IB Biology HL Complete Study Guide

Water

A polar molecule essential for life with unique properties due to hydrogen bonding.

Hydrogen Bonding

Attraction between slightly positive hydrogen atoms and slightly negative oxygen atoms; weaker than covalent bonds.

Cohesion

The tendency of water molecules to stick together, important for transport in xylem.

Adhesion

The clinging of water to other surfaces, aiding in capillary action.

Specific Heat Capacity

The amount of heat required to raise the temperature of water, contributing to temperature stabilization.

Solvent Properties of Water

Ability of water to dissolve polar and ionic substances, crucial for cytoplasm and blood plasma.

DNA Structure

Double helix structure with antiparallel strands made of nucleotides containing phosphate, deoxyribose sugar, and nitrogenous bases.

Base Pairing

Adenine pairs with thymine, and cytosine pairs with guanine in DNA.

RNA Structure

Single stranded molecule made up of ribose sugar and uracil, which replaces thymine.

Semi-Conservative Replication

Each new DNA molecule consists of one old strand and one new strand.

Transcription

The process of synthesizing RNA from a DNA template in the nucleus.

Translation

Process by which ribosomes read mRNA and tRNA brings amino acids to form proteins.

Competitive Inhibition

A type of enzyme inhibition where inhibitors compete with substrates for the active site.

Noncompetitive Inhibition

Inhibition where an inhibitor binds to an enzyme at a site other than the active site, changing its shape.

Fluid Mosaic Model

Structure model of cell membranes composed of a phospholipid bilayer with embedded proteins.

Passive Transport

Movement of substances across a membrane without energy expenditure, including diffusion and osmosis.

Mitosis

Cell division process that results in two identical daughter cells.

Central Dogma of Molecular Biology

The flow of genetic information from DNA to RNA to protein.

PCR

Polymerase Chain Reaction, a technique to amplify DNA sequences.

Homeostasis

The maintenance of stable internal conditions in an organism.

Allele

An alternative form of a gene located at a specific position on a chromosome.

Gene

A sequence of DNA that encodes for a protein or functional product.

Osmosis

The diffusion of water across a selectively permeable membrane.

Species

A group of organisms that can interbreed and produce fertile offspring.

Stem Cell

Undifferentiated cell with the potential to develop into different cell types.

Enzyme

A biological catalyst that accelerates chemical reactions in cells.

Antigen

A substance that triggers an immune response.

ATP

Adenosine triphosphate; main energy carrier in cells.

Codon

A three-base sequence on mRNA that specifies an amino acid.