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Y4 Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a polymer?

A

Marco-molecule, composed of many repeated subunits

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2
Q

Definition of condensation reaction

A

2 or more simpler molecules joined together to form a larger biological molecule with the removal of water

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3
Q

Definition of Hydrolysis

A

Splitting up of complex biological molecule into its component units with the addition of water molecules

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4
Q

Elements which make up carbohydrates

A

Carbon, hydrogen, oxygen

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5
Q

Ratio of hydrogen to oxygen atoms

A

2 : 1

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6
Q

State the 3 main groups of carbohydrates from simplest to most complex

A

monosaccharides (simple sugar)
disaccharides (complex sugar)
polysaccharides (complex carbohydrate)

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7
Q

Properties of monosaccharides

A

sweet-smelling
soluble in water
able to lower water potential of solutions

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8
Q

What is the bond formed between 2 monosaccharides in 1 disaccharides and which is elements is the bond present in

A

Glycosidic Bond

H-O-H

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9
Q

Building units for maltose, lactose and sucrose

A

Maltose: Glucose, Glucose
Lactose: Glucose, Galactose
Sucrose: Glucose, Fructose

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10
Q

How are polysaccharides formed

A

Formed by the joining of many monosaccharides through the condensation reaction

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11
Q

What are the monomers of polymers(polysaccharides) hint: 1 monomer

A

glucose

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12
Q

Structure of starch (found in plants)

A

Long straight chains/branched chains

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13
Q

Structure of glycogen

A

molecules are joined up in highly branched chains

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14
Q

Why are starch and glycogen suitable as storage materials

A

Insoluble in water; do not affect water potential in cells

Too large to diffuse through the cell membranes, stay in cell

Compact shape, occupy less space than all individual glucose molecules

Easily hydrolysed to glucose when needed

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15
Q

Why does cellulose have different property from starch

A

glucose molecules that form cellulose are bonded differently

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16
Q

cellulose soluble in water (T/F)

A

False; insoluble

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17
Q

Structure of cellulose cell walls in plant cells (structure + permeability)

A

cellulose fibres embedded in a polysaccharide matrix, fully permeable

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18
Q

2 functions of cellulose cell wall

A

Provide mechanical support for plant cells and to the plant

Resists expansion when water enters by osmosis, ensuring integrity of plant cell and provide turgidity

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19
Q

Describe Benedict’s Test and purpose

A

Purpose: Test for presence of reducing sugar

Description of test:
To 2cm3 of food solution, add equal volume of benedict’s solution.

Shake the mixture

Place test tube in boiling water bath for maximum of 5 mins

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20
Q

One common disaccharide that cannot be tested as it is non-reducing sugar

A

Sucrose

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21
Q

Colours of benedict’s test and what they suggest

A

brick-red: very high concentration
orange: high concentration
yellow: moderate concentration
green: little concentration
blue: absent

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22
Q

Describe Iodine Test and purpose

A

purpose: test for starch

Description:
place food substance on white tile. (solid foods may need to be chopped)

add 2-3 drops of dilute iodine solution to substance tested

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23
Q

What does the colouration of iodine test formed suggest

A

Blue-black: presence of starch
brown: remain brown

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24
Q

What are lipids?

A

Organic compounds containing hydrogen, carbon and oxygen

25
Q

Lipids have much lesser oxygen than carbon and hydrogen (T/F)

A

True

26
Q

Solubility of lipids in water and organic solvents

A

Lipids are insoluble in water but soluble in organic solvent

27
Q

What is triglycerides consisted of

A

3 molecules of fatty acids and 1 molecule of glycerol

28
Q

What is a fatty acid (what type of chain and functional group)

A

long hydrocarbon chain that has carboxyl functional group -COOH

29
Q

How to tell if a fatty acid is saturated/unsaturated

A

Saturated: absence of carbon-carbon double bond

Unsaturated: presence of 1 or more carbon-carbon double bond

30
Q

Are fatty acids hydrophilic or hydrophobic

A

hydrophobic, do not mix well with water

31
Q

Formula for glycerol

Glycerol is an alcohol

A

C3H8O3

32
Q

What is the bond formed between 3 fatty acids and glycerol and which elements is the bond present in

A

Ester bond
O
||
O-C

33
Q

How are triglycerides formed and what are released

A

Condensation reaction. 3 molecules of water and triglycerides.

34
Q

How to determine whether a triglyceride is fats or oil

A

Fats: If solid at 20 degrees

Oil: If liquid at 20 degrees

35
Q

Properties of fats (triglycerides with saturated fatty acids) (apart from carbon-carbon double bond)

A

Higher melting and molecular weight

Insoluble and do not affect water potential in cells, so stored as droplets inside adipose cells

36
Q

Property of oils (triglycerides with unsaturated fatty acids) (apart from carbon-carbon double bond)

A

Lower melting point and molecular weight

37
Q

Another generic property of triglycerides

A

Compact and insoluble in water

38
Q

How are fats stored in specialised fat cells and why so

A

Stored as droplets.

Insoluble, do not affect water potential in cells

39
Q

Functions of triglycerides (at least 4) and usages

A

Conducts heat slowly, excellent heat insulator against heat loss

Buoyancy in aquatic animals. Less dense than water; very thick layers of blubber for large animals in sea

Protective layer. Absorb shock; surrounding delicate, vital organs

Important component of myelin shealth. Electrical insulator allow rapid transmission of electrical impulses along myelinated neurons in never cells

40
Q

Why are triglycerides better at energy storage but carbohydrates most utilised

A

Triglycerides have more C-H bond/gram than starch/hydrogen and yields twice much energy for same mass as carbohydrates. Half mass of triglycerides for same amount of energy stored -> lightweight

Carbohydrates most direct source of energy in living things as they are metabolised quickly both in aerobic and anaerobic conditions

41
Q

How can triglycerides provide metabolic water

A

Oxidation of triglycerides provide metabolic water. Triglycerides release twice as much water as carbohydrates when oxidised during respiration

42
Q

What is the hydrophilic and hydrophobic components of the phospholipids

A

hydrophilic: phosphate group
hydrophobic: fatty acid tails

43
Q

Structure of Phospholipids

A

2 molecules of fatty acids, 1 molecule of glycerol and 1 molecule of phosphate group

44
Q

Why does phosphate group face exterior(aq environment) while fatty acid tails face the inside of the bilayer

A

phosphate group (hydrophilic)
fatty acid tail (hydrophobic)

45
Q

Function of phospholipids

A

Phospholipid bilayer in cell membrane

46
Q

Purpose and description of ethanol emulsion test

for solid just chop and put into test tube

A

purpose: test for fats

description:
add 2cm3 of ethanol to 2cm3 of food solution in test tube

shake mixture thoroughly

decant ethanol mixture into another test tube containing 2 cm3 of water

47
Q

What does white emulsion formed in ethanol emulsion test suggest

A

fats present

48
Q

What are proteins

A

Made up of elements carbon, hydrogen, oxygen and nitrogen

49
Q

What happens when proteins are heated

A

Denatured, lose 3-dimmensional shape

50
Q

Proteins have unique 3-d shape, thus have diverse functions (T/F)

A

True

51
Q

What is the monomers of proteins

A

amino acids

52
Q

How are dipeptides formed

A

Condensation reaction of amino acids with removal of water molecules

53
Q

How are polypeptides formed

A

Continued condensation reaction result in long chain of amino acids to form polypeptides

54
Q

How is the unique 3d-shape of a protein achieved

A

By the folding of the polypeptide chain folds into a particular 3d-shape

55
Q

Name 3 functions of proteins

A

Synthesis of new cells for growth, repair of worn-up cells

biological catalysts to speed up rate of reaction

Transport proteins such as haemoglobin transport oxygen in red blood cell

56
Q

Purpose and description of biuret’s test

A

purpose: test for proteins

description: to 2cm3 of food solution, add 1 cm3 of sodium hydroxide solution. shake thoroughly. add 1% copper (II) sulfate solution, drop by drop to observe colour change

57
Q

How to know if protein is present

A

violet concentration observed

58
Q

why is a violet concentration observed if protein is present

A

in presence of copper(II) ions, in an alkaline solution, compound containing peptide bonds will form violet colouration

Y4 Biology (6 decks)

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