Pinocytosis can be recognized when the CELL IS ENGULFING EXTRACELLULAR FLUID
Explanation:
Pinocytosis is the process whereby the cell takes in macromolecules such as bacteria and antigens in form of fluid from the extracellular fluid.
The macromolecules in the form of droplets of fluid bind to the outer surface of the cell
The cell membrane enviginates around the droplets of fluid and are engulfed by the cell.
They form vacuoles with the macromolecules and are transported into the inner of the cell.
The formed structure is called ENDOSOMES which lysozomes combine with and form secondary endosomes containing enzymes to break down the macromolecules.
Slugs are organisms which belong to the Phylum Mollusc.
Their specific morphological feature is that they lack a proper shell structure.
Their bodies store a huge amount of water and they also produce mucus called slime which help them protect against desiccation and predators.
In the given question, the slugs are kept in a chips packet.
The chips packet is lined with particles of salt.
The concentration of salt inside the chips packet, that is, outside the body of the slug is more than the concentration of salt inside the body of the slug. This makes the chips packet a hypertonic environment as compared the interior of the body of the slug.
Also, the concentration of water is higher inside the body of the slug as compared to that inside the chips packet. This makes the interior of slug body hypotonic as compared to chips packet.
Osmosis is the process by which molecules move from a region where their concentration is high to a region where their concentration is low across a selectively-permeable membrane.
Also, Osmosis can be defined as the process by which water tend to move from a region where the concentration of solute (salt) is low (inside the slug body) to the region where the concentration of solute (salt) is high (in the chips packet) across a selectively permeable membrane (the external lining of the slug body).
Hence, the slug releases the water present in its body in the form of mucus, which is the slime, and shrinks in size when kept in a hypertonic environment.