IB Biology - Labs & Skills (For Paper 3) Test
Questions And Correct Answers.
What evidence led to the proposal of the Davson-Danielli model? - Answer Chemical analysis
showed that membranes were composed of phospholipid and protein, evidence suggested that
the plasma membrane had enough phospholipids to form an area twice as large, experiments
showed that membranes form a barrier to some substances (and layers of proteins could act as
the barrier)
What evidence led to the falsification of the Davson-Danielli model and the proposal of the
Singer-Nicholson model? - Answer Freeze-fracture electron micrographs showed globular
proteins (present in the centre of the phospholipid bilayer), analysis of membranes showed that
parts of the surfaces were hydrophobic, fusion of cells with membrane proteins (tagged with
different coloured fluorescent markers) showed that proteins can move (within the membrane,
as the colours became mixed)
What is the formula to determine BMI? - Answer Mass/[Height] squared (kg/m)
Who published evidence for semi-conservative DNA replication? - Answer Meselson and Stahl
What two isotope densities were used by Meselson and Stahl? - Answer 15N and 14N
How dense was the DNA used by Meselson and Stahl after 1 generation? - Answer
Intermediate
What did Meselson and Stahl observe after 2 generations? - Answer 2 equal bands (one still
14N/15N and one 14N)
What does a respirometer measure? - Answer Respiration rate
Between what wavelengths is an absorption spectrum drawn? - Answer 400 and 700
What does an absorption spectrum show? - Answer The range of wavelengths absorbed by a
pigment
Questions And Correct Answers.
What evidence led to the proposal of the Davson-Danielli model? - Answer Chemical analysis
showed that membranes were composed of phospholipid and protein, evidence suggested that
the plasma membrane had enough phospholipids to form an area twice as large, experiments
showed that membranes form a barrier to some substances (and layers of proteins could act as
the barrier)
What evidence led to the falsification of the Davson-Danielli model and the proposal of the
Singer-Nicholson model? - Answer Freeze-fracture electron micrographs showed globular
proteins (present in the centre of the phospholipid bilayer), analysis of membranes showed that
parts of the surfaces were hydrophobic, fusion of cells with membrane proteins (tagged with
different coloured fluorescent markers) showed that proteins can move (within the membrane,
as the colours became mixed)
What is the formula to determine BMI? - Answer Mass/[Height] squared (kg/m)
Who published evidence for semi-conservative DNA replication? - Answer Meselson and Stahl
What two isotope densities were used by Meselson and Stahl? - Answer 15N and 14N
How dense was the DNA used by Meselson and Stahl after 1 generation? - Answer
Intermediate
What did Meselson and Stahl observe after 2 generations? - Answer 2 equal bands (one still
14N/15N and one 14N)
What does a respirometer measure? - Answer Respiration rate
Between what wavelengths is an absorption spectrum drawn? - Answer 400 and 700
What does an absorption spectrum show? - Answer The range of wavelengths absorbed by a
pigment
