What is diffusion?
The net movement of particles from a region of higher concentration to a region of lower concentration, as a result of their random movement.
What is osmosis?
The net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane.
A solution is made of what two things?
Solvent, the dissolving fluid; and the solute, the particles dissolved in the solvent.
What is active transport?
The movement of particles through a cell membrane from a region of their lower concentration to a region of higher concentration, using energy from respiration.
How are molecules transported across a cell surface membrane during active transport?
Using protein molecules called carriers.
What do all organic molecules contain?
Carbon and hydrogen atoms.
What are the four main groups of organic chemicals used by living things?
Carbohydrates, lipids, proteins and nucleic acids.
What are subunits?
The similar smaller molecules that make up larger organic molecules.
What is hydrolysis?
Reaction that splits molecules into their individual subunits. Uses water.
What is condensation?
Reaction that joins subunits together, perhaps in new combinations. Produces water.
What is metabolism?
The sum of all the chemical reactions in a living organism.
What is an anabolic reaction?
Anabolic reactions build up large molecules from smaller ones, and usually require an input of energy.
What is a catabolic reaction?
Catabolic reactions break down large molecules into smaller ones, and often release energy.
The molecules that react in the enzyme-catalysed reaction are called ___, and the molecules produced in the reaction are ___.
Substrates and products.
What are intracellular enzymes?
Enzymes that work inside the cell.
What are extracellular enzymes?
Enzymes made inside cells and then released from the cell to perform their function.
What elements do all carbohydrates possess, and what are their subunits?
Carbon, hydrogen and oxygen. Glucose.
What elements do all lipids possess, and what are their subunits?
Carbon, hydrogen and oxygen. (But less oxygen than carbohydrate) Fatty acids and glycerol.
What elements do proteins possess, and what are their subunits?
Carbon, hydrogen, oxygen and nitrogen; sometimes also sulfur or phosphorus. Amino acids.
How do you test for starch?
Starch test: Add a few drops of iodine solution to a solution of the food. Blue/black colouration if it's a positive result.
How do you test for glucose?
Benedict's test: Add an equal amount of Benedict's solution to a solution of the food and boil carefully. Orange/brick red colouration if it's a positive result.
How do you test for protein?
Biuret test: Add a few drops of Biuret reagent to the solution of food and mix carefully. Purple colouration if it's a positive result.
How do you test for lipids?
Emulsion test: Dissolve the food in ethanol, then pour the solution into a test tube of water. A white emulsion is formed if it's a positive result.
How do you test for Vitamin C?
DCPIP test: DCPIP is a deep blue colour. Add vitamin C solution drop by drop, shaking the mixture after each one. The number of drops of vitamin C solution needed before the mixture decolourises depends on how concentrated the vitamin C solution is.
What is a catalyst?
A substance that increases the rate of a chemical reaction and is not changed by the reaction.
What is photosynthesis?
The process by which organisms synthesise carbohydrates from raw materials using energy from sunlight.
What are the two equations for photosynthesis?
light
carbon dioxide+water>glucose+oxygen
chlorophyll
6CO2 + 6H2O → C6H12O6 + 6O2
What does light energy do during photosynthesis?
Splits water molecules into hydrogen and oxygen. Hydrogen reduces carbon dioxide into glucose (this part of photosynthesis is catalysed by enzymes).
What are the factors for photosynthesis?
The availability of light. The presence of a pigment to absorb the light. A supply of carbon dioxide and water. A temperature suitable for enzyme activity.
What is a limiting factor?
A limiting factor is a condition, that when in shortage, slows down the rate of a reaction.