The biological process by which new individuals are formed.

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1answer
37 views

Can you naturally change your DNA that's passed to your offsprings? [on hold]

Is it possible to change the genes that you'll pass on to your offsprings by natural activity and behavior. For example if you do body building for quite a long time build strong muscles then would ...
1
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0answers
34 views

Why is sex pleasure giving activity but not childbirth?

Asking from an evolutionary viewpoint. Sex is a pleasure giving activity so that it encourages reproduction and spreading of genes. But childbirth ,the most crucial part of the reproductive process, ...
2
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0answers
72 views

Why does it take many sperm for one sperm to fertilize an 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 ...
4
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2answers
347 views

How do traits with no negative effects get “weeded out” via evolution?

If only those who are most fit to reproduce are the ones reproducing the most, it makes sense that traits that prevent one from reproducing would eventually disappear from a population. But what ...
1
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1answer
62 views

How do heredity and regression to the mean work with respect to intelligence?

I am trying to understand the heredity of intelligence between generations in general, and how regression to the mean works in detail in particular. The answer I'm looking for should preferably answer ...
1
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0answers
44 views

What types of species can produce genetically identical offspring? [closed]

Talking about identical twins, triplets, etc. I'm curious which types of species are able produce genetically identical offspring. Let's limit the scope to species that reproduce sexually and ...
0
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0answers
24 views

Shrews have the highest brain-to-body mass ratio of vertebrates. Also one of the few animals to menstruate. Coincidence? [closed]

Shrews have the highest brain-to-body mass ratio of vertebrates. Also one of the few animals to menstruate other than humans. Coincidence? Have any parallels been found between the small group of ...
4
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2answers
65 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 ...
5
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2answers
76 views

Relationship between lifespan and reproductive age?

I remember reading a while ago that there is a "general rule" in biology between an animals lifespan and when they reach reproductive age. In other words, an organism that reaches sexual maturity ...
0
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1answer
79 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 ...
1
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1answer
29 views

Resting stage of primary oocytes

In my biology textbook, I read that the primary oocyte gets arrested in the early stages of meiosis in prophase I (diplotene stage). I wanted to know why this is so. I searched google, and this ...
1
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0answers
14 views

What drives male fish to spray their milt?

In mammals the sexdrive of the males is because the intercourse provides a satisfaction where after, the sperm is ejaculated into the female. However, the male sperm doesn't enter the female fish but ...
4
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4answers
218 views

Gametes of two different species

I always wondered why gametes from two different species dont fuse together to form an offspring. eg a donkey (sperm) and a female dog (egg) I know this is not possible but I'm just curious.
0
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1answer
12 views

After hysterectomy does FSH secretion stop?

This question came in an exam, and my reference book says yes, it does. But it hasn't explained why. If the ovaries are also removed, then the menstrual cycle should stop. In absence of hormones ...
7
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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 ...
0
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0answers
13 views

What did William Harvey discover from experimenting with deer?

On his wikipedia page, I read the following: In particular, Charles' hunting expeditions gave Harvey access to many deer carcasses; it was upon them that Harvey made many observations and ...
1
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0answers
64 views

Does reproduction cause aging ? Is aging just a strategy to increase reproductive success in all organisms? [closed]

Background for why I am asking this: I read a book—modern biological theory and experiments on celibacy— which uses life history theory to imply that reproduction is the reason why organisms grow old....
1
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1answer
43 views

How is excess semen removed if ejaculation does not occur?

There are some attempts to answer the question that I found via cursory Google search, but none of them were appropriately sourced. This site claims that they are "recycled like blood cells", but ...
3
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0answers
23 views

Breeding Southern Right Whales Genetics

I don't know much about biology. I just like watching David Attenborough videos and this made me curious. I just watched this video about breeding Southern Right Whales, and these two quotes puzzled ...
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0answers
15 views

Function of prostate gland and seminal vesicles

Multiple sources (my textbook, internet, videos) have been confusing me as they state various things. Which structure produces most of the semen and produces carbohydrates for the sperm; the seminal ...
2
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2answers
71 views

What animal produces male gametes by mitosis?

The following question came up in my biology examination but I could not answer it: "What animal produces male gametes by mitosis?" I know that some plants produce their gametes by mitosis in ...
1
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1answer
45 views

What's the difference between evolution fitness and reproductive success?

What's the difference biological fitness and reproductive success in the biological terminology?
1
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0answers
76 views

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

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, ...
0
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0answers
5 views

Is the bulbourethral (Cowper) gland turned on during puberty or is it on at birth?

I am trying to find information about the bulbourethral (Cowper) gland and if it gets turned on during puberty or not. I tried asking several other online sites and they said they couldn't help. I don'...
6
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2answers
2k 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?
3
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2answers
180 views

Are gametes determined by the sex of an organism?

In the Wikipedia article for biological sex, I read the following sentence. "The gametes produced by an organism are determined by its sex:..." However, is it not through the gametes produced by ...
3
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1answer
75 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 ...
7
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2answers
80 views

Do babies conceived naturally or artificially have any differences in long-term health?

Are there any long-term differences in children conceived via artificial insemination or sexual intercourse, pending that the mother successfully delivers the child?
4
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1answer
78 views

Why do chickens continuously lay unfertilized eggs?

As per subject: why do chickens continuously lay eggs even if they are not fertilized? Is this sort of behaviour found in other species of birds (or other egg-laying animals), or only in chickens? Is ...
-1
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3answers
103 views

Are seedless fruits considered life? [closed]

From school, I remember that for something to be considered life, it must be able to reproduce. With the creation of seedless fruits (such as watermelon), would this be considered life as they don't ...
0
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0answers
44 views

What is effect of sperm in blood?

Staphylococcus aureus, Streptococcus pyogenes, and Clostridium perfringens all produce hyaluronidase. Each of these bacteria are pathogens (use hyaluronidase as a virulence factor to destroy the ...
8
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2answers
235 views

Why did women historically have such a high mortality rate during birth?

Historically women had a relatively high chance of dying while giving birth. At first thought it seems to me that this would be a disadvantage for the species for the obvious reason that a dead ...
5
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1answer
544 views

What is the function of the polar bodies produced during oogenesis?

Why are polar bodies produced during oogenesis in human females? I read that polar bodies are produced during meiosis so that the oogonium (or gamete mother cell) can be converted into a haploid ...
2
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0answers
85 views

Difference between Fragmentation and Budding [closed]

I have heard about two terms stating similar things - Fission and Fragmentation . I know Amoeba undergoes fission and Fragmentation is done by spirogyra. So what's the main difference between them?
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2answers
159 views
4
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28 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 ...
5
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1answer
155 views

Why are mice with a single X chromosome and no Y chromosome males?

I was searching online and I read this article Mice can be male without Y chromosome and this is a part of it: The experiments demonstrate that there are multiple ways to make males, says Richard ...
22
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4answers
7k views

Why are not all species hermaphrodites?

If a hermaphrodite animal (like slug, snail, etc) finds a partner they can mate immediately. If another animal with "normal" reproduction (lets say a mouse) finds a partner they can only mate if they ...
9
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2answers
345 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 ...
0
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0answers
14 views

Does the spermatogonia divide to form primary spermatocyte or grow into primary spermatocyte?

I have two contrasting sources. One says that a spermatogonia 'divides' into two primary spermatocytes. The other says that there are two types of spermatogonia, one of which 'grows' into a primary ...
0
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0answers
38 views

How many children could Hunter-Gatherer support?

Hunter-Gatherers, to my knowledge, have to cover a fair amount of ground in order to be able to live off the land. This ought to have a placed a limitation on the number of children that they could ...
1
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2answers
3k views

Difference between inbreeding and interbreeding

Is inbreeding the same as interbreeding? On this site interbreeding is defined as (http://www.thefreedictionary.com/interbreeding): To breed with another kind or species; hybridize. To breed ...
13
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1answer
873 views

Can an organism exist as a single cell but come together as multi-cellular during certain times?

I am trying to remember a particular segment from a BBC special, in which there was single cellular species. However, at certain times all the individual cells came together to form a structure, not ...
4
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2answers
248 views

Is the DNA different in each type of cell? What DNA is passed to offspring?

Our body contains many 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. So ...
1
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1answer
47 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 ...
3
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1answer
42 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 ...
7
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1answer
213 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 ...
2
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2answers
270 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 ...
5
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2answers
237 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 ...