IB biology essential terms Flashcards
What is cell theory?
A theory that states that all organisms are composed of cells; cells are the primary units of life and all life comes from preexisting life.
What are stem cells?
Undifferentiated cells with the potential to develop into many different types of cells in the body.
What is diffusion?
A net flow of particles from a region of high concentration to a region of low concentration resulting from random thermal motion of molecules.
What is osmosis?
The movement of water molecules across a semipermeable membrane down their concentration gradient (toward a higher concentration of solute).
What is active transport?
The movement of molecules into or out of a cell through the cell membrane, against their concentration gradient using energy released during respiration.
What is a sodium-potassium pump?
A membrane protein that moves sodium ions out of the cells and potassium ions into the cell against their concentration gradients.
What is metabolism?
Life-sustaining chemical reactions of an organism.
What is an enzyme?
A biological catalyst.
What is photosynthesis?
A process during which plants produce glucose from sunlight, CO2, and water.
What is cell respiration?
Controlled release of energy from organic compounds to produce ATP.
What is ATP?
Adenosine-triphosphate, the principal molecule for storing and transferring energy in cells.
What is a gene?
A heritable factor consisting of a length of DNA, influencing a specific characteristic.
What is an allele?
Specific forms of a gene.
What is a genome?
Whole genetic information of an organism.
What is a genotype?
The collection of alleles of an organism.
What is a phenotype?
The set of observable features of an organism.
What is mitosis?
Division of cell nucleus by which one nucleus divides into two genetically identical diploid nuclei.
What is meiosis?
Division of cell nucleus by which one diploid nucleus divides into four haploid nuclei for sexual reproduction.
What is a clone?
An organism genetically identical with another organism.
What is a species?
A group of organisms that can potentially interbreed to produce fertile offspring.
What is a population?
A group of organisms of the same species who live in the same area at the same time.
What is a community?
Population of different species living together and interacting with each other.
What is an ecosystem?
All the living organisms, their physical environment, and all their interrelationships in a particular area.
What are autotrophs?
Producers; organisms that can produce their own food using light, water, carbon dioxide, or other chemicals.
What are heterotrophs?
Organisms that obtain nutrients by consuming other organisms.
What is evolution?
Cumulative change in heritable characteristics of a population.
What is natural selection?
Differential survival and reproduction of individuals due to differences in phenotype.
What is speciation?
The process of two separated populations gradually diverging into different species by evolution.
What is a cladogram?
A tree diagram showing the most probable sequence of divergence in clades.
What is digestion?
Breaking down of large molecules in food into small molecules so that they can be absorbed by an organism.
What is absorption?
The process by which the products of digestion are absorbed into the blood to be supplied to the rest of the body.
What is a pathogen?
A disease-causing microorganism.
What is an antibody?
A large, Y-shaped protein used by the immune system to identify and neutralize pathogens. They are produced by B lymphocytes (and plasma cells) and are specific to a given antigen.
What is an antigen?
A molecule capable of triggering an immune response, typically on a surface of a pathogen (or allergen).
What are memory cells?
Long living lymphocytes that survive in the body for many years, producing low levels of circulating antibodies.
What are plasma cells?
White blood cells that secrete large quantities of antibodies.
What is ventilation?
Pumping of fresh air into alveoli and removing stale air from them.
What are antagonistic muscles?
A pair of muscles enabling opposing movements. When one contracts, the other relaxes, and vice versa.
What is resting membrane potential?
Voltage across the membrane of a neuron of about -70mV maintained in the resting state of the neuron by the sodium-potassium pump.
What is action potential?
A rapid change in membrane potential, consisting of depolarization and repolarization.
What are synapses?
Junctions between neurons, and between neurons and receptor or effector cells.
What are neurotransmitters?
Chemical substances used to send signals across synapses.
What are hormones?
Chemical messengers that are secreted into the transport system and transported throughout the body of an organism to regulate processes in body tissues.
What is homeostasis?
Maintaining stable internal environment.
What are gametes?
Organism’s reproductive cells. They are haploid cells, and each cell carries only one copy of each chromosome.
What is a zygote?
A cell formed by fusion of two gametes in the process of fertilization.
