Definitions Flashcards
binomial system
an internationally agreed system in which the scientific name of an organism is made up of two parts, showing the genus and the species
excretion
removal of waste products of metabolism and substances in excess of requirements
growth
a permanent increase in size and dry mass
movement
an action by and organism or part of an organism causing a change of position or place
nutrition
the taking in of materials for energy, growth and development
reproduction
the process that makes more of the same kind of organism
respiration
the chemical reactions in cells that break down nutrient molecules and release energy for metabolism
sensitivity
the ability to detect and respond to changes in the internal or external environment
species
a group of organisms that can reproduce to produce fertile offspring
cell
the smallest basic unit of an animal or plant; it is microscopic and acts as a building block
magnification
the observes size of an image divided by the actual size of the image
organ
a structure made up of a group of tissues working together to perform a specific function
organ system
a group of organs with related functions working together to perform a body function
organism
a living thing that has an organised structure can react to stimuli, reproduce, grow, adapt, and maintain homeostasis
tissue
a group of cells with similar structures working together to perform a shared function
active transport
the movement of particles through a cell membrane from a region of their lower concentration to a region of higher concentration, using energy from respiration
diffusion
the net movement of particles from an area of their higher concentration to a region of lower concentration, as a result of their random movement
osmosis
the net movement of water molecules from a region of higher water potential to a region of lower water potential, through a partially permeable membrane
photosynthesis
the process by which plants synthesise carbohydrates from raw materials using energy from light
absorption
the movement of nutrients from the intestines into the blood
assimilation
the uptake and use of nutrients by cells
balanced diet
diet that contains all the essential nutrients in the correct proportions to maintain good health
the nutrients needed are carbohydrate, fat, protein, vitamins, mineral ions, fibre, and water
chemical digestion
the breakdown of large insoluble molecules into small soluble molecules
digestion
the breakdown of food
egestion
the passing out of food that has not been digested or absorbed, as faeces through the anus
ingestion
the taking of substances (e.g. food, drink) into the body through the mouth
physical digestion
the breakdown of food into smaller pieces without chemical change to the food molecules
transpiration
the loss of water vapour from leaves
translocation
the movement of sucrose and amino acids in the phloem from sources to sinks
circulatory system
a system of blood vessels with a pump and valves to ensure one-way flow of blood
pathogen
a disease causing organism
transmissible disease
a disease in which the pathogen can be passed from one host to another
active immunity
defence against a pathogen by antibody production in the body
antibodies
proteins that bind to antigens, leading to direct destruction of pathogens or marking of pathogens for destruction against phagocytes
aerobic respiration
the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy
anaerobic respiration
the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen
excretion
removal of waste products of metabolism and substances in excess of requirements
deamination
the removal of the nitrogen-containing parts of amino acids to form urea
gravitropism
a response in which parts of a plant grow towards or away from gravity
homeostasis
the maintenance of a constant internal environment
hormone
a chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs
phototropism
a response in which parts of a plant grow towards or away from the direction of the light source
reflex action
a means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors
sense organ
a group of receptor cells responding to stimuli, such as light, sound, tough, temperature and chemicals
synapse
a junction between two neurones
set point
the physiological value around which the normal range fluctuates
drug
any substance taken into the body that modifies or affects chemical reactions in the body
asexual reproduction
the process resulting in the production of genetically identical offspring from one parent
fertilisation
the fusion of the nuclei from a male gamete and a female gamete
pollination
the transfer or pollen grains from the anther to the stigma
sexual reproduction
a process involving the fusion of gametes to form a zygote and the production of offspring that are genetically different from each other
sexually transmitted infection
an infection that is transmitted through sexual contact
cross pollination
the transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species
self pollination
the transfer of pollen grains from the anther of pa flower to the stigma of the same flower, or a different flower on the same plant
allele
an alternative form of a gene
dominant (allele)
an allele that is expressed if it is present in the genotype
gene
a length of DNA that codes for a protein
genotype
the genetic makeup of an organism in terms of the alleles present
heterozygous
having two different alleles of a particular gene; therefore, a heterozygous individual will not be pure breeding
homozygous
having two identical alleles of a particular gene; two homozygous individuals that breed together will be pure breeding
inheritance
the transmission of genetic information from generation to generation
phenotype
the observable features of an organism
recessive
an allele that is expressed only when no dominant allele of the gene is present in the genotype
codominance
a situation in which both alleles in a heterozygous organism contribute to the phenotype
diploid nucleus
a nucleus containing two sets of chromosomes
haploid nucleus
a nucleus containing a single set of chromosomes
meiosis
reduction division in which the chromosome number is halved from diploid to haploid, resulting in genetically different cells
mitosis
nuclear division giving rise to genetically identical cells
sex-linked characteristic
a feature in which the gene responsible is located on a sex chromosome, which makes it more common in one sex than another
stem cell
an unspecialized cell that divides by mitosis to produce daughter cells that can become specialised for a specific purpose
adaptive feature
an inherited feature that helps an organism to survive and reproduce in its environment
mutation
genetic change
variation
the differences between individuals of the same species
adaption
the process, resulting from natural selection, by which population become more suited to their environment over many generations
gene mutation
a random change in the base sequences of DNA
carnivore
an animal that gets its energy by eating other animals
community
all of the populations of different species in an ecosystem
consumer
an organism that gets its energy by feeding on other organisms
decomposer
an organism that gets its energy from dead or waste organic material
ecosystem
a unit containing the community of organisms and their environment, interacting together
food chain
a chart showing the transfer of energy from one organism to the next, beginning with a producer
food web
a network of interconnected food chains
herbivore
an animal that gets its energy by eating plants
population
a group of organisms of one species, living in the same area, at the same time
producer
an organism that makes its organic nutrients , usually using energy from sunlight, through photosynthesis
trophic level
the position of an organism in a food chain, food web, or ecological pyramid
biodiversity
the number of different species that live in an area
sustainable
a resource that is produced as rapidly as it is removed from the environment, so that it doesnt run out
genetic modification
changing the genetic material of an organism by removing, changing or inserting individual genes
