IB Biology Topic 1.3 MCQ's

What feature of cell membranes allows endocytosis to occur? A. Fluidity of phospholipid bilayer B. Presence of protein pumps C. Presence of carrier proteins D. Glycoprotein binding sites

A

What is the approximate thickness of the plasma membrane of a cell? A. 10 nm B. 50 nm C. 10 µm D. 50 µm

A

Which process is possible due to the fluidity of cell membranes? A. Endocytosis B. Osmosis C. ATP production D. Cell recognition

A

Which evidence falsifies the Davson-Danielli model? I. The presence of globular proteins within the phospholipid bilayer II. Non-polar amino acids cause proteins to remain embedded in membranes III. Membrane proteins remain in a fixed position inside a membrane A. I only B. I and II only C. II and III only D. I, II and III

B

What is a role of cholesterol in animal cells? A. It increases body fat. B. It controls membrane fluidity. C. It lines the inner wall of capillaries. D. It is a constituent of bile.

Bw

A number of different proteins are involved in nerve function. Which of the following does not require a membrane protein? A. Active transport of sodium B. Diffusion of K+ into the cell C. Diffusion of the neurotransmitter across the synapse D. Binding of the neurotransmitter to the post-synaptic membrane

C

Cladograms can be created by comparing DNA or protein sequences. The cladogram on the left is based on DNA sequences and the cladogram on the right is based on comparing protein sequences. What is the reason that cladograms based on DNA sequences are more reliable predictors of the phylogenetic relationship of species than cladograms based on protein sequences? A. Amino acids are not as chemically stable as DNA nucleotides. B. DNA mutates but amino acids do not. C. Several different triplets of bases can code for the same amino acid. D. There are 20 different amino acids but only 4 nucleotides.

C

The cell membrane model proposed by Davson-Danielli was a phospholipid bilayer sandwiched between two layers of globular protein. Which evidence led to the acceptance of the Singer-Nicolson model? A. The orientation of the hydrophilic phospholipid heads towards the proteins B. The formation of a hydrophobic region on the surface of the membrane C. The placement of integral and peripheral proteins in the membrane D. The interactions due to amphipathic properties of phospholipids

C

Which are functions of membrane proteins? A. Hormone binding sites and DNA replication B. Cell adhesion and translation C. Cell to cell communication and protein pumps D. Passive transport and glycosis

C