O Level Biology

Describe a catalyst as a substance that increases the rate of a chemical reaction and is not changed by the reaction

Describe and be able to do chemical tests for: (a) starch (iodine solution) (b) glucose and maltose (Benedict’s solution) (c) protein (biuret test) (d) lipids (ethanol emulsion test)

State that large molecules are made from smaller molecules, limited to: starch, cellulose and glycogen from glucose; proteins from amino acids; lipids from fatty acids and glycerol; DNA from nucleotides

Explain the importance of active transport in ion uptake by root hair cells

Describe active transport as the movement of molecules or ions into or out of a cell through the cell membrane, from a region of their lower concentration to a region of their higher concentration (i.e. against a concentration gradient), using energy released during respiration

Investigate osmosis using materials such as dialysis tubing

Investigate and explain the effects on plant tissues of immersing them in solutions of different concentrations, using the terms turgid, turgor pressure, plasmolysis and flaccid

Describe the effects of osmosis on plant and animal tissues and explain the importance of water potential gradient and osmosis in the uptake and loss of water

Understand that plants are supported by the pressure of water inside the cells pressing outwards on the cell wall

Investigate the factors that influence diffusion, limited to: surface area, temperature, concentration gradient and distance