A-level biological molecules

• Molecuie are made up of living things such as carbohydrate, proteins, lipids and nucleic acids

  these must contain a combination of H,O,C,N
• Water can get between molecules and surrounds them
• Water has a very high heat capacity of 4200jkg
• Organic substances protects organisms from extreme heat changes
• The reason why the body cools down when you swear is because the energy required to break them turns liquid in the body to a gas so when this is high the nerdy evaporated from the skin leaving the body cooler
• Adhension - sticks to the side of xylem wall stops gravity from doing transpiration
• Cohesion - allows animals to sit on the top of the water and not sink in
• 72-73% of human body is water
• Plants need water for maintaining the structure of the cell, transporting substances, and photosynthesis.
• Human need water as it is a vital component as it keeps us hydrated but also keeps the blood flow easy

  water is also a key part for respiration (breathing)

  important for metabolite
• Condensation is removing water from a reaction molecule

  hydrolysis reaction is adding water
• A water molecuke is said to be dipoles because it has a positive and negative pole as a results of uneven distribution of electrons within it
• This created attractive forces called hydrogen bonding between water molecules causing them to stick together
• The stickiness of water means that it’s molecules are pulled inwards at this surface
• This force is called cohesion water is able to split large molecules into smaller ones by a process known as surface tension
• Water is the raw material for the process of photosynthesis in green plants
• Test for glucose Benedict solution brick red high glucose

  green low glucose blue is 0% of glucose
• Starch test is iodine test blue-black is positive
• Monosaccharides is one unit of carbohydrates.

  e.g. glucose fructose galactose - soluble
• Polymer - many units bonded together

  e.g. starch , DNA
• Disaccharides - 2 units of carbohydrates joined together by a glycosidic bond
• Disaccharides are formed when two monosaccharides join together by condensation

  e.g. sucrose, maltose and lactose
• Sucrose - glucose + fructose

  maltose - glucose + glucose

  lactose - glucose + galactose
• Disaccchairdes are non reducing sugars
• Polysaccharides - many monosaccharides molecules joined together by condensation starch , glycogen and cellulose

  e.g. starch , glycogen and cellulose starch ,
• Glycogen - highly branched chains of a glucose

  cellulose - straight chain of B-glucose held together by hydrogen bonding
• What is the main focus of the study material provided?

  Monosaccharides and the test for reducing sugars using Benedict's reagent
• What are the materials tested in the reducing sugars test using Benedict's reagent?

  • 1% glucose solution
  • Distilled water (control)
  • 1% sucrose solution
• What observation is made when testing a 1% glucose solution with Benedict's reagent?

  A change from a blue solution to a brick red suspension
• What does the observation of a blue solution remaining unchanged indicate when testing distilled water with Benedict's reagent?

  It confirms that distilled water is not a reducing sugar
• What does the observation of a blue solution remaining unchanged indicate when testing a 1% sucrose solution with Benedict's reagent?

  It confirms that sucrose is not a reducing sugar
• What can be deduced about glucose based on the observations from the test with Benedict's reagent?

  Glucose is confirmed as a reducing sugar and a monosaccharide
• What is the significance of the color change in the test for reducing sugars using Benedict's reagent?

  The color change indicates the presence of reducing sugars in the solution
• In the test for reducing sugars using Benedict's reagent on glucose, where does the color change begin in the blue solution?

  The color change begins at the point of heating over a Bunsen burner
• Why does the color change occur in the test for reducing sugars using Benedict's reagent?

  The color change occurs due to the reduction of copper(II) ions to copper(I) oxide
• What is a reducing sugar?

  A reducing sugar is a sugar that can donate electrons to another chemical, reducing it.
• What is a non-reducing sugar?

  A non-reducing sugar is a sugar that cannot donate electrons and does not change the color of Benedict's reagent.
• How does the presence of reducing sugars affect the results of the Benedict's test?

  The presence of reducing sugars leads to a color change in the Benedict's reagent, indicating a positive result.
• Dipoles function - made up of 2 atoms of hydrogen and 1 oxygen.

  no overall charge but slightly negative

  negative and positive pole= dipolar
• Bonding

  opposites attract called a hydrogen bond

  fairly weak bonding 1/10 strong as a covalent bond