Question

reviewing the concepts: the cell membrane and cell transport
part i. vocabulary practice: use the word bank below to fill in the blanks. all words will be used.
osmosis diffusion permeable facilitated phospholipids hydrophobic proteins
cholesterol active transport phagocytosis exocytosis hydrophilic simple

1. the diffusion of water across the cell membrane is called osmosis
2. the cell membrane is described as selectively __________ as it only permits certain molecules to pass through. it is composed of a bilayer of ________, with __________ embedded within.
3. __________ is the movement of molecules from high concentration to low concentration across the cell membrane, while __________ moves molecules against their concentration gradient.
4. with __________ diffusion, molecules can pass directly through the phospholipid bilayer, while with __________ diffusion, molecules pass through a membrane protein.
5. ____________ is embedded within the cell membrane in order to prevent the phospholipids from sticking together.
6. each phospholipid is composed of a water - loving, or __________, phosphate head and a water - fearing, or __________, lipid tail.
7. __________ is a form of active transport which takes in food particles by engulfing them. the opposite of this process is called __________.

part ii. diagram labeling
using the word bank, label the diagram of the cell membrane.
phosphate head
lipid tail
transport protein
cholesterol
receptor protein

Explanation:

1. Osmosis is the specific term for water - diffusion across the cell membrane.
2. The cell membrane is selectively permeable, made of a phospholipid bilayer with proteins embedded.
3. Diffusion is passive movement down a concentration gradient, while active transport is against it.
4. Simple diffusion is through the bilayer, facilitated diffusion uses a membrane protein.
5. Cholesterol is in the membrane to prevent phospholipid sticking.
6. Phospholipids have hydrophilic heads and hydrophobic tails.
7. Phagocytosis is engulfing food particles (active transport), and exocytosis is the opposite.

Answer:

1. Permeable; Phospholipids; Proteins
2. Diffusion; Active Transport
3. Simple; Facilitated
4. Cholesterol
5. Hydrophilic; Hydrophobic
6. Phagocytosis; Exocytosis

For Part II (Diagram Labeling, from left - to - right, top - to - bottom):
Phosphate Head; Transport Protein; Cholesterol; Receptor Protein; Lipid Tail; Lipid Tail