The biological process by which new individuals are formed.

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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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3answers
100 views

Are missing limbs hereditary?

So with my basic understanding of biology, DNA can change over time. Does this mean that if one (or both) parents have something major missing (like a limb), the kid will come out without a limb? ...
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3answers
77 views

Do adult humans exchange beneficial bacteria? If so, how?

Recently there has been increasing interest and research into symbiotic bacteria present in humans and human gut. I'm aware of two new discoveries: humans are surrounded by a unique cloud of ...
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2answers
1k views

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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0answers
14 views

what is the natural way of rose to propagate by its vegetative cells?

I have read that rose reproduces sexually. But I have also heard that it can propagate by its vegetative cells (vegetative cells in its root). Is this correct? If yes, can I know how does it propagate ...
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2answers
220 views

Why are female not competitive for reproduction like males?

I have wondered if competition for mate among males and the race among sperm cells would result in healthy offspring, why no such mechanisms exist among females and egg cells? (Even females are ...
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1answer
11 views

What is the change in ratio of histone to protamine in men with infertility called?

I am neither a biology researcher nor a student. In a paper (written by a biology researcher) I am translating into English, there is the following statement which, according to the text, must have a ...
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0answers
83 views

Why does the ovum prefers to be arrested at metaphase 2 of meosis before fertilization? What is the possible advantage of this process?

Why does the human ovum prefers to be arrested at metaphase 2 of meosis before fertilization? What is the possible advantage of this process??Please help me with it.
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1answer
58 views

Are progenies factually half-clones of the parents?

Given that a "clone" (if anything, in the context of human cloning) is taken to be, as far as I have understood, a specimen possessing the same genome as his "father/mother", aren't all "non-cloned" ...
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2answers
43 views

Why are so many spermatozoa produced when only one of them fertilises the ovum?

During fertilisation only one sperm can fertilise the ovum. So why so many millions of sperms are produced?? Isn't this a waste of energy?
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35 views

Why do earthworms cross-fertilise being hermaphrodite

Although the earthworms are hermaphrodites, they dont di self fertilisation but crossfertilisation. What is the logical reason behind them doing it?
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1answer
415 views

What is this Sacrificial Reproductive Strategy Called?

The reproductive strategy of salmon is 'suicidal'. Before breeding the males metamorph permanently into a form suited for the breeding season but unsuited for survival. The females devote so much of ...
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252 views

When does meiosis occur in flowering plants?

At what point in the development of a flower does meiosis occur?
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3answers
645 views

Why don't the apples seeds from grafted trees produce the same kind of apples?

As Wikipedia says: Grafting is a horticultural technique whereby tissues from one plant are inserted into those of another so that the two sets of vascular tissues may join together. In most ...
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0answers
24 views

Zygote Implantation and Pregnancy Detection

In a normal pregnancy, the embryo (blastocyst) implants between 8-9 days after ovulation. My understanding is that it is able to implant because the fertilized embryo produces a hormone that triggers ...
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1answer
41 views

Heteromaternal Superfecundation - Any known cases?

Superfecundation in mammals (fertilization of two or more ova from the same cycle by sperm from separate acts of sexual intercourse) -- Is possible in nature from different fathers (Heteropaternal) as ...
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0answers
70 views

Why did life on Earth develop with two sexes? [duplicate]

If evolution gives us the best adapted organisms for survival of the fittest, why does so many of Earth's organisms require two sexes for reproduction? Shouldn't this have been bred out of our ...
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1answer
2k views

Can females be recreated from male DNA?

A chromosomal male is XY and a chromosomal female is XX. Now imagine if, one day, this world has only males - is it possible to "recreate" a female by using two X chromosomes from two different males? ...
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1answer
710 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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0answers
63 views

How often does parthenogenesis in mammals happen?

Probably everyone knows that mammals can't produce viable offspring by parthenogenesis. But there are reports of human chimeras (see: a human parthenogenetic chimaera) and it's known for mice to ...
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5answers
6k views

Can the third sex be categorized as Male or Female?

Hijra are people who have a penis (not sure if sexually active) but look much like a female (perhaps for some feminine biological property). Wikipedia says they are "physiological males who have ...
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1answer
60 views

Why are siblings unidentical? (Which chromosome of the pair do gametes have?) [closed]

I know that a normal human cell has 23 pairs of chromosomes (total: 46). On the other hand, a gamete has only 23 chromosomes. Which chromosome does the gamete choose out of each pair? And if "One of ...
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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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0answers
33 views

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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3answers
624 views

Does the genetic material the sperm carries affect its physical properties

Basically, what I'm asking is, is the actual sperm cell built from the blueprint in the DNA of the man or is it itself also a consequence of the DNA it carries? I'd like to know a few more things ...
3
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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
93 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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3answers
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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1answer
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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1answer
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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2answers
1k views

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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0answers
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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0answers
107 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 ...
7
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3answers
1k views

What exactly does adaptive mean?

This is a quote from Dey et al 2014: Hatching asynchrony is thought to be adaptive because... What exactly does adaptive mean here? Does it mean hatching asynchrony has fitness benefits? Or does ...
9
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1answer
166 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 ...
3
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0answers
110 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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1answer
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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0answers
76 views

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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0answers
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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2answers
2k views

How was birth control realized in ancient days? [closed]

In ancient days, there were no birth control methods like condoms or contraceptive pills available. How did they control pregnancy?
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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 ...
5
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1answer
206 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 ...
6
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1answer
372 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 ...
9
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1answer
366 views

Why does the sex of the parent species determines the species of a hybrid offspring

I've read a little about hybrid animals, and have been amazed by the fact that the sex of the parent species determine the species of the offspring, in some hybrids. A male horse and a female donkey ...
3
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0answers
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, ...
4
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0answers
112 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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0answers
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 ...
14
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2answers
487 views

Have we ever observed two drosophila lineages that evolved reproductive isolation in labs?

Background The standard definition of species refers to the concept of reproductive isolation. If two lineages are found to be reproductively isolated, then we consider these two lineages to belong ...
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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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50 views

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 ...