AQA A-Level Biology Topic 1: Biological
Molecules What are monomers?(ANS Monomers are small units which are the components of larger molecules.What are polymers?(ANS Polymers are molecules made from many monomers joined together.What are examples of monomers?(ANS Monosaccharides, amino acids and nucleotides What are examples of polymers?(ANS Polysaccharides, polypeptides and polynucleotides What reaction allows two monomers to bond together?(ANS condensation reaction allows two monomers to be joined together by a chemical bond, releasing a water molecule What reaction breaks the chemical bond between two molecules?(ANS hydrolysis reaction allows the chemical bond to break between two molecules and this happens due to the addition of water.What are carbohydrates?(ANS Carbohydrates are molecules which consist only of carbon, hydrogen and oxygen.What is the small unit that makes up a carbohydrate
. (ANS
Monosaccharides 1 / 3
What is formed when two monosaccharides go through condensation reaction?(ANS *disaccharide* is formed.What is the special bond that is formed during the condensation reaction between two monosaccharides?(ANS *glycosidic bond* What is formed when many monosaccharides go through condensation reaction?(ANS *polysaccharide* is formed.What are examples of monosaccharides?(ANS *Glucose* (*α-glucose* and *β glucose*)
- *Galactose*
- *Fructose*
- *Starch* (formed by the condensation of α-glucose) 2 / 3
What is the structure of both α-glucose and β glucose?(ANS They both have *6 carbon atoms*, α-glucose has its OH group attached at the *bottom right* and β glucose has its OH group attached at the *top right*.Which disaccharide is formed when two α-glucose molecules join together?(ANS Maltose Which disaccharide is formed when a glucose molecule and fructose join together?(ANS Sucrose Which disaccharide is formed when a glucose molecule and galactose join together?(ANS Lactose What are the three polysaccharides that are formed from glucose monomers?(ANS - *Glycogen* (formed by the condensation of α-glucose)
- *Cellulose* (formed by the condensation of β glucose)
- / 3
What is starch?(ANS Starch is what plants *store as excess glucose*. When plants require glucose for respiration and energy, starch is broken down into glucose.What mixture does starch consist of?(ANS *Amylose* and *Amylopectin* Describe the structure of starch?(ANS Amylose is a *long, unbranched chain of α-glucose* molecules. Due to its specific glycosidic bonding, its shape becomes *coiled*, which makes it very *compact*.Amylopectin is a *long, branched chain of α-glucose* molecules. It has got many *side branches* on it.Explain the relationship between the structure and function in starch.(ANS The coiled and compact shape of amylose allows a *lot of energy to be stored*, therefore making it good for energy storage.The side branches on amylopectin allow *enzymes to break down* the molecule and make it *easier to break the glycosidic bond*. This means that energy can be *released quicker* for important functions like *respiration*.Starch is also *insoluble* and therefore *do not affect the water potential*, so water cannot enter cells by osmosis.What is the test for starch?(ANS Add the test sample to iodine solution* (potassium iodide solution).If the solution turns from *brown/orange to blue/black*, then *starch is present*.