Tag: bio-chemistry

Quizzes (82) Questions (1918)

Questions Related to bio-chemistry

Multiple choice bio-chemistry plant physiology active transport and passive transport types of plant transport atp

Which of the following is not true of the carrier molecules involved in facilitated diffusion?

  1. They increase the speed of transport across a membrane

  2. They concentrate solute molecules on one side of the membrane

  3. They have specific binding sites for molecules they transport

  4. Transport protein may undergo conformational change upon binding of solutes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Carrier molecules in facilitated diffusion assist in moving solutes across a membrane down their concentration gradient, meaning they cannot build up a higher concentration on one side against the gradient without energy input.

Multiple choice bio-chemistry plant physiology active transport and passive transport types of plant transport atp

Which of the following have no effect at rate of facilitated diffusion?

  1. Transport saturation

  2. Presence and absence of membrane protein

  3. Low ATP concentration

  4. Concentration gradient difference
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Facilitated diffusion is the movement of water and other substances against the concentration gradient. The movement is through ions channels or membrane proteins which are present on the surface of the membrane. It requires the energy for the movement of substances. The movement is dependent upon the concentration gradient.

So, the correct option is 'Transport saturation'.

Multiple choice bio-chemistry plant physiology active transport and passive transport types of plant transport atp

Facilitated diffusion

  1. Needs a carrier protein

  2. Is an active process

  3. Occurs against the concentration gradient

  4. Needs ATP
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Substances having a hydrophilic moiety find it difficult to pass through the membrane. Their movement has to be facilitated. So, facilitated diffusion needs a 'carrier protein'. 

Thus, the correct answer is 'Needs a carrier protein.'

Multiple choice bio-chemistry plant physiology active transport and passive transport types of plant transport atp

Select the incorrect statement regarding facilitated diffusion.

  1. It is a very specific process

  2. It is a passive process

  3. It helps the hydrophilic substances to be transported across the membrane

  4. It is faster than active process
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Facilitated diffusion is a passive process that does not require energy. While it is faster than simple diffusion, it is generally not faster than active transport, which can move substances against a gradient.

Multiple choice bio-chemistry plant physiology active transport and passive transport types of plant transport atp

In apoplast pathway, water moves exclusively through the

  1. Plasmodesmata

  2. Cell walls

  3. Intercellular spaces

  4. Both B and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Apoplast pathway consists of non-living parts of plant body i.e., cell walls and intercellular spaces. In apoplast pathway, water passes from root hair to xylem through the walls of intervening cells without crossing any membrane or cytoplasm. The pathway provides the least resistance to movement of water. However, it is interrupted by the presence of impermeable lingo-suberin casparian strips in the walls of endodermal cells.
So, the correct answer is 'Both B and C'.
Multiple choice bio-chemistry plant physiology active transport and passive transport types of plant transport atp

When transport proteins simultaneously move two molecules across a membrane in the same direction, the process is called

  1. Uniport

  2. Antiport

  3. Symport

  4. Diffusive port
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Some carrier proteins allow transport only if two types of molecules move together. This is called cotransport. It is of two types: symport and antiport method. In symport method of cotransport, both molecules cross the membrane in the same direction at the same time. In antiport method of cotransport, both molecules move in opposite direction. When a molecule move across a membrane independent of other molecule, the process is called uniport.
So, the correct answer is 'Symport'.
Multiple choice bio-chemistry plant physiology active transport and passive transport types of plant transport atp

The type of diffusion in which substance move across the membrane along their concentration gradient in the presence of certain or transport proteins is called as 

  1. Simple diffusion

  2. Facilitated diffusion

  3. Osmosis

  4. Active transport
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The diffusion of hydrophilic substances along the concentration gradient through fixed membrane transport proteins without involving energy expenditure, is called facilitated diffusion. Facilitated diffusion is very specific as it allows cell to select substances for uptake. It is sensitive to inhibitors as well as show saturation effect. Two major types of transport proteins are known viz, carrier proteins(also called carriers, transporters) and channel proteins. Carrier proteins bind the particular solute to be transported and deliver the same to the other side of the membrane.
So, the correct answer is 'Facilitated diffusion'.
Multiple choice bio-chemistry plant physiology active transport and passive transport types of plant transport atp

Which of the below mentioned properties is not true with respect to facilitated transport?

  1. Requires special membrane proteins

  2. Transport saturates

  3. Uphill transport

  4. Highly selective
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Active transport is also known as uphill transport that requires the transport of molecules from a low-concentration region to a high-concentration region.  whereas facilitated transport is the passive transport of molecules or ions across a biological membrane via specific transmembrane integral proteins.
So the correct answer is 'Uphill transport'.
Multiple choice bio-chemistry cell membrane active transport and passive transport types of plant transport atp

When a molecule moves across a membrane independent of other molecules, the process is called (i) Uniport (ii) Symport (iii) Antiport?

  1. i

  2. i and ii

  3. i and iii

  4. ii and iii

  5. iii
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When a molecule moves across a membrane independent of other molecule, it is called uniport.

When two molecules move simultaneously across the membrane in the same direction, it is called symport.
When two molecules move in opposite direction to each other across the membrane, it is called antiport. Thus, the correct answer is A.

Multiple choice bio-chemistry cell membrane active transport and passive transport types of plant transport atp

When a molecule moves across a membrane independent of other molecules, the process is called

  1. Uniport

  2. Symport

  3. Antiport

  4. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A uniporter is an integral membrane protein that transports a single type of substrate species (charged or uncharged) across a cell membrane. It may use either facilitated diffusion and transport along a diffusion gradient or transport against one with an active transport process. They can be either ion channels or carrier proteins. In facilitated diffusion, molecules diffuse across the plasma membrane with assistance from membrane proteins, such as channels and carriers.

So the correct option is 'None of the above'