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alevel biology ocr > chapter 3- water, carbs, general bm (inc chemical structures) > Flashcards

chapter 3- water, carbs, general bm (inc chemical structures) Flashcards

1
Q

explain the charges in a water molecule

A

the oxygen atom is slightly negative and the hydrogens are slightly positive so they are attracted

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2
Q

how is water made very stable

A

hydrogen bonds are weak but collectively strong so water is made very stable as adjacent water molecules are attracted. this is vital in living organisms

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3
Q

what type of bonds do water molecules have

A

covalent

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4
Q

how is water used in reproduction (2 things)

A

used to bring male and female gametes together in fertilisation, in mammals the foetus develops in a water filled sac providing physical and thermal stability

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5
Q

how does water provide support in animals

A

water filled tissues provide skeletal support , eg annelids hydrostatic skeleton allows muscles to contract, provides buoyancy for aquatic organisms

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6
Q

how does water provide support in plants

A

in plant cells it provides turgidity to maintain ariel parts of the plant to prevent wilting. maintain max leaf surface area for light absorption for photosynthesis

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7
Q

what is an ionic bond

A

a chemical bond formed by the attraction between 2 oppositely charged ions

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8
Q

what is a covalent bond

A

a strong chemical bond where 2 atoms share a pair of electrons

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9
Q

in a glucose molecule which carbon atom is carbon 1?

A

the carbon on the right to the oxygen

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10
Q

what is a glycosidic bond

A

a covalent bond between a carbohydrate and a hydroxyl group on another molecule resulting from a condensation reaction

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11
Q

how is sucrose formed and what bond

A

condensation of glucose and fructose forming a 1, 4 glycosidic bond (alpha)

there is oxygen in the middle

A condensation reaction is taking place between the molecules glucose and fructose. Water is eliminated to form a disaccharide called sucrose

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12
Q

how is lactose formed and what bond

A

condensation of glucose and galactose forming a 1,4 glycosidic bond (beta)

lactose is a disaccharide

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13
Q

how is maltose formed and what bond

A

between the condensation of 2 (alpha)glucose molecules forming a 1,4 glycosidic bond (alpha)

the oh on one glucose and the h adjacent h on the other form a water molecule allowing the maltose to form

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14
Q

what are the chemical elements that make up carbohydrates

A

carbon, hydrogen and oxygen

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15
Q

what is the chemical compostion of carbohydrates (2 elements and a ratio)

A

hydrogen and oxygen in a ratio of 2:1

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16
Q

Glucose and galactose bond and eliminate a water molecule.

What is the resulting disaccharide? and what is the process called

A

lactose
condensation reaction

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17
Q

The disaccharide sucrose is broken down through the addition of water. The products from this reaction are…

This process is called a

A

glucose + fructose
hydrolysis reaction.
gluey fruit sucks

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18
Q

describe the structure of starch

A

a polysaccharide made up of many alpha glucose molecules joined by glycosidic bonds

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19
Q

what are the 2 polysaccharide molecules known collectively as starch

A

amylose and amylopectin

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20
Q

describe the structure of amylose

A

alpha glucose molecules linked by only 1,4 glycosidic bonds the angle of which allows the long chain to twist forming a helix stablised by H bonds from within = more compact and less soluble than just glucose

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21
Q

describe the strucutre of amylopectin

A

alpha glucose molecules with long chains linked by 1,4 glycosidic bonds and branches linked by 1,6 glycosidic bonds that occur every 25 glucose subunits

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22
Q

what is the general formula for carbohydrates

A

Cx(H2O)y

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23
Q

examples of disaccharides

A

lactose
sucrose

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24
Q

examples of polysaccharides

A

glycogen, cellulose and starch

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25
glucose contains .... carbon atoms making it ..... sugar
6 carbon atoms hexose sugar
26
general formula of glucose
C6H12O6
27
is glucose soluble or insoluble
soluble
28
what is the main form carbohydrates are transported around the body of animals
glucose
29
What are isomers?
Isomers are molecules which have the same molecular formula but a different arrangement of atoms.
30
what are 2 structural isomers of glucose
alpha glucose and beta glucose w
31
what is the difference between alpha and beta glucose
the OH group on carbon 1 is below on alpha and above on beta
32
what enzyme will digest maltose and what into
maltase into 2 glucose molecules
33
what are the 2 pentose sugars you need to know
ribose and deoxyribose (will not be asked to draw them)
34
what is the difference between ribose and deoxyribose
on carbon 2 ribose has 1 H atom and 1-OH group whereas deoxyribose and 2H and no OH group
35
what is the difference between an alpha and beta glycosidic bond
alpha the bonds point down to O beta the bond goes up O then down vv
36
in polymers, monomers are joined up by
glycosidic bonds
37
polysaccharides are mainly used for (2)`
energy store structural components of cells (cellulose plant cell wall)
38
how is starch usually stored
stored as intracellular starch grains in plastids
39
what are plastids
organelles including chloroplasts and amyloplasts eg in potatoes
40
describe the structure of glycogen
a branched polysaccharide made up of many glucose molecules with long chains linked by 1,4 glycosidic bonds and branches formed by 1,6 glycosidic bonds
41
is cellulose branched or unbranched
unbranched
42
is glycogen branched or unbranched
branched
43
is amylose branched or unbranched
unbranched
44
is amylopectin branched or unbranched
branched
45
amylopectin is a ...... molecule (length) so
it is a long molecule so it cannot leave the cell as it cannot cross the plasma membrane
46
what is the benefit of glycogen having a branched structure
more efficient storage and release of glucose for respiration than amylopectin etc as it increases the amount of free ends so that glucose can be stored (added) or released quicker
47
glycogen is less..... and more..... than starch and what is the benefit of this
less dense more soluble it can be broken down more rapidly/quicker to digest as animals need to mobolise reserves quicker
48
starch and glycogen are ...... in water, why does this make them good storage molecules
insoluble , it means they dont affect the water potential of the cell
49
starch and glycogen are ...... why does this make them good storage molecules (think space)
coiled, it means they are compact
50
starch and glycogen are...... why does this make them good storage molecules (think structure)
branched, it means there are more ends for fast breakdown.
51
starch and glycogen are polymers of ....., why does this make them good storage molecules
glucose, it means they can provide glucose for respiration
52
what is the starch that is found in animals and fungi
glycogen
53
starch and glucose are .... molecules, why does this make them good storage molecules (think size)
large, it means they cant cross the cell surface membrane
54
why is glycogen insoluble
because it doesn't have enough free polar groups to participate in hydrogen bonding with water. This is because most of the polar OH groups in glycogen hydrogen bond with other groups within the molecule leaving few groups available to participate in bonding with water.
55
what is the most abundant organic polymer
cellulose
56
cellulose prevents cells from
bursting when they take in excess water
57
describe the structure of cellulose
long chains of beta glucose molecules joined by [beta]1,4 gbonds, the glucose chains form rope like microfibrils which are layered to form a network
58
is cellulose a branched or straight chain molecule and why
straight because beta 1-4 gbonds cant form branches as one glucose has to flip so that the OH groups are close enough to react but that means that it cannot coil or form branches and so it is straight
59
is cellulose easy or hard to digest
hard because we lack the neccessary enzymes to breakdown the beta gbonds
60
cellulose molecules form ... bonds with each other meaning
H bonds forming microfibrils which join together to form macrofibrils which combine to produce fibres that provide tensile strength for the plant cell wall they are also insoluble and tough
61
in starch the polysaccharide that makes up the coiled shape is
amylose
62
in starch the polysaccharide that makes up the branched part is
amylopectin
63
what is a hydrogen bond
a weak chemical bond between the partial positive charge on a hydrogen atom and the partial negative charge on the adjacent molecule
64
Any bond with partial charges is called a…
polar bond
65
what is a polysaccharide
a polymer molecule formed of one or more monosaccharides joined by glycosidic bonds
66
define cohesion
the force of attraction between water molecules which makes them stick to each other
67
explain how the polar properties of water molecules cause cohesion
a positively charged H atom of one water molecule is attracted to the negatively charged O atom of another water molecule forming a H bond between the two molecules
68
describe the process of adhesion in plants
water molecules are attracted to the impermeable wall of xylem tissue
69
what is a monomer
the smaller unit from which larger molecules are made
70
what is a polymer
a molecule made from a large number of monomers chemically joined together
71
what is a condensation reaction
a reaction that forms a chemical bond between 2 molecules and eliminates a water molecule
72
what is a hydrolysis reaction
a reaction that breaks a chemical bond between two molecules and uses a water molecule
73
What chemical test is used to detect the presence of reducing and non-reducing sugars and what colour change would be seen with a positive result?
is detected using the Benedict's test + result: change from blue to green, yellow, orange or brick red depending on the conc of the sugar
74
is glycogen quicker or slower to digest than starch and why is this beneficial
it is quicker to digest which is necessary because animals are mobile and plants arent
75
compare the density and the solubility of glycogen and starch
glycogen is less dense and more soluble than starch
76
how is glycogen stored
as small granules in the muscles and liver
77
animals do not store starch but
as glycogen
78
what do hydrolysis reactions do
break poly/disaccharides into monosaccharides
79
break poly/disaccharides into monosaccharides
starch and cellulose in plants and glycogen in animals
80
what are polysaccharides mainly used fo
as an energy store and as structural components of cells
81
what are polysaccharides
long chain carbohydrates formed from many monosaccharides joined by glycosidic bonds . they are formed by condensation reactions
82
what effect does the structural differences of alpha and beta glucose have
major effect on the biological role
83
glucose is the main form in which.....
carbohydrates are transported around the body
84
what are examples of disaccharides
glycogen, cellulose and starch
85
what are disaccharides
large sugars, double sugars formed from 2 monosaccharides
86
what are examples of monosaccharides
glucose, fructose, ribose
87
what is a monosaccharide
a small simple sugar
88
what is the general formula of monosaccharides
(CH20)n where n can be 3-7
89
what does amphipathic mean
a molecule that has both hydrophobic and hydrophilic parts
90
how is a glycosidic bond formed
via a condensation reaction
91
explain why alcohol is used in antiseptic wipes
alcohol can disrupt and dissolve bacterias plasma membrane due to their non polar nature, killing them
92
true or false: some polymers are composed of several monomers that are similar in structure but not identical
true
93
which is correct about the structure of cellulose: a) alternate alpha glucose monomers rotate 180deg b) straight chains contain 1,4 glycosidic bonds
B
94
outline how the different properties of glucose, starch and glycogen relate to their function in cells (4)
glucose is soluble and polar, has chemical energy in its bonds, or respiratory substrate/source of energy starch/glycogen are insoluble and compact and larger/bigger sa used for energy/glucose storage and allows quick release of..... glycogen is broken down faster than starch due to higher sa/many branch ends
95
What is an organic substance?
An organic substance is a molecule that contains carbon and at least one other element.
96
what is a skeletal formula and what is represented
they represent each carbon as a corner on a zig zag line and the hydrogens bonded to each carbon arent included
97
What does an ‘R group’ represent in a skeletal formula?
The rest of the molecule
98

alevel biology ocr (30 decks)

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