Answer:
1. simple diffusion.
2. facilitated diffusion.
3. active transport.
4. both simple and facilitated diffusion.
Step-by-step explanation:
1. Simple diffusion can be defined as transport of small, non-polar, uncharged molecules, such as urea, gases, water through the lipid bilayer without the help of transport proteins.
As molecular oxygen and carbon dioxide are gases, these molecules would be transported by simple diffusion.
Thus, statement 1 correctly matches with option (D).
2. Facilitated diffusion involves transport of polar, charged, and large molecules, such as ions, glucose, and amino acids with the help of membrane proteins, known as transport proteins.
Passive transport is an example of of facilitated diffusion, which includes transport of molecules from higher to lower concentration (along their concentration gradient) without use of energy.
As ions are travelling down their concentration gradient, it is an example of facilitated transport.
Thus, statement 2 correctly matches with option (B).
3. Active transport is a type of facilitated diffusion that involves transport of molecules against their concentration (from lower to higher) with the help of energy. As glucose is travelling against its concentration, it is an example of active transport.
Thus, statement 3 correctly matches with option (C).
4. Water molecules are small, charged molecules that can be transported by both simple diffusion through lipid bilayer or facilitated diffusion through transport proteins, aquaporins.
Thus, statement 4 correctly matches with option (A).