CELL BIOLOGY
1.- Which treatment is most effective in breaking as many hydrogen bonds as possible in an aqueous solution (pH 7.0) of 1 mg/mL DNA and 10 mg/mL protein ?
A. Addition of hydrochloric acid to make the pH 1.0.
B.- Addition of sodium hydroxide solution to make the pH 13.0.
C.- Addition of urea to a concentration of 6 mol/L.
D.- Addition of sodium dodecyl sulfate (a detergent) to a concentration of 10 mg/mL.
E.- Heating the solution to 121ºC.
F.- Freezing the solution to -80ºC.
I.B.O. 2009 JAPAN Theoretical test Part A
2.- The movement of a ciliated protozoan is controlled by a protein called RacerX. When this protein binds
to another protein, speed, found at the base of the cilia, it stimulates the cilia to beat faster and the proto-
zoan to swin faster.Speed can only bind to RacerX after phosphorylation of a specific threonine residue
How would you expect the mutant protozoan to behave if this threonine residue in Speed is repleced by
an alanine residue?
A.- Swims fast occasionally.
B.- Always swims fast.
C.- Never swims fast.
D.- Switches rapidly back and forth between fast and slow swimming.
E.- Cannot move at all
I.B.O. 2009 JAPAN Theoretical test Part A
3.- What structure in the bacterial cell has the most enzymatic activity ?
A.- Cell membrane
B.- Cell wall
C.- Mesosome
D:- Capsule.
E:- Flagellum
I.B.O. 2006 ARGENTINA Theoretical test Part A.
4.- Which of the following functions are carried out in the rough endoplasmic reticulum?
I. Addition of carbohydrates to protein.
II. Synthesis of lisosomal protein.
III. Addition of carbohydrates to lipids.
IV. Synthesis of membrane proteins.
V. Formation of glycolipids.
I.B.O. 2006 ARGENTINA Theoretical test Part A.
5.- A scientist, studying the process of photosynthesis, illuminates a culture of unicellular green algae for a
certain period of time. Then she turns off the light and adds radioactive CO2 by bubbling it in the culture
for 30 minutes. Immediately she measures radioactivity in the cells. What is she likely to observe?
A.-No radioactivity in the cells , because light is necessary to produce sugars starting from CO2 and
water.
B.- No radioactivity in cells, because CO2 is used to produce O2 during yhe light-dependent reactions.
C.- No radioactivity in the cells, because CO2 is taken by the plant cells only during illumination.
D.- Radioactivity in cells, because CO2 is used to produce sugars even in the dark.
E.- Radioactivity in cells, because CO2 is incorporated into NADPH in rhe dark.
I.B.O. 2009 JAPAN Theoritical test Part A.
C.I.B. BARBARA McCLINTOCK RESEARCH & DEVELOPMENT - O.I.A.B COACHING APRIL 2012.
