CHAPTER 3 Movement of Substances Chapter 3 Movement
CHAPTER 3 Movement of Substances
Chapter 3 Movement of Substances 3. 1 Diffusion 3. 2 Osmosis 3. 3 Surface Area to Volume Ratio 3. 4 Active Transport
3. 1 Diffusion Learning Outcomes After this section, you should be able to: • define diffusion; and • discuss the importance of diffusion in nutrient uptake and gaseous exchange in plants and humans.
3. 1 Diffusion How do particles move? Think of a time when you detected the smell of perfume in a room. How has the smell travelled to your nose? Region A with higher concentration of particles Region B with lower concentration of particles Movement of particles
3. 1 Diffusion What is diffusion? Diffusion is the net movement of particles from a region where they are of higher concentration to a region where they are of lower concentration, that is, down a concentration gradient.
Diffusion Concentration gradient is the difference in concentrations between two regions. direction of movement of particles molecules diffuse down a concentration gradient Concentration 3. 1 Point A Point B Distance
3. 1 Diffusion How is a concentration gradient related to diffusion? • The movement of fluid particles is diffusion. • Particles will diffuse down their concentration gradient. • The steeper the concentration gradient, the higher the rate of diffusion. URL
3. 1 Diffusion of a dissolved substance gas jar water copper sulfate crystal 1. A copper sulfate crystal is dropped into a gas jar containing water. 2. The gas jar is allowed to stand for a few days. 3. The blue colour gradually spreads throughout the water. 4. The copper sulfate particles diffuse evenly throughout the water.
3. 1 Diffusion across a membrane • Both the ______ and ______ are able to pass through a _____________. permeable membrane potassium iodide particle copper sulfate particle Copper sulfate and potassium iodide particles evenly distributed
3. 1 Diffusion of gases in the lungs ___________ in the lungs occurs via diffusion. air space in the lungs CO 2 diffuses from blood into the lungs O 2 diffuses from lungs into the blood lung cell red blood cell
Chapter 3 Movement of Substances 3. 1 Diffusion 3. 2 Osmosis 3. 3 Surface Area to Volume Ratio 3. 4 Active Transport
3. 2 Osmosis Learning Outcomes After this section, you should be able to: • define osmosis; and • discuss the effects of osmosis on plant and animal tissues.
3. 2 Osmosis What is osmosis? A ________________ allows some substances to pass through it but not others. A 10% sucrose solution (less water, more sucrose) B 5% sucrose solution (more water, less sucrose) sucrose molecule water molecule partially permeable membrane
3. 2 Osmosis What is osmosis? The partially permeable membrane allows water molecules to pass through but not sucrose molecules. rise in level of solution partially permeable membrane A B drop in level due to movement of water molecules to A
3. 2 Osmosis How can we demonstrate osmosis? 1. An experiment is set up as shown. 2. The level of the solution in the thistle funnel is observed to rise. 3. This is due to water molecules moving into the thistle funnel from the beaker. thistle funnel retort stand sucrose solution cellophane paper beaker water
3. 2 Osmosis What is water potential and how is it related to osmosis? • The __________________ is known as water potential. • A dilute solution has a higher water potential. • A concentrated solution has a lower water potential.
3. 2 Osmosis What is water potential and how is it related to osmosis? A _______________ is established when a partially permeable membrane separates two solutions of different water potentials. more solute, lower water potential gradient established partially permeable membrane less solute, higher water potential water moves down the gradient
3. 2 Osmosis What is water potential and how is it related to osmosis? _______ is the net _________ from a solution of higher water potential to a solution of lower water potential, through a _______________. URL
3. 2 Osmosis How does osmosis affect living organisms? Cells are living ____________. Plant cell Animal cell partially permeable cell surface membrane fully permeable cellulose cell wall enclosed nucleus and cytoplasm containing various dissolved substances
3. 2 Osmosis What happens to a cell in a solution with higher water potential? cell sap in vacuole 1 cell sap has lower water potential than surrounding solution 2 water enters by osmosis in solution of higher water potential plant cell 3 cell expands and becomes _____ 4 cell wall prevents cell from bursting
3. 2 Osmosis What happens to a cell in a solution with higher water potential? cytoplasm has lower water potential than outside solution, water enters by osmosis in solution of higher water potential animal cell expands and _____
3. 2 Osmosis What happens to a cell in a solution with lower water potential? cell sap in vacuole 1 cell sap has higher water potential than surrounding solution 2 water leaves by osmosis in solution with low water potential plant cell 3 cytoplasm shrinks away from cell wall and cell becomes _______ 4 cell becomes ______
3. 2 Osmosis What happens to a cell in a solution with lower water potential? cytoplasm has higher water potential than surrounding solution, water leaves by osmosis in solution of lower water potential animal cell URL cell shrinks in size and becomes _______
3. 2 Osmosis What happens to a cell in a solution of the same water potential? A cell immersed in a solution with the same water potential as its cytoplasm ___________.
3. 2 Osmosis Why is turgor important in plants? • Turgor plays an important role in _________________ in plants. • It keeps herbaceous (non-woody) plants ________________. • Loss of turgidity causes the plant to _____.
3. 2 Osmosis Why is turgor important in plants? • Changes in turgor also cause the movements of some plant parts, e. g. opening and closing of stomata. turgor in guard cells causes stoma to open in the day lack of turgor in guard cells causes stoma to close at night
3. 2 Osmosis Why is turgor important in plants? • Plasmolysis causes tissues to become limp or ________. • When cells of a plant become flaccid, the plant _______. • Water may be added to the soil to dilute the soil solution. This causes water moelcules to enter the plant cells and keeps the plant firm and upright.
Chapter 3 Movement of Substances 3. 1 Diffusion 3. 2 Osmosis 3. 3 Surface Area to Volume Ratio 3. 4 Active Transport
3. 3 Surface Area to Volume Ratio Learning Outcomes After this section, you should be able to: • explain how surface area to volume ratio affects the rate of movement of substances.
3. 3 Surface Area to Volume Ratio What does surface area to volume ratio mean to a cell? The ______ the surface area to volume ratio, the _______ the rate of _______.
3. 3 Surface Area to Volume Ratio What does surface area to volume ratio mean to a cell? Cube Surface area/cm 2 Volume/c m 3 Surface area: volume Cell A 1 (side 1 cm) 6 1 _____ Cell A 2 (side 2 cm) 24 8 _____ Cell A 3 (side 3 cm) 54 27 _____ As a cell becomes bigger, its surface area to volume ratio decreases.
3. 3 Surface Area to Volume Ratio Each shaded square represents a unit volume of protoplasm food + O 2 in waste products out Cell A 2 Cell A 1 Y Cell A 3 Z X loss in surface area
3. 3 Surface Area to Volume Ratio How are cells adapted for the absorption of materials? • Cells which function in absorption have an __________________. • For example, root cells have long processes and epithelial cells have a folded cell membrane. Root hair cell Epithelial cell
Chapter 3 Movement of Substances 3. 1 Diffusion 3. 2 Osmosis 3. 3 Surface Area to Volume Ratio 3. 4 Active Transport
3. 4 Active Transport Learning Outcomes After this section, you should be able to: • define active transport; • explain that active transport is an energyconsuming process by which substances are transported against a concentration gradient; and
3. 4 Active Transport What is active transport? • ___________ is the process in which energy is used to move the particles of a substance across a membrane _____________, that is, from a region where the particles are of lower concentration to a region where they are of higher concentration.
3. 4 Active Transport ___ _ con _____ cen trat _____ ion gra down a ___ dien ___ t a co ____ _ n req centra ____ uire a s __ tion gr gainst ___ adie n ___ t higher concentration of solute molecules, e. g. glucose. lower concentration of solute molecules, e. g. glucose.
3. 4 Active Transport • Since active transport requires energy, active transport occurs only in __________. • Dissolved mineral salts are taken up by root hair cells via active transport. root hair cell path taken by substances absorbed by root hair cell soil solution mineral salts
Chapter 3 Movement of Substances
Chapter 3 Movement of Substances The URLs are valid as at 15 January 2014.
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