Q1: Transport Mechanisms

Question 1

It refers to the movement of substances across the cell membrane.

Answer 1

Cell Transport

Question 2

The most important feature of a cell’s phospholipid membrane is that they are ____________________, i.e., it has control over what molecules or ions can enter or leave the cell.

Answer 2

selectively permeable

Question 3

True or False:

The permeability of a membrane is not dependent on the organization and characteristics of the membrane lipids and proteins.

Answer 3

False

Question 4

True or False:

Cell membranes help maintain a state of homeostasis within cells (and tissues, organs, and organ systems) so that an organism can stay alive and healthy.

Answer 4

True

Question 5

Types of Transport

Answer 5

• Passive Transport
• Active Transport

Question 6

It involves the movement of material along a concentration gradient.

Answer 6

Passive Transport

Question 7

It does not require the expenditure of energy.

Answer 7

Passive Transport

Question 8

The net movement of molecules from a region of high concentration to a region of low concentration.

Answer 8

Simple Diffusion

Question 9

This directional movement along a
gradient is passive and will continue until molecules become evenly dispersed (equilibrium).

Answer 9

Simple Diffusion

Question 10

Molecules that will be able to freely diffuse across cell membranes (e.g. O2, CO2, glycerol).

Answer 10

Small and non-polar (lipophilic) molecules

Question 11

The rate of diffusion can be influenced by a number of factors, including:

Answer 11

• temperature
• molecular size
• steepness of gradient

Question 12

Main types of passive transport

Answer 12

• simple diffusion
• osmosis
• facilitated diffusion

Question 13

The net movement of water molecules across a semi-permeable membrane from a region of low solute concentration to a region of high solute concentration (until equilibrium is reached).

Answer 13

osmosis

Question 14

The diffusion of free water molecules and hence occurs from regions of low solute concentration.

Answer 14

osmosis

Question 15

True or False:

In osmosis, solute will move to equalize the two solutions, because water cannot cross a cell membrane unaided.

Answer 15

False

In osmosis, water will move to equalize the two solutions, because solute cannot cross a cell membrane unaided.

Question 16

True or False:

The movement of water across cell membranes and the balance of water between the cell and its environment are crucial to organisms.

Answer 16

True

Question 17

The passive movement of molecules across the cell membrane via the aid of a membrane protein.

Answer 17

facilitated diffusion

Question 18

It is utilized by molecules that are unable to freely cross the phospholipid bilayer (e.g. large, polar molecules and ions).

Answer 18

facilitated diffusion

Question 19

Facilitated diffusion is mediated by
two distinct types of transport proteins namely:

Answer 19

• channel proteins
• carrier proteins

Question 20

It uses energy to move molecules against a concentration gradient.

Answer 20

active transport

Question 21

Active transport may either be generated by:

Answer 21

• primary active transport (direct hydrolysis of ATP)
• secondary active transport

Question 22

The indirect coupling transport with another molecule that is moving along its gradient.

Answer 22

secondary active transport

Question 23

Types of Solution

Answer 23

• Isotonic
• hypertonic
• hypotonic

Question 24

A solution whose osmotic pressure is equal to that of the cell, no change will occur thus a balance is maintained.

Answer 24

isotonic solution

Question 25

A solution whose osmotic pressure is greater than that of the cell.

Answer 25

hypertonic solution

Question 26

It will cause water to leave the cell, thus the cell will shrink or crenate.

Answer 26

hypertonic solution

Question 27

A solution whose osmotic pressure is lower that of the cell.

Answer 27

hypotonic solution

Question 28

It will cause water to enter the cell, thus the cell will swell or hemolyze or even burst in animal cell.

Answer 28

hypotonic solution.