Cell Membrane

Question 1

Features of fluid-mosaic phospholipid bilayer model (PPCG)

Answer 1

Protein channels- Allows movement of specific charged particles into/out of the cell
Phospholipids- a barrier to protect the cell against various environmental threats
Cholesterol- Regulates Membrane Fluidity
Glycoproteins- is able to recognize and bind hormones

Question 2

Endocytosis

Answer 2

Endocytosis is a form of active transport that usually moves large polar molecules that cannot pass through the hydrophobic cell membrane into the cell

Question 3

Phagocytosis

Answer 3

Phagocytosis is when the cell encloses around (solid intake) a large particles such as microorganisms and dead cells are ingested via large endocytic vesicles.

Question 4

Explain how the cell membrane maintains relatively stable internal conditions via the process of active transport of a named substance against a concentration gradient

Answer 4

By allowing for fluid movement across the membrane the cell can maintain a state of homeostasis as different levels of concentration within the cell will disturb the nature of the cell.

Question 5

Describe how the cell membrane maintains relatively stable internal conditions via the passive movement (diffusion, osmosis) of some substances along a concentration gradient

Answer 5

In passive transport, substances cross the cell membrane down their concentration gradient. Osmosis allows cells to maintain water to salt balance as their environment changes.

Question 6

Explain how the size of a cell is limited by the relationship between surface area to volume ratio and the rate of diffusion.

Answer 6

As the cell gets bigger, its surface-to-volume ratio decreases, making diffusion less efficient. The larger the size of the sphere, or animal, the less surface area for diffusion it possesses