Chapter 3 Movement of Substances Across the Plasma Membrane

Which chemical substance is impermeable to the plasma membrane?

• Steroid

• Carbon dioxide

• Vitamin D

• Potassium ions

Which of the following statement wrongly describes the fluid mosaic model of a plasma membrane?

• Protein molecules are floating or embedding along double layers of phospholipid substances and gives the structure a dynamic nature.

• Cholesterol molecules are sandwiched between double layers of phospholipid molecules in order to stabilize the structure.

• Glycoproteins are formed by carbohydrate portions being joined to the protein molecules floating on the surface of phospholipid bilayers and they act in cell-cell identification.

• Nucleic acids are fixed between phospholipid bilayers, which help to store the genetic information about the plasma membrane itself.

All processes taking place across the plasma membrane do not require the breakdown of ATP molecules except:

• simple diffusion

• osmosis

• active transport

• facilitated diffusion

The absorption of amino acid across small intestine in human body through small projections called villi occurs via __________________.

• osmosis

• simple diffusion

• facilitated diffusion

• endocytosis

The diagram shows a complex molecule. Choose the correct statements about this molecule.

I It consists of hydrophilic head and hydrophobic tail.

II These molecules will arrange themselves in two layers called bilayer.

III These molecules will form micelles when dispersed in water

IV It is made in rough endoplasmic reticulum

• I, II, III

• I, II, IV

• I, III, IV

• II, III, IV

Choose the wrongly pairs between types of proteins and their functions.

• Glycoproteins – cell-cell identification

• Carrier proteins – transporting certain molecules

• Peripheral proteins – stabilizing the structure of plasma membrane

• Pore proteins – shaping the pore for allowing molecules enter the cells

Rahman soaked a chicken egg in a saturated salt solution. After a few days, he found that the egg tasted salty. Which statements explain the phenomenon?

I The egg shell and membrane are permeable to salt

II Salt particles diffuse into the egg

III Salt particles enter the egg by active transport

IV Saturated salt solution is hypotonic to the egg

• I, II

• II, III

• II, IV

• III, IV

Which living process across plasma membrane does not involve large molecules?

• Phagocytosis

• Active transport

• Pinocytosis

• Exocytosis

Protein is made up of many small units called amino acids. Most of the time, the cell will take in amino acids through ____________ and they will be used to manufacture proteins by ribosomes. Nevertheless, there is another way of protein transport, in which protein molecule is wrapped by ___________ and taken into the cell as a whole.

• Simple diffusion, exocytosis

• Facilitated diffusion, endocytosis

• Simple diffusion, active transport

• Facilitated diffusion, active transport

The diagram shows the movement of molecule P across the plasma membrane through process R with the help of protein molecule.

Choose the statement that is not corresponding with process R or molecule P.

• Process R occurs against the concentration gradient.

• Process R does not need energy to happen.

• Molecule P is most probably glucose molecule as it cannot pass through the phospholipid bilayer directly.

• The movement of molecule P is caused by kinetic energy within the particles itself.