The biological process by which new individuals are formed.

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17
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2answers
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 ...
7
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1answer
358 views

What will happen if a foetus is Rh- and the mother is Rh+?

If a mother has Rh-negative blood and her foetus has Rh-positive blood it will result in rhesus incompatibility and lead to erythroblastosis fetalis. What will happen if the reverse occurs, when a ...
0
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1answer
63 views

What makes animal to continually reproduce? [closed]

I was reading about Trypophobia and reached to Surinam Toad's reproduction methods. Then I had this doubt- Why would animals want to reproduce so much? In case of humans we mostly have the offsprings ...
1
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1answer
62 views

Genotype of children conceived after stem cell transplant?

If you have sickle cell disease and have a succesful stem cell or bone marrow transplant, your blood type changes to AA. But what about your future children? Do your sperm or egg cells continue to ...
5
votes
1answer
611 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 ...
6
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2answers
116 views

What are possible health risks to women having large numbers of children?

What is the possible health issue the women would face in this record? The record for most children born to a single couple belongs to the first wife of Feodor Vassilyev of Russia. In 27 ...
6
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1answer
193 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 ...
0
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1answer
54 views

When does lactation occur?

High levels of estrogens and progesterone antagonize prolactin’s effect on the mammary glands, and it’s only after the placenta has been removed and the levels of estrogens and progesterone has ...
23
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2answers
1k views

Why is menstruation in wild animals not a disadvantage to organismal survival?

When I watch wilderness specials for more than a few minutes, I notice a familiar pattern: predators are depicted as being alerted by the scent of blood. Wounded animals seem to make the best prey and ...
8
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1answer
146 views

What is the main challenge in creating a chemical male contraceptive?

More than 50 years after hormonal contraception for women was invented, a contraceptive pill for males is still not available. With the obvious major biological differences in mind, why does it appear ...
0
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0answers
32 views

How can my baby DNA be “brand new”? [duplicate]

If it is assumed that "over time, our body and our DNA get damaged until we can no longer function properly", how is it that if I make a baby at the age of 40 with a partner of the same age, our baby ...
3
votes
1answer
88 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 ...
5
votes
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 ...
1
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3answers
115 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? ...
2
votes
3answers
82 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 ...
6
votes
2answers
2k 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 ...
1
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0answers
15 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 ...
1
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2answers
223 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 ...
0
votes
1answer
12 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 ...
1
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0answers
84 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.
0
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1answer
59 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" ...
1
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2answers
44 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?
0
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0answers
45 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?
5
votes
1answer
417 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 ...
0
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0answers
284 views

When does meiosis occur in flowering plants?

At what point in the development of a flower does meiosis occur?
2
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3answers
966 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
25 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 ...
2
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1answer
44 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 ...
8
votes
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?
10
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1answer
796 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 ...
1
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0answers
69 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 ...
3
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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 ...
0
votes
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 ...
3
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4answers
178 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 ...
0
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0answers
37 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 ...
5
votes
3answers
667 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
votes
1answer
76 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 ...
0
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1answer
108 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?
0
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3answers
176 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" ...
3
votes
1answer
32 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 ...
1
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1answer
229 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 their ...
1
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0answers
43 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 ...
1
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0answers
113 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
votes
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 ...