Fertilisation in the context of Mosaic (genetics)

Marine protists are defined by their habitat as protists that live in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. Life originated as marine single-celled prokaryotes (bacteria and archaea) and later evolved into more complex eukaryotes. Eukaryotes are the more developed life forms known as plants, animals, fungi and protists. Protists are the eukaryotes that cannot be classified as plants, fungi or animals. They are mostly single-celled and microscopic. The term protist came into use historically as a term of convenience for eukaryotes that cannot be strictly classified as plants, animals or fungi. They are not a part of modern cladistics because they are paraphyletic (lacking a common ancestor for all descendants).

Most protists are too small to be seen with the naked eye. They are highly diverse organisms currently organised into 18 phyla, but not easy to classify. Studies have shown high protist diversity exists in oceans, deep sea-vents and river sediments, suggesting large numbers of eukaryotic microbial communities have yet to be discovered. There has been little research on mixotrophic protists, but recent studies in marine environments found mixotrophic protists contribute a significant part of the protist biomass. Since protists are eukaryotes (and not prokaryotes) they possess within their cell at least one nucleus, as well as organelles such as mitochondria and Golgi bodies. Many protist species can switch between asexual reproduction and sexual reproduction involving meiosis and fertilization.

Stunted growth, also known as stunting or linear growth failure, is defined as impaired growth and development manifested by low height-for-age. Stunted growth is often caused by malnutrition, and can also be caused by endogenous factors such as chronic food insecurity or exogenous factors such as parasitic infection. Stunting is largely irreversible if occurring in the first 1000 days from conception to two years of age. The international definition of childhood stunting is a child whose height-for-age value is at least two standard deviations below the median of the World Health Organization's (WHO) Child Growth Standards. Stunted growth is associated with poverty, maternal undernutrition, poor health, frequent illness, or inappropriate feeding practices and care during the early years of life.

Among children under five years of age, the global stunting prevalence declined from 26.3% in 2012 to 22.3% in 2022. It is projected that 19.5% of all children under five will be stunted in 2030. More than 85% of the world's stunted children live in Asia and Africa. Once stunting occurs, its effects are often long-lasting. Stunted children generally do not recover lost height, and they may experience long-term impacts on body composition and overall health.

Legitimacy, in traditional Western common law, is the status of a child born to parents who are legally married to each other, and of a child conceived before the parents obtain a legal divorce.

Conversely, illegitimacy, also known as bastardy, has been the status of a child born outside marriage, such a child being known as a bastard, a love child, a natural child, or illegitimate. In Scots law, the terms natural son and natural daughter carry the same implications.

Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete (haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote that develops into an organism composed of cells with two sets of chromosomes (diploid). This is typical in animals, though the number of chromosome sets and how that number changes in sexual reproduction varies, especially among plants, fungi, and other eukaryotes.

In placental mammals, sperm cells exit the penis through the male urethra and enter the vagina during copulation, while egg cells enter the uterus through the oviduct. Other vertebrates of both sexes possess a cloaca for the release of sperm or egg cells.

Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds. Pollinating agents can be animals such as insects, for example bees, beetles or butterflies; birds, and bats; water; wind; and even plants themselves. Pollinating animals travel from plant to plant carrying pollen on their bodies in a vital interaction that allows the transfer of genetic material critical to the reproductive system of most flowering plants. Self-pollination occurs within a closed flower. Pollination often occurs within a species. When pollination occurs between species, it can produce hybrid offspring in nature and in plant breeding work.

In angiosperms, after the pollen grain (gametophyte) has landed on the stigma, it germinates and develops a pollen tube which grows down the style until it reaches an ovary. Its two gametes travel down the tube to where the gametophyte(s) containing the female gametes are held within the carpel. After entering an ovule through the micropyle, one male nucleus fuses with the polar bodies to produce the endosperm tissues, while the other fuses with the egg cell to produce the embryo. Hence the term: "double fertilisation". This process would result in the production of a seed, made of both nutritious tissues and embryo.

Meiosis (/maɪˈoʊsɪs/ ) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, the sperm or egg cells. It involves two rounds of division that ultimately result in four cells, each with only one copy of each chromosome (haploid). Additionally, prior to the division, genetic material from the paternal and maternal copies of each chromosome is crossed over, creating new combinations of code on each chromosome. Later on, during fertilisation, the haploid cells produced by meiosis from a male and a female will fuse to create a zygote, a cell with two copies of each chromosome.

Errors in meiosis resulting in aneuploidy (an abnormal number of chromosomes) are the leading known cause of miscarriage and the most frequent genetic cause of developmental disabilities.

Mutualism describes the ecological interaction between two or more species where each species has a net benefit. Mutualism is a common type of ecological interaction. Prominent examples are:

• the nutrient exchange between vascular plants and mycorrhizal fungi,
• the fertilization of flowering plants by pollinators,
• the ways plants use fruits and edible seeds to encourage animal aid in seed dispersal, and
• the way corals become photosynthetic with the help of the microorganism zooxanthellae.

Mutualism can be contrasted with interspecific competition, in which each species experiences reduced fitness, and exploitation, and with parasitism, in which one species benefits at the expense of the other. However, mutualism may evolve from interactions that began with imbalanced benefits, such as parasitism.

The male reproductive system consists of a number of sex organs that play a role in the process of human reproduction. These organs are located on the outside of the body, and within the pelvis.

The main male sex organs are the penis and the scrotum, which contains the testicles that produce semen and sperm, which, as part of sexual intercourse, fertilize an ovum in the female's body; the fertilized ovum (zygote) develops into a fetus, which is later born as an infant. The corresponding system in females is the female reproductive system.

A mother is the female parent of a child. A woman may be considered a mother by virtue of having given birth, by raising a child who may or may not be her biological offspring, or by supplying her ovum for fertilisation in the case of gestational surrogacy.

A biological mother is the female genetic contributor to the creation of the infant, through sexual intercourse or egg donation. A biological mother may have legal obligations to a child not raised by her, such as an obligation of monetary support. An adoptive mother is a female who has become the child's parent through the legal process of adoption. A putative mother is a female whose biological relationship to a child is alleged but has not been established. A stepmother is a non-biological female parent married to a child's preexisting parent, and may form a family unit but generally does not have the legal rights and responsibilities of a parent in relation to the child.

Lazzaro Spallanzani (Italian pronunciation: [ˈladdzaro spallanˈtsaːni]; 12 January 1729 – 11 February 1799) was an Italian Catholic priest (for which he was nicknamed Abbé Spallanzani), biologist and physiologist who made important contributions to the experimental study of bodily functions, animal reproduction, and animal echolocation. His research on biogenesis paved the way for the downfall of the theory of spontaneous generation, a prevailing idea at the time that organisms develop from inanimate matters, though the final death blow to the idea was dealt by French scientist Louis Pasteur a century later.

His most important works were summed up in his book Expériences pour servir a l'histoire de la génération des animaux et des plantes (Experiences to Serve to the History of the Generation of Animals and Plants), published in 1785. Among his contributions were experimental demonstrations of fertilisation between ova and spermatozoa, and in vitro fertilisation.

The United States anti-abortion movement, also called the pro-life movement or right-to-life movement, is a movement in the United States that opposes induced abortion and advocates for the protection of fetuses. Advocates support legal prohibition or restriction on ethical, moral, or religious grounds, arguing that human life begins at conception and that the human zygote, embryo, or fetus is a person and therefore has a right to life. The anti-abortion movement includes a variety of organizations, with no single centralized decision-making body. There are diverse arguments and rationales for the anti-abortion stance. Some allow for some permissible abortions, including therapeutic abortions, in exceptional circumstances such as incest, rape, severe fetal defects, or when the woman's health is at risk.

Before the Supreme Court 1973 decisions in Roe v. Wade and Doe v. Bolton, anti-abortion views predominated and found expression in state laws which prohibited or restricted abortions in a variety of ways. (See Abortion in the United States.) The anti-abortion movement became politically active and dedicated to the reversal of the Roe v. Wade decision, which struck down most state laws restricting abortion in the first trimester of pregnancy.In the United States, the movement is associated with several Christian religious groups, especially the Catholic Church and Evangelical churches, and is frequently, but not exclusively, allied with the Republican Party. The movement is also supported by secular organizations (such as Secular Pro-Life) and non-mainstream anti-abortion feminists. The movement has campaigned to reverse Roe v. Wade and to promote legislative changes or constitutional amendments, such as the Human Life Amendment, that prohibit or at least broadly restrict abortion.

In therian mammals, pregnancy is the period of reproduction during which a female carries one or more live offspring from implantation in the uterus through gestation. It begins when a fertilized zygote implants in the female's uterus, and ends once it leaves the uterus.

Male (symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilisation. A male organism cannot reproduce sexually without access to at least one ovum from a female, but some organisms can reproduce both sexually and asexually. Most male mammals, including male humans, have a Y chromosome, which codes for the production of larger amounts of testosterone to develop male reproductive organs.

In humans, the word male can also be used to refer to gender, in the social sense of gender role or gender identity.

The egg cell or ovum (pl.: ova) is the female reproductive cell, or gamete, in most anisogamous organisms (organisms that reproduce sexually with a larger, female gamete and a smaller, male one). The term is used when the female gamete is not capable of movement (non-motile). If the male gamete (sperm) is capable of movement, the type of sexual reproduction is also classified as oogamous. A nonmotile female gamete formed in the oogonium of some algae, fungi, oomycetes, or bryophytes is an oosphere. When fertilized, the oosphere becomes the oospore.

When egg and sperm fuse together during fertilisation, a diploid cell (the zygote) is formed, which rapidly grows into a new organism.