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a level aqa biology > 1a; biological molecules > Flashcards

1a; biological molecules Flashcards

1
Q

what is the evidence for evolution?

A

information which supports the theory of evolution

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2
Q

what is the theory of evolution?

A

the theory that all organisms on Earth are descended from one or a few common ancestors, and that they have changed and diversified over time

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3
Q

what do all organisms on Earth share?

A

the same biochemistry:
- the same groups of carbon-based compounds that interact in similar ways

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4
Q

what do the biochemical similarities in animals and plants suggest?

A

that animals and plants have a common ancestor (which then provides indirect evidence for evolution)

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5
Q

what are polymers?

A

large, complex molecules composed of long chains of monomers joined together

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6
Q

what are some examples of polymers? (3)

A

carbohydrates, proteins and nucleic acids

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7
Q

what are monomers?

A

small, basic molecular units that came form a polymer

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8
Q

what are some examples of monomers? (3)

A

monosaccharides, amino acids and nucleotides

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9
Q

how are polymers made?

A

from monomers undergoing a condensation reaction

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10
Q

what does a condensation reaction do?

A

forms a chemical bond between monomers, releasing a molecule of water

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11
Q

how are polymers broken down?

A

from polymers undergoing a hydrolysis reaction

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12
Q

what does a hydrolysis reaction do?

A

breaks down the chemical bond between monomers using a water molecule

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13
Q

what elements do all carbohydrates contain?

A

carbon (C), hydrogen (H), and oxygen (O)

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14
Q

what monomers make up carbohydrates?

A

monosaccharides

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15
Q

what are some examples of monosaccharides? (3)

A

glucose, fructose and galactose

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16
Q

what type of sugar is glucose?

A

hexose

17
Q

what does a ‘hexose’ sugar mean?

A

a sugar with six carbon atoms in each molecule

18
Q

what are the different types of glucose

A

alpha and beta

19
Q

what are alpha and beta glucose?

A

structural isomers

20
Q

what does the term ‘structural isomer’ mean?

A

a molecule with the same chemical/molecule formula, but different structure

21
Q

what is the difference alpha glucose and beta glucose’s structures?

A

alpha glucose’s OH group is at the bottom of the molecule, whereas beta glucose’s is at the top

22
Q

when is a disaccharide formed?

A

two monosaccharides are joined together

23
Q

what bond forms between monosaccharides after they are joined by condensation reaction?

A

glycosidic

24
Q

what molecules form the disaccharide maltose?

A

two alpha glucose molecules

25
Q

what molecules form the disaccharide sucrose?

A

one molecule of alpha glucose, and one molecule of beta fructose

26
Q

what molecules form the disaccharide lactose?

A

one molecule of alpha glucose, and one molecule of beta galactose

27
Q

what are the two different types of sugar?

A

reducing and non-reducing

28
Q

which sugars are reducing?

A

all monosaccharides and some disaccharides

29
Q

how do you test for sugars?

A

the Benedict’s test

30
Q

how do you test for a reducing sugar?

A
  • add Benedict’s reagent to sample
  • heat in water bath at 95°c
  • if the sample forms a green → yellow → orange → brick red precipitate, a reducing sugar is present.
31
Q

how do you test for a non-reducing sugar?

A
  • heat sample with dilute HCl
  • neutralise by adding NaHCO₃
  • add Benedict’s reagent to sample
  • heat in water bath at 95°c
  • if the sample forms a green → yellow → orange → brick red precipitate, a non-reducing sugar is present.
32
Q

when is a polysaccharide formed?

A

when more than two monosaccharides are joined together by condensation reactions

33
Q

how can polysaccharides be broken down into their constituent monosaccharides?

A

by hydrolysis reactions

34
Q

what does the polysaccharide amylase become after hydrolysis?

A

alpha glucose molecules

35
Q

where do cells get energy from?

A

glucose

36
Q

how do plants store excess glucose?

A

as starch

37
Q

what is starch made up of?

A

two glucose polysaccharides: amylose and amylopectin

38
Q

what is amylose?

A
  • a long unbranched chain of alpha glucose
  • the angles of the glycosidic bonds give it a coiled structure
  • this makes it compact
39
Q

what is amylopectin?

A
  • a long, branched chain of alpha glucose
  • its side branches allow the enzymes to easily break down the molecule to get to at the glycosidic bonds easily
  • this means that glucose can be released quickly

a level aqa biology (20 decks)

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