Biology Notes - A3.1 Diversity of Organisms

Variation

Differences that exist between organisms.

Genetic variation

Variation generated when mutation occurs and when alleles are combined in different ways during sexual reproduction.

Discontinuous variation

Variation where characteristics fall into distinct categories, e.g., black fur vs brown fur.

Continuous variation

Variation where characteristics can be measured incrementally on a scale, e.g., height.

Taxonomy

The science of classification.

Morphological classification

Classification based on observable characteristics.

Binomial system of nomenclature

A method of naming species that involves giving a species a two-part name.

Biological species concept

A concept stating that a species is a group of organisms that can interbreed to produce fertile offspring.

Asexual reproduction

A type of reproduction that does not involve the fusion of gametes.

Speciation

The process by which one species gives rise to two or more new species.

Chromosome number

The number of chromosomes possessed by an organism, varies between species.

Karyotype

The appearance of a complete set of an individual's chromosomes, including their number, size, shape, and banding.

Genome

All of the genetic information in an organism, including DNA present within every cell.

Single-nucleotide polymorphism (SNP)

A difference in a single nucleotide present in the DNA sequence.

Phylogenetics

The classification of species based on their evolutionary origins and relationships.

Dichotomous key

A tool containing a series of paired statements used to identify species.

Variation

Differences between organisms known as variation.

Aspect of Variation

Includes visual appearance, behavior, and biochemistry.

Causes of Variation

Combination of genetic and environmental factors.

Genetic Variation

Generated by mutations and the recombination of alleles during sexual reproduction.

Environmental Factors

Includes temperature, nutrient availability, and oxygen concentration influencing variation.

Classification

The process of organizing organisms into logical groups.

Taxonomy

The science of classification of organisms.

Species

The smallest taxonomic group that organisms can be classified into.

Morphological Classification

Determination of species based on observable characteristics.

Carl Linnaeus

The 18th-century botanist known as the father of taxonomy.

Binomial System

The method of naming species using a two-part name.

Genus

The first part of a binomial name, indicating the broader category.

Species Name

The second part of a binomial name which identifies the specific organism.

Biological Species Concept

Defines a species as a group that can interbreed to produce fertile offspring.

Limitations of Biological Species Concept

Challenges include asexual reproduction and fertile hybrids.

Asexual Reproduction

Reproduction that doesn't involve mating, e.g., in bacteria.

Fertile Hybrids

Offspring from different species that can reproduce, e.g., 'wholphins'.

Chromosome Number

The total number of chromosomes in a cell.

Diploid Cells

Cells that contain two complete sets of chromosomes (2n).

Haploid Cells

Cells containing one complete set of chromosomes (n), usually gametes.

Karyotype

The appearance of a complete set of an individual's chromosomes.

Karyogram

An image showing all the chromosomes in a cell arranged by size and shape.

Genome

All of the genetic information within an organism, including DNA.

Single-Nucleotide Polymorphism (SNP)

A difference in a single nucleotide in DNA.

Eukaryotic Genome Diversity

Variation in genome size and composition among eukaryotic organisms.

Genome Sequencing

The process of determining the base sequence of an organism's genome.

Phylogenetics

Classification of species based on their evolutionary relationships.

Genome Size

Measured in base pairs, varies widely between organisms.

Evolutionary Relationships

Determined by comparing DNA sequences across species.

Dichotomous Key

A tool used for identifying species through paired statements.

Speciation

The process by which one species gives rise to two or more new species.

Horizontal Gene Transfer

The transfer of genetic information between organisms of the same generation.