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Transcript of SKEMA BIOLOGI K2






Question 1

Ques 1(a)(i)

Criteria Able name structure Q Answer:

Marks 1

Q : Epithelial tissue 1(a)(ii ) Able to state on adaptation of Q Sample answer P1 : consists of many / a group of epithelial cells P2 : has cilia Any 1 1( b ) Able to state two functions of structure Q in the trachea. Sample answer: P1 : build the lining wall of the trachea P2 : Cilia to sweep dust P3 : Secrete mucus that traps dust particles Any 2 Able to state the cell organization of level 4 Answer : System Able to explain one function of trachea in respiratory system Sample answer :. P1: Allows oxygen intake / carbon dioxide elimination P2; during inhalation/exhalation P3 : as trachea does not collapse P4 : made up of rings of cartilage Any 2 Able to explain one adaptation of the lung. Sample answer: P1: has many alveoli P2 : increase total surface area P3 : efficiency of gases exchange P4 : surface moist P5: easy for respiratory gases to dissolve Any 2 1( e ) Able to explain one difference in structure of the lung in individual M and N2

1 1

1 1 2 1 1 1 1 1 2 1 1 1 1

1( c )(i)


1( d )


1 1 1 1 1 3

Sample answer P1 : surface area of the lung in M is larger than N P2 : lung M has more smaller ( rounded ) structures/ alveolus /air sacs compare to N P3 : as( more ) alveolus/ (rounded) structures/air sacs in N have been damaged P4:by cigarette smoke in N P5: N alveolus shows symptom of emphysema P5 : decrease rate of gases exchange Any three Total 1 1 1 1 1


Question 2 Num 2(a) (i)

Criteria Able to name ways of transport X and Y and give reasons Sample answer X : Active transport t/ Passive transport Reason : Transportation molecules is against concentration gradient //lower molecules to higher molecules concentration Y : Facilitated diffusion Reason : Transportation is following concentration gradient //higher molecules concentration to lower molecules concentration 1 1 1 1

Marks 4

2( a )( ii )

Able to state two differences between way of transport X and Y . Sample Answer


X Needs energy ATP Against concentration gradient

Y Does not need energy Follows concentration gradient

1 1 1


Occurs in living cells

Occurs in living and non living cell Any 2

2( b )

Able to explain how amino acids molecules are transported by Y Sample answer P1 : Concentration of amino acids molecules is higher in outside cell compare to inside cell P2 : amino acids molecules binds to the binding site of carrier protein P3 :carrier protein changes shape P4 :allow molecules to pass through to the other side of plasma membrane P5 : carrier proteins change back to its original shape Any 3 1 1 1 1 1


2( c )

Able to explain the effect of cyanide in the transport of minerals Sample answer P1 : Active transport cannot be carried out P2 : Active transport needs energy P3 : cyanide disrupts respiration P4 : no energy is produced P5 : less/no mineral intake Any 3 Total 1 1 1 1 1



Question 3 Num





Able to name the type of cell division and stage M and N. Answer Type of cell division: Meiosis Stage M : Metaphase I Type of cell division : Mitosis Stage N : Metaphase Able to state the chromosomal behaviour of cell N. Sample Answer 1 1 1 1





P1: the chromosome /sister chromatids line up at the metaphase 1 plate /equator P2: the spindle fibre holds on the chromosome at the centromere 1 Any 1 Able to name structure P. Answer Centriole 1


3(c)(ii) Able to explain what happen to the daughter cell formed if there is no structure P in the cell Sample answer P1: no spindle fibres formed P2 : chromosomes are not held at the centromere during metaphase P3: (sister) chromatids are not separated P4 ( sister ) chromatids not able to move to the opposite poles P5 : daughter cell with unequal number of chromosomes formed P5: may lead to genetic disorder disease//any suitable name of the genetic disorder disease Any 3 Able to explain the importance of process Q to an organism Sample answer P1: process P is crossing over// exchange of genetic material P2 : leads to variation P3 : better adaptation to the environment P4 : better chance of survival of the species P5 : better adaptation to the environment Any 3 Total 1 1 1 1 1



3 1 1 1 1 1 12

Question 4 Num 4(a)

Criteria Able to identify organ R and S 5

Mark s 2


Answer: S : Stomach T : Pancreas Able to state the function of S/ stomach in the digestion process. Sample answer P1 : P2 : P3 : P4 : Gastric glands in S produced / secrete gastric juice Consists of pepsin / rennin / hydrochloric acid Pepsin hydrolyses protein to polypeptides Rennin coagulates soluble milk / caseinogens to casein. P5 : Hydrochloric acid provides an acidic medium// kill bacteria//stops the action of amylase Any 2

1 1 2

1 1 1 1 1

4(b) (ii)

Able to state the effect of taking meal at irregular time. Sample answer: P1 ( Having meals at irregular times ) result in the absence of food in the stomach at certain period. P2 : gastric juice (secreted by gastric gland) act on (the epithelial lining of) the stomach wall P3 : result to gastric ulcer / gastritis// pain in the stomach Any 2 1 1 1



Able to state the function of pancreas and effect of cancer of pancreas to the process of lipid digestion Sample answer P1: Cancer of pancreas prevents the pancreas from releasing the pancreatic juice into duodenum P2 : Lipase not secreated P3 : Lipids not hydrolysed by lipase P4 :to produce fatty acid and glycerol. Any 2 1 1 1 1



Able to state two adaptations of vilii in absorption process. Sample answer P1 : Has dense network of blood capillaries / lacteal P2 : Has a very thin wall / one cell thick wall 6 1 1


P3 : Has moist surface P4 : Has large number of villus P5 : to increase the rate of absorption of nutrient. Any 2 4(e) Able to explain the how amino acids is assimilated by liver Sample answer: P1 : Excess amino acid will be transported to liver/R P2 : By deamination process P3 : Liver /R hydrolysed amino acid into glucose and urea. P4 : This will lower the concentration of amino acid in the blood P5: Liver /R synthesized plasma proteins// forms enzymes/hormones Any 2 Total

1 1 1 2

1 1 1 1 1


Question 5 No. 5(a) ( i )

Criteria Able to name species in zone R , S and T Answer Zone R : Avicenia / Sonneratia Zone S : Rhizophora 7 1 1

Mark 3

Zone T : Brugeira 5(a)( ii) Able to explain two adaptations of species in zone R to survive in the ecosystem. Sample answer P1 : Has (long)cable root P2 :To give support in muddy soil/ traps the mud/soil P3 : Has viviparity seed /seed germinate while still being attached to parent tree P4 : To float / avoid sink in sea water / stands upright in the mud P5 : Has pneumatophores / breathing roots P6 : To obtain oxygen during high tide P7 : Leaves have thick cuticle// sunken stomata P8 : Reduce transpiration/water loss Any 4 Able to explain the changes in the ecosystem that will happen to zone S after 10 years Sample answer P1 : Zone S has prop roots P2 : trapped mud/sediments P3 : hardened the soil P4 : increase the soil level P5 : soil more fertile P6 : condition no more favorable for species in zone S P7 : Species in zone T replace species in zone S 5(c) Any 3 Able to explain one importance of mangrove swamp to maintain biodiversity Sample answer P1 : Provides habitat to organisms P2 : Provides breeding places for organisms P3 : Avoid from extinction P4 : Balanced the carbon cycle P5 : Maintain a balanced ecosystem Any 2 Total Question 6 Num Criteria 6(a) Able to explain the adaptations of alveolus in gaseous exchange. Sample answer P1: the wall of alveolus is only one cell thick P2: enables rapid diffusion of gases 8 1 1 1 1 1 1 1 1 1 1 1 1 1

1 4



1 1 1 1 1 1 1 2

12 Marks 4

1 1

6( b )

P3: inner surface of each alveolus is lined with a layer of moist epithelial cells P4: enables respiratory gases to dissolve in the fluid before diffusing across alveolar wall P5: outer surface is covered by a dense network of blood capillaries P6 : which provides a large surface area for rapid diffusion of gases to and from the alveoli. Any 4 Able to explain inhalation process in human Sample answer

1 1 1 1


P1: the external intercostal muscles contract P2: internal intercostal muscles relax P3: rib cage move outwards / upwards P4: diaphragm contracts and flattens P5: volume of thoracic cavity increases P6: causing air pressure within alveoli to decrease P7: higher atmospheric pressure outside causes air to rush in Any 4 6( c ) ( i ) Able to explain the need for anaerobic respiration. Sample answer P1: oxygen in muscle cells is insufficient P2: causes oxygen debt P3: lactic acids accumulates in muscle cells P4: may lead to muscle cramp P5 : panting/deep breath P6 : to pay oxygen debt Any 2

1 1 1 1 1 1 1


1 1 1 1 1 1

6( c )( ii )

Able to state 5 differences between aerobic respiration and anaerobic respiration Sample answer P1: Oxidation of glucose is complete in aerobic respiration 9 1


but 6( d ) oxidation of glucose is incomplete in anaerobic respiration P2