Harm caused by exposure to toxic arsenic compounds. Acute and prolonged exposure can produce different patterns of injury, and toxicity depends on chemical form; detecting total arsenic alone does not identify the exposure source or establish its biological effect.

Treatment using a molecule that binds a metal through several coordinating groups, changing its distribution or elimination. The relevant metal and clinical circumstances matter: chemical binding alone does not demonstrate benefit for every form of poisoning.

A rank in taxonomy grouping closely related species.

Identification of constituents from characteristic emission lines or absorption lines in a resolved spectrum. Historical prism instruments used a narrow slit, collimator, prism and observing telescope.

The distribution of emitted radiation with wavelength or frequency. Resolved atomic spectral lines correspond to transitions between energy levels; a source's excitation and optical depth affect the observed intensities.

Software engineering develops and maintains software through systematic design, implementation and evaluation. It connects requirements to program structure, verification, deployment and later change. For example, altering a data format can require changing its parser, stored files and clients together; a locally correct code edit does not by itself ensure a working system. Software testing, version control and explicit interface contracts help manage these dependencies. The subject includes technical trade-offs between correctness, performance, maintainability and the constraints of the intended users.

Gestation is the period during which an embryo or fetus develops within a maternal body before birth. In placental mammals, the placenta supports exchange between maternal and fetal circulations; gestation therefore involves coordinated maternal physiology as well as growth of the offspring.

Dating conventions matter. Human clinical gestational age is ordinarily counted from the start of the last menstrual cycle, rather than directly from fertilization, so it is commonly about two weeks greater than age since fertilization in an idealized 28-day cycle. Variable ovulation means that this offset is not an exact biological constant.^[ref]

Menstruation is cyclic shedding of blood and endometrium tissue through the vagina. During a human menstrual cycle, ovarian hormones regulate the growth and maintenance of the endometrium; a decline in hormonal support is followed by shedding when a pregnancy has not become established.^[ref]

The first day of bleeding conventionally starts a new menstrual cycle. Menstruation describes a uterine event, whereas ovulation describes release of an oocyte from an ovary; treating the two as interchangeable obscures how the hypothalamic–pituitary–ovarian axis coordinates different organs.

Plant reproduction produces new plant individuals through sexual reproduction or asexual reproduction. In land plants, alternation of generations connects a gametophyte that makes gametes to a sporophyte that makes spores. A seed is a developing plant embryo with protective and nutritive structures, rather than another name for a spore.

A rhizome can extend and establish new shoots through vegetative reproduction, while pollination can initiate the sequence leading to fertilization and seed production in a flowering plant. These routes differ in how parental genetic variation is transmitted and combined.

Menopause marks the end of menstrual cycling associated with loss of ovarian reproductive activity. Natural human menopause is identified retrospectively after twelve months without menstruation, when another cause does not account for the absence. The preceding transition can include irregular cycles and changing ovarian hormone production.^[ref]

A single hormone measurement cannot reliably locate every individual within that transition because concentrations fluctuate. Irregular menstruation during the transition does not itself establish that ovulation has permanently stopped.^[ref]

Semen is the fluid discharged by the male reproductive tract during ejaculation. In humans it normally contains sperm suspended in secretions from reproductive glands, including the prostate and seminal vesicles. Semen is therefore a mixture, whereas a sperm is an individual gamete.^[ref]

Fluid volume and the number or movement of sperm describe different properties. A sample can contain fluid but few or no sperm, so visible semen alone does not establish successful gametogenesis or fertilization.

A live birth is delivery of offspring showing signs of life after separation from the mother. In human vital statistics, breathing or a beating heart can provide such evidence; being born alive and surviving the subsequent neonatal period are distinct outcomes.^[ref]

In comparative reproduction, delivery of living young is associated with viviparity, whereas oviposition releases eggs whose embryonic development continues outside the maternal body. The evolutionary question concerns where and how the developing offspring is supported, rather than whether the mother produces ova.

Ovulation is release of an oocyte from an ovarian follicle in the ovary. In the human menstrual cycle, rising luteinising hormone precedes this event; the released oocyte can subsequently encounter sperm in a fallopian tube. Ovulation and fertilization are separate events: releasing an oocyte does not establish a pregnancy.^[ref]

Calendar day alone is an imperfect marker because the timing of ovulation varies among individuals and cycles. An observed hormonal change measures part of the regulatory sequence rather than directly observing fusion of gametes.

Serum albumin is an abundant soluble blood-plasma protein that binds and transports diverse small compounds, including fatty acids. Its abundance also contributes substantially to the osmotic behaviour of plasma proteins. Binding can change the free fraction of a carried molecule, so total concentration and freely available concentration need not be equal. The serum name does not imply that the protein is absent from plasma before clotting. ^[ref]

Gluten is the viscoelastic protein-rich network formed when wheat storage proteins, principally gliadins and glutenins, interact during hydration and mixing. Glutenins contribute network elasticity, while gliadins contribute extensibility and flow. Its behaviour depends on composition and intermolecular interactions rather than one unique gluten molecule. This connects protein assembly to the mechanical properties of dough. ^[ref]

Fibrin is the insoluble protein network formed from fibrinogen during blood clotting. Proteolytic removal of small peptide segments permits assembly into fibres, and crosslinking stabilizes the network. This turns a soluble precursor into a structure that helps retain cells and reinforce a clot. Fibrin is distinct from fibrinogen: the names refer to different stages of the assembly pathway. ^[ref]

An apolipoprotein is a protein component of a lipoprotein particle. It can help stabilize the lipid-water interface, interact with receptors or regulate lipid-processing enzymes. Its function therefore extends beyond merely carrying an inert lipid load. Changing an apolipoprotein can change particle recognition and clearance without changing the chemical identity of every lipid molecule inside it. ^[ref]

An alkaline copper colour reaction that detects suitable arrangements of peptide bonds. It is a general protein test rather than proof of one particular protein.

A yellow colour reaction with nitric acid involving suitable aromatic residues; it can corroborate a protein examination without identifying a unique protein species.

A family of milk proteins whose precipitation can follow acidification. It should not be identified in an unrelated tissue solely from one nonspecific protein reaction.