The biological process by which new individuals are formed.

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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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Why do some animals and fungi prefer asexual reproduction?

Animals like Sponges and Hydra and fungi like Yeast and Mushroom can reproduce both asexually and sexually. However, they only reproduce sexually if the 'circumstances' are 'bad'. Is there a specific ...
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Is there a database of pollen-seed distances across plant species?

I was enjoying Richard Smith's excellent answer to this question, and wondered: If you consider the pollen/seed distribution range to be plant locomotion, is there a database that compares these ...
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1answer
93 views

How might IVF (and related technologies) alter epigenetic marks?

I was reading up on KCNQ1, which encodes a voltage-gated potassium channel, and I discovered that it happens to be only maternally expressed. This is regulated by KCNQ1OT1, a non-coding RNA, which is ...
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Can mammals from different species reproduce?

I'm curious on how genetically different can two animals be in order to reproduce. Could they belong to different species? One example is the mule which is the offspring of a donkey and a horse, in ...
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Why aren't antheridia and archegonia touching?

Antheridia and archegonia are the two male and female gametangia, respectively, and they are found in bryophytes. To cause fertilization, usually a thin film of water must be present for the sperm ...
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Are chromosomes from each parent split between gametes with equal probability (esp. in humans)?

I've recently read a little on Wikipedia about genetics, but I can't find a direct answer to this question. My rough understanding is this: Both males and females have pairs of chromosomes, one ...
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Male behaviour during breeding season

The mountain blue bird build nests to attract females and exhibit aggression towards other males during breeding season. Which of the following is likely to give the birds maximal evolutionary ...
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Regarding inherited fertility in animals

If an animal is fertile does it follow that both its parents of the same species (not necessarily the same species of the offspring)? Was it Mayer who said a fertile male and fertile female of two ...
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Are there other methods besides surgery and hormonal treatments to help undescended testicles? [closed]

I've been doing some reading on undescended testicles and common treatments. It looks like the most common treatment for a baby is to give it time to see if the testicles drop on their own. If not, ...
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148 views

Need of X or Y chromosome protein after meiosis

After meiosis each spermatid get either the X chromosome or the Y chromosome. I know that the 4 spermatids formed from 1 spermatogonia are connected by cytoplasm and so the proteins made by X or Y ...
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Which C. elegans would be appropriate for general study?

Would wild type N2 be best or Dyp-11? I know they're different, but I just want to observe the worms to see life stages, movement, etc. Dyp-11 seems like it would be easy to see but N2 is the wild ...
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Sexual Reproduction [closed]

The primary oocyte of a bird which has 80 autosomes and WZ sex chromosomes is going to divide. How many daughter cells and chromosomes are there in each cell at the end of meiosis I and II?
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Negative role of Placenta

How can a placenta turn hostile to the mother or fetus ? What are the abnormalities found during placental delivery ?
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Is asexual and sexual reproduction a universal feature of Bryozoans?

I found some clues that most, if not all, bryozoans can reproduce and multiply by asexual and sexual means, for example: Thomsen & Hakansson 1995: "Sexual Versus Asexual Dispersal in Clonal ...
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21 views

Chemical events of fertilization

During the acrosome reaction, the activation enzyme present in the sperm dissolves the corona radiata and zona pellucida enabling the sperm to reach the plasma membrane of the egg. Also calcium and ...
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1answer
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The probability of indirect human fertilization (follow-up)

This question is a follow-up to this one. I've been wondering how small that probability is. As we all know, "safe" sex, that is (correctly) using a condom and all that, isn't perfectly safe. So, in ...
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Meiosis I or II [closed]

Suppose an organism has 8 chromosomes. When the female and male organisms mate, how many chromosomes will the mother contribute to the offspring? Why?