2.1.2 Biology Biological Molecules Exam
Questions with Latest Update
What is the charge of oxygen in a H2O molecule? - Answer-Slightly negative
Draw a diagram of hydrogen bonding on paper - Answer-Diagram of hydrogen bonding
Why is ice less dense than liquid water? - Answer-The hydrogen bonds between
molecules in ice are slightly further apart than the average distance between liquid
water molecules
What is an advantage to living organisms of ice being less dense than water? - Answer-
Ice floats and forms an insulating layer on top of ponds, maintaining a constant
temperature for organisms
Why is water a good solvent? - Answer-It's polar so other charged molecules are
attracted to it
Why is water's high specific heat capacity useful for organisms? - Answer-It can be
used as a coolant, to buffer temperature changes during chemical reactions and to
provide a constant temperature for aquatic organisms
Why is water cohesive and adhesive? - Answer-Water is cohesive because the
hydrogen bonds mean water molecules are attracted to one another. Water is adhesive
because it can be attracted to other polar molecules.
Why is it useful to organisms that water is cohesive and adhesive? - Answer-Water acts
as a good transport medium. These properties also mean that it can move upwards
through narrow tubes via capillary action.
What are 3 examples of hexose monosaccharides? - Answer-Glucose, fructose,
galactose
What is a hexose monosaccharide? - Answer-One with 6 carbon
What is a pentose monosaccharide? - Answer-One with 5 carbons
What are 2 examples of pentose monosaccharides? - Answer-Ribose and deoxyribose
What is the difference between alpha and beta glucose? - Answer-The OH group is
below Carbon 1 on alpha, and above it on beta
Why is glucose soluble in water? - Answer-Because it contains OH groups which make
it polar
, What is the bond between two monosaccharides called? - Answer-Glycosidic bond
What is the disaccharide version of alpha glucose? - Answer-Maltose
What is a reaction which creates water called? - Answer-A condensation reaction
What is the addition of water to a disaccharide in order to split it into 2 monosaccharides
called? - Answer-Hydrolysis
What is the test for reducing sugars called? - Answer-Benedict's test
What is Benedict's Reagant? - Answer-An alkaline solution of Copper (II) Sulfate
What colour would blue Benedict's Reagant change to if reducing sugars are present? -
Answer-Red
Are all monosaccharides reducing sugars? - Answer-Yes
Are most disaccharides reducing or non-reducing sugars? - Answer-Non-reducing
Why does Benedict's Reagant turn red when reducing sugars are present? - Answer-
Because the blue Cu2+ ions have an electron is added to form brick red Cu+ ions
What is the method for testing for reducing sugars? - Answer-1. Add 2cm cubed of a
food sample (liquid or crushed with water)
2. Add 2cm cubed of Benedict's Reagant
3. Place the test tube in an 80°C water bath
What is the method for testing for a non-reducing sugars? - Answer-1. Confirm that the
sugar is not a reducing sugar
2. Add 2cm cubed of food sample in liquid form to a test tube
3. Add 2cm cubed of hydrochloric acid
4. Place in 80°C hot water bath for 5 minutes
5. Remove and slowly add sodium hydrogencarbonate until the solution is neutral
6. Re-test the solution using the Benedict's test
How can you make the Bendict's Test quantitative? - Answer-Use a colorimeter to test
the transmission of red light in the solutions. More reducing sugars= more red light
What are 2 examples of biosensors? - Answer-Pregnancy test, blood sugar monitor
What is an analyte in a biosensor? - Answer-The sample containing the molecule you
are testing for
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