Diffusion, Osmosis & Active Transport

Fill-in-the-blank practice flashcards covering diffusion, factors affecting diffusion rate, osmosis principles and experiments, plant and animal cell responses to water potential, and active transport.

Diffusion is the net movement of molecules from a region of its higher concentration to a region of its lower concentration as a result of their __________.

random movement

The cell membrane is a partially permeable membrane where the simplest sort of selection is based on the __________ of the molecules.

size

The continuous random movement of all particles at all times is known as __________.

Brownian motion

The energy that drives diffusion comes from the __________ of the random movement of molecules and ions.

kinetic energy

In plant leaves, oxygen diffuses from air spaces between mesophyll cells to the __________ in all cells.

mitochondria

In plant leaves, carbon dioxide diffuses from air spaces between mesophyll cells to the __________ in mesophyll cells.

chloroplasts

In the lungs, oxygen moves by diffusion from the alveolar air space into the __________.

blood in capillaries around alveoli

The bigger a cell or structure is, the smaller its __________ is, which slows down the rate of movement across its surface.

surface area to volume ratio

Blood capillaries and alveoli ensure fast diffusion rates because their walls are only __________ thick.

one cell

Higher temperatures increase the rate of diffusion because particles gain energy, leading to more frequent collisions against the __________.

cell membrane

A greater concentration gradient increases diffusion rates because on the side with the higher concentration, more __________ occur.

random collisions against the membrane

Osmosis is the diffusion of water molecules from a dilute solution to a more concentrated solution across a __________.

partially permeable membrane

In extended terms, osmosis is the net movement of water molecules from a region of higher water potential to a region of __________ across a partially permeable membrane.

lower water potential

In vegetable cylinder osmosis practicals, cylinders are left immersed in test solutions for __________ before being dried and reweighed.

$$20-30\,\text{minutes}$$

If immersed plant tissue gains mass, the surrounding solution must be more __________ than the plant tissue.

dilute

When plant cells absorb water by osmosis, water pushes the cell membrane against the cell wall, increasing the __________ inside the cell.

turgor pressure

The plant cell shown in the diagram has taken in water until the cell membrane firmly pushes against the cell wall, making it __________.

turgid

When plant cells are placed in a concentrated solution and lose water by osmosis, they become __________.

flaccid

In the diagram, water has exited the cell causing the cell membrane to pull away from the cell wall, meaning the cell is __________.

plasmolysed

When animal red blood cells are placed into a strong sugar solution with a lower water potential, they lose water by osmosis and become __________.

crenated (shrivelled up)

Animal cells placed in distilled water will continue to take in water until they burst because they lack a __________.

supporting cell wall

Active transport is the movement of particles through a cell membrane from lower to higher concentration using energy from __________.

respiration

Active transport requires energy because particles are being moved __________ a concentration gradient.

against

In animals, active transport facilitates the uptake of glucose by epithelial cells in the villi of the small intestine and by kidney tubules in the __________.

nephron

In plants, active transport is used to take up mineral ions from soil water into __________.

root hair cells