T3W5 ZHSS 4E BIO Prelim MS 2023 Final

1 Zhonghua Secondary School Preliminary Examination 2023 Secondary 4E Biology Paper 2 – Section A: Structured Questions (50 marks) No Marking Points Marks Remarks 1(a) Salt / Sodium chloride / any solute that can be found in sea water (eg. sucrose, glucose, amino acids) 1 1(b) As the % seawater increases, the rate of contractile vacuole output decreases As the % seawater increases, the difference of water potential between seawater and cytoplasm decreases Contractile vacuoles expel less water to maintain osmotic pressure / water potential in the organism to prevent dehydration 1 1 1 1 ORA not accepted due to nature of question 1(c) The higher the seawater %, the smaller the body volume 1 ORA not accepted due to nature of question 1(d) The cell burst / undergo lysis Any one The contractile vacuole is ineffective in expelling water (at % lower than 20% seawater The cell takes in too much water via osmosis (leading to lower rate of contractile output) 1 1 1 2(a)i Anywhere in shaded area between 2 and 9 min 1 2(a)ii The lungs and heart cannot meet the oxygen demand 1 2(b) Oxygen uptake cannot meet demand + during the 4 min Anaerobic respiration occurs; Glucose oxidised to lactic acid + energy release to supplement demand; 1 1 1 2(c)i Decreases from high at time 0 + Levels at about 12 mins and remains 1 2(c)ii Glycogen is broken down into glucose (thus increasing blood glucose concentration); for increased respiration rate + to meet increased energy demand 1 1 2(d) lactic acid curve rises sooner / higher / takes longer to return to normal 1

2 No Marking Points Marks Remarks 3(a) Aerobic respiration / oxidation of glucose takes place to release energy for active transport (during selective reabsorption) 1 1 3(b) Provide a large surface area to volume ratio; rapid diffusion/reabsorption of nutrients like glucose and amino acids 1 1 3(c) Difference Proximal tubular cells are replaced by thin dialysis membrane surrounded by dialysis fluid; no active transport in dialysis machine but diffusion occurs; Similarities with same concentration of glucose and minerals; Microvilli are similar to long narrow tubing + to provide large surface area to volume ratio both processes aid in removal of urea 1 1 1 1 1 4(a)i C – sweat gland D – adipose/fatty tissue/layer 1 Reject: fat (it is not a structure) 4(a)ii any two from: less food eaten / less fat in diet / exercise; so fat used by body + for respiration / release energy ; body using more energy than it is taking in ; 1 1 1 4(b) A is a receptor / nerve ending; touch / pressure / pain / temperature ; examples of uneven distribution e.g. high density in fingers / lips ; exposed areas + need higher sensitivity AW ; 1 1 1 4(c) less blood flows + in blood vessel / close to skin surface decrease in radiation / he