Formative Practice 3.4 (Form 4 Biology Textbook Exercise and Answer)

Question 1:Explain why green chillies are preserved using vinegar and sugar. Answer:The concentrated sugar solution is hypertonic to the cell sap of chili. Water diffuses out of the chili via osmosis. The chilli undergoes dehydration. Bacteria is unable to survive without water. Thus, pickled green chili can be kept for a long time.Vinegar reduces pH. … Read more

Formative Practice 3.3 (Form 4 Biology Textbook Exercise and Answer)

Question 1:Explain what will happen to the following cells when they are soaked in a solution with a higher concentration of solutes compared to the intracellular fluid:(a) red blood cells(b) plant cells Answer:(a) Red blood cells undergo crenation.(b) Plant cells undergo plasmolysis. Question 2:Explain the effect of the hypotonic solution on red blood cells. Answer:When … Read more

Formative Practice 3.2 (Form 4 Biology Textbook Exercise and Answer)

Question 1:Give some examples of substances that are able to pass through the phospholipid bilayer. Answer:Oxygen, carbon dioxide, water. Question 2:Describe how sodium ions are transported out of the cell. Answer:Three sodium ions bind to the carrier protein. The ATP molecule is broken down to ADP and P. The phosphate group binds to the carrier … Read more

Formative Practice 3.1 (Form 4 Biology Textbook Exercise and Answer)

Question 1:What are the two main components of the plasma membrane? Answer:Proteins and phospholipids Question 2:Explain the meaning of fluid mosaic model. Answer:The fluid mosaic model refers to protein molecules that are suspended in the phospholipid bilayer forming an ever-changing mosaic pattern. The phospholipid bilayer, proteins and cholesterols are not static but form a dynamic … Read more

3.4.2 The Movement of Substances Across the Plasma Membrane in Everyday Life (Structured Question 1 & 2)

Question 1:Diagram I and Diagram II show the movement of substances P and Q across the plasma membrane respectively. The movement of P needs energy but the movement of Q does not.(a) Name the processes involved in the movement of P and Q. (2 marks)(b)(i) Name one example of P and Q. (2 marks)(b)(ii) Describe … Read more