Transport in plants

Active transport is important because it can move molecules –

• From their high concentration to a lower concentration

• From their low concentration to a higher concentration

• With less ATP than might otherwise be used to move molecules

• by increasing their diffusion coefficient

You place cells in a solution of glucose and measure the rate at which glucose enters the cells. As you increase the concentration of glucose solution, the rate at which glucose enters the cells increases. However when the glucose concentration of the solution is increased above 10M, the rate at which glucose enters no longer increases. Which of the following is the most likely mechanism for glucose transport in the cells?

• Facilitated diffusion via a carrier protein

• Facilitated diffusion without carrier protein

• Active transport

• Symport

Transporting substances across a membrane from an area of lower concentration to an area of higher concentration requires –

(a) (b) (c) (d)

• energy

• phospholipid

• Diffusion

• Facilitated diffusion

Tags

NGSS.HS-LS2-5

Which does not affect the rate of diffusion of a substance –

• Temperature and concentration gradient

• Electrical charges of the diffusing materials

• Presence of the other substances in the solution

• Molecular diameter of the diffusing materials

Tags

NGSS.HS-PS1-5

Facilitated diffusion –

I. Is a very specific process

II. Is a passive process

III. Helps the substances, hydrophilic in nature, to be transported across the membrane

IV. Is faster than active process

• All are correct

• I, IV are correct

• I, II and IV are correct

• All are correct except IV

Facilitated diffusion –

• Needs a carrier protein

• Is an active process

• Occurs against the concentration gradient

• Needs ATP

Which one / ones is / are correct?

• Smaller substances diffuse faster

• Hydrophilic substances cannot pass through the cell membrane due to lipid present in the cell membrane

• Diffusion is rapid over short distance but extremely slow over long distance

• All

Go through the following points regarding diffusion –

I. It is a passive and slow process

II. It is an active and fast process

III. It needs ATP

IV. It does not need energy

V. It occurs against the concentration gradient

VI. Molecules move in a random manner, the net result being substances moving from region of higher concentration to region of lower concentration

• I, III and V are correct

• II and V are correct

• All are correct except III

• All are correct except II, III and V

9. Factors affecting the rate of diffusion are –

I. Gradient of concentration

II. Permeability of the membrane

III. Temperature

IV. Pressure

V. Size of diffusing material

• I, III and V are correct

• I and V are correct

• I, II, III, IV, V are correct

• Only V is correct

Transport of organic and inorganic materials is –

• Unidirectional

• Multidirectional

• bidirectional

• first undirectional then bidirectional