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carbohydrates and lipids Flashcards

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Biology 101 flashcards
1
Q

What is a monomer? 1

A

Small identical /similar molecules which can be joined together to make LARGER molecules called POLYMERS

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2
Q

What is a POLYMER? (2)

A

A large molecule made from the joining (by chemical bonds) of 3 or more similar or identical monomer molecules.

Formed by condensation reaction.

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3
Q

State 3 carbohydrate monomers (Monosaccharides).

A

Glucose
Fructose
Galactose

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4
Q

Name 3 Polysaccharides.

A

Cellulose
(Formed from BETA glucose monomers)

Starch
(Formed from ALPHA glucose monomers)

Glycogen
(Formed from ALPHA glucose monomers)

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5
Q

State 3 biological monomers

A

Amino acids (all 20 of them)
Monosaccharides (Glucose / Fructose / Galactose)
Nucleotides (DNA or RNA)

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6
Q

Name the TWO main types of biochemical reaction.

A

HYDROLYSIS: The breaking of a chemical bond, using a water molecule. Polymers to Monomers

CONDENSATION: The formation of a chemical bond, releasing a water molecule. Monomers to Polymers.

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7
Q

State the elements found in all carbohydrates.

A

Carbon (C)

Hydrogen (H)

Oxygen (O)

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8
Q

What is the ratio of Hydrogen to Oxygen in (Most) monosaccharides,

(True when number of Carbons range between 3 AND 6)

A

2:1

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9
Q

State the chemical formula for glucose isomers.

A

C6H12O6

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10
Q

What is a DIMER?

A

TWO similar/identical monomers joined together by a chemical bond by condensation reaction.

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11
Q

What is a SIX carbon sugar called?

A

HEXOSE sugar

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12
Q

Name the monosaccharides that make MALTOSE

A

TWO Alpha Glucose molecules

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13
Q

Name the monosaccharides that make SUCROSE

A

Alpha Glucose

AND

Fructose

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14
Q

Name the monosaccharides that make LACTOSE

A

Alpha Glucose

AND

Galactose

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15
Q

A starch molecule has a spiral shape.

Explain why this shape is important to its function in cells. (1)

A

Compact/occupies small space/tightly packed;

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16
Q

The structure of cellulose is related to its role in plant cell walls. Explain how. (4)

A

Long, straight, unbranched chains of Beta glucose;
(Joined by) many WEAK hydrogen bonds;
Form microfibrils / macrofibrils;
Provide rigidity/strength/support;

17
Q

Give one feature of starch and explain how this feature enables it to act as a storage

substance.

A

Helical / spiral So compact / tightly packed / can fit (lots) into a small space;
Insoluble So no osmotic effect / does not leave cell / does not affect water potential;
Large molecule / long chain (So) does not leave cell / contains large number of glucose units;
Branched chains (So) rapid hydrolysis to remove glucose for respiration;

18
Q

Hydrogen bonds are important in cellulose molecules. Explain why. (3)

A

Holds chains/cellulose molecules together/forms cross links between chains/cellulose molecules/forms microfibrils;
Providing strength/rigidity (to cellulose/cell wall);
Weak Hydrogen bonds provide strength in large numbers;

19
Q

Describe how the student would show that reducing sugars were present in a solution. (3)

A
  1. Add Benedict’s;
  2. Heat to 95°C;
  3. Red/orange/yellow/green precipitate (shows reducing sugar present);
20
Q

Describe how you would test a sample of food for the presence of starch. (2)

A
  1. Add potassium iodide (KI) solution to the food sample;
  2. Blue/black/purple indicates starch is present;
21
Q

Describe how you would test a liquid sample for the presence of lipid and how you would recognise a positive result. (2)

A
  1. (Mix / shake sample) with ethanol, then add water and shake;
  2. Cloudy White / milky (emulsion);
22
Q

Describe the biochemical tests you would use to confirm the presence of lipid, non-reducing sugar and amylase in a sample. (6)

A

Lipid

  1. Add ethanol/alcohol then add water and shake/mix OR Add ethanol/alcohol and shake/mix then pour into/add water;
  2. White/milky emulsion OR emulsion test turns white/milky;

Non-reducing sugar

  1. Do Benedict’s test and stays blue/negative;
  2. Boil with acid then neutralise with alkali;
  3. Heat with Benedict’s and becomes red/orange (precipitate);

Amylase

  1. Add biuret (reagent) and becomes purple/violet/mauve/lilac;
  2. Add starch, (leave for a time), test for reducing sugar/absence of starch;
23
Q

Compare and contrast the structure of starch and the structure of cellulose. (6)

A

Similarities:

  1. Both polysaccharides OR Both are glucose polymers OR Both are made of glucose monomers;
  2. Both contain glycosidic bonds (between monomers);
  3. Both contain carbon, hydrogen and oxygen/C, H and O;

Differences:

  1. Starch has α-glucose WHEREAS cellulose has β-glucose;
  2. Starch (molecule) is helical/coiled HOWEVER cellulose (molecule) is straight;
  3. Starch (molecule) is branched WHEREAS cellulose is not/unbranched;

7.Cellulose has (micro/macro) fibrils HOWEVER starch does not;

  1. Starch has 1–6 glycosidic bonds AND cellulose does not

OR Starch is amylose AND amylopectin and cellulose is one type of molecule;

24
Q

Describe how lactose is formed. (3)

A

Glucose and galactose
Joined by condensation
Joined by glycosidic bond

25
Q

Omega-3 fatty acids are unsaturated. What is an unsaturated fatty acid? (2)

A

Double bond(s);
(Bonds) between carbon atoms within the hydrocarbon chain;

26
Q

Describe how an ester bond is formed in a phospholipid molecule. (2)

A
  1. Condensation (reaction) OR Loss of water;
  2. Between OH of glycerol and COOH of fatty acid;
27
Q

Some seeds contain lipids. Describe how you could use the emulsion test to show that a seed contains lipids. (4)

A
  1. Crush/grind;
  2. With ethanol/ alcohol, to dissolve the lipid;
  3. Then add water then shake;
  4. Forms a white cloudy emulsion;
28
Q

What are the differences between a triglyceride and a phospholipid? (2)

A
  1. Fatty acid removed;
  2. Replaced with a phosphate group;
29
Q

Compare and contrast the structure and properties of triglycerides and phospholipids (5)

A

Both contain ester bonds
Both contain glycerol
Fatty acids on both may be saturated or unsaturated
Both are insoluble in water
Both contain C, H and O but phospholipids are also contain P

Triglyceride has three fatty acids and phospholipids have two fatty acids plus phosphate group
Triglycerides are hydrophobic/non-polar and phospholipids have hydrophilic and hydrophobic region
Phospholipids form monolayer/micelle/bilayer but triglycerides don’t.

30
Q

A student carried out the Benedict’s test. Suggest a method, other than using a colorimeter, that this student could use to measure the quantity of reducing sugar in a solution. (2)

A
  1. Filter and dry (the precipitate);
  2. Find mass/weight;
31
Q

Compare and contrast the structure and properties of triglycerides and phospholipids. (5)

A

Both contain ester bonds
Both contain glycerol
Fatty acids on both may be saturated or unsaturated
Both are insoluble in water
Both contain C, H and O but phospholipids are also contain P
Triglyceride has three fatty acids and phospholipids have two fatty acids plus phosphate group
Triglycerides are hydrophobic/non-polar and phospholipids have hydrophilic and hydrophobic region
Phospholipids form monolayer/micelle/bilayer but triglycerides don’t.

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