SUGGESTION ANSWER PSPM 16/17

Session 2016/2017

1 (a) Define enzyme. [1 mark]

Globular protein / biological catalyst that speed up/ increase the

( rate of reaction).

(b) State t h r e e (3) properties of enzymes. [3 marks]
Globular protein

Highly/ very specific (in action)

Lower the activation energy

Influenced by temperature/ pH value /optimal, very high, extreme /

enzyme concentration/ cofactor/ inhibitor / substrate concentration

Reusable // Does not change at the end of the reaction

(c) What determines the amount of product produced in an enzymatic

reaction? [2 marks]

Amount / concentration of substrate
(Presence of) non-competitive inhibitor

(d) What will happen to the rate of enzyme activity when the shape of

enzyme's active site is altered? Give a reason. [2 marks]

Decrease / lower // No reaction occur
Substrate cannot bind to active site //Enzyme- substrate complex

(e) Catecolase causes the browning of cut fruits like apples. An apple was

bitten in two areas; one area was exposed while another area was covered

with lime juice. Why had the exposed area turned brown? [2 marks]

Catecolase is active / not denatured
Oxidation occurs

2. FIGURE 2 shows a diagram of cellular respiration.

FIGURE 2

(a) Name the process shown in FIGURE 2. [1 mark]
Fermentation

(b) (i) State the condition on how the process can occurs. [1 mark]
In the absence of oxygen / does not required oxygen

(ii) Give o n e ( 1 ) example the used of this process in industry. [1 mark]
Bread making

Manufacture of beer / wine/ alcohol beverages

Making / fermented dairy product such as yoghurt /cheese

Manufacture of ethanol

Making of fermented food taucu /tapai / cencalok /tempoyak / budu

/soy sauce /tempe

(c) Name compound A, B, C and D. [4 marks]
[1 mark]
A: carbon dioxide
B : ethanol/ acetaldehyde
C: ethanol
D: lactic acid / lactate
(d) Identify the role of NADH in the above respiratory process.
Hydrogen donor // reducing agent // electron carrier

(d) Write the chemical equation to summarise the respiratory process that
takes place in FIGURE 2 if it happens in :

(i) Plant cells

C6H1206 2C2H5OH+ 2CO2

(ii) Animal cell

C6H1206 2CH3(OH)COOH / 2C3H6O3

3. FIGURE 3 shows the structure of a nephron in the human kidney

FIGURE 3

(a) Name the structures labelled Q and R. [2 marks]
Q: Proximal (convoluted) tubule
R: Collecting duct

(b) State the main processes which occur in structures P and S. [2 marks]
P: Ultrafiltration
S: Reabsorption

(c) State the substance that is absent in structure P and give a reason.
[2 marks]

Glomerular basement membrane // Protein // Red blood cell// White
blood cell /Platelet // blood cells
They are too large to pass through the filter/glomerulus

(d) Explain the absence of glucose in the urine. [2 marks]

All glucose has been reabsorbed (into the blood capillaries) in the

proximal tubule (of the nephron)

(e) Explain briefly how the concentration of substances in the urine changes

after a heavy intake of meat. [2 marks]

Meat protein are hydrolyzed into amino acids and are converted into

urea (in the liver)

Concentration of urea in the urine increases

4. FIGURE 4 shows a condition of skeletal muscle based on the sliding filament
mechanism.

FIGURE 4 [1 mark]
(i) State the condition of the above muscle. [3 marks]

Fully contracted

(ii) Identify structures labelled M, N and O.

M: Myosin / thick filament
N: Actin / thin filament
O: Sarcomere

(iii) What happens to I band and H zone during the muscle condition shown in

FIGURE 4? [1 mark]

I band shorten and H zone disappear

6. (a) Define natural selection. Describe the types of natural selsction with the aid of
correctly labelled selection curves.

Natural selection : a process by in which individuals that have certain heritable
traits survive/ reproduce at higher rates than other individuals // A process of
selection involving environmental factor as selecting agent, resulting in favourite
traits being more represented/dominant (and unfavourite traits being less
represented/less dominant) in the next generations

Directional selection

Directional selection acts to eliminate/ against one extreme from an array of
phenotypes. // Directional selectional favors individuals at one extreme ends of
the phenotypic range

Curve with label.

Requirement:

Correct curve, arrow, labelling for initial and final population.

Disruptive selection

Environmental conditions favor individuals at both extremes of the phenotypic
range over those with intermediate phenotypes

Curve with label.

Requirement:

Correct curve, arrow, labelling for initial and final population.

Stabilizing selection

Selection acts to eliminate / against both extreme phenotypes. // Stabilizing
selection favors intermediate variants and acts against extreme phenotypes.

Curve with label.

Requirement:

Correct curve, arrow, labelling for initial and final population.

7. (a) What is meant by photosynthesis and write the equation of photosynthesis.

[5 marks]

-The synthesis of organic compound from carbon dioxide and water

- With the aid of light energy/ sunlight +photon

- Captured / absorbed by photosynthesis pigments / chlorophyll // takes
places

in chloroplast in plant.

Light

- 6CO2 + 12H2O C6H1206 + 602 + 6H2O

(chloropyll)

Or

Light

- C6H12O6 + 602 6CO2 + 6H2O

(chloropyll)

7(b) Describe the flow of electrons in non-cyclic photophosphorylation

1. Light energy is absorbed by antennae pigment of PSI/P700 and PSII/P680

2. Electron at PSII/P680 becomes photoactivated/photoexcited/high
energy/excited

3. Photoactivated / photoexcited electron captured by primary acceptor

4. PS II/P680 becomes electron deficient/unstable /P680

5. Photolysis of water occurs // H2O +1/202+2e + 2H+

6. Electron from photolysis of water will replace the loss of electron from
PSII/P680

7. Electron from primary electron acceptor pass through electron transport

chain/ETC//Platoquinone, cytochrome complex and plastocyanin

8. At the same time, PSI/P700 release its photoexcited electron to primary electron

acceptor

9. Electon from PSII/P680 will replace the loss of electron in P700

10. Electron pass through second ETC/ferredoxin

11. And accepted by NADP+ to form NADPH

12. Catalyzed by NADP+ reductase

7(c) State five (5) differences between cyclic photophosphorylation and non-
photophosphorylation.

Cyclic photophosphorylation Non-cyclic

photophosphorylation

Involve only photosystem I Involve photosystem I and II

Produce ATP, NADPH Produce only ATP

and oxygen

Electron travel in a cyclic Electrons travel in non-cyclic
manners/returns to reaction center manners/

do not to reaction center

Photolysis of water is absent Photolysis of water is present

Oxygen is not evolve/release Oxygen is evolve/release
System is prominent in bacteria System is prominent in green plant

8(a) Explain Bohr effect in active tissue.
 In active tissue, respiration rate increase
 More CO2 is release / increase
 CO2 release and reacts with water
 Forming carbonic acid / catalyzed by carbonic anhydrase H2CO3
 H2CO3 dissociated
 Forming H+ / hydrogen ion and HCO3 / carbonated ion/hydrogen carbonated
 Increase acidity / decrease pH in blood
 Reduced affinity of hemoglobin for 02
 Oxygen dissociation curve shifts to the right
 More oxygen dissociate from oxyhemoglobin Hb(02)4
 02 can be loaded more efficiently to active tissue

8(b) Explain how light becomes a factor in relating the stomata
 During day time / light present guard cells carry out photosynthesis
 Glucose is produced
 Glucose dissolves in water
 Decreasing the water potential of the guard cells
 Water diffuses / enters from epidermal cells into the guard cell by osmosis
 Turgor pressure increase
 Guard cells become turgid

 The stomata opens
 During night time absent of light guard cells do not carry out

photosynthesis
 Glucose is converted into starch
 Increase water potential of the guard cells
 Water diffuses/ enters into the epidermal cells from the guard cells osmosis
 Turgor pressure decrease
 Guard cells became flaccid
 The stomata closes

9. (a) Explain the cardiae cycle that lead to heartbeat
 Sinoatrial /SA node pace maker/generate electrical inmmpulse
 Spread to both atria to contract / atrial systole // both atria contract
 Blood flows from atria to ventricles
 Impulses arrives at AV node and delayed for 0.1 second
 Impulse travels to bundle of His and bundle branches
 To the heart apex and spreads to the both ventricles via Purkinje fiber/
tissue
 Both ventricles contract/ ventricles systole
 Pressure in ventricles is higher than pressure in atria
 Causing AV valve to close (to prevent backflow of blood into atria)
 Lub' sound is produced
 Semilunar valve open, blood pumps/ flows out of heart through aorta and
pulmonary artery

 Both atria and ventricles relax / diastole
 Pressure in aorta/pulmonary artery is higher than ventricles
 Semilunar valve close (to prevent backflow of blood into ventricles)
 Dub' sound is produced
9(b) By using Pressure Flow Hypothesis, describe sugar transportation in phloem
 Sucrose is produced by photosynthesis in source cell // Glucose is

produced by photosynthesis and converted to sucrose in source (cell)
 Sucrose is loaded from source cell into sieve tube
 By active transport // using Alp supplied by companion cells
 Accumulation of sucrose in the sieve tube lowers than water potential
 Water diffuses / moves from xylem into sieve tube by osmosis
 Increase hydrostatic/ turgor pressure in sieve tube
 Hydrostatic pressure in the sieve tube near the sink cells is low
 Creating pressure gradient along the sieve tube (between the source and

the sink)
 (Hydrostatic pressure) force phloem sap to flow along the sieve tube from

source to sink cell
 Sucrose is unloaded from sieve tube into sink cell
 Water potential in sieve tube (near the sink cell) increase
 Water diffuses/ moves from sieve tube into the xylem by osmosis