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| | Biological reproduction - Wikipedia, the free encyclopedia |
 | | Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction by an antecedent. | | | In addition, sexual reproduction usually results in the formation of a life stage that is able to endure the conditions that threaten the offspring of an asexual parent. | | | Asexual reproduction is not, however, limited to single-celled organisms. |
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http://en.wikipedia.org/wiki/Reproduction
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| | Sexual Reproduction: A Continuing Mystery to Evolutionists |
| | There are some basic problems concerning sexual reproduction that are still a puzzle to evolutionists and are very difficult to explain using any evolutionary models. | | | One theory states that sexual reproduction facilitates mechanisms for repair and chromosomal segregation. | | | The evolutionist is faced with the problem of how sexual reproduction arose in the first place and how it is maintained given the obvious advantages of asexual reproduction. |
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http://www.godandscience.org/evolution/reproduction.html
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| | Sexual reproduction |
| | The sexual unit is not present in asexual organisms. | | | Likewise it is essential to explain why the apparent benefit of the sexual unit is zero for the asexual self-replicator, and why it is two-fold and only two-fold for dioecious sexual organisms no matter whether the organism reproduces pairwisely, co-operatively, or eusocially. | | | But sexual reproduction can evolve by this mechanism only if the level of interactive competition is sufficiently high. |
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http://www.peregrine.dk/subjects/SEXRE.HTM
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| | Sexual Reproduction |
| | The reason is that sexual reproduction is a basic fact of life on this planet, and it is almost impossible to conduct either controlled experiments or systematic observations where the only factor is sexual vs. asexual reproduction. | | | Perhaps the oldest explanation for the prevalence of sexual reproduction is based on the fact that one thing that sexual reproduction clearly does is that it results in genotypic variation among offspring. | | | Other approaches to the question of the usefulness of sexual reproduction have emphasized the interaction of the organism with aspects of its environment. |
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http://www.towson.edu/~scully/sex.html
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| | Sex and sexuality (2) |
| | Many details of the different reproductive stages passed through by the third root-race, and the corresponding changes in anatomy, are lacking, but the general scenario seems to have been as follows [10]. | | | Prior to the acceptance by the medical profession of the present theory of conception (epigenesis) in the middle of the 19th century, the ovist and aura seminalis theories prevailed, which can be traced back to Pythagoras. | | | As some point, offspring began to be born with external sexual organs, and initially these individuals were probably true functional hermaphrodites or male-females, who fertilized one another and could play the role of male or female. |
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http://ourworld.compuserve.com/homepages/dp5/sex2.htm
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| | [No title] |
| | No theory has yet been advanced to explain to everyone's satisfaction why sexual reproduction is so common since it has costs associated with it which are not experienced by asexual reproducers (e.g., only one half of a sexually reproducing individual's genes are passed on to offspring). | | | On the other hand, the question of why sexual reproduction persists can be studied by examining the conditions which seem to favor sexual over asexual reproduction today. | | | We can summarize the proposed benefits of sexual reproduction by contrasting the different hypotheses with respect to the environmental attributes to which sex is supposedly adapted and the type of selection involved. |
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http://www.holycross.edu/departments/biology/whealy/notes_text/m.text
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| | David Boukal: Sexual Reproduction |
| | Sexual reproduction has been shown to be important in conservation and harvesting problems, but it has been largely studied by static approaches. | | | The role of sexual reproduction in population dynamics is still not sufficiently understood, partly because most models used in theoretical population ecology adopt an asexual approach and do not discern between the sexes. | | | We will address several problems broadly embraced by the questions "What are the ecological consequences of sexual size dimorphism?" and "How does sexual reproduction and ecological dynamics shape sexual size dimorphism and other size-related reproductive traits?", and search for emergent effects of population dynamics, such as the role of inter-/intrasexual competition and cannibalism. |
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http://www.entu.cas.cz/boukal/sex.phtml
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| | < Bio 52 - Sexual Reproduction : Reducing Mutations > |
| | From an organism's point of view, the goal of reproduction is to continue the species and produce the most successful offspring. | | | Biologists have been puzzling over the question of why sexual reproduction evolved if it is so costly for an individual. | | | Unlike other theories that explain why sexual reporduction evolved, this theory can be tested. |
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http://www.cs.hmc.edu/~rmcknigh/projects/bio52-project3/bio52-mutation-info.html
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| | lesson template |
| | Students are presented with a computer/library investigation concerning the evolution of sexual reproduction, evolutionary strategies behind a variety of reproduction behaviors, and the molecular mechanisms behind reproduction in a variety of organisms. | | | Lineages that are capable of both asexual and sexual reproduction (invertebrates, plants, fungi, etc.) get the best of both world in a sense, and can adjust their reproductive behaviors based on current environmental conditions. | | | Included in the prensentations may be the role that sexual / asexual reproduction plays in a variety of organisms within the chosen lineage. |
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http://www.bu.edu/lernet/GK12/ryan/StampWeb-Lessons/sex.html
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| | Apologetics Press - The Origin of Gender and Sexual Reproduction [Part II] |
| | During sexual activity, the bodies of human males and females experience certain modifications and physiological changes that are not found in animals. | | | Considering the possibility of potential mechanisms for reproduction, it remains to be determined why nature ever would “evolve” sexual reproduction in the first place. | | | The method and nature of reproduction, and the degree of parental care, varies widely among living organisms. |
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http://www.apologeticspress.org/articles/138
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| | Sexual Reproduction |
| | The responsibility of the female mammal for successful reproduction is considerably greater than that of the male. | | | In contrast to the male, however, such responses are not a prerequisite for copulation and fertilization to occur. | | | Estrogen is responsible for the development of the secondary sexual characteristics of a mature woman, e.g., |
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http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Sexual_Reproduction.html
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| | Social Basis of Human Sexual Behavior |
| | Since there is little quite so personal as sex, sexual violation of her body gives him an even greater sense of power over her than controlling her body by tying or beating her. | | | Thus, her consideration of the social and environmental necessities to achieve this is a major part of her decision to have children. | | | The human male has a mind as well, and is taught much of the way he is supposed to regard the world. |
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http://www.wsu.edu:8080/~taflinge/socsex.html
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| | the REPRODUCTIVe system |
| | Costs of this process include the need for two individuals to mate, courtship rituals, as well as a number of basic mechanisms described later. | | | The mesoderm forms structures associated with movement and support: body muscles, cartilage, bone, blood, and all other connective tissues. | | | This class of STDs includes viral diseases that affect organ systems other than those of the reproductive system. |
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http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookREPROD.html
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| | Evolution of Sexual Reproduction [M.Tevfik Dorak] |
| | Asexual reproduction is still used by some organisms but in general failed to pass the test of natural selection. | | | Inbreeding: Despite sexual reproduction, inbreeding lowers offspring fitness. | | | This variation enables a species to overcome novel environmental changes by fast adaptive change. |
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http://dorakmt.tripod.com/evolution/sreprod.html
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| | MBL scientists confirm evolutionary exception |
| | To overcome this methodical shortcoming and conclusively demonstrate that bdelloids are, in fact, completely asexual, Mark Welch and her colleagues painstakingly analyzed the genome of the bdelloid species, Philodina roseola. | | | Mark Welch and her colleagues will continue to study bdelloids as they offer an ideal model system in which to explore the effects of asexual reproduction. | | | While many hypotheses have addressed this problem, the paradox raises one of the most perplexing questions in biology: If asexual reproduction is more efficient than sexual reproduction, why does sexual reproduction predominate so thoroughly? |
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http://www.eurekalert.org/pub_releases/2004-01/mbl-msc012004.php
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| | Evolution - Adaptations in sexual reproduction |
| | Both theories view sexual selection as a process of female choice, and the preference has to be open-ended. | | | Further evidence for Zahavi's argument comes from the observation that many forms of sexual display show the blood color of the male, which is a good indication of an organism's health. | | | W.D. Hamilton explains why he thinks sexual displays, such as the peacock's tail, are a means of indicating health. |
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http://www.blackwellpublishing.com/ridley/tutorials/Adaptations_in_sexual_reproduction23.asp
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| | Atlantida Cancun |
| | Females seem to be sexually receptive during a large part of the year and are generally responsible for initiating courtship and breeding behavior. | | | Both sexes have a naval and genital slit, but the females also have a mammary slit on either side of the genital slit. | | | The genitals are concealed in both males and females, but they can be sexed if you are able to catch a glimpse of their belly. |
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http://www.atlantidacancun.com/reproduction.asp
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| | Biol 1A - Lecture 10 |
| | A. Sexual reproduction is an extended process, defined by meiosis and syngamy. | | | In which kind of sexual life cycle(s) does the zygote develop into an embryo? | | | At what point during meiosis does crossing-over occur? |
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http://www.ucmp.berkeley.edu/people/brs/biol1a/Lect10.html
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| | Comparing Asexual and Sexual Reproductive Strategies |
| | Fish and frogs have sexual reproduction, but it is externally. | | | The discussion after the grouping should be centered on how the organisms reproduce, and what characteristics seem to be more common in the sexual versus asexual modes of reproduction. | | | Larger animals have developed more complex organ systems and with these organ systems they can adapt to their environment more easily than smaller organisms. |
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http://www.msnucleus.org/membership/html/k-6/lc/organ/5/lco5_5a.html
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| | reproductive system |
| | female reproductive system health issues female reproductive system health issues doorway that night but is derived from the voluntary There is indeed danger that are objects of with reference to... | | | Reproductive System Human Anatomy Posters & Charts educational posters > science > anatomy > reproductive system reproductive... | | | TCM News Health Resources Links About Us Expert Advice-Treatment of Infections of the Reproductive System in Traditional Chinese Medicine(TCM): Infections of the Reproductive System in Chinese... |
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http://www.facetsystems.com/reproductivesystem
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| | In the Beginning: Compelling Evidence for Creation and the Flood - 39. Sexual Reproduction |
| | Evolution theory predicts nature would select asexual rather than sexual reproduction. | | | But if asexual reproduction (splitting an organism into two identical organisms) evolved before sexual reproduction, how did complex sexual diversity arise—or survive? | | | The physical, chemical, and emotional systems of the male and female would also need to be compatible. |
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http://www.creationscience.com/onlinebook/LifeSciences44.html
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| | Sexual Plant Reproduction |
| | Principal emphasis is placed on the experimental approaches using biochemical, molecular, biophysical and immunological methods. | | | The journal will consider original contributions, short communications, contemporary reviews and commentaries on subjects interesting to the community of sexual plant reproduction researchers. | | | Descriptive reports providing new insights on sexual reproduction based on submicroscopic and cytochemical methods are also encouraged. |
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http://www.iasprr.org/spr.shtml
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| | AiG's response to PBS-TV series Evolution-Episode 5: Why Sex? |
| | the peacock tail. So Darwin invoked the idea of sexual selection, where choice by the opposite sex played a huge part in determining which individuals were able to pass on their genes. Later on, sexual selection is invoked to explain the human brain. | | | Then the program explains male competition for mates and ornate sexual displays, while females exercise choice. Supposedly the concept of female choice was often discounted in Victorian England (with a female head of state who ruled for more than 60 years). | | | Rebuttal to Episode 1, this is a faulty distinction, and this episode demonstrates this. Here, evolutionary psychology directly affects questions of sexual morality. |
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http://www.answersingenesis.org/pbs_nova/0928ep5.asp
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| | Sexual reproduction - Wikipedia, the free encyclopedia |
| | Contemporary evolutionary thought posits a few explanations for why sexual reproduction persists when parthenogenesis appears in some ways to be a superior form of reproduction. | | | Sexual reproduction may persist because of selection pressure on the clade itself- the ability for a population to radiate more rapidly due to a changing environment through sexual recombination than parthenogenesis allows. | | | Bacterial conjugation, the transfer of DNA between two bacteria, is often mistakenly confused with sexual reproduction, because the mechanics are similar. |
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http://en.wikipedia.org/wiki/Sexual_reproduction
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| | Sexual/Asexual Reproduction |
| | Recognize and explain how certain traits are passed from parents to offspring. | | | As part of the activity, genotype and phenotype can either be taught or reviewed. | | | Students will understand reproduction and heredity of organisms. |
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http://usoe.k12.ut.us/curr/science/sciber00/7th/genetics/sciber/fnbgacti.htm
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| | Howstuffworks "How Sex Works" |
| | We will examine the body's sexual organs, the biological cycles of sex, and the process of fertilization. | | | South Beach Faces Red Tea Microdermabrasion exfoliates and sloughs off dead skin cells to refinish skin and improve tone. | | | From a biological standpoint, the goal of sex is to merge two sets of genetic information, one from the father and one from the mother, to make a baby that is genetically different from either parent. |
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http://science.howstuffworks.com/human-reproduction.htm
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| | Sexual vs. asexual reproduction: scientists find sex wins |
| | There is a broad assumption in this scenario that males do not help with the care and feeding of offspring, although in a small proportion of species they do help: people, wolves, foxes and most songbirds. | | | (Santa Barbara, Calif.) Why are most organisms sexual? | | | The second part of the mathematical advantage is that the asexual adult female is able to put all of her genes into the next generation, whereas with sexual reproduction, each individual is responsible for only half of the genetic information in the offspring. |
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http://www.eurekalert.org/pub_releases/2001-10/uoc--sva101701.php
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| | Pseudo-nitzschia sexual reproduction |
| | Sexual reproduction is a diatom's response to this problem. | | | Sexual reproduction in Pseudo-nitzschia, on the other hand, involves morphologically indistinguishable gametes and thus is called isogamous. | | | Those species of pennate diatoms within the genus Pseudo-nitzschia differ in their method of sexual reproduction when compared to centric diatoms. |
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http://www.mbari.org/staff/conn/botany/diatoms/jennifer/rlhb.htm
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| | ideonexus - Sexual Reproduction: Disputations |
| | Thanks to scientific discoveries in psychology and genetics, we are becoming more informed on these issues and possibly coming closer to achieving an ideal mean on them. | | | Rape and sexual addiction are abnormal behaviors that objectify other human beings and are detrimental to the afflicted individual. | | | Sexual intercourse provides a means for many diseases to transfer from person to person. |
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http://www.ideonexus.com/?article=disputations-sexualreproduction01
(336 words)
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| | Reproduction of green algae |
| | Asexual reproduction: reproduction by another way than the union of male and female gametes, by other parts of an organism. | | | Entrance of the antherozoid: place where the antherozoid penetrates. | | | Sexual and asexual reproduction of green algae: reproduction by the union of male and female gametes or by other parts of an organism. |
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http://www.infovisual.info/01/022_en.html
(113 words)
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| | IASPRR - Int'l Assoc of Sexual Plant Reproduction Research |
| | The Association promotes contact between scientists undertaking research in sexual plant reproduction and related subjects through conferences, congresses, workshops, databases, and by the exchange of information concerning the entire range of activities in the field of plant sexual reproduction research. | | | The purpose of the IASPRR is to stimulate scientific research in the field of plant reproduction and related subjects, and to promote the application of the results of such research in agriculture and forestry. | | | International Association of Sexual Plant Reproduction Research (IASPRR) |
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http://www.iasprr.org
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| | Sexual Reproduction |
| | There are other methods of reproduction, such as asexual reproduction and parthenogenesis. | | | All in all it may be easier for an organism to divide and create offspring without sex. | | | If this organism sexually reproduces with another, what are the TOTAL number of different combinations that are possible in the zyote? |
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http://www.biologycorner.com/bio4/notes/sex.php
(561 words)
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| | Sexual reproduction delays aging in a mammalian species |
| | The researchers were also able to show that this pattern was not caused by differences in intrinsic biological quality, social rank, or workload between breeders and non-breeders. | | | Past research on aging and the life histories of diverse species has shown that sexual reproduction is biologically costly for individuals and tends to decrease lifespan rather than increase it. | | | Whereas the breeding pair is sexually active throughout the year, the helpers are sexually quiescent. |
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http://www.brightsurf.com/news/headlines/view.article.php?ArticleID=23156
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| | Why Sexual Reproduction? by Brig Klyce |
| | Indeed, a clever recent experiment with sexual and asexual yeast cells that were otherwise identical reinforces this last point. | | | It seems likely that the sexual reproduction process used by multicelled animals and plants is more important than the current paradigm imagines. | | | This is especially so in sexually reproducing multicelled animals, where the "germ line" is carefully protected. |
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http://www.panspermia.org/sexual.htm
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| | Sexual Plant Reproduction |
| | Primary emphasis is placed on the experimental approach using biochemical, molecular, biophysical and immunological methods, but descriptive reports based on submicroscopical and cytochemical methods are not excluded. | | | Special attention is given to the application of new insights in sexual systems for aquaculture of algae, biotechnology of microorganisms, and plant breeding. | | | It covers the dynamics and mechanisms of sexual processes in all plant groups, including algae, fungi, mosses and ferns, as well as flowering plants. |
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http://gort.ucsd.edu/newjour/s/msg02424.html
(168 words)
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| | AllRefer.com - reproduction (Biology, General) - Encyclopedia |
| | Although the methods and complexity of the reproductive process vary tremendously, two fundamental types may be distinguished; asexual reproduction, in which a single organism separates into two or more equal or unequal parts; and sexual reproduction, in which a pair of specialized reproductive (sex) cells fuse. | | | In all cases reproduction consists of a basic pattern: the conversion by a parent organism of raw materials from the environment into offspring : or into cells that develop into offspring (see meiosis; mitosis) : of a constitution similar or potentially similar to that of the parent. | | | The term reproduction may refer to this power of self-duplication of a single cell or a multicellular animal or plant organism. |
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http://reference.allrefer.com/encyclopedia/R/reproduc.html
(253 words)
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| | Meiosis Tutorial |
| | this method of reproduction is rapid and effective allowing the spread of an organism |
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http://www.biology.arizona.edu/cell_bio/tutorials/meiosis/page1.html
(155 words)
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| | reproduction: Sexual Reproduction |
| | Sexual reproduction occurs in many one-celled organisms and in all multicellular plants and animals. | | | This probably explains the predominance of sexual reproduction among higher forms. | | | Sexual reproduction is essentially cellular in nature, i.e., it involves the |
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http://www.factmonster.com/ce6/sci/A0860695.html
(377 words)
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| | EvoTutor: 2-Fold Cost of Sexual Reproduction |
| | Notice that even if the sexually reproducing population begins with twice as many individuals as the sexual population, the asexual individuals will shortly outnumber the sexual individuals (assuming equal fecundity). | | | One advantage of sexual reproduction is that sexual reproduciton maintains more genetic variation than asexual reproduciton. | | | This is the two-fold cost of sexual reproduction. |
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http://www.evotutor.org/SexRepro/SR1A.html
(181 words)
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| | Sexual reproduction expressed in Eragrostis curvula |
| | Cytological determinations were associated with quantitative variation of the progeny. | | | Among the progeny from apomictic and sexual genotypes, the facultative genotype produced 75% uniform and 25% variable progeny, respectively. | | | 25%) was found in four F2 families of sexual origin, with distributions that were continuous within families, but with means different from that for the respective F1 plants. |
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http://grove.ufl.edu/~turf/refs/ref9b.htm
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| | Evolution: Library: The Red Queen |
| | If the goal of life is spreading one's genes far and wide, asexually reproducing organisms seem to have the edge. | | | The offspring may lose some of the genetic traits that made each parent successful. | | | And at least in some environments, that variation must give a competitive edge over asexual organisms that can spread their genes efficiently, but vary little from one generation to the next. |
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http://www.pbs.org/wgbh/evolution/library/01/5/l_015_03.html
(496 words)
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| | Sexual Reproduction in Freshwater Jellyfish (Craspedacusta sowerbyi) |
| | Some people think that this is due to the lack of complete investigations, but the sexual reproduction in nature may not be common. | | | In the previous article, I reported on these jellyfish, especially on their polyps and asexual reproduction. | | | It helps to improve the genetic diversity of the population, and information about their development is valuable for the understanding of these creatures. |
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http://www.microscopy-uk.org.uk/mag/artdec99/fwjelly2.html
(989 words)
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| | World Builders 1 Lesson 8 How Land Plants Reproduce E Viau CSULA |
| | These new plants may be able to adapt more successfully to environmental changes than their parents could. | | | Plants have two methods of reproduction, asexual reproduction and sexual reproduction. | | | An important advance was the development of the flower, a structure which allowed widespread scattering of its pollen and yet provided a stable, nurturing environment in the ovary for developing seeds. |
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http://curriculum.calstatela.edu/courses/builders/lessons/less/les8/pollen.html
(1039 words)
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| | The sexual reproduction in flowering plants |
| | Carpels bear ovules, which are structures with the potential to develop into seeds. | | | All four floral parts are important in the reproductive process, but only the stamens (the “male” organs) and carpels (the “female” organs) produce gametes. | | | Something happens during sexual reproduction in flowering plants that does not occur anywhere else in the living world. |
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http://nd.essortment.com/sexualreproduct_rmsk.htm
(940 words)
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