Exam (elaborations) 2021 Bio Mock Paper 1B latest

This paper must be answered in English INSTRUCTIONS FOR SECTION B (1) After the announcement of the start of the examination, you should first write your Candidate Number in the space provided on Page 1 and stick the barcode labels in the spaces provided on Page 1, 3, 5, 7 and 9. (2) Refer to the general instructions on the cover of the Question Paper for Section A. (3) Answer ALL questions. (4) Write your answer in the spaces provided in this Question- Answer Book. Do not write in the margins. Answers written in the margins will not be marked. (5) Supplementary answer sheets will be supplied on request. Write your Name, mark the question number box and fasten them with string INSIDE this Question-Answer Book. (6) Present your answers in paragraphs wherever appropriate. (7) The diagrams in this section are NOT necessarily drawn to scale. (8) No extra time will be given to candidates for writing personal information or filling in the question number boxes after the ‘Time is up’ announcement. © Billy Chu 及其生物科團隊 保留版權 Billy Chu and his Biology Team All Rights Reserved 2021 1 2 2. Read the passage below and answer the questions that follow: Ciguatoxin Ciguatoxin is a fat-soluble toxic chemical produced by some algae found in the tropical and subtropical coral reef. When fish feed on the algae, they will get the toxin. The toxin is difficult to be broken down or excreted by the fish. If a human consumes the comtaminated fish, ciguatera fish poisoning may result. The risk is higher if the comtaminated fish consumeed is of mass greater than 2 kg. The toxin can affect our nervous, digestive and/or cardiovascular systems. (a) Name the kingdom which algae belongs to. (1 mark) _________________________________________________________________ (b) In the space provided below, draw a pyramid of numbers for the food chain mentioned (i.e. algae  small fish  big fish  humans). (2 marks) (c) Explain why eating bigger fish is more likely to cause ciguatoxin poisoning than eating smaller fish. (2 marks) _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ (d) Suppose that the water where the ciguatoxin-producing algae live is moderatly polluted with nirtrogenous fertilizers. Describe and explain the effect of such pollution on fish population. (3 marks) _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 3 4 4. In 1972, Singer and Nicolson proposed the modern ‘Fluid Mosaic Model’ to explain the structure of plasma membranes. (a) In the space below, draw a simple labelled diagram to indicate the arrangement of components in a plasma membrane as described in ‘Fluid Mosaic Model’. (3 marks) (b) Before the well establishment on the concept of the cell membrane structure, science have enquiries about whether integral proteins are able to move laterally in the plasma membrane. In order to investigate that, Larry Frye and Michael Edidin labelled membrane proteins of mouse and human cells using different-coloured fluorescent dyes to distinguish between them. Then they fussed mouse and human cells to produce hybrid cells. After a brief period of incubation, mouse and human cells inter-mixed over the surface of the hybrid cells. After about 40 minutes, the proteins of each species had become randomly d