Questions tagged [sexual-reproduction]
Reproduction involving two morphologically distinct gametes, such as sperm and egg, where offspring inherit genes from two parents.
0
votes
0answers
11 views
Characteristics of tubal fluid
Tubal fluid is present in the fallopian tube. What is its color? Is it off-white/yellowish?
Also what role does it play in fertilization (apart from being a place where it happens), specifically with ...
1
vote
1answer
30 views
In what fluid does the sperm swim in the oviduct?
We know that after sexual intercourse, sperm enters the female body and continues to pass through the oviduct by swimming. "Swimming" implies the presence of fluid.
I want to know what that fluid is ...
-2
votes
0answers
31 views
Reproduction - can we say that the rejuvenation is not miracle and the Nature is doing it constantly? [closed]
I am big fan of rejuvenation and indefinite life extension - there are good research along these lines, e.g. http://www.sens.org/research/introduction-to-sens-research/extracellular-junk (the best, ...
0
votes
2answers
89 views
In men, why do over 80% of sperm have abnormal form? [duplicate]
Here is the percentage of normal forms among fertile mens according to the centile (Source: Cooper et al. 2010):
2.5: 3%
5 (below this is Teratozoospermia): 4%
10: 5.5%
25: 9%
50 (median): 15%
75: ...
0
votes
0answers
32 views
How does acetylcholine (aCh) cause erection?
I have read this article on physiology of erection :
Activation of cholinergic receptors on the endothelial cell by acetylcholine or stretching of the endothelial cells as a result of increased ...
-2
votes
1answer
51 views
Is dandelion a sporophyte or gametophyte?
My text book claims all land plants undergo alternation of generation. However, I don't see how it could be with dandelion. The flower head gets pollinated and then turn back on itself. After a while ...
0
votes
2answers
215 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
votes
1answer
62 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 ...
1
vote
1answer
345 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
votes
0answers
121 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, ...
0
votes
1answer
68 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 ...
1
vote
0answers
34 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
votes
2answers
77 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 ...
0
votes
1answer
159 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
votes
1answer
606 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
votes
1answer
95 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
votes
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
votes
0answers
113 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 ...
1
vote
0answers
293 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.
3
votes
2answers
64 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 ...
0
votes
0answers
105 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 ...
0
votes
1answer
1k 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 ...
0
votes
0answers
85 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
vote
1answer
819 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 ...
0
votes
0answers
229 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. ...
1
vote
2answers
320 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
vote
0answers
65 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 ...
1
vote
2answers
134 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
votes
0answers
51 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 ...
-1
votes
1answer
91 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
vote
1answer
58 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 ...
1
vote
0answers
417 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
votes
1answer
162 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 ...
1
vote
0answers
218 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 ...
0
votes
0answers
53 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
vote
2answers
936 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?
0
votes
2answers
232 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
votes
0answers
79 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
vote
1answer
539 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
votes
1answer
109 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
172 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
101 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?
...
-1
votes
1answer
392 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
6
votes
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
votes
1answer
516 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 ...
1
vote
0answers
78 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
votes
2answers
22k 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 ...
8
votes
3answers
1k 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
votes
0answers
203 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/...
