Unit 2 IB HL Biology

Made for Multiple choice and True or False, not open answer.

Variation

Variation

differences among the genomes of members of the same species.

Linnaeus

creator of the binomial nomenclature, a system where each species is given a two-part Latin name

morphological species concept

one of the traditional biological species concepts used to define and identify species based on their physical characteristics, or morphology.

biological species concept

a concept in biology that defines a species as a group of interbreeding populations that are reproductively isolated from other such groups.

binomial nomenclature

a system of naming species of living organisms by giving each a name composed of two parts. Consists of the genus name followed by the specific epithet or species name

Homo Sapiens

the scientific name for the modern human species.

Genome

the complete set of genetic material (DNA in most organisms, and RNA in some viruses) present in an individual or organism.

Single-Nucleotide polymorphisms

variations at a single position in a DNA sequence among individuals (A, T, C, G)

Chromosome number

refers to the total number of chromosomes present in the cells of an organism.

Haploid

refers to a cell or organism that has a single set of chromosomes.

Diploid

refers to a cell or organism that has two sets of chromosomes

Human Chromosome number

46 chromosomes, 23 pairs

Chimpanzee Chromosome number

48 chromosomes, 24 pairs

Chromosome fusion

refers to the joining or merging of two separate chromosomes into a single chromosome.

Karyogram

a visual representation of the complete set of chromosomes present in an individual's cells.

Karyotype

refers to the complete set of chromosomes in the nucleus of a cell.

• Homologous chromosomes

pairs of chromosomes that carry the same genes at corresponding locations. One chromosome in each pair is inherited from the mother, and the other is inherited from the father.

Autosomes

the chromosomes that are not involved in determining an individual's sex, in humans, pairs 1-22.

Sex Chromosomes

a pair of chromosomes that play a fundamental role in determining the biological sex of an individual.

Locus/Loci

refers to the specific physical location of a gene or a DNA sequence on a chromosome.

Alleles

variant forms of a gene that arise by mutation and are found at the same place on a chromosome.

Dichotomous Key

a tool used in biology and other sciences to help identify and classify organisms based on their characteristics

Taxon/Taxa

a term used in biology to refer to a group of one or more populations of an organism or organisms that are recognized as a unit for the purposes of classification.

Taxonomy

branch of biology that deals with the identification, classification, naming, and organization of living organisms into hierarchical groups based on shared characteristics.

Domain

one of the highest levels of classification that groups living organisms based on fundamental differences in their cellular structure, organization, and genetic makeup.

Bacteria

unicellular organisms with prokaryotic cells lacking membrane-bound organelles and a nucleus. The genetic material is typically a single circular DNA molecule located in the nucleoid region of the cell.

Archaea

unicellular and have prokaryotic cells. the genetic material is typically a single circular DNA molecule located in the nucleoid region of the cell.

Eukarya

cells with a true nucleus and membrane-bound organelles.

The genetic material is organized in linear chromosomes located within the nucleus. membrane-bound organelles, including the nucleus, endoplasmic reticulum, Golgi apparatus, mitochondria, and others.

Kingdom

one of the main categories into which living organisms are classified.

Animalia

• Characteristics: Multicellular, eukaryotic organisms.

• Nutrition: Generally heterotrophic (obtain nutrients by consuming other organisms).

• Mobility: Most are capable of movement.

• Reproduction: Typically sexual reproduction, with varied modes such as internal fertilization and external fertilization.

Plantae

• Characteristics: Multicellular, eukaryotic organisms.

• Nutrition: Autotrophic (produce their own food through photosynthesis).

• Cell Walls: Typically have cell walls made of cellulose.

• Reproduction: Primarily through sexual reproduction involving alternation of generations, as well as asexual reproduction.

Fungi

• Characteristics: Mostly multicellular, eukaryotic organisms.

• Nutrition: Heterotrophic, often obtaining nutrients through absorption after breaking down organic matter.

• Cell Walls: Have cell walls, often composed of chitin.

• Reproduction: Reproduce both sexually and asexually, often through the formation of spores.

Protista

• Characteristics: Diverse group of mostly unicellular eukaryotes.

• Habitats: Found in various environments, including aquatic and moist habitats.

• Nutrition: Heterotrophic or autotrophic.

• Reproduction: Varied reproductive strategies, including sexual and asexual reproduction.

Phylum

a major taxonomic rank that groups together organisms based on shared structural features and evolutionary relationships

Class

groups together organisms within a phylum that share additional specific characteristics.

Order

a way of grouping together related families based on similarities in evolutionary history and structural characteristics

Family

a major taxonomic rank or category that falls below the order and above the genus.

Genus

a major taxonomic rank or category that falls below the family and above the species.

Species

is the fundamental unit of classification and represents a group of individuals that are capable of interbreeding and producing fertile offspring under natural conditions

Cladogram

a diagram that shows the evolutionary relationships among a group of organisms.

Clade

describe a group of organisms that includes an ancestral species and all its descendants.

Root

represents the common ancestor of all the organisms depicted in the tree (cladogram)

Node

refers to a point of divergence or branching where a common ancestor splits into two or more descendant lineages.

Terminal Branch

refers to the end segment of a branch that represents a specific taxon

Derived Characteristics

features or traits that are present in a group of organisms and their common ancestor but are not found in more distant ancestors

Outgroup

a taxon that is closely related to, but outside of, the group of interest (the ingroup) being studied.

Evolution

the process of gradual change in all forms of life over generations. It refers to the genetic adaptation and development of species over time

Natural Selection

a process that leads to the adaptation of populations to their environments over time

Gene flow

the transfer of genetic material (genes) from one population to another within a species

Genetic drift

a mechanism of evolution that involves random changes in the frequency of alleles (different versions of a gene) in a population over time.

Mutation

a process that introduces genetic variation by altering the DNA sequence of an organism's genome

Molecular data

refers to information about biological entities that is obtained at the molecular level, primarily focusing on macromolecules such as nucleic acids (DNA and RNA) and proteins.

Molecular clock

molecular evolution that suggests a relatively constant rate of nucleotide substitutions or amino acid changes in DNA, RNA, or protein sequences over time.

• Selective breeding/artificial selection

a process in which humans deliberately choose certain individuals with desirable traits to be the parents of the next generation.

Comparative Anatomy

the study of the similarities and differences in the structure and organization of the anatomical features (both internal and external) of different organisms.

Homologous structures

anatomical features that are similar in structure and origin, indicating a common evolutionary ancestry.

Analogous structures

structures in different species that have similar functions but are not derived from a common evolutionary ancestor.

Vestigial structures

anatomical features or organs in a species that have reduced in size and function over the course of evolution.

Embryology

the branch of biology that studies the development of embryos from the fertilization of the egg cell (zygote) to the formation of a fully developed organism

Biogeography

the scientific study of the distribution of living organisms across space and through time.

convergent evolution

biological phenomenon where unrelated or distantly related organisms evolve similar traits or characteristics.

divergent evolution

a pattern of evolution in which two or more related species become more dissimilar over time

Adaptive radiation

a process in evolutionary biology where a single ancestral species rapidly diversifies into a wide variety of forms to adapt to different environments or ecological niches.

Fossil Records

the cumulative collection of fossils, which are the preserved remains or traces of organisms from past geological ages.

Law of superposition

states that in a sequence of undisturbed sedimentary rocks, the youngest rocks are at the top, and the oldest rocks are at the bottom.

Radiometric dating

a method used to determine the absolute age of rocks and minerals by measuring the concentrations of certain isotopes and their decay products

Transitional fossil

fossilized remains of an organism that exhibits traits common to both an ancestral group and its derived descendant group.

Speciation

the process by which new biological species arise, leading to the branching of the evolutionary tree. It occurs when populations of a single species become reproductively isolated from each other, meaning that they can no longer interbreed and produce fertile offspring.

Allopatric speciation

occurs when a population becomes geographically isolated from the rest of the species, leading to reproductive isolation and the evolution of distinct species.

Sympatric speciation

occurs when populations within the same geographic area undergo reproductive isolation without the presence of a physical barrier

Prezygotic barrier

a mechanism that prevents the formation of a zygote (fertilized egg) between individuals of different species, thus maintaining reproductive isolation.

Geographic isolation

Populations are physically separated by geographic barriers such as mountains, rivers, oceans, or other features.

Temporal isolation

Populations have different mating seasons, activity periods, or times of day when they are reproductively active.

Behavioral isolation

Differences in mating behaviors, courtship rituals, or communication signals prevent successful mating between individuals of different species.

Ecological isolation

Populations inhabit different ecological niches within the same geographic area, reducing opportunities for encounters and mating.

Mechanical isolation

Structural differences, such as differences in genitalia or reproductive organs, prevent successful mating or transfer of gametes.

Postzygotic barrier

mechanisms that operate after the formation of a zygote (fertilized egg) between individuals of different species. These barriers reduce the fitness of hybrid offspring or prevent the hybrid from developing into a viable, fertile adult.

Reduced Hybrid Viability

occurs when the hybrid offspring has lower viability and does not survive to reach reproductive maturity.

Reduced Hybrid Fertility

occurs when hybrid individuals are sterile and cannot produce viable offspring.

Hybrid breakdown

form of postzygotic reproductive isolation that occurs in the offspring of hybrids over successive generations.

Gradualism

a concept in evolutionary biology that suggests that evolution occurs through the slow, continuous accumulation of small, incremental changes over long periods of time.

Punctuated equilibrium

a concept in evolutionary biology that proposes that most species undergo relatively little change for most of their geological history, punctuated by short periods of rapid evolution during which significant morphological and ecological changes occur.

Polyploidy

a condition in which an organism has more than two complete sets of chromosomes in its cells.

Mass extinction

an event in Earth's history characterized by a significant, rapid decline in the diversity and abundance of life forms across multiple taxa.

Biodiversity

refers to the variety of life on Earth at all levels of biological organization, including the diversity of species, ecosystems, and genetic variation within species.

Genetic diversity

refers to the variety of life on Earth at all levels of biological organization, including the diversity of species, ecosystems, and genetic variation within species.

Species diversity

a measure of the number of different species present in a particular area or ecosystem and the relative abundance of each species

Species richness

refers to the total number of different species present in a specific area or community.

Species evenness

considers how evenly the individuals are distributed among different species in a community.

Ecosystem diversity

refers to the variety of different ecosystems or habitat types within a specific geographic area or across the entire planet.

Community

refers to a group of interacting species that occur together in a particular geographic area.

Anthropogenic species extinction

refers to the extinction of plant and animal species as a direct result of human activities.

Overexploitation

refers to the excessive use, extraction, or harvesting of natural resources, often to the point where it threatens the sustainability and survival of a species, population, or ecosystem.

Ecosystem/habitat loss

refers to the reduction or elimination of a natural habitat, often due to human activities, resulting in the degradation or destruction of ecosystems

Climate change

refers to long-term changes in the average weather patterns that have been observed on Earth.

Habitat Fragmentation

a process by which large and continuous habitats are broken into smaller, isolated fragments.

Deforestation

the process of clearing or removing large expanses of forests, usually for the purpose of converting the land for agriculture, logging, urban development, or other human activities.

Invasive species

non-native organisms that, when introduced to new environments, can cause significant harm to the native ecosystems, biodiversity, and even human activities.

Captive Breeding

a conservation strategy that involves breeding and raising species in controlled environments, such as zoos, aquariums, or dedicated breeding facilities, with the goal of preserving and potentially reintroducing them into their natural habitats.

Rewilding

a conservation approach that seeks to restore and reintroduce natural processes, species, and ecological functions to areas that have been degraded or altered by human activities.