disadvantages of multicellularity
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Answers:An advantage is that a single cell can be specialized to perform a task very well. Something that it could not be specialized to do if the organism was single cellular. A disadvantage is that specialization causes the cell to be incapable of living on its own. It must be part of the multicellular organism. Think nerve cell. The way a nerve cell is set up makes it great at carrying a charge along its body to the next nerve cell. But a nerve cell could not live on its own since it needs support cells.
Answers:When a multicellular organism has specialised cells, these can carry out particular tasks (like carrying oxygen, moving the skeleton, protecting against infections) with great efficiency. This is called the division of labour - the tasks needed to sustain life are carried out by specialised cells. The disadvantage is that all the cell typew rely on each other to complete all of the tasks. If one cell type fails, they are all doomed. ..
Answers:Wow! Usually multiple choice questions are incredibly stupid (giving one obvious choice, and several easily eliminated, or even absurd 'alternatives') ... and they usually teach the student almost nothing ... especially if the student just comes here and asks what letter to circle. (So I'm assuming that you've thought about it a bit and don't know how to approach the question.) But this one is incredibly subtle and takes some thought. So I think the answer is (e) ... but please read this carefully ... don't just circle the answer ... and understand why this is a *tough* (and advanced) question. First, let's clarify that this is not saying that multicellularity and diploidy evolved *together*. Evolutionary theory holds that the evolution of diploidy (and thus sexual reproduction) occurred *long* before multicellularity. So the question (as I understand it) is this ... given that an organism already has alternating haploid and diploid stages in its life cycle (e.g. green algae) ... what advantage to reproduction itself is there for the diploid stage to become multicellular. For the answer, look at a haploid-diploid, but single-celled organism that reproduces by meiosis (a diploid individual splitting into two haploid individuals) followed by fertilization (or fusion) of two haploid cells into a single new diploid individual. If such an organism is reproducing away (expending a lot of energy), in a short time it is a little ball of reproducing cells. But in the interior of the ball, the cells are going through the trouble of meiosis, splitting into two haploid cells, and then immediately recombining with other identical cells. So this defeats the entire advantage of sexual reproduction ... the recombination (or cross-fertilization) with other genetically different individuals to produce more genetic variation. It is only at the outer edges of this ball that the haploid-stage cells can encounter haploid-stage cells from another individual. Multicellularity improves this situation dramatically. The interior cells can undergo mitosis (not meiosis), where the diploid cells simply replicate genetically identical copies of themselves ... which requires far less wasted energy than meiosis. This allows the organism to grow in size, and even to have dispersal organs that shoot haploid cells (spores) out into the world far away from original organism, thus increasing the chances of fertilization (fusion with haploid cells from another individual). The only time meiosis occurs is specifically to produce those haploid cells (spores or gametes) used for reproduction. So let's consider our candidates: (a) Yes, it does raise the potential for independence between diploid and haploid stage ... but *by itself* this doesn't qualify as an "advantage"; (b) Hmm ... very tricky! It increases the *chances* of *fertilization* (recombination of haploid cells from two genetically different individuals) ... but not the *rate* of fertilization (as it takes a plant a lot longer to grow to sexual maturity to be able to disperse spores or seeds than algae); (c) No, this has no advantage or disadvantage to gamete production; (d) Yes, it increases the size of the diploid stage ... but again, *by itself* this doesn't qualify as an "advantage." (e) Yes ... the reason it is an advantage to increase spore production for each fertilization event is to increase the chances of *more* fertilization events ... which ultimately is the *primary* advantage of sexual reproduction as far as natural selection goes. So I think the answer is (e).
Answers:Nice one. Aren't we lazy. Just took this test and got 100% ;) 1. Taxonomy 2.division 3carolus 4classifys organisms 5monera 6monera 7class 8eucariotic multicellular 9protists 10species 11 all of the above 12canis lupus 13varys 142 species same genus 15kidney bean, scarlet runner 16genus and species 17taxonomy 18monera 19pland 20chordate 21toad