Cell Walls & How They Regulate Plant Shape (L7)

Question 1

What is the most abundant organic macromolecule on earth?

Answer 1

Cellulose

Question 2

What is the cell wall structure made of?

Answer 2

Cellulose = which turns into strong microfibrils.

Question 3

When the cell wall is just made of a matrix of cellulose microfibrils.

Answer 3

Crystalline Microfibrillar Phase

Question 4

• involves hemicellulose and pectin (helps keep cells together) polysaccharides plus a network of extensin

Answer 4

Non-Crystalline Matrix

Question 5

This protein dehydrates the cell well by crosslinking pectin and cellulose together to form a strong and rigid structure

Answer 5

Extensin

Question 6

The synthesis of the primary cell wall is a coordinated synthesis of what 3 components?

Answer 6

cellulose at the plasma membrane, hemicellulose and pectin at the golgi transported to cell wall via vesicles, and extensin from er

Question 7

What are the functions of the cell wall?

Answer 7

Cell wall regulates cell shape.
- it also provides structural support and prevents excessive water uptake (due to protein extensin - which helps make the cell wall more rigid as it grows to its max size)

Question 8

What are the ways in which a cell can grow? (Orientations)

Answer 8

• randomly oriented = cell will grow equally
• long axis oriented = expansion longitudinally in a specific axis

Question 9

What is another word that describes the plasma membrane of a plant cell?

Answer 9

Protoplast = pushes against the cell wall to make it more rigid.

• water loss from cells reduces protoplast volume
• inversely, when water goes into the cell, the protoplast expands and puts pressure on the cell wall

Question 10

Why are vacuoles important?

Answer 10

• they are important in preventing excessive water uptake
• they contain the water for the plant
• because water causes the protoplast to expand, which limits the amount of water that can go into the cell

Question 11

An organelle surrounded by a single membrane. Makes up most of a plant cell.

Answer 11

Vacuole

Question 12

Is the diffusion of water (high water concentration - low water concentration) across a selectively permeable membrane

Answer 12

Diffusion

Question 13

This is a thicker and stronger version of the primary cell wall and only develops/forms when the cell gas stopped growing. The orientation of cellulose can be in multiple different directions and it contains more cellulose, less pectin, and most especially Lignin.

Answer 13

Secondary Cell Wall

Question 14

This is the second most abundant organic macromolecule. It’s properties contain: providing strength and rigidity to secondary cell wall.

Answer 14

Lignin

Question 15

Intercellular connections that enable cell to cell communication. Usually found beneath the plasma membrane.

Answer 15

plasmodesmata

Question 16

How does the vacuole contribute to cell shape?

Answer 16

The vacuole basically acts as the protoplast. It is high in solutes and so prompts the uptake of water (via osmosis) to build up internal pressue for plant cells that contributes to plant structural support.

Question 17

How is the endoplasmic reticulum connected?

Answer 17

Through the plasmodesmata

Question 18

Which is the incorrect statement: Plasmodesmata:

a) allows intercellular communication
b) is small enough to prevent organelle movements
c) does not allow free exchange of molecules
d) is connected to endoplasmic reticulum

Answer 18

c) because plasmodesmata allows free exchange of molecules

Question 19

Which is the incorrect statement: Plasmodesmata:

a) allows intercellular communication
b) is small enough to prevent organelle movements
c) does not allow free exchange of molecules
d) is connected to endoplasmic reticulum

Answer 19

c) because plasmodesmata allows free exchange of molecules