IB Biology A - Unity and Diversity Key Definitions

70S ribosomes are small ribosomes found in prokaryotic cells, as well as in the mitochondria and chloroplasts of eukaryotic cells. They are responsible for protein synthesis, translating messenger RNA (mRNA) into functional proteins.

80S ribosomes are larger ribosomes found in eukaryotic cells that synthesize proteins.

The origin of life from non-living matter, such as simple organic compounds.

Adaptive radiation is the evolutionary process by which a single ancestral species rapidly diversifies into many species, each specialized to exploit a different ecological niche.

The attraction between water molecules and other surfaces, enabling water to cling to them and move against gravity.

Allopatric speciation occurs when populations are physically separated by a geographical barrier, such as a river, mountain range, or ocean.

A molecule with both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions, such as a phospholipid.

Analogous structures are anatomical features in different species that serve similar functions but do not share a common evolutionary origin.

Gradual accumulation of point mutations in surface proteins, which creates new viral variants.

A sudden genetic reassortment occurs when two different viral strains infect the same host cell, producing a radically new subtype.

A binomial name is a two-part Latinized name that uniquely identifies a species. The first word represents the genus, and the second word represents the specific species within that genus.

Biodiversity is the total variety of life on Earth.

The biological species concept (BSC) defines a species as a group of organisms capable of interbreeding and producing fertile offspring, emphasizing reproductive isolation.

The boundary paradox describes the problem of placing discrete boundaries in a continuous evolutionary process.

Buoyancy is the upward force exerted by a fluid (liquid or gas) on an object immersed in it.

Capillary action refers to the movement of water through narrow spaces, even against gravity.

The process of increasing the rate of a chemical reaction by using a substance called a catalyst, which is not consumed during the reaction. Catalysts lower the activation energy needed for the reaction to occur, making it faster and more efficient.

The cell cycle is a series of stages that a cell goes through to grow, replicate its DNA, and divide into two daughter cells.

A fundamental principle of biology stating that:

• All living organisms are composed of one or more cells.
• The cell is the basic unit of structure and function in all living things.
• All cells arise from pre-existing cells.

The cell wall is a rigid, protective layer located outside the plasma membrane of certain cells, including prokaryotes, plants, fungi, and some protists. It provides structural support, protection, and shape to the cell.

An organelle found in plant and algal cells that is responsible for photosynthesis, the process of converting light energy into chemical energy

Chromosomes are the carriers of genetic information in all living organisms. They consist of two essential components: deoxyribonucleic acid (DNA) and proteins.

Groups that include a common ancestor and all descendants

Cladistics is a method of classifying organisms into groups (clades) based on common ancestry, determined by analysis of base sequences of DNA or amino acids.