1.

The diagram shows a summary of some of the steps in aerobic respiration. P y ru v a te L in k re a c tio n N A D N A D H + H A c e ty l C o e n z y m e A+

e le c tr o n - tr a n s p o r t c h a in

K re b s c y c le

N A D N A D H + H

+

e le c tro n - tr a n s p o rt c h a in

(a)

State precisely where Krebs cycle takes place within a cell. ....................................................................................................................................(1)

(b)

Name the process that results in the production of ATP from ADP by the electrontransport chain. ....................................................................................................................................(1)

(c)

With reference to the diagram, explain why Krebs cycle can only take place when oxygen is available. .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... ....................................................................................................................................(2) (Total 4 marks)

1

2.

The diagram below shows a summary of glycolysis and two alternative pathways that may follow this process in anaerobic conditions. G lu c o s e G ly c o ly sis P a th w a y A T a k e s p la c e in e x e r c is in g m u s c le s L a c tic a c id P a th w a y B T a k e s p la c e in y e a st c e lls W a s te p ro d u c ts

X

(a)

Substance X is the final product of glycolysis. Name this substance. .(1)

(b)

In glycolysis, NAD is converted to its reduced form (NADH + H+). Describe how NAD is regenerated in pathway A. . . . .(2)

(c)

Name the waste products of pathway B. .(1)

(d)

Describe the role of reduced NAD (NADH + H+) when respiration takes place in aerobic conditions. . . . . . . .(3) (Total 7 marks)

3.

Give an account of the stages of respiration that take place in the mitochondrion, stating the location of each stage. (Allow three lined pages)(Total 10 marks)

4.

Give an account of the anaerobic respiration of glucose by yeast. (Allow three lined pages)(Total 10 marks)

3

5.

The flow chart below illustrates some of the stages that occur in glycolysis. G l u 2 2 6 2 2 G l y c a r b o n p c o A A h s e T o N N h A D PiP

+ h D D o

2 r y

P l a t e d 2 2 i n A A - p + P t e r m D T h o P P s p h + e d 2 i

s p Ai

o x i d r e d u 3iP

i s e d c e d h o s p

c e r a t e A A P y r u D T v P

- p + P

a Gt e l y

c e r a t e A A D T v PiP

3

a t e

a t e

P

y

r u

a t e

(a)

State the net gain in ATP from one molecule of glucose in glycolysis. ............................................................................................................................................(1)

(b)

Explain why the yield of ATP from the respiration of one molecule of glucose when oxygen is present is more than the yield of ATP from the respiration of one molecule of glucose under anaerobic conditions. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................(5) (Total 6 marks)

6.

The diagram below shows part of a metabolic pathway which occurs in mitochondria.

c i- sa c o

n

i t a t e

i s o

c i t r a t e

o

x

a l o

s u

c c i n

a t e

N

A+

D

+

N

A

D

H

+

H

(a)

Explain what is meant by the term metabolic pathway. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................(2)

5

(b)

Suggest what happens to the NADH + H formed during the conversion of isocitrate to oxalosuccinate. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................(2)

+

(c)

The conversion of cis-aconitate to isocitrate is catalysed by the enzyme aconitase. The leaves of some plants contain a substance called fluoroacetate. If this is eaten by animals, it is absorbed into their cells where it is converted to fluorocitrate. Fluorocitrate is an inhibitor of the enzyme aconitase. Suggest what effect fluorocitrate would have on the production of ATP by mitochondria. Give an explanation for your answer. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................(4) (Total 8 marks)

7.

The diagram below shows a section through the membranes of a mitochondrion. I n n e r m e m b r a n e

O C r i s t a e

u

t e r

m

e m

b

r a n

e

I n t e r m s p a c e

e m

b

r a n

e

S p

t a l k e d a r t i c l e s

With reference to the structures labelled on the diagram, describe the role of the mitochondrial membranes in the production of ATP. . . . . . . . . . .(Total 5 marks)

7

8.

In an investigation, small samples of tissue were removed from the leg muscles of international athletes of the same age and sex. The athletes included sprinters (100 m), middle distance runners (800 m) and long distance runners. SDH is an enzyme involved in the reactions of the Krebs cycle. LDH is an enzyme that catalyses the conversion of pyruvate to lactate. The results of the analysis of the muscles are shown in the table below. Athletes Mean percentage of slow twitch fibres 24 52 70

Mean SDH activity /arbitrary units 1.70 2.00 2.25

Mean LDH activity /arbitrary units 1.60 1.10 1.00

100 m sprinters 800 m runners Long distance runners

(a)

Explain why successful sprinters usually have a low percentage of slow twitch fibres in their leg muscles. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(2)

(b)

Explain the relationships between the mean activity of SDH and LDH in the leg muscles and the distances run by the athletes. (i) SDH ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(2)

(ii)

LDH ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(2)

(c)

Describe the role of the electron transport chain of mitochondria in the synthesis of ATP. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(4)

(d)

Explain the fate of lactate produced by the activity of LDH in athletes such as sprinters. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(2) (Total 12 marks)

9

9.

An investigation was carried out into the effect of cyanide on the respiration of yeast cells. Cyanide is an electron transport inhibitor. It binds irreversibly with one of the electron carriers. The yeast cells were mixed with a buffer solution which had ADP, phosphate ions and glucose dissolved in it. This suspension was incubated for 30 minutes and during this time the oxygen content of the solution was monitored using an oxygen probe. The experiment was then repeated but cyanide was added to the suspension after 5 minutes of incubation. The results obtained are shown in the graph below. 1 0 o f C y a n i d e a d d e d

O x y g e n c o n t e n t t h e s u s p e n s8 i o n / a r b i t r a r y u n i t s 6 4 2 0 0 5 T i m

N 1 e o 0 f i n 2 15 53 c u b 0

o 2

c y 0 n /

a n m

i d i n

e u

a d t e s

d

e

a t i o

(a)

State precisely where the electron transport chain is found. ......................................................................................................................................(1)

(b)

Explain why the oxygen content of the suspension did not change after the cyanide was added. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ......................................................................................................................................(2)

(c)

Suggest why the oxygen content of the suspension of cells without cyanide did not reach zero. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ......................................................................................................................................(2) (Total 5 marks)

11

10.

The flow diagram below shows some of the steps involved in glycolysis and the Krebs cycle. Some ATP is made directly. Hydrogen is also released and this can result in the production of more ATP.

(a)

Describe how the hydrogen released during glycolysis and the Krebs cycle results in the production of ATP. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... .......................................................................................................................................(4)

(b)

Using the information in the diagram, state the number of ATP molecules produced from one triose phosphate molecule. .......................................................................................................................................(1)

(c)

As well as carbohydrates, triglycerides can be respired. The first step is to break down each triglyceride molecule into glycerol and three fatty acids. Each fatty acid is broken down into acetyl CoA molecules. The acetyl CoA molecules then enter the Krebs cycle. (i) Using the information in the diagram, state the number of ATP molecules produced from one acetyl CoA molecule. ................................................................................................................................(1)

13

(ii)

Suggest why fatty acids can only be respired under aerobic conditions. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................(3) (Total 9 marks)

11.

The diagram below summarises some of the stages of a metabolic pathway responsible for generating ATP in mitochondria. r e d u c e d h y d r o g e n c a r r i e r 2 H ( f r o m r e d u c e d o x i d i s e d c y t o c h r o

m

e

2 N A D )

e

2

e

o x i d i s e d h y d r o g e n c a r r i e r

2

+ H

r e d u c e d c y t o c h r o

m

e

(a)

(i)

Name the metabolic pathway shown in this diagram.(1)

...........................................................................................................................

(ii)

Name the type of enzyme involved in this pathway and explain its role. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(2)

(b)

Explain what happens to the electrons released at the end of this pathway. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(2) (Total 5 marks)

15

12.

In oxidative phosphorylation, ATP is formed when electrons pass down the electron transport chain from one component to the next. ATP is synthesised at three sites. The order of some components in the electron transport chain and the three sites of ATP synthesis are shown in the diagram below. R C C C C C O y y y y e d o u e n t o t o t o t o x y c e d S i t e z y c h S c 1h c h c h S g N 1 c e d b c c a F A D A D

m R e e dQ u r o m 2 m m m 3 e e e e

i t e r o r o r o i t e e n

(a)

The oxidation of one molecule of reduced NAD (NADH + H ) yields three molecules of ATP. Using the information given in the diagram above and your knowledge of mitochondria and oxidative phosphorylation, explain how the three molecules of ATP are made. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(4)

+

17

(b)

The diagram below shows some of the stages that occur in the Krebs cycle. 1 P y r u v a t e ( 3 C r e d ) A u c e d c e t y l N C A o D e n z y m e A ( 2 C )

O

x

a l o

a c e t a t e

( 4 CC

i) t r a t e

( 6

C

)

1

r e d

u

c e d

N

A

D

1 C C ) - k

2O

r e d

u

c e d

N

A

M

a l a t e

( 4

e t o 1

g 2O

l u

t a r a t e r e d u

( 5

C N

)

c e d

A

F

u

m

a r a t e

( 4 S C u )c c i n

C a t e

( 4

C

)

1

r e d

u

c e d

F A

D

Using the information given in both diagrams, explain why the oxidation of one molecule of succinate to oxaloacetate yields only five molecules of ATP. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(3)

(c)

State where in the cell the following processes take place. Glycolysis................................................................................................................... Conversion of pyruvate to acetyl coenzyme A.......................................................... Krebs cycle.................................................................................................................(3) (Total 10 marks)

13.

The diagram below shows some of the stages in aerobic respiration. G 2 2 H p H y r u l u c o A T v X l s e P A a t e

a c e t y

C

o

A

4 c o A T P X

c a r b o n m p o u n

d

6 c o

c a r b o n m p o u n B X 2 H

d

6

H

5 c o

c a r b o n m p o u n

d

(a)

(i)

Name substance X:(1)

X ........................................................................................................................

(ii)

Name stages A and B: A ........................................................................................................................ B ........................................................................................................................(1)

19

(b)

Explain what happens to the hydrogen that is produced during stage B. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(4)

(c)

Explain how ATP is able to supply energy for biological processes. ..................................................................................................................................... .....................................................................................................................................(1) (Total 7 marks)

14.

Give an account of anaerobic respiration of glucose in a mammalian muscle cell. (Allow two lined pages).(Total 10 marks)

15.

The table below refers to three major stages of aerobic respiration and the products of each stage. Complete the table by inserting the part of the cell in which the stage occurs and two products in the blank spaces. Stage Glycolysis Krebs cycle Electron transport chain Matrix of mitochondrion ATP and water(Total 4 marks)

Part of cell in which it occurs

Two products

16. G

(a) l u

The diagram below shows an outline of anaerobic respiration in a yeast cell. c o s e 2 H

P

y

r u

v

a t e

E

t h

a n

a l

E

t h

a n

o

l

S

u

b

s t a n

c e

X

(i)

Name substance X. ...........................................................................................................................(1)

21

(ii)

Explain why it is necessary for the cell to convert ethanal to ethanol. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(2)

(b)

A student carried out an investigation into the effect of glucose and sucrose on the rate of respiration of yeast cells. Triphenyl tetrazolium chloride (TTC) is an artificial hydrogen acceptor, which is colourless in the oxidised form and red when reduced. A colorimeter is an instrument used to measure the percentage of light transmitted through a liquid. In this investigation, when the TTC is fully oxidised 100% of the light is transmitted through the liquid. The darker the red colour of the TTC solution becomes, the lower the percentage of light transmitted. Yeast cells were suspended in 0.5% glucose solution. The student set up a tube containing 10 cm3 of this suspension and 1 cm3 of TTC solution. The tube was covered and placed in a water bath for 20 minutes. During this time, the percentage of light transmitted through the solution was measured at two-minute intervals. The experiment was repeated using yeast cells suspended in 0.5% sucrose solution. The results of the investigation are shown in the graph below. 1 0 0

8

0

P e r c e n t a g e o f l i g 6h 0t t r a n s m i t t e d ( % ) 4 0

G

l u

c o

s e

2

0

S

u

c r o

s e

0

0

2

4

6

8 T

1 i m

0

1 e

2 /

1 m

4

1 i n

6

1

8

2

0

23

(i)

Describe the rate of respiration of yeast in the glucose solution during the 20 minutes of this investigation. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(3)

(ii)

State one way in which the rate of respiration of yeast in the sucrose solution differs from the rate in the glucose solution. ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(1)

(iii)

Explain why the tubes were covered during this investigation. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(2)

(iv)

Explain why the student placed the tubes in a water bath. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(2) (Total 11 marks)

17.

The diagram below shows a simple respirometer used to investigate gas exchange in germinating seeds.

1

c 3 ms y

r i n

g

e

S

c a l e

C

o

n

t a i n

e r

o

f

g

e r m

i n

a

R P o

o

l l

o

f

f i l t e r m h y

p d

a p r o

e r x i d e

t a s s i u

C

a p

i l l a r y

t u

b

e

c o

n

t a i n

i n

g

c o

l o

u

r e d

l

25

(a)

Suggest a function for each of the following. (i) The syringe ........................................................................................................................... ...........................................................................................................................(1)

(ii)

The potassium hydroxide solution ........................................................................................................................... ...........................................................................................................................(1)

(b)

Suggest why immersing the respirometer in a water bath helps to ensure that the results are reliable. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(2)

(c)

In an investigation to measure the rate of oxygen uptake by the seeds, the coloured liquid moved 12 mm up the right hand side of the capillary tube in 15 minutes. The cross2 sectional area of the capillary tube is 0.19 mm . Calculate the volume of oxygen taken up per minute by the seeds. Show your working.

Answer = ................................... mm oxygen min

3

1

(3) (Total 7 marks)

18.

(a) The diagram below shows some of the stages of anaerobic respiration in a muscle cell.

G

l u

c o

s e

S

t a g

e

1

F G l y c o l y s i s

r u

c t o

s e

1

, 6

- b

i s p

h

o

s p

h

a t e

S

t a g

e

2

G

l y

c e r a t e

3

- p

h

o

s p

h

a t e

S

t a g

e

3

S

u

b

s t a n

c e

A

S

t a g

e

4

L

a c t i c

A

c i d

(i)

Name substance A. ...........................................................................................................................(1)

(ii)

State which of the stages shown in the diagram: Uses ATP .......................................................................................................... Produces ATP ...................................................................................................(2)

27

(b)

The Krebs cycle occurs during aerobic respiration and is an example of a metabolic pathway. (i) Explain why the Krebs cycle is described as a metabolic pathway. ........................................................................................................................... ...........................................................................................................................(1)

(ii)

State precisely where in the cell the Krebs cycle occurs. ...........................................................................................................................(1)

(c)

The diagram below shows some of the stages that occur in the Krebs cycle. A c e t y l C o e n z y m e A ( 2 C )

O 1 r e d u c e d M

x N F

a l o A D

A a c e t a t Ce

i ( t 4 r aC t e) B

( 6 1

C

) u c e d N A D

r e d

a l a t e E F u m

( 4

C

)

a- k C

CO 2 e t o g l u 1 ) C O2

t a r a t e u c e d N a t e A ( 4 D C

r e d S u

a r a t e D 1 r e d u

( 4

C

c c i n

c e d

F A

D

Oxidoreductase enzymes are involved in some of the reactions in the Krebs cycle. Using the letters A to F and the information given in the diagram, list all the stages that involve an oxidoreductase enzyme. .....................................................................................................................................(1) (Total 6 marks)

19.

Isolated mitochondria in a solution containing inorganic phosphate and an electron donor can be used to study respiration. An electrode is used to record changes in oxygen concentration while mitochondria respire. The graph below shows changes in oxygen concentration for some isolated mitochondria.

A

D

P

a d

d

e d

o x y g e n c o n c e n tra tio n o f s o lu tio n / a rb itra ry u n its

T

i m

e

/

m

i l l i s e c o

n

d

s

(a)

(i)

Describe and explain the trends shown on the graph above.

........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(3)

(ii)

Name an electron donor used in the electron transport chain in mitochondria. ...........................................................................................................................(1)

(iii)

State the location of the electron transport chain in mitochondria. ...........................................................................................................................(1)

29

(iv)

Describe how ATP is synthesised in the electron transport chain. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(3)

(b)

ATP is used to provide an immediate supply of energy for biological processes. Describe the role of ATP in the following processes. (i) Nerve impulse transmission ................................................................................................................ ............... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(2)

(ii)

Hyperpolarisation of rod cells in the retina ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(2) (Total 12 marks)