AH Biology definitions

Risk

Risk is the likelihood of harm arising from exposure to a hazard.

IEP

IEP is the pH at which a soluble protein has no net charge and will precipitate out of solution

Proteome

The proteome is the entire set of proteins expressed by a genome

ER

The endoplasmic reticulum (ER) forms a network of membrane tubules continuous with the nuclear membrane

Golgi apparatus

The Golgi apparatus is a series of flattened membrane discs

Lysosomes

Lysosomes are membrane-bound organelles containing a variety of hydrolases that digest proteins, lipids, nucleic acids and carbohydrates

Vesicles

Vesicles transport materials between membrane compartments

Channels

Channels are multi-subunit proteins with the subunits arranged to form water-filled pores that extend across the membrane.

Resting membrane potential

Resting membrane potential is a state where there is no net flow of ions across the membrane

Action potential

An action potential is a wave of electrical excitation along a neuron’s plasma membrane

Microtubules

Microtubules are hollow cylinders composed of the protein tubulin. They radiate from the microtubule organising centre (MTOC) or centrosome.

Point count

A point count involves the observer recording all individuals seen from a fixed point count location.

Taxonomy

Taxonomy involves the identification and naming of organisms and their classification into groups based on shared characteristics

Phylogenetics

Phylogenetics is the study of the evolutionary history and relationships among individuals or groups of organisms

bacterium

E. coli

plant

Arabidopsis thaliana

nematode

C. elegans

arthropod

Drosophila melanogaster

Latency

Latency is the time between the stimulus occurring and the response behaviour

frequency

Frequency is the number of times a behaviour occurs within the observation period.

duration

Duration is the length of time each behaviour occurs during the observation period

evolution

Evolution is the change over time in the proportion of individuals in a population differing in one or more inherited traits

selection pressures

Selection pressures are the environmental factors that influence which individuals in a population pass on their alleles.

HW principle

The Hardy-Weinberg (HW) principle states that, in the absence of evolutionary influences, allele and genotype frequencies in a population will remain constant over the generations

Absolute fitness

Absolute fitness is the ratio between the frequency of individuals of a particular genotype after selection, to those before selection

Relative fitness

Relative fitness is the ratio of the number of surviving offspring per individual of a particular genotype to the number of surviving offspring per individual of the most successful genotype

Coevolution

Co-evolution is the process by which two or more species evolve in response to selection pressures imposed by each other

Red Queen hypothesis

The Red Queen hypothesis states that, in a co-evolutionary relationship, change in the traits of one species can act as a selection pressure on the other species

Meiosis

Meiosis is the division of the nucleus that results in the formation of haploid gametes from a diploid gametocyte

Homologous chromosomes

Homologous chromosomes are chromosomes of the same size, same centromere position and with the same sequence of genes at the same loci.

Independent assortment

Each pair of homologous chromosomes is positioned independently of the other pairs, irrespective of their maternal and paternal origin.

Hermaphrodites

Hermaphrodites are species that have functioning male and female reproductive organs in each individual

Monogamy

the mating of a pair of animals to the exclusion of all others

polygamy

individuals of one sex have more than one mate.

polygyny

one male mates exclusively with a group of females.

polyandry

one female mates with a number of males in the same breeding season.

honest signals

Honest signals can indicate favourable alleles that increase the chances of survival of offspring (fitness) or a low parasite burden suggesting a healthy individual.

Ecological niche

An ecological niche is a multi-dimensional summary of tolerances and requirements of a species

Fundamental niche

A species has a fundamental niche that it occupies in the absence of any interspecific competition

realised niche

A realised niche is occupied in response to interspecific competition

definitive host

The definitive host is the organism on or in which the parasite reaches sexual maturity.

transmission

Transmission is the spread of a parasite to a host

virulence

Virulence is the harm caused to a host species by a parasite

epidemiology

Epidemiology is the study of the outbreak and spread of infectious disease

herd immunity threshold

The herd immunity threshold is the density of resistant hosts in the population required to prevent an epidemic

null hypothesis

The null hypothesis proposes that there will be no statistically significant effect as a result of the experiment treatment

peer review

Specialists with expertise in the relevant field assess the scientific quality of a submitted manuscript and make recommendations regarding its suitability for publication.

validity

variables controlled so that any measured effect is likely to be due to the independent variable.

reliability

consistent values in repeats and independent replicates

accuracy

data, or means of data sets, are close to the true value.

precision

measured values are close to each other.

multifactorial experiment

A multifactorial experiment involves a combination of more than one independent variable or combination of treatments.

placebo effect

Placebo effect is a measurable change in the dependent variable as a result of a patient’s expectations, rather than changes in the independent variable.

in vitro

In vitro refers to the technique of performing a given procedure in a controlled environment outside of a living organism

in vivo

In vivo refers to experimentation using a whole, living organism

representative sample

A representative sample should share the same mean and the same degree of variation about the mean as the population as a whole

random sampling

In random sampling, members of the population have an equal chance of being selected.

systematic sampling

In systematic sampling, members of a population are selected at regular intervals.

stratified sampling

In stratified sampling, the population is divided into categories that are then sampled proportionally

statistically significant result

A statistically significant result is one that is unlikely to be due to chance alone