Question

3.3 vocabulary check
cell membrane phospholipid fluid mosaic model
selective permeability receptor
go back and highlight each sentence that has a vocabulary word in bold.
circle the correct word from the choices below.

1. which material has selective permeability, a sponge or a shovel? which material has selective permeability, cell membrane or phospholipid?
2. which contains the other, cell membrane or phospholipid?
3. which receives signals, a fluid mosaic model or a receptor?

3.3 the big picture

1. what does the cell membrane do for the cell?
2. describe how the phospholipids are arranged in the cell membrane.
3. do cells respond to every signal? explain.
4. explain how a tea bag is an example of selective permeability.

Explanation:

1. The cell membrane has selective permeability, not a sponge or shovel. Phospholipids are components of the cell - membrane.
2. The cell membrane contains receptors. Receptors are embedded in the cell membrane.
3. Receptors receive signals. The fluid mosaic model is a description of the cell - membrane structure, not a signal - receiving entity.
4. The cell membrane acts as a barrier, controls the movement of substances in and out of the cell, and helps in cell - cell recognition and communication.
5. Phospholipids are arranged in a bilayer in the cell membrane, with the hydrophilic heads facing outward (towards the extracellular fluid and the cytoplasm) and the hydrophobic tails facing inward.
6. Cells do not respond to every signal. They have specific receptors, and only signals that match these receptors can trigger a response.
7. A tea bag is an example of selective permeability because it allows water (a solvent) to pass through its pores and extract the tea compounds (solute), while keeping the tea leaves inside.

Answer:

1. cell membrane
2. cell membrane
3. receptor
4. Acts as a barrier, controls substance movement, and aids in cell - cell recognition and communication.
5. Arranged in a bilayer with hydrophilic heads outward and hydrophobic tails inward.
6. No. Cells have specific receptors and only respond to signals that match these receptors.
7. Allows water to pass through to extract tea compounds while keeping tea leaves inside.