BIOLOGICAL MOLECULES A LEVEL
BIOLOGY EXAM WITH QUESTIONS AND
CORRECT ANSWERS.
What is a non-reducing sugar? - Correct Answers -~ Some disaccharides
like sucrose
How to evaluate the concentration of reducing sugar? - Correct Answers -~
Filter the solution and weigh the precipitate
~ Remove the precipitate and use a colorimeter to measure the absorbance
of light of remaining solution - Each colour of precipitate lets a certain
amount of light through
Describe the test for starch (E.g. amylopectin & amylose)? - Correct
Answers -~ Add iodine dissolved in potassium iodide solution to the sample
~ Positive result means it will go from browny-orange to a blue-black
colour
Describe the structure of triglycerides? - Correct Answers -~ Have one
molecule of glycerol with 3 fatty acids attached
~ Fatty acids made of hydrocarbons
~ The tails are hydrophobic so makes triglycerides insoluble
How does a monosaccharide form? - Correct Answers -~ Joined by a
condensation reaction forming a glyosidic bond
~ A molecule of water is released
,Draw a triglyceride - simple version? - Correct Answers -
What is the general structure of a fatty acid? - Correct Answers -
Draw A triglyceride - complex version? - Correct Answers -
Describe the differences between a saturated and unsaturated fatty acid? -
Correct Answers -~ Saturated fatty acids don't have any double bonds
between their carbon atoms while a unsaturated does
Draw a saturated and unsaturated fatty acid? - Correct Answers -
How is a triglyceride formed? - Correct Answers -~ By a condensation
reaction between fatty acids and a glycerol
~ Ester bond is formed and a molecule of water is removed
Draw the condensation reaction of the formation of a triglyceride? - Correct
Answers -
Draw a diagram of a phospholipid? - Correct Answers -
Where are the hydrophobic & hydrophilic regions on a phospholipid? -
Correct Answers -~ Hydrophobic fatty acid tail
~ Hydrophilic phosphate group
Describe the test for lipids? - Correct Answers -Called the emulsion test
, ~ Shake the test substance with ethanol and then pour into water
~ Any lipids present will show up as a white emulsion
~ The greater the presence of emulsion means more lipids present
Relate the structure of triglycerides to their function? - Correct Answers -~
Mainly used a energy storage molecules - good because they have long
hydrocarbon tails which contain lots of chemical energy. When broken
down they release twice as much energy as carbohydrates
~ They are insoluble in water so do not effect water potential - which causes
water to enter by osmosis - As triglycerides bundle into insoluble droplets
as the tails are hydrophobic
Draw a insoluble triglyceride droplet? - Correct Answers -
Relate the structure of a phospholipid to its function? - Correct Answers -~
Make up a bilayer of cell membranes controlling what enters and leaves cell
- As the tails are hydrophobic so point inwards and the heads a hydrophilic
so point into water.
~ So allows membrane to be a barrier as water-soluble substances can't
easily pass through
Draw the general structure of a amino acid? - Correct Answers -
How many different types of amino acids are there? - Correct Answers -~
Only 20 different types
Define polypeptide? - Correct Answers -~ A molecule formed from more
than 2 amino acids bonded by peptide bonds
BIOLOGY EXAM WITH QUESTIONS AND
CORRECT ANSWERS.
What is a non-reducing sugar? - Correct Answers -~ Some disaccharides
like sucrose
How to evaluate the concentration of reducing sugar? - Correct Answers -~
Filter the solution and weigh the precipitate
~ Remove the precipitate and use a colorimeter to measure the absorbance
of light of remaining solution - Each colour of precipitate lets a certain
amount of light through
Describe the test for starch (E.g. amylopectin & amylose)? - Correct
Answers -~ Add iodine dissolved in potassium iodide solution to the sample
~ Positive result means it will go from browny-orange to a blue-black
colour
Describe the structure of triglycerides? - Correct Answers -~ Have one
molecule of glycerol with 3 fatty acids attached
~ Fatty acids made of hydrocarbons
~ The tails are hydrophobic so makes triglycerides insoluble
How does a monosaccharide form? - Correct Answers -~ Joined by a
condensation reaction forming a glyosidic bond
~ A molecule of water is released
,Draw a triglyceride - simple version? - Correct Answers -
What is the general structure of a fatty acid? - Correct Answers -
Draw A triglyceride - complex version? - Correct Answers -
Describe the differences between a saturated and unsaturated fatty acid? -
Correct Answers -~ Saturated fatty acids don't have any double bonds
between their carbon atoms while a unsaturated does
Draw a saturated and unsaturated fatty acid? - Correct Answers -
How is a triglyceride formed? - Correct Answers -~ By a condensation
reaction between fatty acids and a glycerol
~ Ester bond is formed and a molecule of water is removed
Draw the condensation reaction of the formation of a triglyceride? - Correct
Answers -
Draw a diagram of a phospholipid? - Correct Answers -
Where are the hydrophobic & hydrophilic regions on a phospholipid? -
Correct Answers -~ Hydrophobic fatty acid tail
~ Hydrophilic phosphate group
Describe the test for lipids? - Correct Answers -Called the emulsion test
, ~ Shake the test substance with ethanol and then pour into water
~ Any lipids present will show up as a white emulsion
~ The greater the presence of emulsion means more lipids present
Relate the structure of triglycerides to their function? - Correct Answers -~
Mainly used a energy storage molecules - good because they have long
hydrocarbon tails which contain lots of chemical energy. When broken
down they release twice as much energy as carbohydrates
~ They are insoluble in water so do not effect water potential - which causes
water to enter by osmosis - As triglycerides bundle into insoluble droplets
as the tails are hydrophobic
Draw a insoluble triglyceride droplet? - Correct Answers -
Relate the structure of a phospholipid to its function? - Correct Answers -~
Make up a bilayer of cell membranes controlling what enters and leaves cell
- As the tails are hydrophobic so point inwards and the heads a hydrophilic
so point into water.
~ So allows membrane to be a barrier as water-soluble substances can't
easily pass through
Draw the general structure of a amino acid? - Correct Answers -
How many different types of amino acids are there? - Correct Answers -~
Only 20 different types
Define polypeptide? - Correct Answers -~ A molecule formed from more
than 2 amino acids bonded by peptide bonds
