IBDP Biology 2025 Topic 1 Nature of Biology and Stats

Binomial nomenclature

the system of nomenclature in which two terms are used to denote a species of living organism, the first one indicating the genus and the second the specific epithet.

Box-and-whisker

• A diagram that summarizes data using the median, the upper and lower quartiles, and the values. Used when the

Chlamydomonas

unicellular green algae

Class

in classification, a group of closely related orders

Continuous variation

variation in a population showing an unbroken range of phenotypes rather than discrete categories

Descriptive statistic

a statistic that quantifies or characterizes a dataset without drawing inferences about some larger population

Dichotomous key

step by step approach to identify an organism using a series of paired descriptions

Discrete variation

variation in a heritable characteristic that has an either/or form, such as either being albino or not being albino

Domain

A taxonomic category above the kingdom level. The three domains are Archaea, Bacteria, and Eukarya.

Emergence

when 2 or more items are combined together a different property comes into existence

Error bar

Representation of uncertainty displayed on a graph.

Excretion

Process by which metabolic wastes are eliminated from the body

Growth

increase in size or number of cells

Homeostasis

process by which organisms maintain a relatively stable internal environment

Interquartile range

The difference between the upper quartile and the lower quartile.

Interspecies

arising or occurring between species

Intraspecies

within the same species

Kingdom

large taxonomic group, consisting of closely related phyla

Mean

the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores

Median

the middle score in a distribution; half the scores are above it and half are below it

Metabolism

the chemical processes that occur within a living organism in order to maintain life.

Mode

The value that occurs most frequently in a given data set.

Movement

Change in position of the body or of a body part; motion of an internal organ

Nutrition

the process of providing or obtaining the food necessary for health and growth.

Order

(biology) taxonomic group containing one or more families

Organism

An individual living thing

Outlier

A value that "lies outside" (is much smaller or larger than) most of the other values in a set of data.

Paramecium

a single-celled freshwater animal that has a characteristic slipperlike shape and is covered with cilia.

Phylum

in classification, a group of closely related classes

Qualitative

Data in the form of words

Quantitative

Data that is in numbers

Range

Distance between highest and lowest scores in a set of data.

Reproduction

Ability to generate offspring

Response

An action or change in behavior that occurs as a result of a stimulus.

Species

A group of organisms that are closely related and can mate to produce fertile offspring

Standard deviation

a measure of variability that describes an average distance of every score from the mean

Taxonomy

The scientific study of how living things are classified

Unicellular

A single celled organism

Variation

differences in physical traits of an individual from the group to which it belongs

genus and species

Two parts of the Scientific names of organisms.

Genus

A classification grouping that consists of a number of similar, closely related species

Family

(biology) a taxonomic group containing one or more genera

Cladogram

a branching diagram showing the cladistic relationship between a number of species.

Paramecium

contractile vacuole (paramecium)

The cell structure that collects extra water from the cytoplasm and then expels it from the cell

Oral grove

where the food enters in the paramecium then is broken down and distributed

Anal Pore (Paramecium)

region of the cell membrane of a ciliate where waste-containing food vacuoles fuse and are then emptied into the environment

food vacuole

Stores nutrients for the cell

Cilia

The hairlike projections on the outside of cells that move in a wavelike manner

Cell plasma membrane

phospholipid bilayer that protects and encloses the cell; controls transport into and out of the cell; maintains homeostasis

cytoplasm

the material or protoplasm within a living cell, excluding the nucleus. Site of metabolic reactions

Nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction

gene flow

Movement of alleles into or out of a population due to the migration of individuals to or from the population

crossing over

the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.

random orientation

the random position of each pair of chromosomes in the nucleus when the spindle microtubules become attached. Their random orientation will eventually result in which chromosomes end up where.

Mutation

change in a DNA sequence that affects genetic information

Genetic Variation Sources

Mutations, gene flow, meiosis, and sexual reproduction.

random fertilization

source of genetic variation caused by the unlimited number of possible sperm & egg combinations

nomenclature

technical names or naming system in an art or science