5.1 Cell Membrane

Question 1

A detailed membrane structure was studied only after the advent of the ______ in year ______.

Answer 1

electron microscope; 1950s

Question 2

The chemical studies on the cell membrane, especially in ___, enabled scientists to deduce the possible structure of the plasma membrane.

Answer 2

Human red blood cells (RBCs)

Question 3

Cell membrane is mainly composed of ___.

Answer 3

Lipids and Proteins

Question 4

In the cell membranes, major lipids are _____ that are arranged in a ______.

Answer 4

Phospholipids; bilayer

Question 5

In a lipid bilayer, the part of lipids that lie:

I. towards the outer side is _____
II. towards the inside side is _____

Answer 5

I. Polar Heads
II. Non-polar Hydrophobic Tails

Question 6

In lipid bilayer, Non-polar tail of ______ is protected from the ______ environment.

Answer 6

saturated hydrocarbons; aqueous

Question 7

In addition to phospholipids, Cell membrane also contains __

Answer 7

Cholesterol

Question 8

Apart from cholesterol and lipids, other biomolecules that make up the cell membrane are _____.

Answer 8

Proteins and carbohydrates

Question 9

The ratio of ______ and ______ varies in different cell types.

Answer 9

protein and lipid

Question 10

The membrane of Human erythrocyte has ____ % protein and ____ % lipids.

Answer 10

52%; 40%

Question 11

Depending on the ease of extraction, Membrane proteins are classified as:

Answer 11

Integral and peripheral proteins

Question 12

______ proteins lie on the surface, while ______ proteins are partially or totally buried in the membrane.

Answer 12

Peripheral proteins; Integral proteins

Question 13

The fluid mosaic model is a structure of ______, proposed by ______ in ____ year.

Answer 13

Cell membrane; Singer and Nicolson; 1972

Question 14

According to the fluid mosaic model,

______ nature of lipids enables ______ movement of proteins within the bilayer.

Answer 14

Quasi-fluid nature; Lateral movement

Question 15

The ability of the protein to move within the membrane is measured as its _____.

Answer 15

Fluidity

Question 16

The fluid nature of the membrane is important for functions like:

Answer 16

I. Cell growth
II. Formation of intercellular junctions
III. Secretion
IV. Endocytosis
V. Cell division, etc.

Question 17

________ is the most important function of the plasma membrane.

Answer 17

Transport of molecules across it

Question 18

______ is the nature of plasma membrane.

Answer 18

Selectively permeable

Question 19

The membrane is selectively permeable to all molecules present on either side of it.
T/F

Answer 19

False,
selectively permeable to some molecules

Question 20

The movement of molecules across the membrane without any energy requirement is called ______.

Answer 20

Passive transport

Question 21

Movement:

I. Along concentration gradient is-
II. Against concentration gradient is-

Answer 21

I. From higher to lower concentration.
II. From lower to higher concentration

Question 22

Neutral solutes move across the membrane by the process of ______, which is _______ (along/against) the concentration gradient.

Answer 22

Simple diffusion; along

Question 23

The movement of water by diffusion is called ______.

Answer 23

Osmosis

Question 24

______ molecules cannot pass through the nonpolar lipid bilayer.

Answer 24

Polar molecules

Question 25

______ are required by polar molecules to facilitate their transport across the membrane.

Answer 25

Carrier proteins

Question 26

A few ions or molecules are transported across the membrane against their concentration gradient is called ______.

Answer 26

Active transport

Question 27

Active transport is an energy ______ (dependent/independent) process as ______ is utilized.

Answer 27

energy-dependent; ATP

Question 28

An example of active transport is

Answer 28

Na+/K+ pump