生物 1991 年 DSE、CE 選擇題（第 3 頁）

21.

Questions 21 and 22 refer to the graph below which shows the exchange of carbon dioxide between a green plant and the atmosphere under different light intensities :

Which of the following can be deduced from the graph ?

(1)At a light intensity of 1 arbitrary unit, only respiration takes place.

(2)At a light intensity of 2 arbitrary units, there is no net carbon dioxide taken in or given out.

(3)At a light intensity of 9 arbitrary units, the rate of photosynthesis is greater than the rate of respiration.

22.

Questions 21 and 22 refer to the graph below which shows the exchange of carbon dioxide between a green plant and the atmosphere under different light intensities :

At a light intensity of 5 arbitrary units, how many units of carbon dioxide are used up in photosynthesis ?

23.

Questions 23 and 24 refer to a ringing experiment. A woody plant had a ring of bark removed and left to grow again. The diagram below shows the appearance of the plant after a few months :

The swelling may be due to

(1)active cell division.

(2)the accumulation of water.

(3)the accumulation of food.

24.

Questions 23 and 24 refer to a ringing experiment. A woody plant had a ring of bark removed and left to grow again. The diagram below shows the appearance of the plant after a few months :

The plant may die eventually because

25.

The wall of an artery is thicker than that of a vein because the artery

(1)contracts rhythmically to transport blood forward.

(2)possesses valves to prevent the backflow of blood.

(3)has to withstand high blood pressure.

26.

Questions 26 and 27 refer to the diagram below which shows the blood vessels associated with the liver and the small intestine of a mammal :

Which of the following is correct ?

	Blood vessel I	Blood vessel III
	less oxygen	more oxygen
	less urea	more urea
	valves present	no valves
	thinner wall	thicker wall

27.

Questions 26 and 27 refer to the diagram below which shows the blood vessels associated with the liver and the small intestine of a mammal :

Which of the following statements about vessel II is correct ?

28.

Which of the following blood transfusions causes harm to the recipient ?

	Donor’s blood group	Recipient’s blood group
	A	AB
	AB	B
	O	AB
	O	A

29.

Which of the following descriptions about skeletal muscles are correct ?

(1)They are attached to bones by ligaments.

(2)Their activities are usually under voluntary control.

(3)They become fatigued easily during exercise.

30.

In the fruit fly, red eye is dominant to white eye. A homozygous red-eyed fly is crossed with a heterozygous red-eyed fruit fly. The expected phenotypic ratio among the offspring is