sains dan biologi adlh kehidupan untuk mengenali Maha Pencipta: 2012

SKEMA JAWAPAN PEPERIKSAAN PERTENGAHAN TAHUN 2012

BIOLOGI KERTAS 2

NO.

SCORING CRITERIA

MARK

REMARK

1 (a)

(i) able to label the structures of P,Q,R and S

P : nucleus

Q : chloroplast

R : Mitochondria

S : vacuole

4 correct= 2m

2-3 correct =1m

0-1 correct=0m

2 m

(ii) able to state a function of the structures P and R

P : controls all the activities which take place in the cell (example the synthesis of proteins is regulated by coded information contained in the chromosomes)

R : sites of cellular respiration//release energy through the oxidation of food substances ( such as glucose) // generate energy in the form of ATP ( which can be used readily by cells)

Accept any suitable answer

(iii) able to state one similarity between Q and R

Ø Both have double menbrane

(iv) able to explain why organelle Q present in a green plants only

F1 : green plants cells need chlorophyll that contain in this organelle/chloroplast

E1 : chlorophyll absorbs/traps light energy (and convert light energy into chemical energy during photosynthesis.

(v) able to exlplain how S maintain cell turgidity

F1 : the cell sap in the S/vacuole contains water and dissolved substances

E1 : when water enter/diffuse into the cell(by osmosis), it fills up the vacuole causing it to expand

E2 : this creates turgor pressure within the cell and maintains its turgidity

1(b)

Able to state two differences between a palisade cell and cheek cell

Palisade cell	Cheek cell
Cell wall present	Cell wall absent
Chloroplast is present	Chloroplast is absent
A large central vacuole is present	No large central vacuole
Have a fixed shape	Do not have a cheek cell

Any 2

TOTAL

12 M

2(a)

Able to label the structures

J- hydrophilic heads

K-hydrophobic tails

L-pore protein

M-carrier protein

2(b)

Able to name the model

Ø Fluid mosaic model

2(c)

(i) able to state the characteristics

Ø Semi permeable

(ii) able to explain the substances

P1: glucose/amino acids/nucleic acids because large polar molecule/not soluble in lipid

P2 : Mg²⁺/Na⁺/Cl^-(any suitable ions) because the molecule is ions/charged

(iii) able to state the structure

Ø Carrier protein/M

2(d)

Able to name two factors

Ø Polarity

Ø Size

2(e)

Able to explain the statement

Ø To make plasma membrane more rigid and stable/flexible and dynamic

TOTAL

12M

3(a)

Able to label X,Y and Z in figure 3.1

X : lactose

Y : glucose

Z : galactose

3-2 correct= 2m

1 correct =1m

3(b)

Able to state the characteristics of enzyme

P1 : do not destroyed by the reactions they catalyst

P2 : highly specific

P3 : can catalysed the reaction in either direction/reversible

3 (c)

Able to explain different effectiveness of cleaning in different temperature

F1 : all (the organic) stain remove from the cloth at 40⁰C

E1 : because enzyme is active // can hydrolysed organic stain

F2 : (the organic) stain is partially remove at 0⁰C

E2 : because enzyme is not active//cannot hydrolysed organic stain

F3 : (the organic) stain is not remove at 60⁰C

E3 : the enzyme cannot hydrolysed (the organic) stain totally because enzyme is denatured

3(d)

Able to predict the effectiveness of cleaning her cloth

F : (the organic) stain is partially removed

E1 : lime juice cause medium of cleaning become acidic

E2 : enzyme cannot hydrolysed the organic stain

TOTAL

12M

4(a)

Able to answer what is the cell

Ø The basic unit of life/living thing

4(b)

Able to name cell P and tissue Q

P : epithelium cell

Q : smooth muscle tissues

4(c)

Able to explain the organization and functions of tissues Q and stomach

Tissue Q :

Ø Made up of (many) smooth muscle cell

Ø Perform/ carry out (specific function) muscle contraction/contraction of stomach wall

Stomach :

Ø Made up of (many) tissues Q/epithelial tissues and smooth muscle tissues

Ø Perform / carry out (specific function) the digestion of food/protein

4(d)

(i) able to state the level R of the cell organisation

Ø Organ

(ii) able to state the formation of the level R

R : an organ is formed by two or more type of tissues working together to perform a particular function

4(e)

Able to explain the differentiation process of cell P to secrete gastric juice in stomach

P1 : cell P grows and changed their structure

P2 : they are organized into tissues that lining the inner space of stomach

P3 : cell P become specialized and adapts to become a group of cell and form gastric glands

P4 : in form of tissues, secretion of gastric juices more efficiently

TOTAL

5(a)

Able to give the name of the process

X : simple diffusion

Y : facilitated diffusion

Z : osmosis

5(b)

(i) able to give definition of osmosis

F : the movement of water molecule from higher concentration of water molecule/hypotonic solution to lower concentration of water molecule/hypertonic solution through semi-permeable membrane (until dynamic equilibrium is achieve)

5(b)

(ii) able to explain the preservation of fish

P1 : immersed fish in the natrium solution

P2 : water in fish diffuse out by osmosis cause bacteria in fish die

5(c)

Able to state the similarities and differences between facilitated diffusion and active transport

Similarities

S1 : both require protein molecule

S2 : both the movement of substances from higher concentration molecule substances to lower concentration

S3 : both occur through plasma membrane

Differences

D1 : facilitated diffusion no need energy while active transport need energy

D2 : in facilitated diffusion, the movement of substances down the concentration gradient while active transport against concentration gradient.

Any one

Any two

5(d)

Able to explain how sodium solution move out.

P1 : the sodium solution in the cell move out by active transport/ against concentration gradient

P2 : energy/ATP is required

P3 : sodium ion bind with active site of the carrier protein

P4 : carrier protein is modified/change their shape (to move out the sodium ion)

TOTAL

12m

6(a)

(i) able to state what is the internal environment and physical and chemical factors

F : consist of the interstitial fluid and the blood plasma

P1 : physical factors : temperature/blood pressure/osmotic pressure

P2 : chemical factors : pH value/salt/sugar content

6(a)

(ii) able to explain the importance of regulating the optimum condition of the internal environment

F : oppose the effects changes

E1 : ensure optimum cellular activities

E2 : stable internal environment

E3 : enable organism to live in wider range of habitats

E4 : metabolic activities/ physiological process can still continue(even though the external environment change)

E5 : organism able to control metabolic rate

E6 : more efficient and optimal metabolism in the cell

6(b)

(i) able to name the system involves the organ in diagram 6.1 and explain how the organ react to maintain the body temperature at 37⁰C in a hot day

F1 : integumentary system

E1 : erectors muscle relaxes

E2 : to enable the hair follicle lie down

E3 : less/thin layer of air trap

E4 : sweat gland active secrete sweats

E5 : increase amount of heat lost to the surroundings

6(b)

(ii) able to state another two system that help to regulate body temperature and describe how does the system work in hot day

F1 : nervous system

E1 : when body temperature rises, the receptors in the skin detect the changes

E2 : information transmitted to the brain /hypothalamus

E3 : brain/hypothalamus activates various effectors/sweat gland/blood vessels

F2 : circulatory system

E4 : arterioles/ blood vessel (in epidermis) dilate

E5 : more blood flows to the skin //more heat release

F3 : endocrine system

E6 : produces hormones to reduces the metabolic rate

E7 : produces hormones to reduces production of heat

Any 2F and 4E

TOTAL

20 m

7(a)

(i) able to explain the process experienced by plant cell after immersion in 30% sucrose solution for 30 minutes

E1 : cell undergoes plasmolysis

E2 : 30% sucrose solution is hypertonic than the plant cell

E3 : water molecules diffuse out of the large central vacuole by osmosis

E4 : both the vacuole and cytoplasm shrink

E5 : plasma membrane pulls away from the cell wall

E6 : the cell become flaccid

E7 : the cellulose cell wall does not shrink because it is strong

Any 6

7(a)

(ii) able to describe how do you make the plant cell in retains its normal shape

E1 : by immersing the plant cell Q in 0.5% sucrose solution/isotonic solution

E2 : 0.5% sucrose solution is isotonic to the plant cell sap

E3 : water diffuses into and out of the cell at equal rate

E4 : by osmosis

E5 : no net movement of water across the plasma (causes the cell retains its normal shape)

Any 4

7(b)

Able to explain the concepts applied in the preservation of the pickled papaya

E1 : papaya slices is soaked in a concentrated sugar solution

E2 : these preservatives/sugar solution will make the solution outside the papaya slices/fruit/food more concentrated/hypertonic compared to the content of the papaya cells

E3 : water molecules diffuse into the papaya cells by osmosis

E4 : the cells in papaya become dehydrated/flaccid//the food become dry

E5 : causing the microorganism/bacteria/fungus cannot survive

E6 : (at the same time) microorganism/bacteria/fungi also lose water by osmosis(to surrounding solution) and will eventually die

E7 : as a result, the papaya/ fruit can last longer

Any 6

7(c)

Able to explain the differences between the process experienced by the red blood cell X and Y after being immersed for half an hour.

Red blood cell X	Red blood cell Y
Cell X undergo crenation	Cell Y undergo heamolysis
3 % sodium chloride solution hypotonic compared to cytoplasmic fluid cell X	0.1 % sodium chloride solution hypertonic compared to cytosplamic fluid cell Y
Water molecules diffuse from cell X to 3 % sodium chloride solution by osmosis	Water molecules diffuse from 1% sodium chloride solution into cell Y by osmosis
Cell X shrink/shrivel/plasma membrane of the cell X crinkles up	Cell Y swells up and eventually burst.

TOTAL

20M

8(a)

Able to state the importance of water in cells

E1 : as a medium for biochemical reaction in the cell

E2 : a good solvent for many substances

E3 : as a transport medium within cells / between the cell

E4 : as a major component of protoplasm

E5 : allows the chemical changes to take place in solution

E6 : provide moisture to the respiratory surface/alveoli to enable respiratory gases/oxygen and carbon dioxide to dissolve

E7 : provide support for non-woody/herbaceous plant when the cell turgid

E8 : maintain body temperature

Any 6

8(b)

(i) able to describe the structure of nucleic acids

E1 : nucleic acids contains carbon, hydrogen, phosphorus and nitrogen

E2 : basic unit of nucleic acids is nucleotide

E3 : nucleotide consist of pentose sugar, phosphate and nitrogen base

E4 : two type of nucleic acids : RNA( ribonucleic acids) and DNA (deoxyribonucleic acids)

E5 : DNA consists of two strands polynucleotide twisted into a double helix

E6 : RNA consist of single strands of polynucleotide

Any 4

8(b)

(ii) able to state importance of nucleic acids in cells

E1 : carry genetics information (in all living cell)

E2 : control all the main activities in the cell

E4 : (carry genetics information) for synthesis of proteins

Any 2

8(c)

(i) able to name structures A,B, C and D

A : primary structure of protein

B : secondary structure of protein

C : tertiary structure of protein

D : quarternary structure of protein

1111

8(c)

(ii) able to explain the type of amino acids and classes of protein

Two type of amino acids :

E1 : essential amino acids : amino acids cannot be synthesised by body cell

E2 : non-essential amino acids : amino acids can be synthesised by body cell

Two classes of protein :

E3 : first class protein : contain all the essential amino acids

E4 : second class protein : lacks a few of essential amino acids

TOTAL

20 M

9(a)

(i) able to name the stages and state two importance of mitosis

P : metaphase

Q : prophase

R : anaphase

Importance :

P1 : produced new cells

P2 : replace dead and damage cells

P3 : basic of asexual reproduction

Any 2

9(a)

(ii) able to rearrange the stages in correct sequence and draw daughter cells

Q >> P >> R

Drawing :

ü Must have two daughter cells

ü Correct number of chromosomes – 4

ü Label at least 3:

Ø Chromosomes/chromatid

Ø Nuclear membrane

Ø Cell membrane

Ø Nucleolus

9(b)

Able to explain the differences of cytokinesis process in animal and plant cell

F1 : cytokinesis in animal cell occur by formation of cleavage furrow while in plant occur by the formation of cell plate

Cytokinesis in animal cell

E1 : actin filaments contract to pull a ring of plasma membrane inward

E2 : forming a groove called cleavage furrow

E3 : (cleavage furrow) pinches the equator of the cell

Cytokinesis in plant cell

E4 : a vesicle gather at an equator(between two nuclei)

E5 : (vesicle) fuse to form a cell plate

E6 : (cell plate) grow outwards and fuse with the plasma membrane

Any 6

9(c)

Able to explain the technique of tissues culture

F1 : method used tissues culture/cloning

E1 : tissues from parent plant/stem/shoot/leaves is taken out

E2 : tissues is sterile to prevent infection of microorganism

E3 : cultured in sterile medium(containing nutrients and growth hormones)

E4 : cells divide by mitosis to form a callus

E5 : plantlets transferred to the soil and grow into adult plants

Any 4

TOTAL

20M

nama	overall sum	Gred
AZRIEF RAZIQ KHAN BIN MOHAMED AMIR KHAN	70	A-
CHEW HUI YEE	86	A
CHEW JIA TEE	76	A-
CHING JOO YEE	66	B+
CHONG JIA LIN	77	A-
CHUA YU ZE	64	B
CHUNG WEI LENG	82	A
GUNASUNDARY A/P CHANDRAMOHAN	72	A-
HO HAO YANG	78	A-
HU ZHEN XHUO	76	A-
IZZAH SYAZWANI BINTI ROSLI	54	C
SYUKRI BIN SUHADI	81	A
JESSICA TEO WEI SHAN	73	A-
KOKKILAH A/P BALU	77	A-
LAW JIA HAO	78	A-
LEE YI LING	76	A-
MARILYN A/P CHRI STEVEN	76	A-
MIZAN QISTINA BINTI HAJI ISMAIL	48	D
NORHIDAYAH BINTI ROSLAN	47	D
NUR SYAZWANI BT ABD GHANI	57	C+
NURALIAH BINTI MAHPORD	71	A-
NURASHIRAH BINTI MAHPORD	70	A-
ROZERA NATRAH BINTI ABD RAHMAN	54	C
SARMELA A/P RAJA SEKARAN	85	A
SITI HAMIZAH BINTI SAMSUDIN	58	C+
SOBANA A/P MANIVANNAN	70	A-
SU XIN YI	78	A-
TAN HUI JEE	67	B+
TAN KOON SAN	75	A-
TAN PEI ZHIN	68	B+
THAM HWEE PENG	70	A-
YAP SHOU XUAN	74	A-

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