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Biology Unit 2 > The Variety Of Life > Flashcards

The Variety Of Life Flashcards

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1
Q

How many haem groups are in one molecule of haemoglobin?

A

4 haem groups, each one containing a Fe2+ ion, which is why 4 O2 molecules can be carried by one haemoglobin molecule

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2
Q

Where does haemoglobin have a high and low affinity in the body?

A
  • high affinity = lungs, haemoglobin associates with O2

- low affinity = muscles, haemoglobin disassociates from O2

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3
Q

What is partial pressure?

A

The amount/ concentration of O2 in the blood

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4
Q

In an area where there is low/high conc of CO2 what is the affinity for O2?

A

High CO2: low affinity

Low CO2: high affinity

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5
Q

What type of haemoglobin will an organism with a low metabolic rate & that lives in an environment with little O2 have?

A

Haemoglobin that readily combines with O2 to absorb enough to survive

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6
Q

What type of haemoglobin will an organism that lives in an environment with plenty of O2 and has a high metabolic rate have?

A

Haemoglobin that releases oxygen easily

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7
Q

Why do different haemoglobins have different affinities for O2?

A

Different haemoglobin molecules have slightly different sequences of amino acids =different tertiary structures

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8
Q

What is the purpose of partial pressure?

A

Determines haemoglobin’s affinity for O2

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9
Q

What is an oxygen dissociation curve?

A

Shows the relationship between haemoglobin saturation with oxygen (the % of oxyhaemoglobin)

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10
Q

How many O2 atoms bind to one haemoglobin?

A

8 - one molecule is O2

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11
Q

What are the two advantages of the four globules in a haemoglobin molecule?

A

each globule…

  • provides correct environment for O2 to bind to haem
  • haemoglobin soluble in cytoplasm of red blood cell
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12
Q

How may human haemoglobins differ from other species?

A
  • diff number of haem groups

- diff sequence amino acids on polypeptide chains

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13
Q

Explain co-operative binding

A
  • first O2 molecule binds to haemoglobin
  • this alters shape
  • second O2 molecule binds more easily
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14
Q

Why is the O2 dissociation curve S-shaped?

A

Co-operative binding

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15
Q

What happens at the beginning (bottom) of the O2 disassociation curve?

A

Haemoglobin lets go of O2

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16
Q

What happens at the end (top) of the O2 dissociation curve?

A

Haemoglobin is highly saturated with O2, takes it up

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17
Q

What does the steepness of the O2 disassociation curve show?

A

The sensitivity of haemoglobin - a slight change in partial pressure triggers a rapid uptake/ dropping of O2

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18
Q

Explain how the respiring cells in muscle tissue affect haemoglobins affinity for O2

A
  • respiring cells produce CO2
  • CO2 dissolves in water to form Carbonic acid
  • this is broken down, to produce H+ ions & hydrogen carbonate ions
  • H+ ions = low pH
  • if left in blood will poison
  • haemoglobin drops O2 to bind H+ ion to haem group and carries it away to lungs to be exhaled
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19
Q

What is the Bohr-Shift?

A

The shifting to the right of the O2 disassociation curve

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20
Q

When does the Bohr-Shift occur?

A

During exercise - curve at resting point shifts right so the % of haemoglobin saturated decreases showing more O2 being released

21
Q

What does the gap between the two curves (resting curve & Bohr Shift curve) represent?

A

The difference shows the additional O2 released from oxyhaemoglobin at any particular point

22
Q

What other factors of exercise trigger the Bohr-Shift?

A
  • acidic (low) pH
  • high lactic acid conc
  • increased temp
23
Q

What is the advantage of the Llama having a curve shifted to the left of the Sheep?

A
  • llama lives in high altitude
  • partial pressure of O2 is low
  • llamas haemoglobin has higher affinity for O2 than sheep
24
Q

Why could a mutation in one of the genes coding for haemoglobin lead to a decrease in oxygen-carrying capacity of the blood?

A
  • mutation = different base sequence, codes for different amino acids
  • change in primary structure = change in tertiary structure
25
Q

What is meant by a tertiary structure?

A

A protein made up of more than one polypeptide chain

26
Q

What type of molecule is starch?

A

A polysaccharide

27
Q

Where is starch typically found in plants?

A
  • seeds/storage organs
28
Q

How is a starch molecule composed/structured?

A
  • chains of alpha glucose monosaccharides
  • chains of helixes
  • all linked by glycosidic bonds
29
Q

What type of reaction makes a starch molecule?

A

Condensation

30
Q

How is starch especially suited for energy storage?

A
  • insoluble: doesn’t affect osmotic movements in cell & doesn’t easily diffuse out
  • compact: a lot can be stored
  • hydrolysed to alpha glu: transportation & respiration
31
Q

What is glycogens purpose?

A

Store energy in animal cells

32
Q

Where is glycogen typical stored?

A
  • muscles

- liver

33
Q

What makes glycogen suited for storage?

A
  • insoluble
  • compact
  • when hydrolysed releases alpha-glu very rapidly, it is made up of smaller chains than starch and easily broken down due to high surface area of branched structure
34
Q

How does cellulose differ from starch and glycogen?

A

It’s made from monomers of beta-glu, not alpha

35
Q

What type of molecule is cellulose?

A

A polysaccharide

36
Q

How do cellulose molecules form glycosidic links?

A
  • each beta-glu molecule rotates by 180deg

- OH group is above ring rather than below

37
Q

How is one haemoglobin molecule made up of the four structures?

A
  • primary: 4 polypeptide chains
  • secondary: chains coiled into helixes
  • tertiary: each chain folded into precise shape (factor for carrying O2)
  • quaternary: all four chains linked together for form spherical molecule, each chain associated with one haem group
38
Q

What is the structure of a cellulose molecule?

A
  • straight, unbranched chains
  • parallel chains, H+ cross links
  • very strong structure
  • molecules grouped together to form microfibrils => fibres
39
Q

What is the importance of cellulose in plants?

A
  • rigid plant cell walls
  • stop cell from bursting from osmosis by exerting inward pressure
  • plant cells turgid
  • important in making stems & leaves have max surface area for photosynthesis
40
Q

What type of cell is a plant cell?

A

Eukaryotic

41
Q

What features of a palisade cell suit its function of photosynthesis?

A
  • long&thin: continuous layer to absorb sunlight
  • position of many chloroplasts = max sunlight
  • large vacuole: pushes chloroplasts to edge of cell
42
Q

What are the main features of a chloroplast?

A
  • envelope: double plasma, selective in enter/leaving chemicals
  • grana: stacks of thylakoids
  • thylakoid: chlorophyll pigment
  • intergranal lamella: join adjacent thylakoids together
  • stroma: liquid surrounding grana, starch grains
43
Q

How does the structure of a chloroplast link to its function to photosynthesize?

A
  • grana: large surface area for chlorophyll attachment
  • stroma fluid: enzyme filled = 2nd stage photosynthesis
  • chloroplast DNA & ribosomes: quick manufacture of proteins
44
Q

What are the features of a plant cell wall?

A
  • polysaccharides cellulose

- thin middle lamella layer, boundary between two cells walls

45
Q

What are the functions of the plant cell wall?

A
  • strength: stop it bursting from osmosis
  • strength to plant as a whole
  • allow osmotic movement of water in & out of cell
46
Q

What are the differences between a plant & animal cell?

A 
Plant
- cellulose cell wall & membrane
- chloroplasts
- large vacuole filled with cell sap
- storage starch grains
Animal
- only membrane
- no chloroplasts
- small, scattered vacuoles
- storage glycogen granules
47
Q

State two features of a root hair cell that suit its function

A
  • long tail that reaches deep into the earth to maximize water uptake
  • root hairs along tail = bigger surface area for water uptake
  • large vacuole containing many ions & sugars => mineral ion uptake against conc gradient => carrier proteins give ATP energy for active transport
48
Q

What is the purpose of lignin in the xylem?

A

Forms rings/ spirals around xylem tube to strengthen it

Biology Unit 2 (11 decks)

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