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Northern IrelandBiology

Molecules and Enzymes

4 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How are the four main groups of biological molecules built, and how does structure fit function?

Carbohydrates, lipids and proteins: their monomers, the condensation and hydrolysis reactions that join and break them, the bonds formed, and how molecular structure relates to biological function.
A focused CCEA A-Level Biology answer on carbohydrates, lipids and proteins, covering their monomers, condensation and hydrolysis reactions, the bonds formed, and how structure relates to function.
9 min answer →

How do enzymes catalyse reactions, and what affects how fast they work?

Enzymes as biological catalysts, the induced-fit model of enzyme action, the effects of temperature, pH, substrate and enzyme concentration on rate, and how inhibitors and immobilised enzymes work.
A CCEA A-Level Biology answer on enzymes as biological catalysts, the induced-fit model, the effects of temperature, pH, substrate and enzyme concentration on rate, and how competitive and non-competitive inhibitors act.
11 min answer →

How are DNA and RNA structured, and how is DNA copied and used?

The structure of nucleotides, DNA and RNA, the base-pairing rules, semi-conservative DNA replication, and the role of ATP as the energy currency of the cell.
A CCEA A-Level Biology answer on the structure of nucleotides, DNA and RNA, complementary base pairing, semi-conservative DNA replication, and the role of ATP as the cell's energy currency.
11 min answer →

Why is water essential to life, and what roles do inorganic ions play?

The dipolar nature of water and the hydrogen bonding that gives it its properties, the biological importance of those properties, and the roles of inorganic ions such as nitrate, phosphate, calcium and hydrogen ions.
A CCEA A-Level Biology answer on the dipolar nature of water, the hydrogen bonding behind its properties, the biological importance of water, and the roles of key inorganic ions.
10 min answer →