Biology questions 21-40

Biology questions 21-40 - ? 21.) Eusociality generally...

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? 21.) Eusociality generally involves the breeding of sterile members of the species, which carry out specialized tasks. It effectively caring for the reproductive members may be easier for species like ants to evolve, due to their haplodiploidy, which increases the significance of kin selection. Sisters are more related to each other than to their offspring. This mechanism of sex determination gives rise to what W. D. Hamilton first termed "supersisters" who share 75 per cent of their genes on average. Sterile workers are more closely related to their supersisters than to any offspring they might have, if they were to breed themselves. From the "selfish gene's" point-of-view, it is advantageous to raise more sisters. Even though workers cannot reproduce, they are passing on more of their genes by caring for their sisters than they would by having their own offspring (which would only have 50% of their genes). May have evolved due to one colony taking over another and the ants not wanting to interbreed with their “slaves”. May also have evolved to prevent overpopulation. 22.) Sociobiology is the study of social behavior based on evolutionary theory. A haplodiploid species is one in which one of the sexes has haploid cells and the other has diploid cells. Most commonly, the male is haploid and the female is diploid. In such species, the male develops from unfertilized eggs, a process called arrhenotokous parthenogenesis or simply arrhenotoky, while the female develops from fertilized eggs: the sperm provides a second set of chromosomes when it fertilizes the egg. Haplodiploidy is found in many species of insects from the order Hymenoptera, particularly ants, bees, and wasps. One consequence of haplodiploidy is that the relatedness of sisters to each other is higher than in diploids; this has been advanced as an explanation for the eusociality common in this order of insects as it increases the power of kin selection. This argument has been disputed on the grounds that haplodiploidy also reduces the relatedness of brothers to sisters, theoretically balancing the above effect. In some Hymenopteran species, worker insects are also able to produce diploid (and therefore female) fertile offspring, which develop as normal queens. 23.) Phylum Echinodermata-Sea Stars, Sea Urchins, Sand Dollars, Sea Cucumbers CHARACTERISTICS -Radial symmetry -spiny skinned -nonsegmented -coelomic (no head or brain) -water vascular system -dipleurula larva FIVE CLASSES -Class Asteroidea (sea stars) -Class Ophluroidea (basket stars, brittle stars) -Class Echinoidea (sea urchins) -Class Holothuroidea (sea cucumbers) -Class Crinoidea (sea lilies)
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24.) The
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This homework help was uploaded on 04/18/2008 for the course CELL BIO - taught by Professor - during the Spring '08 term at Miss. College.

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Biology questions 21-40 - ? 21.) Eusociality generally...

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