生物 2004 年 DSE、CE 選擇題（第 6 頁）

51.

The photograph below shows a bacterial culture growing on nutrient agar. The culture is contaminated by a fungus.

Bacterial culture contaminated by a fungus

Which of the following correctly explains the absence of bacterial colonies around the fungus ?

52.

Questions 52 to 54 refer to the diagram below, which shows the flow of energy and carbon in an ecosystem. P, Q and R represent different trophic levels and S represents another group of organisms in the ecosystem. Key: solid arrow = direction of energy flow; dashed arrow = direction of carbon flow

Organisms in S are

53.

Questions 52 to 54 refer to the diagram below, which shows the flow of energy and carbon in an ecosystem. P, Q and R represent different trophic levels and S represents another group of organisms in the ecosystem. Key: solid arrow = direction of energy flow; dashed arrow = direction of carbon flow

Energy is lost from the ecosystem through process 2. What is this process ?

54.

Questions 52 to 54 refer to the diagram below, which shows the flow of energy and carbon in an ecosystem. P, Q and R represent different trophic levels and S represents another group of organisms in the ecosystem. Key: solid arrow = direction of energy flow; dashed arrow = direction of carbon flow

With reference to trophic level Q, the largest amount of energy flow occurs in

55.

P and Q in the diagram below are the reproductive structures of a mammal and a flowering plant respectively.

Which of the following comparisons between P and Q is correct ?

56.

Which of the following statements about antibodies is correct ?

57.

Joe and Jim are twin brothers. Which of the following characteristics of Joe and Jim allows you to determine whether they are identical twins or not ?

Characteristic	Joe	Jim
IQ	110	110
pulse rate	70	75
blood group	A	A
colour vision	normal	colour-blind

58.

Which of the following plants does not bear flowers but reproduces by seeds ?

59.

Questions 59 and 60 refer to an investigation on the enzyme catalase, which breaks down hydrogen peroxide and releases oxygen. In order to show whether a certain plant tissue contains catalase or not, Joyce set up the following experiment:

Joyce observed that a lot of gas bubbles were released in tube 1 but not in tube 2. In order to conclude that the plant tissue contains catalase, what additional steps should be taken by Joyce ?

(1)Test whether the gas bubbles contain oxygen.

(2)Set up a tube containing water and the fresh plant tissue.

(3)Set up a tube containing hydrogen peroxide but no plant tissue.

60.

Questions 59 and 60 refer to an investigation on the enzyme catalase, which breaks down hydrogen peroxide and releases oxygen. In order to show whether a certain plant tissue contains catalase or not, Joyce set up the following experiment:

When gas bubbles stopped coming out from tube 1, Joyce added more hydrogen peroxide into the tube. She observed that gas bubbles were produced again. What can be implied from this observation about the property of enzymes ?