choices happen during meiosis as well, but do not explain the importance of crossing over.
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The pairing behavior of the sex chromosomes in male and female individuals representing seven species of Peromyscus was analyzed by electron microscopy of silver-stained zygotene and pachytene configurations. Six species possess submetacentric or metacentric X chromosomes with heterochromatic short arms. Sex-chromosome pairing in these species is initiated during early pachynema at an interstitial position on the X and Y axes. Homologous synapsis then progresses in a unidirectional fashion towards the telomeres of the X short arm and the corresponding arm of the heterochromatic Y chromosome. The distinctive pattern of synaptic initiation allowed a late-synapsing bivalent in fetal oocytes to be tentatively identified as that of the X chromosomes. In contrast to the other species, Peromyscus megalops possesses an acrocentric X chromosome and a very small Y chromosome. Sex-chromosome pairing in this species is initiated at the proximal telomeric region during late zygonema, and then proceeds interstitially towards the distal end of the Y chromosome. These observations suggest that the presence of X short-arm heterochromatin and corresponding Y heterochromatin interferes with late-zygotene alignment of the pairing initiation sites, thereby delaying XY synaptic initiation until early pachynema. The pairing initiation sites are conserved in the vicinity of the X and Y centromeres in Peromyscus, and consequently the addition of heterochromatin during sex-chromosome evolution essentially displaces these sites to an interstitial position.
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(m)\n\nIn biology, meiosis is the process that transforms one diploid cell into four haploid cells in eukaryotes in order to redistribute the diploid's cell's genome.\n\nMeiosis forms the basis of sexual reproduction and can only occur in eukaryotes. In meiosis, the diploid cell's genome, which is composed of ordered structures of coiled DNA called chromosomes, is replicated once and separated twice, producing four haploid cells each containing half of the original cell's chromosomes. These resultant haploid cells will fertilize with other haploid cells of the opposite gender to form a diploid cell again. The cyclical process of separation by meiosis and genetic recombination through fertilization is called the life cycle. The result is that the offspring produced during germination after meiosis will have a slightly different blueprint which has instructions for the cells to work, contained in the DNA. This allows sexual reproduction to occur.\n\nMeiosis uses many biochemical processes that are similar to those used in mitosis in order to distribute chromosomes among the resulting cells; however the outcome is very different.\n\ngoto the following link for details about meiosis\nhttp://en.wikipedia.org/wiki/Meiosis