Life Cycle, Processes & Properties, PAR-POS
None of us are born looking exactly the way that we do today; this is because humans, like other species, undergo a series of changes as they mature and age, in accordance with their biological life cycle. This process can look very different across different species. In many simple organisms and in higher animals, the life cycle is completed within a single generation, while in most plants, the life cycle is multigenerational.
Life Cycle, Processes & Properties Encyclopedia Articles By Title
parthenocarpy
parthenocarpy, development of fruit without fertilization. The fruit resembles a normally produced fruit but is......
Parthenogenesis
Parthenogenesis, a reproductive strategy that involves development of a female (rarely a male) gamete (sex cell)......
parturient paresis
parturient paresis, in cattle, a disorder characterized by abnormally low levels of calcium in the blood (hypocalcemia).......
pasteurellosis
pasteurellosis, any bacterial disease caused by Pasteurella species. The name is sometimes used interchangeably......
patent ductus arteriosus
patent ductus arteriosus, congenital heart defect characterized by the persistence of the ductus arteriosus, a......
pathology
pathology, medical specialty concerned with the determining causes of disease and the structural and functional......
Peanut
Peanut, (Arachis hypogaea), tropical South American legume plant widely cultivated for its edible seeds. The seeds,......
Pecking order
Pecking order, Basic pattern of social organization within a flock of poultry in which each bird pecks another......
pectus excavatum
pectus excavatum, a chest deformity caused by depression of the breastbone, or sternum. Pectus excavatum is generally......
pedophilia
pedophilia, in conventional usage, a psychosexual disorder, generally affecting adults, characterized by sexual......
pellagra
pellagra, nutritional disorder caused by a dietary deficiency of niacin (also called nicotinic acid) or a failure......
pelvic inflammatory disease
pelvic inflammatory disease (PID), general acute inflammation of the pelvic cavity in women, caused by bacterial......
pemphigus
pemphigus, a group of skin diseases characterized by large blisters that appear on the skin and mucous membranes.......
Pendred’s syndrome
Pendred’s syndrome, hereditary metabolic condition that is characterized by deafness and defective incorporation......
pentosuria
pentosuria, inborn error of carbohydrate metabolism, characterized by the excessive urinary excretion of the sugar......
peptic ulcer
peptic ulcer, lesion that occurs primarily in the mucous membrane of the stomach or duodenum (the upper segment......
perennial
perennial, any plant that persists for several years, usually with new herbaceous growth from a part that survives......
pericarditis
pericarditis, inflammation of the pericardium, the membranous sac that encloses the heart. Acute pericarditis may......
perichondritis
perichondritis, rare inflammation of the perichondrium, the membrane that covers the cartilage of the outer ear.......
periodic paralysis
periodic paralysis, any of the forms of a rare disorder that is characterized by relatively short-term, recurrent......
periodontal membrane
periodontal membrane, fleshy tissue between tooth and tooth socket that holds the tooth in place, attaches it to......
periodontitis
periodontitis, inflammation of the soft tissues around the teeth, characterized by swollen tender gums (gingivitis),......
peristalsis
peristalsis, involuntary movements of the longitudinal and circular muscles, primarily in the digestive tract but......
peritonitis
peritonitis, inflammation of the peritoneum, the membrane that lines the abdominal wall and then folds in to enclose......
pernicious anemia
pernicious anemia, disease in which the production of red blood cells (erythrocytes) is impaired as a result of......
peromelia
peromelia, congenital absence or malformation of the extremities, of rare occurrence until the thalidomide tragedy......
perosis
perosis, a disorder of chicks, turkey poults, and young swans, characterized by enlargement of the hock, twisted......
perseveration
perseveration, the repetitive and uncontrollable continuation of a thought, behavior, or response, even when it......
persistent depressive disorder
persistent depressive disorder, mental disorder characterized by symptoms of depression that are present for two......
personality disorder
personality disorder, any of a group of mental disorders characterized by enduring patterns of cognition, emotional......
perspiration
perspiration, in most mammals, water given off by the intact skin, either as vapour by simple evaporation from......
pervasive developmental disorder
pervasive developmental disorder (PDD), term historically used in reference to any of a group of conditions characterized......
pervasive developmental disorder not otherwise specified
pervasive developmental disorder not otherwise specified (PDD-NOS), condition characterized by impairment in the......
pescatarianism
pescatarianism, dietary practice based on the consumption of fish and shellfish to the exclusion of land-based......
phantom limb syndrome
phantom limb syndrome, the ability to feel sensations and even pain in a limb or limbs that no longer exist. Phantom......
pharyngitis
pharyngitis, inflammatory illness of the mucous membranes and underlying structures of the throat (pharynx). Inflammation......
pharynx
pharynx, cone-shaped passageway leading from the oral and nasal cavities in the head to the esophagus and larynx.......
phenylketonuria
phenylketonuria (PKU), hereditary inability of the body to metabolize the amino acid phenylalanine. Phenylalanine......
phenylthiocarbamide tasting
phenylthiocarbamide tasting, a genetically controlled ability to taste phenylthiocarbamide (PTC) and a number of......
pheochromocytoma
pheochromocytoma, tumour, most often nonmalignant, that causes abnormally high blood pressure (hypertension) because......
pheromone
pheromone, any endogenous chemical secreted in minute amounts by an organism in order to elicit a particular reaction......
phlebitis
phlebitis, inflammation of the wall of a vein. Phlebitis may result from the infection of tissues adjacent to the......
phlebothrombosis
phlebothrombosis, formation of a blood clot in a vein that is not inflamed. Inactivity, such as bed rest during......
phobia
phobia, an extreme, irrational fear of a specific object or situation. A phobia is classified as a type of anxiety......
phoresy
phoresy, transportation of one organism by another, more mobile one. The term is not applied to a parasitic relationship,......
phosphorus deficiency
phosphorus deficiency, condition in which phosphorus is insufficient or is not utilized properly. Phosphorus is......
photodynamism
photodynamism, conversion of certain substances in the skin of animals into other substances by the action of light.......
photolysis
photolysis, chemical process by which molecules are broken down into smaller units through the absorption of light.......
Photoperiodism
Photoperiodism, the functional or behavioral response of an organism to changes of duration in daily, seasonal,......
Photoreception
Photoreception, any of the biological responses of animals to stimulation by light. In animals, photoreception......
photorecovery
photorecovery, restoration to the normal state, by the action of visible light, of the deoxyribonucleic acid composing......
photosynthesis
photosynthesis, the process by which green plants and certain other organisms transform light energy into chemical......
Pi in nature
Pi (π) is the constant that relates a circle’s circumference to its diameter. It is an irrational, transcendental......
pica
pica, mental health condition, a type of eating disorder, characterized by the compulsive eating of substances......
Pick disease
Pick disease, form of premature dementia caused by atrophy of the frontal and temporal lobes of the brain. It resembles......
pickwickian syndrome
pickwickian syndrome, a complex of respiratory and circulatory symptoms associated with extreme obesity. The name......
pineal tumour
pineal tumour, mass of abnormal tissue arising in the pineal gland and occurring most often in children and young......
pinguecula
pinguecula, very common yellow-white nodule in the conjunctiva at the front of the eye, usually on the side of......
pinta
pinta, chronic tropical skin disease characterized initially by the appearance of dry, scaly papular lesions followed......
piriformis syndrome
piriformis syndrome, irritation of the sciatic nerve as it passes over, under, or through the piriformis muscle......
pituitary tumour
pituitary tumour, most common cause of enlargement of the sella turcica, the bone cavity in the head in which the......
placenta
placenta, in zoology, the vascular (supplied with blood vessels) organ in most mammals that unites the fetus to......
placenta accreta
placenta accreta, abnormal adherence of the placenta to the wall of the uterus, so that it remains in the uterus......
placenta praevia
placenta praevia, implantation of the placenta at a point so low in the uterus that the placenta is close to the......
placental abruption
placental abruption, premature separation of the placenta from its normal implantation site in the uterus. The......
placental infarction
placental infarction, formation of yellowish white or bloodstained deposits of fibrin (a fibrous protein) on the......
plague
plague, infectious disease caused by Yersinia pestis, a bacterium transmitted from rodents to humans by the bite......
plant development
plant development, a multiphasic process in which two distinct plant forms succeed each other in alternating generations.......
- Introduction
- Germination, Embryogenesis, Maturation
- Zygote, Embryo, Seedling
- Embryogenesis, Meristems, Apical
- Nutrient Dependence, Embryo Nutrition, Seed Germination
- Breaking Dormancy
- Meristems, Growth, Cells
- Shoot System, Derivatives
- Leaf Production, Photosynthesis, Morphogenesis
- Branching, Shoot, Axillary Buds
- Root System, Derivatives
- Correlations, Morphogenesis, Genetics
- Environmental Control, Hormones, Genes
- Senescence, Aging, Growth
Plant disease
Plant disease, an impairment of the normal state of a plant that interrupts or modifies its vital functions. All......
- Introduction
- Causes, Symptoms, Prevention
- Epiphytotics, Symptoms, Control
- Soil pH, Fungi, Bacteria
- Symptoms, Causes, Control
- Chemical Control, Prevention, Treatment
- Resistance, Breeding, Genetics
- Toxic Chemicals
- Transmission, Pathogens, Symptoms
- Symptoms, Causes, Treatments
- Causes, Symptoms, Prevention
- Nematodes, Parasitic, Control
plantar fasciitis
plantar fasciitis, swelling or degeneration of the plantar fascia, the thick band of connective tissue that runs......
plasmodium
plasmodium, in fungi (kingdom Fungi), a mobile multinucleate mass of cytoplasm without a firm cell wall. A plasmodium......
play
play, in zoology, behaviour performed in the absence of normal stimuli or behaviour elicited by normal stimuli......
pleural effusion
pleural effusion, accumulation of watery fluid in the pleural cavity, between the membrane lining the thoracic......
pleurisy
pleurisy, inflammation of the pleura, the membranes that line the thoracic cavity and fold in to cover the lungs.......
pleurodynia
pleurodynia, viral (coxsackie B) epidemic disease with an incubation period of two to four days, marked by a brief......
pleuropneumonia
pleuropneumonia, lung disease of cattle and sheep, characterized by inflammation of the lungs and caused by the......
Plummer disease
Plummer disease, thyroid condition characterized by marked enlargement of the thyroid gland (goitre), firm thyroid......
pneumoconiosis
pneumoconiosis, any of many lung diseases caused by the inhalation of a variety of organic or inorganic dusts or......
pneumonia
pneumonia, inflammation and consolidation of the lung tissue as a result of infection, inhalation of foreign particles,......
pneumothorax
pneumothorax, condition in which air accumulates in the pleural space, causing it to expand and thus compress the......
poison
poison, in biochemistry, a substance, natural or synthetic, that causes damage to living tissues and has an injurious......
- Introduction
- Cell Membrane, Biochemistry, Transport
- Topical Skin, Biochemistry, Effects
- Dose, Exposure, Biochemistry
- Biotransformation, Toxicity, Antidotes
- Allergies, Toxins, Symptoms
- Carcinogenesis, Toxins, Chemicals
- Toxins, Venoms, Chemicals
- Herbicides, Toxicity, Chemicals
- Air Pollution, Chemicals, Health
- Drugs, Abuse, Biochemistry
- Plant Toxins, Phytotoxins, Alkaloids
- Animal, Zootoxins, Biochemistry
- Radiation, Toxicity, Effects
- UV Rays, Toxins, Health Effects
polio
polio, acute viral infectious disease of the nervous system that usually begins with general symptoms such as fever,......
pollination
pollination, transfer of pollen grains from the stamens (the flower parts that produce them) to the ovule-bearing......
polyarteritis nodosa
polyarteritis nodosa, inflammation of blood vessels and surrounding tissue; it may affect functioning of adjacent......
polychondritis
polychondritis, chronic disease characterized by inflammation and destruction of the cartilage of various tissues......
polycythemia
polycythemia, abnormal increase in red blood cells (erythrocytes) and hemoglobin in the circulation, a situation......
polydactyly
polydactyly, condition that is present at birth in which a person has more than five fingers on a hand or more......
polyembryony
polyembryony, a condition in which two or more embryos develop from a single fertilized egg, forming what in humans......
polyglandular autoimmune syndrome
polyglandular autoimmune syndrome, either of two familial syndromes in which affected patients have multiple endocrine......
polymyalgia rheumatica
polymyalgia rheumatica, joint disease that is fairly common in people over the age of 50, with an average age of......
polymyositis
polymyositis, chronic, progressive inflammation of skeletal muscles, particularly the muscles of the shoulders......
polyomavirus
polyomavirus, (family Polyomaviridae), any of a subgroup of minute oncogenic DNA viruses of the family Polyomaviridae.......
polyp
polyp, in medicine, any growth projecting from the wall of a cavity lined with a mucous membrane. A polyp may have......
polyuria
polyuria, daily output of an excessive amount of urine. In humans, polyuria involves the output of more than three......
Pompe’s disease
Pompe’s disease, hereditary defect in the body’s ability to metabolize glycogen, resulting in a muscle disorder......
porphyria
porphyria, any of a group of diseases characterized by the marked overproduction and excretion of porphyrins or......
Porphyrin
Porphyrin, any of a class of water-soluble, nitrogenous biological pigments (biochromes), derivatives of which......
post-traumatic stress disorder
post-traumatic stress disorder (PTSD), emotional condition that sometimes follows a traumatic event, particularly......
postmature birth
postmature birth, in humans, any birth that occurs more than 42 weeks after conception, at which time placental......
postpartum depression
postpartum depression, depressive disorder sometimes occurring in mothers following childbirth (parturition). Postpartum......