The biological process by which new individuals are formed.

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what DNA you pass on to offsprings?

our body contains dozens of different types of cells and each of those cells have their own DNA (correct me if wrong) like skin cells their own DNA that makes them skin cells instead of muscle cells . ...
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1answer
36 views

Acrosomal enzymes and the female reproductive tract

My textbook wrote that the reason why acrosomal enzymes are so securely contained within the sperm (thus needing capacitation to facilitate their release) is to prevent any premature release in the ...
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25 views

How are instincts inherited and decoded? [closed]

I've studied that instincts are specific behavior ( migration of salmon) , which are inherited from parents to offspring. Since, our genome is passed only to our offsprings. Where are these instincts ...
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15 views

How only one follicle develops into graffian follicle?

I've studied that one out of many follicle develops into mature or graffian follicle. The fact which confuses me is that, since all follicles are in same ovary, close to each other with equal supply ...
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1answer
36 views

Corpus luteum during the luteal phase and gonadotropins

Does the corpus luteum operate independently of the hypothalamic-hypophyseal-ovarian axis? I know that hCG sustains the corpus luteum in the absence of FSH and LH, but in an ovarian cycle where there ...
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1answer
40 views

Male-Male competition limited to breeding season?

I'm currently reading about sexual selection in the context of evolution. Unfortunately, the focus is always on animal behavior during the breeding season. What is 'normal' behavior outside of ...
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1answer
29 views

What is working definition for female infertility?

I've studied infertility and found that its quite complex to define. However, I came to know about a useful working definition of infertility; which was " Failure to achieve pregnancy". Few days later ...
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1answer
181 views

What is most ancestral: isogamy or anisogamy?

Sexual reproduction can be feasible with anisogamy (gametes of different sizes i.e. genders) or isogamy (gametes of same size i.e. mating types) or with undifferentiated gametes (i.e. true random ...
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2answers
194 views

Why asexual reproduction?

When I took a course on genetics and evolution, I learned that recombination and sexual reproduction is advantageous compared to asexual reproduction. Sexual reproduction allows more combinations of ...
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229 views

Can diploidy evolve in absence of sexual reproduction?

Theoretical question Can diploidy (or polyploidy) evolve from a haploid lineage in the absence of sexual reproduction ? For what theoretical reason? How can such evolution take place? Empirical ...
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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 ...
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2answers
826 views

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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1answer
48 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 ...
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15 views

Do only one or both pairs of homologous chromatids exchange genetic material during the process of crossing over?

To be specific: Assume chromosomes A and B are homologous. They've both replicated into A1, A2 and B1, B2 and have formed a tetrad at the equator (synapsis). Most textbooks show either A1 and B1 OR A2 ...
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1answer
268 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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2answers
110 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 ...
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1answer
169 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
47 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 ...
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38 views

Which sperm fertilizes the egg?

Hundreds of acrosomes must undergo exocytosis to digest holes in the zona pellucida. This is one case that does not bear out the adage, “The early bird catches the worm.” A sperm that comes along ...
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27 views

What genetic link would cause a human to have a extra vertebra?

Most people have five vertebrae in their lumbar (lower back) region, which are named L1 to L5. However, some people possess an additional lumbar vertebra located below the L5. This extra vertebra, ...
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0answers
31 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
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1answer
66 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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1answer
61 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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3answers
63 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
730 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
13 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
207 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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80 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
53 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
41 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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27 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
409 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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102 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
317 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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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
30 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
468 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
53 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
5k 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
55 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
148 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
26 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
567 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
57 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
65 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
121 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
103 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 ...