Questions tagged [sexual-reproduction]

Reproduction involving two morphologically distinct gametes, such as sperm and egg, where offspring inherit genes from two parents.

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In the process of oogenesis, when the egg completes meiosis 2, what actually happens? [closed]

oogenesis is the process of egg formation in females. The process of formation of the ovum is as follows oogonium primary oocyte secondary oocyte ovum
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What happens to tube nucleus of the pollen tube after fertilisation?

Background: Pollen tube contains a vegetative cell and a generative cell. The vegetative cell contains the tube nucleus, and the generative cell contains two male gametes. The two male gametes fuse ...
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Why is pollen used as a dietary supplement?

Sporopollenin is the hardest biological substance and can't be degraded by any know enzyme (my school textbook). Then why is pollen used as a dietary supplement if it can't be digested? Also, pollen ...
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Why male gametes doesn't go through antipodal cells in chalazogamy

Male gametes in double fertilisation enter the embryo sac through synergid cells even in chalazogamy i.e. when polen tube enters the ovule through chalazal end. Regarding the fact that compatibility ...
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No. of meiotic divisions to produce specific no. of seeds

If I want to produce 100 seeds. Then the no. of meiotic divisions is 125 which can be calculated by the formula x + x / 4. x = no. of seeds produced. How is this formula derived?
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Why do human females have periods?

Why do human women have periods when most animals don't? It is known that the unfertilized egg needs to be shed from the uterus. But why shed the whole endometrium? Why didn't evolution put ...
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why has evolution favored sexual reproduction using two mates over sexual reproduction using three mates?

Many animals species require two members — a male and a female — to sexually reproduce. Why has nature (or the process of evolution) chosen to favor the form of sexual reproduction which requires two ...
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Sex and human's sexual urge.

Why is it necessary for humans to feel pleasure while having sex? Why is it that other animals don't need to experience it? Is it evolutionary ? Why do we mate for pleasure when it's so energy wasting/...
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Where does new blood comes from when penis get erected? [duplicate]

In Humans, During sexual arousal in males, his penis will get erected with blood. Where does this new blood coming to fill his penis which is required for erection ?
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Motile egg cells

According to the Wikipedia article on anisogamy, some types of this form of sexual reproduction involve motile egg cells, i.e. they're capable of movement under their own power, just like sperm cells. ...
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Flowers in Arachis hypogea, are they clestogamous or chasmogamous?

I have seen the flowers of groundnut, they open and remains open for one day, so they should be chasmogamous, but in my school book, they mentioned it as clestogamous, and I searched for it in ...
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Evolution of sexual reproduction from asexual

How exactly did asexually reproducing organisms evolve into sexually reproducing ones? Why was it considered more favourable?
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What unicellular eukaryotes reproduce sexually?

By sexual reproduction I am referring to, at least, gametogenesis or mating bridges. I was previously under the impression that unicellular organisms did not reproduce sexually at all. So far the ...
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How many plants arise from a polyembryonic seed? [closed]

When I asked this question to my teacher she said that she doesn't know. So I wanted to know? Is there any use of polyembrony in plants?
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Why spermatogenesis is an independent process while formation of ovum is dependent on fertilization by sperm?

At the time of ovulation,secondary oocyte is arrested at Metaphase II and goes into the fallopian tube.If fertilization occurs, sperm binds with secondary oocyte and releases Anaphase promoting factor ...
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In bacterial conjugation, how do F+/F- cells detect each other?

I've just learnt about bacterial conjugation and while it is interesting info about early sexual activity in microbes, one aspect confuses me and doesnt seem to be mentioned in the material I read: ...
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Extremely Scientific Sexual Education Material?

I'm trying to prepare material for 'the talk' about sex and reproduction. I know there's plenty of great books and resources out there for young readers, which I'll use to start with, but I'm also ...
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Is Parthenogenesis known as Sexual reproduction or Asexual reproduction?

I have seen that in some books refer to Parthenogenesis as sexual and in others as asexual. The ones that say it's a form of sexual reproduction,they focus on the fact that meios has happened in the ...
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Conjugation in bacteria

I was studying about conjugation in bacteria, I have a doubt. In conjugation F- cell transforms into F+ cell when there is a formation of sex pilli in between the two. The doubt is if the F- cells ...
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how did we breed after the fusion ? and why can't we bread with chimps? [closed]

after the chromosome fusion happened to one of our ancestors, how did he breed ? if he was allowed to breed because the chromosomal differences were still not very big back then, why can donkey and ...
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Do males ever produce the offspring?

Are there any non-asexual species in which the male of the species produces the offspring? If so, why are they considered male and not female?
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Does increased calorie intake cause increase in libido in humans?

I'm interested in the effect of increased calorie intake on sex hormones and chosen mating strategy in humans. I'm aware that humans have a dual mating strategy - somewhere between pair bond and ...
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Where does female ejaculate actually originate from?

It's common knowledge that it's released via the urethra, but where does it originate? If it doesn't come from a part of the clitoris, then why is the clitoral glans called the clitoral glans? How ...
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How can a haploid plant be bisexual?

According to Wikipedia: Meiosis is a specialized type of cell division that reduces the chromosome number by half. This process occurs in all sexually reproducing single-celled and multicellular ...
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What's the rationale behind freezing one's eggs if cells can be cloned?

It seems to me there's a lot of discussions around the topic of somebody freezing her eggs. What I don't understand though are the following: Why would you freeze your eggs when you know that the ...
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Why are mice with a single X chromosome and no Y chromosome males?

I was searching online and I read this article Mice can be male without Y chromosome and this is a part of it: The experiments demonstrate that there are multiple ways to make males, says Richard ...
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What is the function of the polar bodies produced during oogenesis?

Why are polar bodies produced during oogenesis in human females? I read that polar bodies are produced during meiosis so that the oogonium (or gamete mother cell) can be converted into a haploid ...
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Is Mutation Theory still “valid” for complex organisms?

I'm afraid like most people I suffer from having learned "A History of Evolution" in school, rather than cutting to the chase and learning the actual "up to date" version of the subject. (Imagine if ...
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What's the difference between male and female?

As long as we only look at humans the differences are clear: males have chromosomes XY, produce sperm and don't get pregnant. Females have chromosomes XX, produce egg cells and bear babies. But when ...
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What is most ancestral: isogamy or anisogamy?

Sexual reproduction can be feasible with anisogamy (gametes of different sizes i.e. genders) or isogamy (gametes of same size i.e. mating types) or with undifferentiated gametes (i.e. true random ...
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Difference between inbreeding and interbreeding

Is inbreeding the same as interbreeding? On this site interbreeding is defined as (http://www.thefreedictionary.com/interbreeding): To breed with another kind or species; hybridize. To breed ...
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Can diploidy evolve in absence of sexual reproduction?

Theoretical question Can diploidy (or polyploidy) evolve from a haploid lineage in the absence of sexual reproduction ? For what theoretical reason? How can such evolution take place? Empirical ...
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Can sexual reproduction create new genetic information?

Is there a small chance that in sexual reproduction a new allele forms in the off-spring that was not present in either of the parents, or are the alleles in the offspring always from at least one of ...