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

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2answers
155 views

Among primates, is it true that homosexual behavior is extremely unnatural and uncommon?

I was recently reading a book published by some anonymous biologist known as Lynn Saxon, in which she appears to want to refute Christopher Ryan's thesis in Sex at Dawn that prior to the invent of ...
2
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1answer
49 views

How do the chromosomes arrange themselves after fertilization in humans?

In human reproduction the male produces sperm containing 23 chromosomes and the female has the oovum containing 23 chromosomes , so after fertilization the zygote contains 46 chromosomes. What I want ...
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1answer
144 views

Spermatogenesis question

I found this diagram in my textbook regarding the process of spermatogenesis. But, I doubt if the labelling done is correct or not. Especially, I can't figure out any difference between the cells ...
5
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0answers
75 views

Can any animal ejaculate at will without physical contact?

Note: In this question, I'm asking about animals that have a penis that functions very similarly to humans. I've read some animals have dramatically different methods of copulation and physiologies, ...
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1answer
57 views

Is it Theoretically Possible to Create a Male clone from the donor Cell of a Female?

I understand that Dolly the Sheep was created without the presence of a sperm cell. Instead, nucleus DNA from somatic cells of adult sheep were used. Since Dolly was female, i am assuming that the ...
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0answers
31 views

How diverse are the sperm cells of an individual male due to random mutations?

Due to the sheer number of sperm cells in an individual and the rate of mutations, are they likely to be incredibly diverse and encompass most of what we see across our species? For instance would it ...
2
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2answers
73 views

How does better sperm result in more viable offspring?

Quoting wikipedia: Greater choice and variety of mates increases a female's chance to produce more viable offspring. This led me to the question: "How sperm parameters are connected with entity ...
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1answer
127 views

Do reproductive organs function before puberty?

Testis means one of the two male reproductive glands that produce spermatozoa and secrete androgens. Ovary means one of usually two organs that produce oocytes and secrete oestrogen and progesterone. ...
9
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1answer
282 views

What animal has the longest juvenile period?

I just heard the following complaint from a comedienne. Humans are the only animal that is completely useless for the first twenty five years of life. Obviously this is just a joke but it is true ...
3
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1answer
73 views

Exact meaning of the term “clutch”

When reading a Wikipedia article to do with chickens, I have come across the term "clutch", but I was not able to entirely figure out what this word means. I was wondering whether the term clutch can ...
10
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5answers
3k views

How does DNA still work after recombination?

If you take two computer programs and randomly swapped pieces from each of them. The result is not going to work. It will just be garbage. If you take two novels and randomly swapped chapters the ...
5
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0answers
97 views

Polyploidy, or why plants of different species can produce fertile offspring hybrids more frequently than animals?

This site says: Plants hybridize much more frequently and successfully than animals do. [...] Chromosomal doubling (polyploidy) occurs more frequently in plants and facilitates the fertility of the ...
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0answers
233 views

What is the weight of a single human sperm (spermatozoon) compared to a single human egg

While the difference in dimension is well covered, I have been unable to find the mass measurements of each.
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2answers
61 views

When does genetic randomization happen?

When two parents (regardless of species) reproduce in sexual reproduction each offspring is generally a random combination of genetic traits from each parent. Their developed traits then depend on the ...
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0answers
71 views

Can sex cells divide?

I understand that most somatic cells divide and go through Mitosis, but I am confused to as what goes through Meiosis. Can sperm cells divide and multiply or is it only cells in the testes (which are ...
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1answer
750 views

Hardy-Weinberg sex linked formula

The "big five" assumptions are the ones listed in the main text. However, the basic formulation of Hardy-Weinberg equilibrium also relies on a few other assumptions; Allele and genotype frequencies ...
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0answers
79 views

Does Meiosis I produce haploid gametes?

According to my textbook (and other online sources), Meiosis I produces two haploid cells. After Meiosis (does not note if after Meiosis II), haploid gametes are produced. Does this information mean ...
1
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1answer
680 views

Why are male gametes and female gametes not equally sized

Why is it that male gametes are smaller and produced in larger quantities than female gametes that are large and lesser in number. Why aren't the gametes equally sized, or their sizes the other way ...
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0answers
182 views

Why are oocytes arrested in diplotene of Meiosis 1?

Oocytes are arrested in diplotene in prophase 1. The main reason for this is because the completion of meiosis 1 is not needed in the embryonic stage to result in the formation of primary oocytes. ...
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0answers
17 views

How would transposable elements and recombination affect phylogenetic trees?

I'm hypothesizing connections between concepts learned in my Biology class and I'm trying to see if transposable elements or sexual recombination during prophase I affects how related organisms are to ...
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2answers
272 views

How does sexual reproduction generate more genetic variation?

I'm curious as to why sexual reproduction generates genetic variation. For me, the term genetic variation is a little ambiguous. The way I understand it, it's the number of alleles at a locus in a ...
1
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0answers
51 views

At what level of relation does inbreeding become dangerous?

Inbreeding within first cousins appears to have an established history of dangers, and anything closer than that relationship also. However, how distantly related do two individuals have to be for ...
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0answers
14 views

Why would a sperm's ability to swim be correlated to the fitness of the organism it would produce upon fertilization?

It seems to be a common idea that sperm compete with one another to fertilize the egg, so that (on the balance) the strongest and highest quality sperm are the ones that succeed in fertilizing the egg....
1
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2answers
126 views

How do biologists determine the parents of a child

I am not well-versed in biology so this question might be wrong. As far as I understand meiosis, two germ line cells with 23 chromosomes each (one cell from the father and another from the mother) ...
2
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0answers
47 views

Number of alleles' variations in a mushroom that has over 20,000 sexes

I am trying to understand the mating behavior of a particular species of fungi known as Schizophyllum commune, or the split-gill. I found a blog post that explains the mechanisms that define the ...
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1answer
84 views

A stem cell method for creating artificial wombs?

1) Grow the endometrium using stem cells (It has already been done (Cambridge, 2017)) 2) Attach the embryo to it and allow the placenta to grow. In 2003, there was a researcher at Columbia who did ...
1
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1answer
52 views

Organisms that do not wish to reproduce [duplicate]

Are there any organisms that do not want to reproduce? As humans, there are people who do not want to reproduce with the opposite sex. Do any other organisms replicate this behavior? Also, why does ...
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0answers
335 views

Location of male and female reproductive organs in fern (prothallus)

I can't seem to find an authoritative answer to this anywhere else online. Basically, my school text-book says the antheridium (male organ) is located on the lower surface of the fern prothallus and ...
2
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1answer
143 views

Sexual reproduction in organisms with 1 parent

An organism that carries out sexual reproduction with itself, for example a flower with both the anther and stigma, does it actually contain 2 sets of genes in order to produce genetically ...
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0answers
193 views

How Excessive masturbation can make a person unfit for army? [closed]

Recently I saw this news trending, I never heard single disadvantage regarding masturbation. But China Army considering it has danger for army. So How Excessive masturbation can make a person unfit ...
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0answers
50 views

Evidence for 90 percent accountant, 10 percent rock star?

This might sounds misogynistic but here goes: In Antifragile, Nero claims There is evidence of such a barbell strategy but no clarity about the theory behind it' where the barbell strategy, '90 ...
1
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2answers
838 views

Why can't two different genetically species reproduce to give a viable offspring?

What is the reason that only organisms belong to same species can produce a viable and reproductively healthy offspring but organisms of two different species cannot?
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2answers
174 views

Variations in asexual reproduction

It has always been said that sexual reproduction produces offsprings which are superior to their parents, due to the variations which they acquire causing them to survive better in their environment. ...
2
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0answers
54 views

Role of neuraminidase in preventing polyspermy in humans

Neuraminidase is a hydrolytic enzyme present in the acrosome of human sperm. It removes neuraminic acid (salic acid) from glycoproteins. I have read in a book that due to this reason it (the enzyme) ...
1
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1answer
476 views

Does sperm weight causes sex ratio?

Chromosome X in female sperm is heavier than male Y chromosome. Does it causes difference in fertility of sperm and heavier female sperm is unable to fertilize better than male sperm? This is given ...
4
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1answer
98 views

How is it possible for monosomies to occur?

I was taught in biology class that a cell dies if it doesn't have at least one copy of a chromosome "type". If this is the case, that means that: Zygotes without a copy of a specific chromosome (for ...
5
votes
1answer
164 views

Is there a theoretical maximum on the number of sexes a given species can have?

Background: To the best of my knowledge, most sexually-reproducing species of organism have two sexes, although there are also sexually-reproducing species of organism (flatworms come to mind) which ...
5
votes
1answer
91 views

If a woman was fertilized with her own DNA, would it be her clone?

Several questions: 1) Can human DNA fertilize an egg, without having been naturally packaged in a sperm cell? 2) If a female had her ovum fertilized with her own DNA, would the fetus be her clone? ...
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1answer
299 views

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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1answer
3k views

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 ...
4
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1answer
404 views

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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0answers
40 views

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 ...
4
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2answers
20k views

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?
41
votes
1answer
7k views

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 ...
7
votes
3answers
967 views

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 ...
2
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0answers
197 views

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/...
2
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0answers
112 views

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 ?
3
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0answers
253 views

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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0answers
31 views

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 ...
4
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3answers
644 views

Evolution of sexual reproduction from asexual

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