Select an option
Surface area to volume ratio and gas exchange
Cell membrane structure and permeability
Simple and facilitated diffusion
Osmosis and investigating water potential
Active transport and co-transport
Gas exchange in fish, insects, plants and humans
Mammalian circulatory system and blood vessels
Haemoglobin and the Bohr effect
Heart structure and the cardiac cycle
Heart rate regulation and electrocardiograms
Transport in plants - xylem
Transport in plants - phloem
Carbohydrates: types, structure and function
The structure and function of lipids
The structure and function of proteins
Nucleic acids: DNA and RNA
DNA replication
DNA, genes and chromosomes
RNA, protein synthesis and the genetic code
Enzymes: activation energy, properties and structure
Factors affecting enzyme activity
Inorganic ions: iron, hydrogen, sodium and phosphate
The properties and functions of water
Water is polar because the shared negative hydrogen electrons are pulled towards the oxygen atom. This leaves the other side of each hydrogen atom with a slight positive charge. As oxygen has unshared electrons, it has a slight negative charge.
Cohesion is when molecules of water stick together due to their polarity.
Water is made up of one atom of oxygen joined to two atoms of hydrogen by shared electrons.
Beta