Tips SPM chapter 3 form 4

Chapter 3

The Movement of Substances
across the Plasma Membrane

Focus Point in chapter 3

1) Structure of plasma Membrane

2)How substances move across plasma
membrane.

3)The movement of substances across
plasma membrane in daily life.

The structure of plasma membrane

Structure of plasma Membrane

The component that build up plasma membrane

Bil Substances /structure Function/importance/Necessity

1 Phospholipid bilayer Main structure to form a barrier/ made up of lipid
and phosphate group ( cause selective
character/semi-permeable)- not all substances can
dissolve or cross lipid.

2 Protein (carrier-has a shape that fits the -help in facilitated diffusion to carry large molecule

shape of specific molecules ) such as glucose and amino acid such as Substance

Protein pore- has a pore to provide a that dissolve in water but big in size.

passage for a particular solute - Help in active transport also

Protein Receptor- link with carbo group form

glycoprotein

3) Carbohydrate chain/ -form glycoprotein or glycolipid.-receptor

4) Cholestrol Link the fatty acid together
- Help to stabilize and strengthen the plasma
membrane, making it more flexible

Structure of plasma Membrane

The characteristics of plasma membrane

❖ Selective permeable/ allow only certain substances to pass through/semi-
permeable

❖Will represent by visking tubing in laboratory experiment.
❖Because it has

i. hydrophilic head- attract to water/A polar head (cas)/affinate to
water/facing extracellular fluid and cytoplasm.

ii. Hydrophobic tail- dislike/repel water/A non-polar tail (not cas)/ The tails
of the phospholipid molecule of the two layers face each other.

❖Explain the meaning of fluid mosaic model.
➢The phospholipid bilayer, proteins and cholesterols are not static but form

a dynamic and flexible structure. This contributes to the ‘fluid’
characteristic of the plasma membrane and makes the plasma membrane
more flexible.

.
Concept of movement of substances across a
plasma membrane.

There are 3 factors determined what substances can cross through
1) Phospholipid bilayer
2) Protein- carrie/pore

1st factor : is solubility in lipid
2nd factor: size of molecule
3rd factor : polarity- polar molecules

The plasma membrane is semi-permeable (selective permeable)
Certain substances can move across the membrane freely while others cannot

Lipid soluble molecules Small, uncharged molecules
Fatty acid, Non-polar molecules
Glycerol, - Oxygen
Steroids, - Carbon dioxide
Hormones,
Vitamin A,D,E,K Pore protein

Water (by facilitated diffusion)

Water soluble & large molecules Carrier protein
Glucose
Amino acid (by active transport)
Vitamin C

Charged ions
Na+
K+
Ca2+
Cl-



How substances move across plasma
membrane/what type of transport

The focus questions in the type
of transport.

• Compare and contrast between Passive transport and Active transport.
✓ Point 1: energy used OR NOT
✓Point 2: Concentration gradient (follow or against the concentration

gradient).
✓ Point 3: Reach a dynamic equilibirium or NOT?
✓Point 4 : Substances/materials involved in the movement.
• State the differences between simple diffusion and facilitated diffusion.
❑ point 1 : use protein carrier or NOT
• State the differences between simple diffusion and osmosis.
❖ Point 1: substances involve
❖Point2 : need plasma membrane or NOT

Comparison between passive transport and
active transport in living organism





COMMON QUESTIONS

• Explain the process of active transport/facilitated diffusion/simple
diffusion and osmosis

• Formula to answer this questions.
➢Point 1: explain the concentration gradient both side
➢Point 2: explain the flow/movement of substances
➢Point 3: state the protein involve and how or phospholipid bilayer
➢Point 4: use energy or not
➢Point 4: reach equilibrium or accumulation/ elimination

facilitated diffusion

• (a) - Small water-soluble molecules and ions pass through the pore

protein in the plasma membrane by facilitated diffusion.
• - The pore proteins have specific interior characteristic that only

allow specific ions to pass through them.

b) Large water-soluble pass through the plasma membrane aided by
carrier protein - The molecules bind to the active site of the carrier
protein.- The carrier protein then changes shape to allow the molecules
to pass through the other side of the plasma membrane



ACTIVE TRANSPORT

Example of transportations occur in human
body

1. Simple diffusion- alveolus (respiratory system)- oxygen and carbon
dioxide

2. Facilitated diffusion- villus (digestion system)- glucose,amino acid,
3. Osmosis- villus- digestive system
4. Active transport- neurone (nerve system)
5. Other example:
(a) The absorption of water by root hairs.
(b) Movement of water from one cell to another
(c) Absorption of water in the alimentary- stomach, small intestine and

colon.

Example of transportations occur in human
body

Examples:
Lipid-soluble molecules and small uncharged
molecules pass through the phospholipid bilayer of
the plasma membrane by simple diffusion.

Example: intake of mineral ions by root hairs of a
plant via active transport.

The movement of substances across plasma
membrane in daily life./Living Organims

1) Understande the type of solution (tonicity) –
➢ Isotonic, hypotonic and hypertonic solutions

The effects of hypotonic, hypertonic and
isotonic solutions on animal cells and plant cells

• Focus point to answer the questions
Point 1: compare the concentration of solution and the cell

sap/cell.
Point 2: explain the movement of water molecule diffuse in or out.
Point 3: by osmosis (process)
Point 4: Effect to turgor pressure /plasma membrane (for plant

cell-move away from cell wall or press toward cell wall)
Point 5:effect to the cell (expand /burst or shrink/ become

smaller)

Chapter 3 Movement Of Substances Across The Plasma Membrane

Movement Of Substances Across The Plasma Membrane In Everyday Life

The Effect Of Hypotonic Solution

On Plant Cell On Animal Cell
Water enters cell and
Water enters large centre causes it to swell up and
vacuole by osmosis causes eventually to burst.
it to expand, swell up and Red blood cells will undergo
becomes turgid. haemolysis.

Rigid cell wall prevents cell When immersed in distilled water
from bursting.

water molecules
water molecules

water molecules vacuole fills
with water and

expands

water molecules

When immersed in distilled water

ITeach – Biology Form 4

Chapter 3 Movement Of Substances Across The Plasma Membrane

Movement Of Substances Across The Plasma Membrane In Everyday Life

The Effect Of Hypertonic Solution

On Plant Cell On Animal Cell

Cell undergoes plasmolysis. Red blood cell undergoes
crenation
Cells become flaccid,
causing the plant to wilt. Blood cell shrivel and
plasma membrane crinkle
Vacuole up.
shrinks Cell wall

When immersed in 30% sucrose When immersed in 4% sodium
solution chloride solution

ITeach – Biology Form 4

Chapter 3 Movement Of Substances Across The Plasma Membrane

Movement Of Substances Across The Plasma Membrane In Everyday Life

The Effect Of Isotonic Solution

On Plant Cell On Animal Cell

Water diffuses into and out Net movement of water is
of cell at equal rate. zero.

The cell retains its normal There is no change in the
shape. size of cell

Water molecules When immersed in 0.85% sodium
move chloride solution
at the same rate
in both directions

When immersed in 5% sucrose
solution

ITeach – Biology Form 4

Chapter 3 Movement Of Substances Across The Plasma Membrane

Movement Of Substances Across The Plasma Membrane In Everyday Life

The Phenomenon Excessive use of fertiliser causes plant to wilt.
Of Wilting In
Plants Potassium nitrate cause soil to turn hypertonic to
plant cell when dissolved in soil water.

Therefore, water diffuses from cell sap into the
soil by osmosis and plasmolysis occur.

Lack of water in soil also causes plant to wilt.

Soil water becomes more concentrated. Plant
loses water and cells become plasmolysed.

Chapter 3 Movement Of Substances Across The Plasma Membrane

Movement Of Substances Across The Plasma Membrane In Everyday Life

The Preservation Of Food

• Preservatives cause solution outside the food more
hypertonic than the food.

• This causes water to move out of the food by osmosis.

• Cells in the food substances lose water
• These are not conducive to the growth of microorganisms

such as bacteria and fungi and will eventually die.
• Thus, food can last longer.

Wrong fact/misconcept of wilting phenomena

SALAH BETUL

Kelayuan tumbuhan berlaku setelah pokok itu disirami The plant wilt because there are too much fertilizer.
terlalu banyak air

The plant wilt because of soluble molecule diffuse out The plant wilt because of water molecule from cell

from cell sap. sap of root hair cell diffuse out.

The plant wilt because of concentration of soil water is The plant wilt because of concentration of soil water is
high compared to concetration of water in cell sap. low compared to concetration of water in cell sap.

Plasma membrane and vacule of wilted plant will For wilted plant vacuole will become smaller and
shrink plasma membran move away from cell wall

Wrong fact/misconcept of food preservation

Wrong Correct

Light from the sun kill bacteria and fungus in food Light from sun dehydrate the cell of fish, thus bacteria
tissue. and fungus can not reproduce because not water.

Sugar solution and salt solution which use in pickling Sugar solution and salt solution which use in pickling
are hypotonic compare to food tissue. are hypertonic compare to food tissue.

Water molecule from salt/ sugar solution diffuse into Water molecule from salt/ sugar solution diffuse out
the food by osmosis the food by osmosis.

Food tissue is bath with salt /sugar solution Food tissue is dehydrate because lose water.

Vinegar is used to preserve food because the solution Vinegar is used because the it will reduce the pH value

will poison the bacteria and fungus. of cell sap of food.not suitable for bacteria to

reproduce.