Cell Structure and Function

Which of the following is a key feature of active transport?

• No energy required
• Uses vesicles only
• Always involves water
• Movement against the concentration gradient

What is the function of gap junctions in animal cells, analogous to plasmodesmata in plant cells?

• To anchor cells together
• To prevent water loss
• To synthesize proteins
• To allow direct communication between cells

What is the main reason why large polar molecules cannot pass through the membrane via simple diffusion?

• They are too light
• They are always positively charged
• They are insoluble in water
• They are repelled by the hydrophobic core

Which of the following is NOT a function of the cell wall in plants?

• Providing structural support
• Preventing pathogen entry
• Regulating water uptake
• Carrying out cellular respiration

Which of the following is a correct description of the plasma membrane's structure?

• Single layer of proteins
• Triple layer of carbohydrates
• Solid protein matrix
• Double layer of phospholipids with embedded proteins