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Phagocytosis
The pseupodia are also used for feeding.
Amoeba sp. engulfs food by phagocytosis.
Amoeba sp. is a holozoic organisms which
feed on microscopic organisms such as
bacteria.
The presence of food causes Amoeba
sp.to advance by extending its pseupodia.
The pseupodia encloses the food which is
then packaged in food vacoule.
The food vacoule fuses with lysosome and
the food is digested by hydrolitic enzyme
called lysozyme.
The resulting nutrients are absorbed into
the cytoplasm.
Facilitated Diffusion
For water soluble molecules//molecules
which are not soluble in lipids (ions,
nucleic acid, amino acids and glucose)
Carrier Protein
• The carrier protein function by
binding to the molecules to pass
through the plasma membrane.
• The molecules move to the carrier
protein which is specific for the
molecules.
• Molecules bind with the carrier
protein at the active site.
• Carrier protein changes its shape and
pass the molecules through the
plasma membrane.
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Simple Diffusion
Net movement of molecules or ions from
a region of higher concentration to a
region of lower concentration.
Going down concentration gradient until
an equilibrium is achieved.
The particles are distibuted equally
throughout the system.
The concentration gradient provides
energy to move the molecules into and
out of the cells.
Active Transport
Movement of molecules or ions against
the concentration gradient across the
plasma membranes.
Requires both carrier proteins and
expenditure of energy.
Energy from ATP (adenosine
triphosphate) that is generated during
respiration in the mitochondria.
Has active sites which bind to the ATP
molecules.
The carrier protein changes shape when
the phosphate group from the ATP
molecule binds to it
Then the solute is moved across the
plasma membrane.
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Osmosis: the diffusion of water
Net movement of freely moving water
from a region of lower solute
concentration to a region of higher solute
concentration through a semi-permeable
membrane.//
Net movement of water from region
higher water concentration to a region of
lower water concentration.//
Net movement of water from hypotonic
region to hypertonic region.
Animal and plant cells in an isotonic solution
• Solution in which the solute concentration
is equal to that of the cytoplasmic fluid.
• Water diffuse in and out of the cells at
equal rate.
• No net movement of water.
• Cells retain its normal shape.
1
Hypotonic solution
Concentration of solute outside a cell is lower
than concentration of solute inside cell.
Animal cells
• Is said to be hypotonic solution.
• Cell placed in hypotonic solution.
• Net movement of water into the cells via
osmosis.
• Cell swells up.
• When extremely hypotonic, cells will
eventually burst
• Cannot withstand the osmotic pressure
because of thin plasma membrane.
• E.g : red blood cells (haemolysis)
Plant cells
• Do not burst
• Rigid cell wall.
• Water diffuse into vacoule of cell via
osmosis.
• Cell swells up and becomes turgid
• Tugor pressure in plant.
• Supporting the plant.
Hypertonic solution
The concentration of solute in the solution is
higher than the concentration of solutes within
the cell.
Preservation of fish and vegetables
Fish
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Animal cells
• Net movement of water from inside to
the outside of the cell.
• Cells shrink//shrivel, internal pressure
decrease.
• Red blood cells immersed in hypertonic
solution , the cell shrink and the plasma
membrane crinkles up.
• Cell undergone crenation.
Plant cells
• Water diffuse out via osmosis.
• Vacoule and cytoplasm shrink and plasma
membrane pulls away from the cell wall.
• This process called plasmolysis.
• Cell becomes flaccid.
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Fish is covered by salt solution which is
hypertonic to body fluid/cell/tissue.
More water diffuses out from tissues into
salt solution via osmosis.
Fish becomes hydrated.
Prevents bacterial growth in fish tissues.
Bacteria cells are also
plasmolysed//crenated.
Prevent decay/last longer.
Vegetables
• Vegetables are immersed in vinegar which
is acidic//has low pH.
• Vinegar diffuses into vegetables tissues.
• Vegetables tissues becomes acidic//has
low pH.
• Prevents bacterial growth in tissues.
• Preventing decay//last longer.
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Differences between facilitated diffusion and active transport
D1
E1
D2
E2
D3
E3
D4
D5
D6
Facilitated diffusion
Down the concentration gradient
Molecules moves from higher concentration to lower
concentration
Molecules move in both direction across the plasma
membrane
Molecules can move through pore protein or/and carrier
protein
No ATP/energy used
Molecule can move through pore protein without binding
Molecules need carrier protein and pore protein to help
the movement
Could achieve equilibrium
Not depended in cellular respiration
Similarities between facilitated diffusion and
active transport
• Both (ways of transportation)need carrier
protein.
• To bind with
molecules/ion/substrate/examples
• Both transport specific molecules only.
• Because the carrier protein have specific
site to certain molecules.
• Both processes occur in living cell.
• Because carrier protein need/can change
shape to allow substances to move across.
Active transport
Against the concentration gradient
Molecules moves from lower concentration to
higher concentration
Molecules move in one direction across the plasma
membrane
Molecules move through carrier protein
But
ATP/energy is used
Energy needed for binding/bind with active site
Need carrier protein only to help movement
Will not achieve equilibrium/result in accumulation
Depend on cellular respiration/energy
The Importance of water
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Water is a polar molecule and act as a
solvent.
Transport medium in the blood,
lymphatic, excretory and digestive
systems and in the vascular tissues of
plant.
As a medium for biochemiocal reaction.
Helps in lubricant.
Regulates body temperature.
General characteristics of enzymes
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Alter or speed up the rates of chemical
reactions
Remain unchanged at the end of reaction.
Do not destroyed by reactions they
catalysed.
Have specific sites called active site to
bind with specific substrates.
Needed in small quantities.
Reaction are reversible
Can be slowed down or stopped by
inhibitors. E.g: lead and mercury
Require helper molecules, called
cofactors.
Inorganic cofactor : ferum, copper
Organic cofactor: water soluble vitamins,
B vitamins .
3
Extracellular enzyme
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Extracellular enzyme is produced in a cell,
then packed and secreted from the cell.
It catalyses its reaction outside the cell.
An example is amylase.
The instruction for making the
extracellular enzyme is transcribed from
the deoxyribonucleic acid
(DNA) to ribonucleic acid (RNA) in the
nucleus.
The RNA then leaves the nucleus through
the nuclear pore
and attaches itself to the ribosome
located on the endoplasmic reticulum.
When the synthesis of the enzymes is
completed it is encapsulated in a
transport vesicle which fuses with the
golgi body.
In the golgi body, the enzyme is further
modified before being packed in a
secretory vesicle.
The secretory vesicle transports the
enzyme to the plasma membrane, where
it fuses with it and the enzyme is released
outside the cell.
Prophase
Chromosomes in the nucleus condense.
Chromosomes appear shorter and thicker.
Consist of sister chromatid joined at the
centromere.
Spindle fibres begin to form.
Centrioles migrate at opposite poles.
At the end, nucleolus disappears and the
nuclear membrane disintegrates.
‘Lock and key’ hypothesis
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The substrate molecule fits into the active
site of the enzyme molecule.
The substrate is the ‘key’ that fits into the
enzyme ‘lock’.
Various types of bonds such as hydrogen
and ionic bonds hold the substrate
in the active site forming the enzymesubstrate complex.
Once the complex is formed, the enzyme
changes the substrate to its product.
The product leaves the active site.
The enzyme is not altered by the reaction
and it can be reused.
Effects of temperature on enzyme activity
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Metaphase
Chromosomes align at the metaphase
plate//equatorial plate//middle of the
cell.
Mitotic spindle are fully formed.
Two sister chromatids are still attached to
one another at the centromere.
Ends when the centromere divides.
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At low temperature, reaction takes place
slowly.
As temperature increases, movement of
substrate increase.
Increase their chances of colliding with
each other and with the active site of the
enzymes.
At optimum temperature, the reaction is
at maximum rate.
Beyond the optimum temperature, rate of
reaction will not increase.
Bonds that hold enzyme molecules begin
to break.
Actives sites destroyed.
Enzyme denatured.
Anaphase
Two sister chromatids separate at the
centromere.
Sister chromatids pulled apart at opposite
poles.
Chromatids are referred to as daughter
chromosomes.
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Telophase
Chromosomes reach the opposite poles of
the cell.
Chromosomes uncoil and revert to their
extended state(chromatin).
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Animal cloning
Somatic cells (from the mammary gland
cells) are removed and grown in a culture.
Cells stop dividing and enter a non-diving
phase.
Unfertilised egg is obtained. The nucleus
is sucked out, leaving the cytoplasm and
organelles without any chromosomes.
Electric pulse stimulates the fusion
between the somatic cells and egg cell
without nucleus.
Cells divide repeatedly forming an
embryo.
The embryo is then implanted in a
surrogate mother.
The cloned sheep of the somatic cell
donor is born.
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Cytokinesis
Process of cytoplasmic division.
Begins before nuclear division is
completed.
Actin filament formed contractile ring.
Contracts and constrict pull aring of
plasma membrane inwards.
Groove of cleavage furrow pinches at the
equator between two nuclei.
Vesicles join to form a cell plate.
Cell plate grows until it edges fuse with
the plasma membrane of the cell. Cell
divides.
Cellulose are produced by the cell to
strengthen the new cell walls.
Tissue culture
Small part of plant is cut. E.g : shoots, bud.
The part is called explant.
Enzymes are used to digest the cell walls
of tissue.
Cells are naked (protoplast).
Explant/protoplast are steriled then
placed in a glass container which contains
a nutrient solution.
Culture medium (glucose, amino acids).
Apparatus must be steriled to make sure
free from microorganisms (bacteria).
pH and temperature must be at optimum
level.
Explant divides by mitosis.
Develops into callus.
Callus develops into somatic embryo
(planlet).
Then transferred to soil for growth.
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Uncontrolled mitosis
Cell divides through mitosis repeatedly
without control.
Produce cancerous cells.
Cancer is a genetic disease caused by
uncontrolled mitosis.
Disruption of cell cycle.
Cancerous cells divides freely and
uncontrollably not according to the cell
cycle.
These cells compete with surrounding
normal cells for energy and nutrients.
Cancer cells formed tumour.
Tumour invade and destroy neighbouring
cells.
Advantages of cloning
Biotechnologists to multiply copies of
useful genes or clones.
Clones can be produced in a shorter time
and in large numbers.
Cloned plants, however, can produced
flowers and fruits within a shorter period.
Clones are better quality.
Delayed ripening.
Does not need polinating agents.
Propagation can take place at any time.
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Disadvantages of cloning
Long-term side effects are not yet known.
May undergo natural mutations. Disrupt
the natural equilibrium of an ecosystem.
Clones do not show any genetic
variations.
Has the same level of resistance towards
certain disease.
Certain transgenic crops contain genes
that are resistant to herbicides.
These genes may be transferred to weeds
through viruses. These weeds would then
become resistant to herbicides.
Cloned animals has shorter lifespan.
Meiosis I
1. During prophase I, homologous
chromosomes pair up (synapsis) and
crossing over between non sister
chromatids occurs.
2. During Metaphase I, homologous
chromosomes align at the metaphase
plate (equator, middle) of the cell.
3. During Anaphase I, homologous
chromosomes separates and move to
opposite poles. Sister chromatids are still
attached together and move as a unit.
4. At the end of Telophase I, two haploid
daughter cells are formed. Each daughter
cell has only one of each type of
chromosomes, either the paternal or
maternal chromosomes.
Meiosis II
1. During Prophase II, synapsis of
homologous chromosomes and crossing
over between non-sister chromatids do
not take place.
2. During Metaphase II, chromosomes
consisting of two sister chromatids align
at the metaphase plate (equator/middle)
of cell.
3. During Anaphase II, sister chromatids
separate, becoming daughter
chromosomes that move to opposite
poles.
4. At the end of Telophase II, four haploid
daughter cells are formed. Each daughter
cell has the same number of
chromosomes as the haploid cell
produced in Meiosis I, but each has only
one of the sister chromatids.
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Digestion in mouth
Secretion of saliva by three pairs of
salivary glands
Saliva contains the enzyme salivary
amylase
Begins the hydrolysis of starch to maltose.
Salivary amylase
Starch + water
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maltose
An additional digestive process occurs
further along the alimentary canal to
convert maltose to glucose.
pH is maintained at 6.5-7.5
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Digestion in stomach
Epithelial lining of the stomach contains
gastric glands.
These glands secrete gastric juice.
Consists of mucus, HCL and enzyme
pepsin and renin.
HCL make the pH around 2.0.
High acidity destroy bacteria.
Acidity stop the activity of salivary
amylase enzyme.
pepsin
Protein + water
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polypeptides
Renin coagulate milk by converting the
soluble milk protein, caseinogen into
soluble caesin.
Stomach contents become a semi-fluid
called chyme.
Chyme gradually enter the duodenum.
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Digestion in small intestine
Duodenum received chyme from stomach
and secretion from the gall bladder and
pancreas.
Starch, protein and lipids are digested.
Bile which produced by the liver and
stored in the gall bladder enter the
duodenum via the bile duct.
Bile helps neutralise the acidic chyme and
optimise the pH for enzyme action in
duodenum.
Bile salts imulsify lipids, breaking them
down into tiny droplets.
Providing high TSA for digestion.
Pancreas secrete pancreatic juice into
duodenum via pancreatic duct.
Pancreatic juice contains pancreatic
amylase, trypsin and lipase.
Pancreatic amylase complete the
digestion of starch to maltose.
Trypsin digests polypeptides into
peptides.
Lipase complete the digestion of lipid into
fatty acid and glycerol.
Glands in the ileum (small intestine)
secrete intestinal juice which contain
digestive enzyme needed to complete the
digestion of peptides and disaccharides.
Peptides digested by erepsin into amino
acids.
Maltose digested by maltase into glucose.
Disaccharides digested by its own enzyme
into monosaccharides and glucose.
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Digestion of cellulose by ruminant
Partially chewed food is passed to the
rumen (largest compartment of the
stomach).
Cellulose is broken down by cellulase
produced by bacteria.
Part of the breakdown products are
absobed by bacteria, the rest by the host.
Food enters the reticulum.
Cellulose undergoes further hydrolysis.
The content of the reticulum, called the
cud, is then regurgitated bit by bit into the
mouth to be thoroughly chewed.
Helps soften and break down cellulose,
making it more accessible to further
microbial action.
The cud is reswallowed and moved to the
omasum.
Here, the large particles of food are
broken down into smaller pieces by
peristalsis.
Water is removed from the cud.
Food particles moved into obamasum, the
true stomach of the ruminant. (e.g : cow).
Gastric juice complete the digestion of
protein and other food substances.
The food then passes through the small
intestine to be digested and absorbed in
the normal way.
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Digestion of cellulose by rodent
Caecum and appendix are enlarged to
store the cellulose-digesting bacteria.
The breakdown products pass through the
alimentary canal twice.
The faeces in the first batch are usually
produced at night.
Faeces are then eaten again. To absorb
the products of bacterial breakdown.
The second batch of the faeces are harder
and drier.
Allows rodent (give example) to recover
the nutrients initially lost with the faeces.
Digestion
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Protein
- In stomach, pepsin breakdown
protein into polypeptides.
- HCL being secreted to provide acidic
medium for the digestion to occur.
- In duodenum, trypsin breakdown
polypeptides into peptides.
- In small intestine, arepsin break dwon
peptides into amino acids.
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Fats
- Bile salts breaking up fats into small
fat droplets in the duodenum.
- In duodenum/small intestine, lipase
breaks lipids into fatty acids and
glycerol.
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Carbohydrates
- In mouth, salivary amylase hydrolyse
starch into maltose.
- In duodenum, pancreatic amylase
hydrolyse starch into maltose.
- In small intestine, maltase hydrolyse
maltose into glucose.
8
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Absorption of digested food
Absorption of digested food occur in the
ileum.
Glucose/amino acids initially diffuse into
blood capillaries.
The remaining of the glucose/amino acids
actively transport into blood capillaries.
All blood capillaries converge into hepatic
portal vein, which lead to the liver (and
transport to all parts o fthe body).
Glycerol and fatty acids diffuse to the
epithelial cell which lining the ileum) and
combine to form fat droplets.
Fatty acids and glycerol then enter the
lacteal (lymphatic system).
Return back to the blood stream at left
subclavian vein.
Assimilation of digested food
Explain the assimilation of glucose and amino acid
in body cells.
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Glucose is oxidised to produce energy,
carbon dioxide and water by cellular
respiration.
Amino acid is used to synthesis
protoplasm (the component of cell). By
this way new cells will be synthesised
causing growth.
Amino acid also can be used to synthesis
enzyme, hormone or antibody.
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Formation faeces
Faeces which contain dead cells that are
shed from intestinal linings, toxic
substances and bile pigments enter the
colon by action of peristalsis.
In colon, more water is absorbed. The
undigested food residues harden to
become faeces.
Faeces contain undigestible residues that
remain after the process of digestion and
absorption of nutrients that take place in
the small intestine.
9
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Photosynthesis mechanism
The formation of starch in plants is by the
process ofphotosynthesis which occurs in
chloroplasts.
The two stages in photosynthesis are the
light and dark reactions.
Light reaction:
P3:Takes place in grana.
P4: Chlorophyll captures light energy
which excites the electrons of chlorophyll
molecules to higher energy levels.
P5: In the excited state, the electrons can
leave the chlorophyll molecules.
P6: Light energy is also used to split water
molecules into hydrogen ion (H+) and
hydroxyl ions (OH-) (Photolysis of water).
P7: The hydrogen ions then combine with
the electrons released by chlorophyll to
form hydrogen atoms.
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Photosynthesis mechanism
P8: The energy from the excited electrons
is used to form energy-rich molecules of
adenosine triphosphate /ATP.
P9: Hydroxyl ion loses an electron to form
a hydroxyl group. This electron is then
received by chlorophyll.
P10: The hydroxyl groups then combine to
form water and gaseous oxygen.
Dark Reaction:
P11: Take place in stroma.
P12: Do not require light energy.
P13: The hydrogen atoms are used to fix
carbon dioxide in a series of reactions
catalysed by photosynthetic enzymes
P14: and caused the reduction of carbon
dioxide into glucose.
P15: The glucose monomers then undergo
condensation to form starch which is
temporarily stored as starch grains in the
chloroplasts.
•
Uses of enzyme (Chapter 4)
Enzymes are used as biological
detergents.
· Protease degrades coagulated proteins
into soluble short-chain peptides.
· Lipase degrades fat or oil stains into
soluble fatty acid and glycerol.
· Amylase degrades starch into soluble
shorter-chain polysaccharides and sugars.
•
Enzymes are used in the baking industry.
· Protease is used in the breakdown of
proteins in flour for the production of
biscuits.
· Amylase is used in the breakdown of
some starch to glucose in flour for making
white bread, buns and rolls.
•
Enzymes are used in the medical field.
· Trypsin is used to remove blood clots
and to clean wounds.
· Various other enzymes are used in
biosensors.
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Enzymes are used in industries because:
·They are effective.
·They are cheap and easy to use.
·They can be re-used, thus only small
amounts are needed.
· They don't require high temperature to
work, thus this reduces fuel costs.
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Aerobic respiration
Continuous supply of oxygen.
Glucose molecules are oxidised by
oxygen.
Complete breakdown of glucose in the
presence of oxygen.
A large amount of energy released.
Carbon dioxide and water are produced as
waste products.
Most of the nergy released is used to
synthesise adenosine triphosphate (ATP)
from adenosine diphosphate (ADP) and
inorganic phosphate.
ATP acts as instant energy source.
ATP consists of phosphate bonds which
can be easily broken down to release
energy.
Energy released
ATP
ADP + phosphate + energy
Anaerobic respiration in human muscle
• During a vigorous exercise (running), the
breathing rate is increased.
• This is to supply more oxygen to the
muscles for rapid muscular contraction.
• However, the supply of oxygen to muscles
is still insufficient.
• and the muscles have to carry out
anaerobic respiration to release energy.
• The glucose is converted into lactic acid,
with only a limited amount of energy
being produced.
• An oxygen debt builds up in the body,
when no oxygen use in energy production.
• High level of lactic acid in the muscles
cause them to ache.
• After running, the athlete breathes more
rapidly and deeply than normal for
twenty minutes.
• There is recovery period after 10 minutes
until it reaches 20 minutes when oxygen is
paid back during aerobic respiration.
• About 1/6 lactic acid is oxidized to carbon
dioxide, water and energy.
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Anaerobic respiration in yeast
Yeast normally respires aerobically.
Under anaerobic condition, yeast carry
out anaerobic respiration.
Produces ethanol.
Process known as fermentation.
Catalysed by the enzyme zymase.
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Ethanol produced can be used in
making wine and beer.
In bread making, the carbon dioxide
released during fermentation of yeast
causes the dough to rise.
Similarities between the sturucture of digestive and digestion process of ruminants and rodents
S1
P1
P2
S2
P1
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Both alimentary canal contains bacteria/protozoa
To secrete extracellular enzyme//to digest
To digest cellulose into glucose
Both have large surface area
To increase rate of diffusion //hydrolysed food
11
Differences between the sturucture of digestive and digestion process of ruminants and rodents
Aspects
Number of stomach chamber
Size of caecum
Bacteria
Number of times yhe food passes
through the stomach chamber
Regurgitated
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D1
E1
D2
E2
D3
E3
D4
E4
D5
Breathing mechanism in man
Diaphragm is a muscular sheet in the
body cavity separating the thorax from
the abdomen.
At the start of inhalation, the muscles of
the diaphragm contract , making it less
arched.
This helps to increase the volume of the
thoracic cavity and reduce the pressure
of the thoracic cavity. Air rushes into the
lungs.
When the muscles of the diaphragm
relax , it returns to its arched condition ,
reducing the volume of the thoracic
cavity and increasing the pressure of the
thoracic cavity. Air is forced out of the
lungs.
The muscles between the ribs are known
as intercostals muscles.
During inhalation the external
intercostals muscle contracts and raise
the lower ribs.
Ruminant (has)
4 stomach chamber
Have to digest cellulose
Small//short caecum
Do not digest cellulose
In reticulum
For secrete cellulase enzyme
Twice
To complete the digestion//
Twice in mouth cavity
But
Rodent (has)
1 stomach chamber
Do not have to digest cellulose
Big//long size caecum
A place to digest cellulose
In caecum
For secrete cellulase enzyme
Once
To absorb digested food
Once in mouth cavity
Breathing mechanism in man (continuation)
• This helps to increase the volume of the
thoracic cavity and reduce the pressure of the
thoracic cavity. Air rushes into the lungs.
• During exhalation the external intercostals
muscles contract , the ribs return to their
original position , reduce the pressure of the
thoracic cavity. Air is forced out of the lungs.
• The alveoli are thin-walled air sacs with the
lungs.
• These sacs are surrounded by a network of
capillaries.
• During inhalation the alveoli are filled with
air and gaseous exchange occurs between the
alveoli and the capillaries.
• Oxygen from the alveoli diffuses into the
capillaries while carbon dioxide diffuses from
the capillaries into the alveoli.
Transport of O2 and CO2 in human body
• Gaseous exchange across the alveolus
occurs by diffusion.
• Diffusion of gas depends on differences
in partial pressure between two regions.
• The partial pressure/ concentration of
oxygen in the air of the alveoli is higher
compared to the partial pressure/
concentration of oxygen in the blood
capillaries.
• Therefore, oxygen diffuse across the
surface of the alveolus and blood
capillaries into blood.
• The transport of oxygen is carried out by
the blood circulatory system.
• Oxygen combines with respiratory
pigment called haemoglobin in the red
blood cells.
• To form oxyhaemoglobin.
• When the blood passed the tissue with
low partial pressure of oxygen,
12
Transport of O2 and CO2 in human body
(continuation)
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Explain how energy flows through the food chain
and how it is lost to the environment.
Oxyhaemoglobin dissociates to release
oxygen.
Carbon dioxide released by repairing
cells can be transported by dissolve
carbon dioxide in the blood plasma.
Bind to the haemoglobin.
As carbaminohaemoglobin.
In form of bicarbonate ions.
Carbon dioxide is expelled with water
vapour from the lung.
Colonisation and succession in mangrove
swamps
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Energy flows through the food chain in one
direction .
In the food chain, the plant is the producer,
the rat is the primary consumer, the snake is
the secondary consumer and the eagle is the
tertiary consumer.
In the food chain, the plant is the producer,
the earthworm is the primary consumer, the
bird is the secondary consumer and the
snake/ eagle is the tertiary consumer. Each
level of food chain is called a trophic level.
Energy is transferred from one trophic level
to another trophic level.
When energy is transferred from one trophic
level to another level as much as 90% of the
chemical energy in the food consumed by
primary consumer is used for its metabolic
activities and lost as heat.
Only 10% of the energy in an organism is
passed on to the organism at the next trophic
level.
•
•
•
•
•
•
The pioneer species of a mangrove
swamp are the Sonneratia sp. and
Avicennia sp.
The presence of this species gradually
changes the physical environment of
the habitat.The extensive root systems
of these plants trap and collect
sediments, including organic matter
from decaying plant parts.
As time passes, the soil becomes more
compact and firm. This condition
favours the growth of Rhizophora sp.
Gradually the Rhizophora sp. replaces
the pioneer species.
The prop root system of the Rhizophora
sp. traps silt and mud, creating a firmer
soil structure over time.
The ground becomes higher. As a result,
the soil is drier because it is less
submerged by sea water.
The condition now becomes more
suitable for the Bruguiera sp., which
replaces the Rhizophora sp.
The buttress root system of the
Bruguiera sp. forms loops which extend
from the soil to trap more silt and mud.
As more sediments are deposited, the
shore extends further to the sea. The
old shore is now further away from the
sea and is like terresterial ground.
Over time, terrestrial plants
like nipah palm and Pandanus sp. begin
to replace the Bruguiera sp.
13
Green house effects
•
•
•
•
•
•
Green house effect.
Ultra violet(uv) from solar radiation is
absorbed by the earth and some of them
is reflected back to the atmosphere in the
form of heat/infra red.
Heat or infrared radiation cannot be
reflected back to the atmosphere.
Because it is trapped by green house
gases such as CO2, nitrogen dioxide and
methane.
Heat/infrared warmed the surface of
earth.
Earth temperature increases.
Explain briefly why humans carry out the activity
as shown in diagram above
•
•
•
•
The human population grows rapidly. The
demands for food and housing areas have
increased.
Vast areas of forest are cleared for
agricultural and commercial purposes.
Urbanization and industrialization have
caused more forests to be cleared for
road construction and housing areas.
Deforestation is also caused by the
demands for timber and fuel wood.
Explain the impacts of the activity shown above
on the environment
• Deforestation causes soil erosion ,
landslides, flash floods and global
warming.
• Causes the soil to become loose and less
stable.
• Without the protection of green plants,
the soil is exposed to the forces of wind
and rain.
• The top layer of soil is washed away
gradually by the rainwater.
• This is known as soil erosion.
• Soil erosion causes the depletion of
minerals from the soil, therefore the soil
becomes infertile and unsuitable for
agriculture.
• Landslides may happen on steep hillsides
during heavy rain.
• It is because rainwater flows quickly and
causes the top layer of the soil to
crumble.
• Rivers and drains are silted and the flow
of water is blocked.
• Therefore, water flows inland and this
causes flash floods in the lower areas
during rainy seasons.
14
Human blood vessels
Circulatory system in fish and human
Similarities
- both have closed circulation
- both have a heart
Arteries
- carries blood away from heart
- transport blood quickly, at high pressure
- muscle of tissue enables the artery to
constrict and dilate
Differences
- walls of arteries are strong and elastic,
have small lumen
Fish
Capillaries
Has single circulation
- thin walled blood vessels
Heart divides into 2
- allow rapid gaseous exchange via diffusion
chambers
- nutrients, wastes and hormones are also
Septum is absent
exchanged across here
Deoxygenated blood
- one cell thick
flows from heart to
Veins
gills
- blood returns from capillaries to heart
Oxygenated blood
through veins
flows from gills to
- blood flows in low pressure
body cells
- have large lumens and valves (prevent
back flow)
Difference between blood and lymph
- lymph has a large numbers of lymphocyte
compare to blood
- lymphocyte is produced by lymph nodes
in lymph system
- lymph has lower content of oxygen
compare to blood
-
-
-
Human
Has double circulation
Heart is divided into 4
chambers
Septum is present
Deoxygenated blood
flows from heart to
lungs
Oxygenated blood
flows from lungs to
heart
Type of immunity
active immunity, body produces its own
antibodies in response to stimulation by
an antigen
passive immunity, body receive an
antibodies from outside source
-
-
-
Blood clotting
clumped platelets, damaged cells, clotting
factors form activators (thromboplastins)
activators together with calcium ions and
vitamin K, converts prothrombin to
thrombin
thrombin catalyses the conversion of
soluble protein fibrinogen into insoluble
fibrin.
fibrin is a fibrous protein which combines
to form a mesh of long threads over the
wounds, trapping red blood cells and
sealing the wound.
blood clot hardens when exposed to air
forming scab
Phagocytosis
the phagocyte is attracted by chemicals
produced by bacterium
Phagocytes extend its pseudopodium
(legs) towards bacterium to engulf it.
ingestion of bacterium forms phagosome
phagosome combines with lysosome
lysosome releases lysozyme into
phagosome
bacterium inside the phagosome will be
destroyed by lysozyme
phagocyte releases the digested products
from cell
15
Lymph – formed - brought back into the blood
circulatory system.
- when blood flows from arteries into
capillaries, there is higher hydrostatic
pressure at artial end of capillaries
- high pressure causes some plasma to pass
through capillary walls into intercellular
spaces
- interstitial fluid fills the spaces between
cells and constantly bathes the cells
- 90% of interstitial fluid diffuses back into
blood capillary
- 10% of interstitial fluid goes into the lymph
capillaries and known as lymph
- lymph capillaries unite forming larger
lymphatic vessels
- from lymphatic vessels, lymph eventually
passes into thoracic duct
- hence lymph drains back into blood
Respiratory gases
Active immunity – Passive immunity
Transportation in respiratory gas.
- oxygen enters alveoli during inhalation
- gaseous exchange occurred at alveoli
(oxygen diffused into blood capillaries
while carbon dioxide diffused out)
- the diffusion of these gases caused by
different of partial pressure of both
gaseous
- partial pressure of oxygen in alveoli is
higher than partial pressure of oxygen in
blood capillaries
- oxygen diffused in cytoplasm of red blood
cell
- oxygen combines with haemoglobin
forming oxyhaemoglobin
- oxyhaemoglobin then sent to all parts of
body
- heart pumped the oxygenated blood to all
body cells
- oxygen diffused from blood capillaries to
cell because partial pressure of oxygen in
blood capillaries is higher than in cell
- carbon dioxide diffuse from cell to blood
capillaries because partial pressure of
carbon dioxide in cell is higher than in
blood capillaries
- deoxygenated blood going back to heart
by vena cava and to lungs by pulmonary
artery
Active immunity
- obtained by vaccination (artificially
acquired)
- vaccine contains dead/weakened
bacteria/pathogen/virus
- white blood cells stimulated to produce
antibodies against pathogen
- also obtained when an individual has
recovered from certain diseases(naturally
acquired)
- a ready made supply of antibody will give
immunity towards the disease
Passive immunity
- obtained by injecting
antibodies/antiserum (artificially
acquired)
- no antigen is put into body, so body does
not produce its own antibodies
- obtained by a baby when antibodies from
mother’s blood plasma diffuse into foetus
through placenta (naturally acquired)
16
Movement of water froom root to leaves
Movement of water from root to leaves aided by
root pressure, capillary action and transpirational
pull.
Root pressure
• cell sap of root hair(usually) hypertonic to
surrounding soil solution
• water diffuses into root by osmosis
• cell cap becomes more dilute compared
to neighbouring cell
• water moves to these adjacent cells which
become more diluted themselves, so
osmosis continues across the cortex
• (at the same time) ions from soil are
actively secreted into xylem vessels and
causes osmotic pressure to increase
• Water flows continuously into xylem and
create a pressure(root pressure)
• Root pressure gives an initial upward
force to water and mineral ions in xylem
Movement of water from root to leaves
Capillary action
• water moves up through xylem in stems
by capillarity
• capillary action is due to combined force
of cohesion(water molecules have
attraction for each other) and
adhesion(water molecules are attracted
to the side of vessels)
• water molecule form a continuous water
column in xylem vessel (due to cohesion
and adhesion)
• the cohesion of water prevent the water
column in xylem breaking apart
• the adhesion of water prevents gravity
from pulling the water down the column
Transpirational pull
• the lost of water from mesophyll cells
during transpiration is replaces by water
which flows in from xylem vessels in
leaves
• this creates a tension/suction force in
water column because water has cohesive
properties called transpiration pull
• the transpiration pull draws water from
xylem in the leaves/stem/roots
• the continuous flow of water through
plant is known as transpiration stream
Effect of no lignin formation on the function of
tissue xylem
• lignin is important to make tissue xylem
strong
-
•
without lignin, tissue xylem will collapse
therefore, it cannot form a continuous
hollow tube
to allow water to flow upwards
continuously
lignin makes the tissue become
impermeable
- materials cannot pass in xylem cells
- causes the tissue to become hollow
- allows continuous flow of water
(choose one of the * and the explanations below)
17
light intensity and stomata and cells effect the
rate of water loss
• F1- from 0500 to 0170(time/hours), rate
of water loss increases
• E1- light intensity increases
• E2- stimulates photosynthesis in guard
cells
• E3- this makes energy available for
potassium to move into guard cells by
active transport
• E4- guard cells become
hypertonic(compared to cell sap) of
epidermal cells
• E5- water molecules from epidermal cells
diffuse into guard cells by osmosis
• E6- causing guard cells to bend outwards
• E7- stoma opens (allows water to escape)
• F2- from 0170 to 0300(time/hours) rate of
water loss decreases
• E8- lisght intensity decreases/rate of
photosynthesis decreases
• E9- guard cells become flaccid and bend
inwards
• E10- stoma closes, prevents water from
escaping
• Notes: (F1 + any 5Es) + (F2 + 3Es)
Adaptation of the muscle which enables it to
contracts
- the skeletal muscle consist of bundles of
muscle fibres and a large supply of nerves
and blood vessels
- a muscle fibre is made up of bundles of
smaller units called myofibrils
- each myofibril is made up of 2 types of
protein filaments: the actin and the
myosin which interact and cause muscle
contractions
- the muscle’s nerve endings control its
contractions
Movement takes place involves muscles,
tendons, bones, ligaments and joints
Muscle
- quadriceps femoris contract while biceps
femoris muscles relax (leg straightened)
- biceps femoris contract while quadriceps
femoris relax (leg bent)
- calf muscles contract to lift up the heels
- feet push downwards and backwards
- repeated contraction and relaxation of
muscle result in running movement
Ligaments
- it connects 2 bones together
- give support and strength to joints for
movement
- strong and elastic
Joints
- a hinge joint allow the movement of leg to
swing back and forth
Tendon
- connect muscles to bones
- strong and non elastic
- force is transferred to bones through
tendons
Bones
- femur/ thigh bone is long, heavy and
strong
- provide support to body weight
18
Adaptation of plant which enable it to float
-
have fine aerenchyma wall tissues (plants
become more lighter)
have air spaces/air sacs (becomes more
easy to float)
have big and swell stem/petiole (increase
the air to help plant floating)
have fine and many roots (trap gas
bubbles)
Skeletal system of earthworm and fish adapted
Adaptive features which helps in birds and fish
for its movement
locomotion
Movements in earthworm
Bird
- earthworm has hydrostatic skeleton
- aerofoil wing – to generate the upward lift
- moves by changing hydrostatic pressure
- a pair of antagonistic muscle (pectorolis
of fluid in its segment
major and minor) pulled down and up the
- each segment of the body has its own set
wings
of muscles
- single organ (one testes/kidney)//small
o an outer layer of circular muscles
skull – to reduce weight
running around the body causes the
- streamlined body shape – reduce air
worm to become long and thin when
resistance
they contract
- waterproof feather – avoid increase in
o an inner layer of longitudinal muscles
body weight during raining
causes the worm to get short and
Fish
thick when they contract
- streamed lined body – reduce water
- as the circular muscles contract, the
resistance
longitudinal muscles will relax
- myotome muscle are W/V – shaped which
simultaneously in antagonistic action
act antagonistically
- causes the hydrostatic pressure to be
- air sac – maintain buoyancy in water
transferred from anterior part to posterior
- fins
part causing the worm to move forward
o dorsal and ventral fin –
prevent/helps in yawing and
Movements in fish
rolling
- fish has an endoskeleton
o tail fin – provides thrust and
- it provides place for attachment of
controls direction
muscles
o pelvin and pectoral fin – act as
- when the left myotome contracts, right
brakes/to slow down
myotome will relax in antagonistic action
- causes the vertebral column to curve
toward the left
- the fish also has fins with different
functions for locomotion
19
Support is achieved in submerged and floating
plants
Osteoporosis and osteoarthritis happen prevented
Submerged plants
- posses air sacs within the leaves and the
stem to help the plant to stay upright in
water
- water buoyancy provides support
- have very few woody tissue/vascular
tissue
- thin/narrow/flexible leaves – provide little
resistance to water flow
Floating plants
- stem have plenty of air sacs
- aerenchyma tissues helps to stay afloat in
water
- do not have woody tissues
- natural water buoyancy to help them float
- have broad leaves that are firm but
flexible to resist being torned by wave
action
Osteoporosis
- a disease in which bone mass is reduced
and the boned become porous and lighter
- occurse most often in old people, partially
women who have gone menopause
- bodies of postmenopausal women do not
produce sex hormone, oestrogen
- causes more bone minerals to be lost than
deposited
- as a results, bones become soft and brittle
- can be prevented by
o doing weight-bearing exercise,
strengthen the muscles and bones
o taking diet rich in calcium,
phosphorus and vitamin D
o takin in vitamin C, increase bone
mass
o refraining from smoking
Osteoarthritis
- Osteoarthritis is part of ageing process
due to wear and tear of cartilage between
bones at certain joints
- Patient has painful, swollen stiff knees
which restrict daily activities (walking,
climbing)
- If treatment fails to relieve the pain, a
surgeon can replace the damaged joints
with artificial ones made of plastic or
metal
Important to have healthy musculoskeletal
system - ways maintaining a healthy
musculoskeletal
The musculoskeleton system where bones,
muscles, ligaments and tendons work together
like a machine to bring about movement
-
-
musculoskeleton helps to support our
body
if any part of system injured, we will
experience discomfort, pain and loss of
mobility
it also affect othe organs and physiological
processes in body (respiration/digestion)
20
Important to have healthy musculoskeletal
Osteoarthritis and arthritis gout occur - effect of
system - ways maintaining a healthy
the diseases
musculoskeletal
Ways to maintain
Muscular dystrophy
- having balanced diet. Take diet rich in
- muscle destroying disorder
proteins, vitamins A, C n D together with
- weakness/weaking of muscles
minerals (calcium,phosphate n iron) for
- mostly in male
building strong bones. Drinking
- affect the heart muscle – heart attack
fluoridated water will also harden the
- results in poor balance/wobbling/poor
bones
movement
- adopt a good posture while standing,
Osteoporosis
- condition characterized by lost of normal
sitting, walking and while performing
density of bone
certain tasks to ensure that our body is
- resulting in fragile bone
always supported. This is important
- bone fracture
because bad posture will put undue
- no symptom before any bone fracture
pressure on our muscles and spine and
- consequences – fracture of
this will in turn affect the functions of our
vertebrae//reduction of in height over
internal organs (lungs, heart and stomach)
time//stooped posture
- wear proper attire for daily activities.
Wear loose and comfortable clothes. Tight
clothes restrict our movement. Woman
wearing high heels tilt the body forwards.
To counteract this, the woman bends her
knees and throws her trunk forwards,
causing the spine to curve even more
- taking precautions during vigorous
activities
- practice correct and safe techniques when
exercisingto prevent serious injuries to
the musculosketonn system
Support system in woody plants differs from that
of non-woody plants
Non-woody plants (herbaceous plants)
- (support in herbaceous plants is) provided
by the turgidity of
parenchyma/collenchyma cells
- (when there is enough warm in the
ground) the cells take in water by osmosis
and become turgid
- The turgor pressure of fluids in the
vacuoles pushes the cell contents/plasma
membrane against the cell wall
- Creating support for its tem/roots/leaves
- The thin thickening die cell walls with
cellulose/collenchyma cells gives support
to herbaceous plants
21
Support system in woody plants differs from that
of non-woody plants
Woody plants
- woody plants have specialized
tissues/sclerenchyma tissues/xylem
vessels.tracheids to give them support
- these tissues have cellulose walls which
have deposits of lignin for added strength
- sclerenchyma cells have very thick walls
(do not allow water to pass through)
- (these cells are dead cells) their function is
to provide support
- Xylem vessels have thick walls of lignin
which are deposited during the plant’s
secondary growth
- The lignified xylem vessels form the
woody tissues of the stem
- This makes the plant stronger and also
provides support for the plant
- Tracheids are also dead cells with thick
walls and very small diameters
- They are found with xylem vessels and
together they support the plants
Synapse – The event as a nerve impulse is
transmitted across a synapse
Ø Synapse is a narrow gap between an axon
terminal and a dendrite of another
adjacent neuron. A chemical is used by
neuron to transmit an impulse across a
synapse. The chemical is called
neurotransmitter
Knee jerk
-
-
Ø The transmission of information across a
synapse involves the conversion of
electrical signal into chemical signal in the
form of neurotransmitter
Ø Neurotransmitter is produced in vesicles
in a swollen part of the axon terminal
called synaptic knob
Ø Synaptic knob contains abundant
mitochondrion to generate energy for the
transmission
Ø When an impulse arrived at the synaptic
knob, the vesicles release the
neurotransmitters into the synapse
Ø The neurotransmitters molecules diffuse
across the synapse to the dendrite of
another neurons
Ø The dendrite of another neurons is
stimulated to trigger a new impulse which
travel down a long neuron
-
-
-
the knee jerk action involves two types of
neurons named afferent and efferent
neurons
when a hammer hits a tendon that
connect to quadriceps muscle in the thigh
to a bone in the lower leg
as the hammer strike, the force stretches
the quadriceps muscle and stimulates the
stretch receptors in the muscles,
triggering nerve impulse
afferent neurons transmit the information
to the quadriceps muscle and the muscle
contracts swing the leg forward
if the patient is able to swing the leg
forward, it indicates that the patient’s
nerve system is still functioning
if there is no response, it shows that the
patient’s nervous system fails to function
properly
22
When the hand touches a hot object
-
the heat on the object stimulates the
nerve endings (receptors) in skin
impulses are triggered
impulses travel along the sensory/afferent
neuron to spinal cord
in spinal cord, the impulses are
transmitted first across a synapse to the
interneurone and then across another
synapse to the motor/efferent neurone
At synapse
- when an impulse reach a presynaptic
membrane, it triggers the synaptic
vesicles to release neutrotransmitter into
the synaptic cleft
- the neurotransmitter diffuse across the
synaptic cleft
- and bind to receptors which are attached
to the postsynaptic membrane
- the binding of the neurotransmitter to the
receptors leads to the generation of a
new impulse
- impulses leave the spinal cord along the
motor/efferent neurone to the effector
- the effector is the biceps muscle which
then contracts. This brings about a sudden
withdrawal of the hand
Roles of cerebellum and medulla oblongata reflex action when finger being stung by a bee
Cerebellum
- coordination of movement
- controls of balance/posture
Medulla oblongata
- controls/increase breathing
- controls/increase heart rate
- controls blood pressure/sweating
Reflex action
- receptors in the skin of the finger detects
pain
- nerve impulse is generated in pain
receptor
- electrical impulses are sent via the
afferent(sensory) neurone to spinal cord
- impulses are transferred to the
interneurone in the spinal cord
- interneurone sents impulses to the
efferent neurone
- efferent neurone sents impulses to
biceps/muscle
- biceps/muscle contract (triceps relax)
causing the arm to bend
Glomerular filtrate formed
-
when blood enters the glomerulus,
ultrafiltration takes place
because blood from the aorta reaches the
nephron/glomerulus at high pressure
and due to the different artiole and
efferent arteriole
the high pressure forces fluid through the
filtration membrane into capsular space
forming glomerular filtrate
23
Structure and the role of nephron - formation of
urine
Structure and the role of nephron
- nephron is the functional unit of a kidney
- a nephron consist of 3 major parts
(glomerulus, and its associated vessels)
- the Bowman’s capsule
- a long narrow tube called the renal
tubule, which made up of proximal
convoluted tubule, loop of Henle and
distal convoluted tubule
- the distal convoluted tubules of several
nephrons join to a common collecting
duct
- the loop oh Henle is a long hairpin-shaped
region of the nephron that descends into
the medulla and then returns to the
cortex
Formation of urine
-
-
-
-
ultrafiltration, reabsoprtion and secretion
blood is under relatively high pressure
when it reaches the nephron
high blood pressure in glomerulus, forces
fluid to filter through the filtration
membrane into the lumen of Bowman’s
capsule
forming glomerular filtrate
contains water, glucose, amino acids,
mineral salts and other small molecules
the glomerular filtrate will flow into
proximal convoluted tubule
selective reabsoption occurs
by active and passive transport
forming relatively high solute
concentration in the peritubular
capillaries
thus large volume of water is reabsorbed
into the blood by osmosis
increase the concentration of urea in the
convoluted tubule
glomerular filtrate then flow into loop of
henle and distal convoluted tubule
more water and minerals being
reabsorbed back into the blood
take place in the distal convoluted tubule
urea/toxins/ammonia/ect being secreted
by passive diffusion and active transport
from blood capillary into distal convoluted
tubule
filtrate reaches the collecting duct (now
called urine). flows down the ureter, the
bladder and urethra and is finally excreted
Consequences of kidney failure
-
-
if both kidneys stop functioning, the blood
osmotic pressure and blood volume
cannot be maintained
the built up of toxic wastes in the body
can result in life-threatening conditions
they have to undergo haemodialysis
another treatment for impaired kidney
functions is the transplant of a healthy
kidney from a donor to the patient
24
Avoid drug and alcohol – why – affects coordination systems
Drugs
- some drugs are stimulants/cocaine
- increases the activities of the central
nervous system
- excessive use leads to temporary
euphoria followed by depression
- causes the user to see/hear/perceive
things that do not exist
- some drugs like narcotic/heroin/morphine
- block pain signals
- induce feelings of euphoria/slows down
nerve impulses
Alcohol
- strong depressant
- affects coordination and judgement
- inhibits releases of ADH from posterior
pituitary
- less water will be absorbed into blood
stream/ more urine produced
-
-
alcohol/drugs are addictive
develop dependence on
alcohol/drugs/develop severe withdrawal
effects
long term usage can damage organs
brain damage/stomach ulcers
Geotropism is brought about in a plant root and
shoot - advantages
Shoot
- the auxin that is produced at the tip of
shoot
- auxin moves downwards/accumulate on
the underside of the shoot tip due to the
pull of gravity
- the high concentration of auxin
accelerates the growth
- stimulating greater cell elongation on the
underside relative to the cells on the
upper side
- this differential elongation causes the
shoot to bend away from gravity/grow
upwards
Root
- the auxin that is produced at the tip of
root
- auxin moves downwards/accumulates on
the underside of the root tip due to the
pull of gravity
- the hight concentration of auxin inhibits
the growth
- slowing down cell elongation on the
underside relative to the cells on the
upper side
- this differential elongation causes the
shoot to bend towards gravity
Tips of shoot contribute to growth in oat
seedlings
- *without tip of a shoot, an oat seedling
cannot grow
- this proves elongation of plumule is
dependent on the presence of the tip of
the shoot
- *if the tip of the coleoptile is first
removed and placed on an agar block
which is transferred onto the cut stump of
another oat seedling the plumule still
grows straight upwards
- this means that the tip of the shoot
carried chemical messengers which has
diffused into the agar block
- the chemical messenger then diffuses into
the plumule and causes the plumule to
elongate
- *if the agar block is placed asymmetrically
(a little to one scale of the center), the
shoots bend away from the scale with the
agar block as though it is growing towards
the light
- This is because a higher concentration of
the growth promoting chemical
messenger accumulates below the agar
block
- This means that the agar block contains a
chemical messenger produced in the
shoot. The chemical stimulates growth as
it diffuses down into the shoot
- The chemical messenger is auxin
25