Cytochrome c is a protein used in the reactions of respiration and is found across species of plants, animals and unicellular organisms. Suggest why the
... [Show More] widespread occurrence of cytochrome c is considered to be evidence for evolution.>>> Cytochrome c is present in the cells of a wide variety of organisms, suggesting they could have all evolved from a common ancestor.
What is a polymer?>>> A polymer is a large, complex molecule composed of many monomers joined together.
What is a monomer?>>> A monomer is a small, basic molecular unit that can form a polymer.
Give two examples of monomers.>>> EXAMPLES
-amino acid
-nucleotide
-monosaccharide
Explain what happens in a condensation reaction between two monomers.>>> A chemical bond is formed between the monomers and a molecule of water is released.
What type of reaction involves the breakage of a chemical bond between two monomers using water?>>> Hydrolysis
What is the name of the bond that forms between two monosaccharides?>>> Glycosidic
What molecule is released during a condensation reaction between two monosaccharides!?>>> Water
Which monosaccharides make up the disaccharides?
Maltose
Sucrose
Lactose>>> Glucose & glucose
Glucose & fructose
Glucose & galactose
Describe how to test for reducing sugars and say what a positive and negative result would look like.>>> -Add Benedict's reagent
-Heat to 95°C
-Positive result= coloured precipitate (e.g. red)
Negative result= remains blue
Name the type of monomer that makes up polysaccharides.>>> Monosaccharide
What is the main storage molecules in plants and in animals?>>> Starch
Glycogen
Which polysaccharide is the major component of plant cell walls?>>> Cellulose
Describe the structure of this polysaccharide and explain how it's structure relates to its function in cell walls.>>> Long straight chains of β -glucose
Joined together by hydrogen bonds to form microfibrils (1,4 glycosidic bonds)
Microfibrils woven to form cellulose fibres
Cellulose fibres woven to form cellulose cell wall
Many hydrogen bonds makes the structure extremely strong thus rigid and suited for its use in a cell wall
Describe the method you would use to test for the presence of starch and say what a positive and negative result would look like.>>> Iodine test
Add iodine dissolved in potassium iodide solution to test sample
Positive result= change to dark blue/black
Negative result= browny orange colour (no change)
Is starch soluble or insoluble?
Use this answer to explain why starch is good for storage.>>> -insoluble
-it doesn't affect the water potential of the cell, thus preventing osmosis so water doesn't enter and make the cell swell & burst
What are the components of a triglyceride?>>> A molecule of glycerol and three fatty acids
Explain the difference between a saturated and unsaturated fatty acid.>>> A saturated fatty acid doesn't have any double bonds between carbon atoms in the hydrocarbon chain, an unsaturated fatty acid does.
Give two reasons why triglycerides are used as energy storage molecules.>>> Because get contain lots of chemical energy and they're insoluble in water.
Explain how the structure of phospholipids makes them able to form the bilayer of cell membranes.>>> Phospholipid heads are hydrophilic and their tails are hydrophobic, so they form a double layer with their heads facing out towards water on either side. This makes the centre of the membrane bilayer hydrophobic, so water soluble molecules can't easily pass through it.
A student carries out an emulsion test on a food sample.
What is the student testing for?
Describe how the student should carry out the test and what they should expect to see if the result is positive.>>> Lipids
Add ethanol, shake, add water, shake, a white cloudy emulsion shows that a lipid is present (a positive result)
What are the monomers of proteins?>>> Amino acids
What is a polypeptide?>>> A chain of more than two amino acids joined together
What sort of reaction links amino acids together?>>> Condensation
What is the name of the bond that forms between amino acids?>>> Peptide
Name three bonds that may be formed between the amino acids in a polypeptide chain to form the tertiary structure of a protein.>>> Hydrogen bonds
Ionic bonds
Disulfide bridges
Explain how the shape of structural proteins make them specialised for their function.>>> Structural proteins are made from long polypeptide chains lying parallel to each other with cross links between them. This makes them physically strong.
The biuret test is used to test for proteins.
What is added to the test solution to make it alkaline?
What is added next to the solution?
What would a positive test result look like?>>> sodium hydroxide solution
copper ii sulfate solution
purple
What term is used to describe an enzyme that acts outside of cells?>>> Extracellular
Explain, in te [Show Less]