Cell membrane transport mechanisms: diffusion, facilitated diffusion, and active transport.

Let’s solve Q.2 first — labeling the model with the correct terms from the box.

We have four types of transport to label:
- Facilitated Diffusion
- Diffusion
- Active Transport
- Passive Transport

Looking at the diagram:

On the LEFT side (before the dotted line), all movements are going FROM high concentration TO low concentration — that means they do NOT require energy. These are all forms of Passive Transport.

So, the big label on the top left should be:
→ Passive Transport

Now, under Passive Transport, there are three sub-types shown:

1. The first one (leftmost) shows molecules moving directly through the membrane without any help — this is simple Diffusion.
2. The second and third ones show molecules using protein channels or carriers — these are both types of Facilitated Diffusion.

Wait — actually, looking again: the second one uses a channel protein (green triangles), and the third one uses a carrier protein (pink circles). Both are still facilitated diffusion — so we can group them together under “Facilitated Diffusion”.

But in the diagram, there are two separate boxes under Passive Transport — so likely:

- Left box under Passive Transport → Diffusion
- Right box under Passive Transport → Facilitated Diffusion (covers both the green triangle and pink circle examples)

Then, on the RIGHT side of the dotted line — movement is AGAINST the concentration gradient (from low to high), and it uses ATP (energy). That’s clearly Active Transport.

So the big label on the top right is:
→ Active Transport

Now let’s assign the labels properly:

Top-left big box: Passive Transport
Under it, left small box: Diffusion
Under it, right small box: Facilitated Diffusion
Top-right big box: Active Transport

That covers all four terms.

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Now Q.3: Which of the following is NOT a type of passive transport?

Options:
a) Diffusion → YES, passive
b) Endocytosis → This is when cells engulf things — requires energy → NOT passive
c) Facilitated Diffusion → YES, passive
d) Osmosis → Also passive (movement of water)

So the answer is b) Endocytosis

Final Answer:
Q.2 Labels (from left to right, top to bottom):
Top-left: Passive Transport
Left small box: Diffusion
Right small box: Facilitated Diffusion
Top-right: Active Transport

Q.3: b) Endocytosis