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26.16: P

Created by: CK-12
paleontologist
scientist who finds and studies fossils to learn about evolution and understand the past
Paleozoic Era
age of “old life” from 544–245 million years ago that began with the Cambrian explosion and ended with the Permian extinction
pancreas
gland near the stomach that secretes insulin and glucagon to regulate blood glucose and enzymes to help digest food
parasite
species that benefits in a parasitic relationship
parasitism
symbiotic relationship in which one species benefits while the other species is harmed
parathyroid glands
a pair of small glands in the neck that secretes hormones that regulate blood calcium
passive immunity
type of immunity to a particular pathogen that results when antibodies are transferred to a person who has never been exposed to the pathogen
passive transport
movement of substances across a plasma membrane that does not require energy
pathogen
disease-causing agent such as a bacterium, virus, fungus, or protozoan
pedigree
chart showing how a trait is passed from generation to generation within a family
penis
male reproductive organ containing the urethra, through which sperm and urine pass out of the body
periosteum
tough, fibrous membrane that covers the outer surface of bone
peripheral nervous system (PNS)
one of two major divisions of the nervous system that consists of all the nervous tissue that lies outside the central nervous system
peristalsis
rapid, involuntary, wave-like contraction of muscles that pushes food through the GI tract and urine through the ureters
Permian extinction
extinction at the end of the Paleozoic Period that was the biggest mass extinction the world had ever seen until then
petal
outer parts of flowers that are usually brightly colored to attract animal pollinators
pH
scale that is used to measure acidity
phagocytosis
process in which leukocytes engulf and break down pathogens and debris
pharmacogenomics
field that is tailoring medical treatments to fit our genetic profiles
pharynx
long, tubular organ that connects the mouth and nasal cavity with the larynx through which air and food pass
phenotype
characteristics of an organism that depend on how the organism’s genotype is expressed
phloem
type of vascular tissue in a plant that transports food from photosynthetic cells to other parts of the plant
phospholipid bilayer
double layer of phospholipid molecules that makes up a plasma membrane
photic zone
area in an aquatic biome that extends to a maximum depth of 200 meters
photoautotroph
producer that uses energy from sunlight to make food by photosynthesis
photosynthesis
process of using the energy in sunlight to make food (glucose)
photosystem
group of molecules, including chlorophyll, in the thylakoid membrane of a chloroplast that captures light energy
phylogenetic tree
diagram that shows how species are related to each other through common ancestors
phylogeny
evolutionary history of a group of related organisms
phytoplankton
bacteria and algae that use sunlight to make food
pineal gland
gland of the endocrine system that secretes the hormone melatonin that regulates sleep-wake cycles
pioneer species
type of species that first colonizes a disturbed area
pistil
female reproductive structure of a flower that consists of a stigma, style, and ovary
pituitary gland
master gland of the endocrine system that secretes many hormones, the majority of which regulate other endocrine glands
placenta
temporary organ that consists of a large mass of maternal and fetal blood vessels through the mother’s and fetus’s blood exchange substances
placental mammal
therian mammal in which a placenta develops during pregnancy to sustain the fetus while it develops inside the mother’s uterus
plant
multicellular eukaryote with chloroplasts, cell walls made of cellulose, and specialized reproductive organs
plasma
golden-yellow fluid part of blood that contains many dissolved substances and blood cells
plasma membrane
thin coat of lipids (phospholipids) that surrounds and encloses a cell
plasmid
small, circular piece of DNA in a prokaryotic cell
platelet
cell fragment in blood that helps blood clot
Platyhelminthes
invertebrate phylum of flatworms that are characterized by a flat body because they lack a coelom or pseudocoelom
pleiotropy
situation in which a single gene affects more than one trait
pneumonia
disease in which the alveoli of the lungs become inflamed and filled with fluid as a result of infection or injury
point mutation
change in a single nucleotide base in the genetic material
polarity
difference in electrical charge between different parts of the same molecule
pollen
tiny grains that bear the male gametes of seed plants and transfer sperm to female reproductive structures
pollination
fertilization in plants in which pollen is transferred to female gametes in an ovary
polygenic characteristic
characteristic, or trait, controlled by more than one gene, each of which may have two or more alleles
polymerase chain reaction (PCR)
biotechnology process that makes many copies of a gene or other DNA segment
polynucleotide
chain of nucleotides that alone or with another such chain makes up a nucleic acid
polyp
basic body plan in cnidarians such as jellyfish that is tubular in shape and typically sessile
polypeptide
chain of amino acids that alone or with other such chains makes up a protein
polysaccharide
chain of monosaccharides that makes up a complex carbohydrate such as starch
population
all the organisms of the same species that live in the same area
population density
average number of individuals in a population per unit of area or volume
population distribution
describes how the individuals are distributed, or spread throughout their habitat
population genetics
science focusing on evolution within populations that is the area of overlap between evolutionary theory and Mendelian genetics
population growth rate (r)
how fast a population changes in size over time
population pyramid
bar graph that represents the age-structure of a population
Porifera
invertebrate phylum of sponges, which have a non-bony endoskeleton and are sessile as adults
precipitation
water that falls from clouds in the atmosphere to Earth’s in the form of rain, snow, sleet, hail, or freezing rain
predation
relationship in which members of one species consume members of another species
predator
species that consumes another in a predator-prey relationship
prediction
statement that tells what will happen under certain conditions
pregnancy
carrying of one or more offspring from fertilization until birth
prey
species that is consumed by another in a predator-prey relationship
primary succession
change in the numbers and types of species that live in a community that occurs in an area that has never before been colonized
probability
the likelihood, or chance, than a certain event will occur
producer
organism that produces food for itself and other organisms
product
substance that forms as the result of a chemical reaction
prokaryote
single-celled organism that lacks a nucleus
prokaryotic cell
cell without a nucleus that is found in single-celled organisms
promoter
region of a gene where a RNA polymerase binds to initiate transcription of the gene
prophase
first phase of mitosis during which chromatin condense into chromosomes, the nuclear envelope breaks down, centrioles separate, and a spindle begins to form
protein
organic compound made up of amino acids
protein synthesis
process in which cells make proteins that includes transcription of DNA and translation of mRNA
protist
kingdom in the domain Eukarya that includes all eukaryotes except plants, animals, and fungi
protozoa (singular, protozoan)
animal-like protists such as Amoeba and Paramecium
pseudocoelom
partial, fluid-filled cavity inside the body of some invertebrates
pseudopod
temporary, foot-like extension of the cytoplasm that some cells use for movement or feeding
psychoactive drug
drug that affects the central nervous system, generally by influencing the transmission of never impulses in the brain
puberty
period during which humans become sexually mature
pulmonary circulation
part of the circulatory system that carries blood between the heart and lungs
punctuated equilibrium
model of the timing of evolution in which long periods of little evolutionary change are interrupted by bursts of rapid evolutionary change
Punnett square
chart for determining the expected percentages of different genotypes in the offspring of two parents
pupa
life cycle stage of many insects that occurs between the larval and adult stages and during which the insect is immobile, may be encased within a cocoon, and changes into the adult form

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Feb 23, 2012

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Aug 18, 2014
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CK.SCI.ENG.SE.1.Biology.26.16

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