The biological process by which new individuals are formed.

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Nature vs Nurture in Rooster mating dance: Are roosters lame dancers because they never learned any better?

I've seen, read about, or heard several avian courtship dances, flights, songs, and other rituals. They are general very impressive, fancy, and beautiful. Roosters, by comparison, are quite lame. The ...
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1answer
70 views

Can sexual selection operate in temperature dependent sex determining organisms?

Or more broadly, are distinct forms of genetic inheritance (ie. sex chromosomes) needed for sexual selection? My thinking was that since there are no sex determining loci, there could not be linkage ...
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1answer
92 views

Why can't gametes of one species fuse with that of the other species? [closed]

I have read that gametes of one species cannot fuse with that of another? For example the sperm of a dog can't fuse with the ova of a cat or a horse?
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160 views

Why didn't humans evolve to reproduce identical twins all the time?

According to the selfish gene theory, it seems like because identical twins sometimes get produced, a mutation to a gene that says, "if you have an identical twin, be fully altruistic towards them" ...
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169 views

Albinism inheritance problem: what are the father's alleles if he got an albino kid?

Albinism is caused by a recessive gen "c". A normal man marries an albino woman. The first son happened to be albino. What are the possible phenotypes of the parents? What is the chance that ...
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31 views

Fruit Fly Hybrids

I have a food waste bin in which I put fruit scraps. The fruits come from all over the world, mainly Europe though. I'm in the UK. I assume the fruit Fly eggs are already in the fruit, in which ...
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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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41 views

Big cat in heat for months?

In this documentary about a lioness and a leopard the leopard is in heat for months. https://www.youtube.com/watch?v=MGqmylkOuKw Usually a big cat would be in heat for 5 days and then not in heat ...
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105 views

About binary fission in amoeba [closed]

We know that amoeba reproduces by binary fission. Then does it mean that it never dies but keeps regenerating? In other words and more generally, does reproduction by fission by unicellular organisms ...
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1answer
165 views

What bacteria do unborn babies contain?

This Scientific American article states that "[human] infestation [by bacteria] begins at birth". This would suggest that unborn babies are free from any bacteria. However, if the mother catches a ...
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109 views

How long does conception take?

I know that conception is a multi-step process. A sperm fuses with an egg. Its contents diffuse into the cytoplasm. Dad's DNA is transported to the nucleus. Proteins are gradually made from Dad's ...
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Why do we produce so many sperm?

So apparently we produce roughly 300 million sperm daily. Is there a reason why this is necessary? Wouldn't a much smaller (but still large) number be sufficient? Like, one million?
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Is there a mechanism by which mammals lose interest in a partner after mating?

I'm reading the book called "Cupid's poison arrow", which revolves around a rather simple assumption: most mammals, including humans have a genetic program that is responsible for ever increasing ...
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61 views

What is the simplest autotrophic cell?

Very simple cells, such as Nanoarchaeum equitans, require a host to provide certain essential ingredients for life. Complex life-forms (like humans) require a whole ...
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1answer
709 views

How is centriole number maintained during meiosis?

I've found a website (Pearson's BioCoach) that claims centrioles duplicate in Prophase II. Is this accurate? Does it depend on the species in question? Looking at three textbook illustrations of ...
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40 views

Can two members of the same sex have a biological baby? [duplicate]

I imagine that this would work using a similar technique to dolly the sheep. For two females, the nucleus of an egg would be placed in a sperm which has had its nucleus removed. The 'female' sperm ...
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1answer
62 views

How does the Platypus grow before it eats?

From this fascinating documentary on monotremes it is mentioned that the Platypus is born less than 1 cm in length, but has doubled its size by day three when it begins to nurse. How does the animal ...
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51 views

Negative association between habitat quality and reproductive success in birds

I'm looking for bird studies that have found either a negative correlation or no correlation between habitat quality and reproductive success. Or in other words, bird studies that have found that ...
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43 views

Expected reproduction rate of a dandelion and/or fern

I am working a basic mathematical/computer simulation of an ecosystem, and I need to know the birth rate of each organism in my simulation. However, I could not find any data for how often a small, ...
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1answer
186 views

Can androgen-insensitive genetic-males get pregnant?

According to the linked report, people with androgen insensitivity syndrome appear as male, but have both feminine and masculine outer genitalia. However, I was not able to find out whether their ...
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1answer
368 views

Isogametes and oogametes

I have found the following definitions of different types of gametes: isogametes: gametes looking and behaving the same; heterogametes: gametes different in size or in behaviour; oogametes: gametes ...
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111 views

Mating types in fungi (and somatogamy)

I would have some related questions about the mating types of fungi. Does a single spore generate a mycelium possessing only one mating type? If it does not in general, do Ascomycota and ...
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36 views

The Human Menstrual Cycle [duplicate]

1) What happens in the ovary and in the bloodstream that brings about this change in the uterus? 2) Why does the level of FSH decrease and remain at a relatively low level during the luteal phase of ...
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1answer
32 views

Do females retain oogonia after puberty?

Oogonia are the precursors of oocytes in females present during embryonic development. I was wondering whether these stem cells are still present in the ovaria at puberty?
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1answer
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How the pattern of fertilization path is determined before the cell division to form the blastocyst? Is it individually specific?

After sperm meets ovum,the inactive nucleus starts following a particular path inside the zygote rather chase a path.This path is biologically known as fertilization path (as mentioned in an article ...
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1answer
205 views

What is the trigger of pollen tube formation when the pollen is on the stigma?

What is the mechanism of pollen tube formation when the pollen is close to the stigma ? Is it because of chemotaxis? In other words, is the growth triggered by some chemical substance that is ...
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2answers
125 views

If the haploid prothallium of a fern fertilizes itself into a diploid sporophyte, does this make all ferns clones?

From what I understand in the alternation of generations in ferns, mature spores germinate into a haploid prothallium. But how does this gametophyte produce recombinant gametes if it itself develops ...
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Is the number of stamens always 9 for geranium?

We are studing in class the reproduction of plants. We start the lesson by observing some components of flowers, it was the Géranium. First of all we start counting the number of sepals , petals and ...
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65 views

What is the developmental basis of the placental sac?

The placental sac is the organ that provides nutrients to the embryo from the mother. My question is that, since this obviously involves a lot of complexity, where does the sac originate from ...
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101 views

How many mitotic divisions do haploid cells undergo before fertilization?

Background This question is about human physiology and gametogenesis. A spermatozoid is not necessarily the direct "offspring" of diploid cell. Stated differently, a spermatozoid cell can be the ...
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47 views

Which monkey species features two distinct male phenotypes?

I remember coming across a popular science article years ago about a monkey species which featured two male genotypes: the first were good looking males who acquired social status (as alphas or betas) ...
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from an ageing reproductive stem cell's DNA to baby's “brand new” somatic cells' DNA

On the one hand, somatic cells's DNA age as life goes on, mitosis after mitosis, and that is reflected into reduced telomeres. On the other hand, during life, reproductive stem cells must age too. ...
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1answer
76 views

Can yeast in a primary fermentation of wine be used as a source of yeast for new fermentation?

So if I were to pitch bread yeast, and get to primary fermentation, which as I understand it, is the point at which regular cellular respiration can no longer continue due to a lack of oxygen , which ...
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37 views

Why do four spermatids have different genomes?

It's been a while since my last class in genetics, so I've forgot most of it. However, I found myself studying human reproduction and I've the following doubt concerning spermatogenesis: the process ...
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What is the maximum number of babies a human woman can have?

I know you could divide the female fertility period (~40 years, right?) by 9 months which would give something like ~50 kids (with no multiple kids per pregnancy). The limiting factor in this ...
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4answers
169 views

The selective pressure of contraceptives

Does it seem probable that the existence of contraceptives (which has reduced human reproduction to below survival-level in many populations) will be a completely new selective pressure on human ...
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332 views

Why do women live longer than men?

According to Wikipedia and many other sources, women live substancially longer than men (over 5 years in the U.S.). Men can reproduce for much longer than women. So longer living men would have the ...
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1answer
57 views

Do all kind of unicellular asexual reproductions let mutations happen, resulting in evolution?

I know about fission, an unicellular asexual reproduction method, where the mother cell splits into two daughter cells. Does this kind of asexual reproductions let mutations happen, leading to much ...
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Location of embryo development in angiosperms

What floral organ does the development of the embryos of angiosperms occurs in? Is it the ovary? The pollen tube grows down through the style and double fertilization occurs and the embryo begins to ...
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222 views

Do changes in an organism's cell modify the genetic information it uses for reproduction?

What I'm actually interested about is whether a modification in one cell during the life of an asexually reproducing organism affects its genetic information? Which cell's genetic information is used ...
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Founders of Cnidarian colony

I know that colonial Cnidaria enlarge their colony by the means of asexual reproduction and sexual and asexual reproduction can originate individuals that will be part of other colonies. ...
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2k views

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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How does a sperm cell die?

What causes an animal sperm cell to die? Does it die somehow from being outside its original environment? I've studied the Wikipedia page on sperm and I see a lot of information on what makes up a ...
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2k views

When is the second polar body extruded from the egg nucleus?

When does the second polar body gets expelled from the egg nucleus during oogenesis ? I know that it occurs after the entry of the sperm into the secondary oocyte but does it occur before the ...
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Can medications or drugs damage oocytes? [closed]

Some drugs are teratogens, but can any drugs cause DNA damage to oocytes before ovulation or conception (eg chemotherapy drugs)?
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226 views

Lyonization vs Genetic Imprinting

Lyonization is the process in which there is inactivation of an X chromosome in females. This process is implicated in mosaic forms of turner's syndrome (in this case the altered ...
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Why are there no artificial wombs yet?

If the conditions within the womb are mimicked, and proper amniotic fluid with constantly recycling nutrients is maintained, is it not possible to obtain an artificial womb? Is there anything missing? ...
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2answers
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Can genetically engineering the DNA of a human zygote, make it a twin of another human in entirety?

My question is simple. If I wanted to make an exact twin of an individual, will genetically engineering the DNA of the zygote to match with the individual suffice?
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444 views

How does a fetus retain a blood group different from its mother?

It's a well-established fact that blood group is decided by genotype. But, when a new child starts its journey in the womb, the mother's blood (along with it's agglutinins and agglutinogens) flows ...
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How can a drone be male?

A drone bee is male and is the product of only a queen bee. How is it that the drone bee can be male. I know that a drone is produced by an unfertilized egg, but this does not explain where the two X ...