TOPIC 3 - Movement into and out of cells

define diffusion

• Diffusion is the passive net movement of particles (molecules or ions) from a region where they are in a higher concentration to a region where they are in a lower concentration (go down conc. gradient) thru a semi peramable membrane, this movement occurs down a concentration gradient.

energy for diffusion comes from…

The energy for diffusion comes from the kinetic energy of the randomly moving molecules and ions. This kinetic energy causes them to move and spread out.

how do some substances move into and out of cells by diffusion

• Some substances move into and out of cells by diffusion, passing through the cell membrane. The cell membrane is partially permeable, allowing some substances to pass through while restricting others.

Describe the importance of diffusion of gases and solutes in living organisms

• gax exhange

• nutritent absorabtion, waste excretion

Gases: Diffusion is crucial for the exchange of gases, such as oxygen (O2) and carbon dioxide (CO2), in processes like respiration and photosynthesis.

Solutes: Diffusion is also important for the movement of solutes (dissolved substances), such as nutrients and waste products, within and between cells.

factors that influence diffusion explain each

: surface area, temperature, concentration gradient and distance

• Surface Area: A larger surface area allows for more diffusion to occur.

• Temperature: Higher temperatures increase the rate of diffusion because the particles gain more kinetic energy and move faster.

• Concentration Gradient: A steeper (larger) concentration gradient (the difference in concentration) results in faster diffusion.

• Distance: Diffusion is faster over shorter distances.

define osmosis

the passive net movement of water molecules moving through a semi permable membrane from an area of higher water concentration to an area of lower concentraion

equlilibrium

the state inwhcih all sides of something are equal

lower solute conc in a substance =

higher water potential

higher solute conc.

lower water potential

Investigate and describe the effects on plant tissues of immersing them in solutions of different concentrations

• Plant tissues (e.g., potato strips) immersed in solutions of different concentrations exhibit different effects:

  • Hypotonic Solution (dilute): Water moves into the plant cells by osmosis.

  • Isotonic Solution (same concentration): There is no net movement of water.

  • Hypertonic Solution (concentrated): Water moves out of the plant cells by osmosis.

Turgid: The state of a plant cell when it is full of water (in a hypotonic solution), with a high turgor pressure, making the cell firm.

Turgor Pressure: The pressure exerted by the water-filled vacuole on the cell wall.

Plasmolysis: The process where the cell membrane pulls away from the cell wall due to water loss (in a hypertonic solution). The cell becomes shrunken.

Flaccid: The state of a plant cell when it has lost water (in an isotonic or hypertonic solution) and has low turgor pressure, making the cell limp.

what and how are plant walls supported by

• Plants are supported by the pressure of water inside their cells pressing outwards on the cell wall. This pressure is called turgor pressure.

Water potential and osmosis are crucial for:

• Uptake of water by organisms.

• Loss of water by organisms.

define active transport

active transport as the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration (i.e. against a concentration gradient), using energy from respiration

give examples of where active transport takes place

• root hair cells

• lumen of intestine

what carries moleucles during actve transport

protein carriers move molecules or ions across a membrane during active transport