answer scheme paper 2 form 5 midterm 2011

8/6/2019 Answer Scheme Paper 2 Form 5 midterm 2011

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ANSWER SCHEME SECTION A (PAPER 2 FORM 5)

No Marking Criteria Marks

1.a.

(i)

(ii)

Active transport is the movement of molecules or ions against the

concentration gradient across the plasma membrane.

Active transport requires carrier protein.

Active transport need energy to transport molecules or ion.

Intake of mineral at the root hair / accumulation of iodide ions in algae

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1

1

1

4

b

Active transport Passive transport

Molecules move against the

concentration gradient from a

region of lower concentration ofsubstances to a region of higher

concentration of substances

Molecules move down the

concentration gradient from a

region of higher concentration ofsubstances to a region of lower

concentration of substances

The process will not reach anequilibrium but result in the

accumulation of substances in the

cell or removal of substances fromthe cell

Occurs until a dynamicequilibrium is reached

ATP or energy is required ATP or energy is not required

Molecules move through carrier

protein only

Molecules move through pore

protein, carrier protein or lipid

bilayer

1

1

1

1

Max

2m

c Carrier protein is specific / carrier protein can change shape to allow the

molecules to pass through

1

1

d Energy is used to change the shape of carrier protein 1 1

e 1. Facilitated diffusion2. Osmosis

3. Simple diffusion

4. Active transport

TOTAL

11

1

1

4m

12m

1


2/15

No. Marking Criteria Mark

2(a)

(b)

(c)

(d)

(e)

Able to state the hypothesis

Answer : Lock and key

Able to label P, Q, R and S

Answer :

P : Enzyme

Q: Substrate

R: Enzyme Substrate Complex

S: Product

i. Enzymes are active site to bind to specific substrates

ii. Enzymes are not destroyed by the reaction they catalyse

iii. Enzymes are protein

iv. Enzymes are denatured by high temperature

v. Enzymes react at maximum rate at optimum temperaturevi. Enzymes action are reversiblevii. enzymes are needed in small quantities

37 C

- At low temperature an enzyme reaction takes place slowly

- As the temperature increases, the movement of substrate

molecules increases

- For every 10 C rise in temperature the rate of enzyme reaction

is doubled- At the optimum temperature the rate of enzyme reaction is at the

maximum rate

- At high temperature the enzyme is denatured, the active site is

destroyed

- The rate of reaction of enzyme decreases.

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1

1

1

1

1

11

1

1

1

1

1

1

1

Any 3

TOTAL

1

4

MAX3

1

MAX

3

12

No Marking criteria Marks Total

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3/15

marks

3 (a)(i) Able to name stages X and Y .

Answer: X : Prophase I

Y : Metaphase I(ii) Able to explain the differences in chromosomal behavior

At X and Y.Sample Answer:

Prophase I Metaphase I

(Paired homologouschromosomes) are arranged

randomly.

(Paired homologouschromosomes) are arranged

on the metaphase plate /

equatorial plane.

Spindle fibre does not hold

on the centromer of thechromosomes .

Spindle fibre holds on the

centromer of thechromosomes.

(The homologouschromosomes paired and)

crossing over take place.

(The homologouschromosomes paired)

crossing over does not take

place.

Any 2

(b)(i) Able to explain the occurrence at Z.

Sample answer:P1 : Four daughter cells formed

P2 : Each daughter cell has two chromosomes / haploid / n

(ii) Able to state the chromosome number in the daughter

cell and give reason for the answer.Answer:

Six (chromosomes)

Reason:

(During meiosis) the daughter cell (n) receives halfThe number of chromosome from the parent cell (2n)

(c)(i) Able to explain why the chromosomes contain 24

chromosomes.

Sample answer:1. Homologous chromosomes fail to separate equally

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1

1

1

1

1

1

2

2

2

2

2

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4/15

(during anaphase I)

2. due to exposure to mutagen // any example of mutagens

(c)(ii) Able to name the genetic disease faced by the

offspring.Downs Syndrome

( c ) iii.Broad face,has short tongue,short stature,slanted eyes

1. // any suitable characteristic.

1

1

1

2

Total 12


4


5/15

4(a)

X : Cellular respiration / aerobic respiration

(b) Y : Carbon dioxide

(c) Able to name the organelle in the cellMitochondria

(d) Able to state differences between aerobic respiration and

anaerobic respiration

Sample answer :

Aerobic respiration Anaerobic respiration

- oxygen is present

- carbon dioxide,

water and energyare produced

- 38 molecules of

ATP are generate

- large amount of

energy is released(2898 kJ)

- in mitochondria

- oxygen is absent

- lactic acid and

energy (in musclecells) or ethanol,

carbon dioxide,

and energy (inyeast)

- 2 molecules of

ATP are generate

- small amount of

energy is released(210 kJ duringfermentation) and

(150kJ in muscle

cells)

- in cytoplasm

(e) (i) Able to state an example of receptor

Sample answer :

Central chemoreceptors // Peripheral Chemoreceptor //Aortic bodies and Carotid bodies

(ii) Able to describe how the change of oxygen content and

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1

1

1

1

1

1

1

1

Max:

2m

5


6/15

carbon dioxide content is regulated by the body.

Sample answer :

- The higher level of carbon dioxide in the blood cause

the drop of pH value

- The drop in pH is detected by Central Chemoreceptorin Medulla Oblongata

- Then the Central Chemoreceptor send the nerveimpulses to the respiratory centre.

- The respiratory centre send nerve impulse to the

diaphragm and intercostal muscle, causing (respiratory

muscles) to contract and relax faster.- Finally, increases the breathing and ventilation rate

- Concentration of carbon dioxide and pH value of the

blood return to normal levels.

(f) (i) Able to state another situationSample answer :- Climbing a mountain

(ii) Able to state the symptom

Sample answer :- headaches/ nausea/ dizziness.

TOTAL

1

1

1

1

12m

Max:

4m


6


7/15

5a)(i)

(ii)

(iii)

Able to name the part labeled P and R

Sample answer

P: Pulmonary vein

R: Septum

Able to shade the cavity of ventricle Q

Able to state the meaning of oxygenated blood.Sample answer

It contains oxygen which was picked up by the capillariessurrounding the alveoli

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1

1

14

(b) Able to explain the different thickness of Q and S.

Criteria:F: blood flow

P: function

Sample answer

F: The Q pump blood out from heart to all round the body

P: To withstand the high pressure of blood flowing through them

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1 2

(c)(i)

(ii)

Able to label the bicuspid valve with letter T.

Able to explain the function of bicuspid valve.

Sample answer

F: to stop/prevent blood flowing from the ventricles back to the

atriaP: (so that when the ventricles contract) the blood is pushed up

into the arteries not back into the atria.

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1

1

3

(d))(i)

(ii)

Able to state one activities of human which cause a clot

Sample answer

High fat diet//smoking//lack of exercise//stressful life//diet whichrich in saturated fat

Able to explain the result of a blockage

Sample answer

F: cardiac muscles run short of oxygen

P: so they cannot contract/stop beating/heart attack/cardiac arrest.

TOTAL

1

1

1 3

12

ANSWER SCHEME SECTION B

7


8/15

Item

number

Criteria Marks Not

6 (a)

(b)

Able to explain how unicellular organisms like theAmoeba sp. carries out the

process of food digestion and absorption;

P1 - Amoeba sp. feeds by phagocytosis

P2 - Amoeba sp. extends its pseudopodia to engulf food particles

P3 - The food particles are packaged in a food vacuole

P4 - The food vacuole fuses with a lysosome which contains hydrolytic enzyme called

lysozyme

P5 - The food particles are digested by lysozyme and the nutrients produced diffuse into

the cytoplasm

Able to explain the problems faced by Paramecium sp. and how they maintain

their water balance;

P1 - The main problem faced byParamecium sp. is the continuous diffusion of water

into the cell by osmosis.

P2 - This is because the external environment is more hypotonic than the cytoplasm of

the cell.

P3 - The control of water balance in the cell (osmoregulation) is aided by two contractile

vacuoles, one at the anterior and the other at the posterior.

P4 - Contractile vacuoles accumulate the excess water

P5 - Periodically, the contractile vacuoles will contract to expel the water through the

plasma membrane

P6 - The plasma membrane ofParamecium sp. is also less permeable to water

TOTAL

1

11

1

1

5 marks

1

1

1

1

1

1

max

5 marks

10 marks

Item

number

Criteria Marks Notes

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9/15

(c)Able to explain why certain cells have a high density of each type of organelle;

P1 - Sperm cells contain a high density of mitochondria because they require energy to

propel themselves towards the uterus and Fallopian tubes,

P2 - to fertilise the ovum during fertilisation

P3 - Mitochondria are also found abundantly in the flight muscle cells of insects and

birds

P4 - to generate energy for movement and flight

P5 - Merismatic cells also have a high density of mitochondria.

P6 - These cells need energy to undergo active cell division to produce new cells

P7 - The Golgi apparatus are found abundantly in the goblet cells in the intestinal

epithelium and respiratory tract

P8 - to secrete mucus

P9 - Smooth endoplasmic reticulum is found abundantly in the intestinal epithelial cells

P10 - to produce digestive enzymes

TOTAL

1

1

1

1

1

1

1

1

1

1

Max

10 marks

Item

number

Criteria Marks Not

7 (a)Able to explain the meaning of a balanced diet;

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(b)

A balanced diet is a diet that

P1 - consists of all the seven classes of food,

P2 - in the correct quantities,

according to the individuals needs to ensure optimum health

Able to explain the effects of insufficient roughage in a diet;

P1 - Constipation. Faeces which remain in the colon for long period of time become

hard and a person will have difficulty in defaecation.

P2 - Chronic constipation is associated with haemorrhoids.

P3 - Haemorrhoids are abnormally swollen veins in the rectum and anus. When bulging

haemorrhoidal veins are irritated, they cause the surrounding membranes to bleed.

Effects of excessive fat intake:

P4 - When a person consumes more calories than is required for metabolism, his body

will store the excess calories in the form of fat in the adipose tissues.

P5 - The habit of consuming a diet high in fat content and of oily food can cause high

blood pressure and give rise to cardiovascular diseases.

P6 - Excess cholesterol deposited on arterial walls (arteriosclerosis) can cause a

blockage of the arteries.

P7 - The lumen of arteries becomes narrow and this inhibits blood flow. Blood pressure

increases (hypertension). The heart is forced to work harder to pump blood.

P8 - If the lumen of the coronary artery (artery in the heart) narrows, a heart attack is

likely to occur, especially when a person is carrying out strenuous activity or when his

emotional condition forces the heart to beat harder. This is known as angina and is

caused by insufficient oxygen supply to heart muscles.

TOTAL

1

1

2 marks

1

1

1

1

1

1

1

1

8 marks

10 marks

Item

numberCriteria Marks Not

(c)Organ Gland/organ Secretion Enzyme activity

Mouth Salivary gland Saliva contains Starch+watermaltose

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11/15

8 (a)

(b)

salivary amylase

Stomach Gastric gland Gastric juice contain

pepsin and rennin

Protien+waterpolypeptide

Caseinogen+watercasein

Duodenum Pancreas Pancreatic juice Starch+watermaltose

Polypeptide+waterpeptide

Lipid droplets+waterfatty

acids+glycerol

TOTAL

Able to explain how the greenhouse effect occurs;

P1- when solar radiation enters the Earths atmosphere, some of its radiation is

reflected back to spaceP2- and most of the radiation is absorbed by Earth which warms the surface of the

earth

P3- heat in the form of infrared radiation is radiated back into space

P4- much of this heat does not escape from the atmosphere because it is trapped by

the greenhouse gases/ carbon dioxide/ CFC/methane/ nitrous oxide

P5- this causing the atmosphere to be warm and increase the temperature of the

Earth

Able to describe the greenhouse effect on the environment and living organisms

on the earth;

F1: melting of the polar ice caps and glaciers takes place at a faster rate/ rise in thesea level

E1: agricultural activities will be disrupted, marine life and biodiversity will be

affected and human health will eventually be affected

F2: the quantity of water vapour in the atmosphere is higher because of greater

evaporation of water

E2: the greenhouse effect more pronounced

F3: changing local weather patterns

E3: drought/ greater rainfall/ change the distribution of species such as extinction

of some species in certain regions/ pest and vectors may spread to new areas

TOTAL

Able to discuss the good and bad effects of the activity;

Good effects:-

10 marks

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1

1

1

1

1

1

1

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1

10 marks

1 Accep

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12/15

F1 Provide jobs

E1 can increase social status

F2 Produce economic resources

E2 can increase national economic

Bad effects:-

F1 Air pollution

E1 Carbon monoxide causes fatigue/impairs alertness//

Sulphur dioxide causes asthmatic attacks/damages respiratory system//

Oxides of nitrogen causes damage to leaves and roots/respiratory infection

F2 Acid rain

E2 Soil becomes very acidic and unsuitable for cultivation of crops//

Causes leaching of mineral such as potassium, calcium and magnesium//

Photosynthetic tissues are destroyed//

Increase acidity in aquatic ecosystem which kills the plankton/change the

food chain //Acidic soil releases the ion of certain heavy metals which may contaminate

the supply of drinking water

F3 Eutrophication

E3 BOD of the water increases/oxygen content in the water decreases//

The aquatic organism in the water dies

F4 Water pollution

E4 agricultural run-offs and waste causes eutrophication//

Untreated sewage reduced light penetration//

Domestic waste such as detergents causes eutrophication//

Effluents from industries contains heavy metals that are highly toxic and

1

1

1

Max

2 marks

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

if F

corre

(2 ma

Accep

if F

correbut

can

accep

for m

than

answ

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13/15

can cause acute nervous disorders in human

F5 Thermal pollution

E5 oxygen becomes less soluble in water//

For algae, their rapid growth are encouraged which in turns leads to a

higher BOD value

TOTAL

1

1

1

1

Max

8 marks

10 marks

Item

number

Criteria Marks Not

9 (a)Able to explain the adaptations of the plant which enables it to float;

P1 - Has aerenchyma so that the plant is light. 1

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14/15

(b)

(c)

P2 - Has air spaces so that the plant can float easily

P3 - Has many roots which are fine to trap gas bubbles

P4 - Stems are large to increase the air content to help the plant to float

Able to explain how the skeletal system of each organism is adapted for its

movements;

Earthworm:-

P1 - Hydrostatic skeleton. It moves by changing the hydrostatic pressure of its body

fluid.

Mempunyai rangka hidrostatik. Cacing bergerak dengan mengubah tekanan

hidrostatik bendalir di dalam badannya.

P2 - Circular muscles and longitudinal muscles act antagonistically. This causes the

transfer of hydrostatic pressure from the anterior to the posterior which causes the bodyto move to the front.

Otot berlingkar mengecut dan otot membujur mengendur secara antagonis. Hal inimenyebabkan tekanan hirdostatik dipindahkan dari bahagian anterior ke posterioryang menyebabkan cacing bergerak ke hadapan.

P3- Causes the transfer of hydrostatic pressure

Menyebabkan pemindahan tekanan hidrostatik

Fish:-P1 - Endoskeleton

Ikan mempunyai rangka dalam

P2 - Muscles attached to endoskeleton

Endoskeleton ialah tempat pelekatan otot.

P3 - Left myotome and right myotome act antagonistically

Otot miotom kiri mengecut dan otot miotom kanan mengendur secara antagonis

P4 - Tail moves left and right producing a forward force

Ekor bergerak ke kiri dan ke kanan menghasilkan tujahan ke hadapan

TOTAL

Able to explain how the above movement takes place;

P1 - Tendons join muscles to bones

Tendon menghubungkan otot kepada tulang

P2 - Tendons are inelastic

Tendon ialah liat/ tidak kenyal

1

1

1

4 marks

1

1

1

1

1

1

1

Max

6 marks

10 marks

1

1

14


15/15

P3 - Force is transferred to the bones through the tendons.

Daya dipindahkan ke tulang melalui tendon

P4 - Ligaments join two bones at a joint

Ligamen mengikat dua tulang pada sendi

P5 - Ligaments give support to the joint during movement

Ligamen memberi sokongan pada sendi semasa pergerakan

P6 - Ligaments are strong and elastic

Ligamen adalah kuat dan kenyal

P7 - Quadriceps/ extensor muscle contracts whereas the biceps femoris muscles

relaxes, leg is straightened

Otot kuadrisep/ ekstensor mengecutmanakala otot bisep femoris mengendurdan

kaki diluruskan

P8 - Biceps femoris muscle contracts whereas the quadriceps femoris musclerelaxes, leg is bent

Otot bisep femoris mengecutmanakala otot kuadrisep femoris mengendurdankaki dibengkokkan

P9 - Calf muscle contracts to pull the heel

Otot betis mengecut untuk membolehkan tumit diangkat

P10 - Feet is pushed downwards and backwards, the repeated action of contraction and

relaxation produces the running action

Tumit ditolak ke bawah dan ke belakang, tindakan pengecutan dan pengenduranotot yang berulang-ulang menghasilkan tindakan berlari

P11 - Long and thick bone- gives strenght to support the body weight

Tulang yang panjang dan tebal di tengah memberikan kekuatan untuk menyokongberat badan

TOTAL

1

1

1

1

1

1

1

1

1

Max

10 marks

15

answer scheme paper 2 form 5 midterm 2011

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