CSIR- NET LIFE SCIENCES - TEST 3

Which of the following criteria can be used to distinguish between prokaryotic and eukaryotic cells ?

• Whether or not they have a plasma membrane

• Whether or not they have a nucleus.

• Comparison of the sequence of homologous proteins.

• Comparison of the signature sequence of 16S rRNA.

Identify a peripheral protein

• structure a

• strucure b

• structure g

• structure h

Plasma membranes are selectively permeable. This means

• anything can pass in and out

• the membrane regulates the passage of the material in and out of the cell

• glucose cannot enter the cell

• cholesterol cannot enter

Which is NOT a function of the membrane?

• it forms a selective barrier

• it has receptors for chemical messages

• it is the control center of the cell

• it is involved in self recognition

Membrane phospholipids

• have hydrophobic heads that face the center of the membrane and are shielded from water

• have hydrophilic tails that face outward

• remain fluid because they are tightly packed

• none of these

The cholesterol associated with membranes

• is attached to proteins and extends into the environment surrounding the cell

• helps stabilize the membrane at body temperature

• is an abnormality resulting from a diet high in cholesterol

• both a and c

Which structure is the hydrophilic polar head of the phospholipid molecule?

• F

• D

• C

• A1

Which structure is the hydrophobic tail of the phospholipid molecule?

• E

• B

• G

• A2

lateral movement of phospholipids occur more often than flip-flop movement

• true
• false

The function of the plasma membrane is....

• regulate what enters and leaves the cell.
• fight bacteria and viruses that enter the cell.
• make sure each cell reproduces 
• make sure each cell can move