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COLLECTION OF BIOLOGY ESSAYS FOR SPM
PREPARED BY : MOHD IKMAL BIN ASMUNINUR HAFIZAH BINTI SAZALI A+ALLAH HELPS THOSE
WHO HELP THEMSELVES
YOU AND ME A+ BIOLOGY
BIOLOGY FORM4&5 ikmal hafizah
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BIOLOGY FORM4&5 ikmal hafizah
Phagocytosis Simple Diffusion Osmosis: the diffusion of water 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.
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.
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.
**Choose any one
Facilitated Diffusion Active Transport Animal and plant cells in an isotonic solution 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.
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.
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.
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BIOLOGY FORM4&5 ikmal hafizah
Hypotonic solution Hypertonic solution Preservation of fish and vegetablesConcentration 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.
The concentration of solute in the solution is higher than the concentration of solutes within the cell.
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.
Fish 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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BIOLOGY FORM4&5 ikmal hafizah
Differences between facilitated diffusion and active transport
Facilitated diffusion
But
Active transportD1E1
Down the concentration gradientMolecules moves from higher concentration to lower concentration
Against the concentration gradientMolecules moves from lower concentration to higher concentration
D2
E2
Molecules move in both direction across the plasma membraneMolecules can move through pore protein or/and carrier protein
Molecules move in one direction across the plasma membraneMolecules move through carrier protein
D3E3
No ATP/energy usedMolecule can move through pore protein without binding
ATP/energy is usedEnergy needed for binding/bind with active site
D4 Molecules need carrier protein and pore protein to help the movement
Need carrier protein only to help movement
D5 Could achieve equilibrium Will not achieve equilibrium/result in accumulationD6 Not depended in cellular respiration Depend on cellular respiration/energy
Similarities between facilitated diffusion and active transport
The Importance of water General characteristics of enzymes
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.
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/maintaining body temperature. Providing support to the cell. High surface tension and cohesion. Providing miosture (respiratory surfaces
such as alveoli). Maintaining osmotic balance and
turgidity.
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 .Extracellular enzyme ‘Lock and key’ hypothesis Effects of temperature on enzyme activity
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BIOLOGY FORM4&5 ikmal hafizah
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 nucleus contains DNA which carries the information for synthesis of enzymes.
Protein that are synthesised at the ribosomes are transported through the spaces within the rough ER.
Proteins that depart from the rough ER wrapped in vesicles tehat bud off from the membrane of the rouhg ER.
These transport vesicle then fuse with the mebranes of the golgi apparatus and empty their contents into the membranous space.
The proteins are further modified during their transport in the Golgi apparatus. For example, carboohydrates are added to protein to form glycoproteins.
Secretory vesicles containing these modified protein bud off from the Golgi apparatus and travel to the plasma membrane.
Enzymes are released.
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 enzyme-substrate 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.
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.
Prophase Metaphase Anaphase 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.
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.
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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BIOLOGY FORM4&5 ikmal hafizah
Telophase Cytokinesis Uncontrolled mitosis Chromosomes reach the opposite poles of
the cell. Chromosomes uncoil and revert to their
extended state(chromatin).
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.
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.Animal cloning Tissue culture Advantages of 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.
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.
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.
Disadvantages of cloning Meiosis I Meiosis II
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BIOLOGY FORM4&5 ikmal hafizah
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.
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.
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.
Synthesis of enzymes1. The information for the synthesis of enzymes is carriied by the DNA
- The sequences of bases on the DNA are codes to make proteins2. In the nucleus, the DNA double helix unwinds and exposes its two strands for the synthesis of a messenger RNA (mRNA) strand
- The messenger RNA is synthesised according to the instruction on the DNA3. The messenger RNA then leaves teh nucleus and moves to a ribosome4. The messenger RNA attaches itself to the ribosome
- The ribosome acts as a workbench for the messenger RNA- The messenger RNA contains information which codes for the sequence of amino acids
5. This genetic information is translated into the primary structure of specific protein6. Each amino acid is bonded to the next and as a result, a chain of amino acids (polypeptide) is formed and is ready for release into the cytoplasm.
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BIOLOGY FORM4&5 ikmal hafizah
Digestion in mouth Digestion in stomach Digestion in small intestine Secretion of saliva by three pairs of
salivary glands Saliva contains the enzyme salivary
amylase Begins the hydrolysis of starch to maltose.
Starch + water maltose
An additional digestive process occurs further along the alimentary canal to convert maltose to glucose.
pH is maintained at 6.5-7.5
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.
Protein + water 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.
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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Salivary amylase
pepsin
BIOLOGY FORM4&5 ikmal hafizah
Digestion of cellulose by ruminant Digestion of cellulose by rodent Digestion 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.
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.
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.
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.
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.
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BIOLOGY FORM4&5 ikmal hafizah
Absorption of digested food Assimilation of digested food Formation faeces 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.
Explain the assimilation of glucose and amino acid in body cells.
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.
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.
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BIOLOGY FORM4&5 ikmal hafizah
Photosynthesis mechanism Photosynthesis mechanism Uses of enzyme (Chapter 4) 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.
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.
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.
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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BIOLOGY FORM4&5 ikmal hafizah
Aerobic respiration Anaerobic respiration in human muscle Anaerobic respiration in yeast 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.
ATP ADP + phosphate + energy
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 fortwenty 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.
Yeast normally respires aerobically. Under anaerobic condition, yeast carry
out anaerobic respiration. Produces ethanol. Process known as fermentation. Catalysed by the enzyme zymase.
- 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 Both alimentary canal contains bacteria/protozoaP1 To secrete extracellular enzyme//to digestP2 To digest cellulose into glucoseS2 Both have large surface areaP1 To increase rate of diffusion //hydrolysed food
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Energy released
BIOLOGY FORM4&5 ikmal hafizah
Differences between the sturucture of digestive and digestion process of ruminants and rodents
Aspects Ruminant (has)
But
Rodent (has)Number of stomach chamber D1
E14 stomach chamberHave to digest cellulose
1 stomach chamberDo not have to digest cellulose
Size of caecum D2E2
Small//short caecumDo not digest cellulose
Big//long size caecumA place to digest cellulose
Bacteria D3E3
In reticulumFor secrete cellulase enzyme
In caecumFor secrete cellulase enzyme
Number of times yhe food passes through the stomach chamber
D4E4
TwiceTo complete the digestion//
Once To absorb digested food
Regurgitated D5 Twice in mouth cavity Once in mouth cavity
Breathing mechanism in man Breathing mechanism in man (continuation) Transport of O2 and CO2 in human body 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.
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.
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,
Transport of O2 and CO2 in human body Explain how energy flows through the food chain Colonisation and succession in mangrove
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BIOLOGY FORM4&5 ikmal hafizah
(continuation) and how it is lost to the environment. swamps 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.
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.
Green house effects Explain briefly why humans carry out the activity Explain the impacts of the activity shown above
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BIOLOGY FORM4&5 ikmal hafizah
as shown in diagram above on the environment 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.
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.
Deforestation causes soil erosion , landslides, flash floods and globalwarming.
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.
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BIOLOGY FORM4&5 ikmal hafizah
Human blood vessels Circulatory system in fish and human Blood clottingArteries
- carries blood away from heart- transport blood quickly, at high pressure- muscle of tissue enables the artery to
constrict and dilate- walls of arteries are strong and elastic,
have small lumenCapillaries
- thin walled blood vessels- allow rapid gaseous exchange via diffusion- nutrients, wastes and hormones are also
exchanged across here- one cell thick
Veins- blood returns from capillaries to heart
through veins- blood flows in low pressure- have large lumens and valves (prevent
back flow)
Similarities- both have closed circulation- both have a heart
Differences
Fish HumanHas single circulation Has double circulationHeart divides into 2 chambers
Heart is divided into 4 chambers
Septum is absent Septum is presentDeoxygenated blood flows from heart to gills
Deoxygenated blood flows from heart to lungs
Oxygenated blood flows from gills to body cells
Oxygenated blood flows from lungs to heart
- 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
Difference between blood and lymph Type of immunity Phagocytosis- 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
- active immunity, body produces its own antibodies in response to stimulation by an antigen
- passive immunity, body receive an antibodies from outside source
- 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
Lymph – formed - brought back into the blood circulatory system.
Respiratory gases Active immunity – Passive immunity
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BIOLOGY FORM4&5 ikmal hafizah
- 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
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)
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BIOLOGY FORM4&5 ikmal hafizah
Movement of water froom root to leaves Movement of water from root to leaves Effect of no lignin formation on the function of tissue xylem
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
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
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)
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BIOLOGY FORM4&5 ikmal hafizah
light intensity and stomata and cells effect the rate of water loss
Adaptation of the muscle which enables it to contracts
Movement takes place involves muscles, tendons, bones, ligaments and joints
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)
- 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
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 movementLigaments
- 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 forthTendon
- connect muscles to bones- strong and non elastic- force is transferred to bones through
tendonsBones
- femur/ thigh bone is long, heavy and strong
- provide support to body weight
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BIOLOGY FORM4&5 ikmal hafizah
Adaptation of plant which enable it to float Skeletal system of earthworm and fish adapted for its movement
Adaptive features which helps in birds and fish locomotion
- 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)
Movements in earthworm- earthworm has hydrostatic skeleton- moves by changing hydrostatic pressure
of fluid in its segment- each segment of the body has its own set
of muscleso an outer layer of circular muscles
running around the body causes the worm to become long and thin when they contract
o an inner layer of longitudinal muscles causes the worm to get short and thick when they contract
- as the circular muscles contract, the longitudinal muscles will relax simultaneously in antagonistic action
- causes the hydrostatic pressure to be transferred from anterior part to posterior part causing the worm to move forward
Movements in fish- fish has an endoskeleton- it provides place for attachment of
muscles- when the left myotome contracts, right
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
Bird- aerofoil wing – to generate the upward lift- a pair of antagonistic muscle (pectorolis
major and minor) pulled down and up the wings
- single organ (one testes/kidney)//small skull – to reduce weight
- streamlined body shape – reduce air resistance
- waterproof feather – avoid increase in body weight during raining
Fish- streamed lined body – reduce water
resistance- myotome muscle are W/V – shaped which
act antagonistically - air sac – maintain buoyancy in water- fins
o dorsal and ventral fin – prevent/helps in yawing and rolling
o tail fin – provides thrust and controls direction
o pelvin and pectoral fin – act as brakes/to slow down
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BIOLOGY FORM4&5 ikmal hafizah
Support is achieved in submerged and floating plants
Osteoporosis and osteoarthritis happen - prevented
Important to have healthy musculoskeletal system - ways maintaining a healthy
musculoskeletalSubmerged 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 flowFloating 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 smokingOsteoarthritis
- 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
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)
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BIOLOGY FORM4&5 ikmal hafizah
Important to have healthy musculoskeletal system - ways maintaining a healthy
musculoskeletal
Osteoarthritis and arthritis gout occur - effect of the diseases
Support system in woody plants differs from that of non-woody plants
Ways to maintain- having balanced diet. Take diet rich in
proteins, vitamins A, C n D together with minerals (calcium,phosphate n iron) for building strong bones. Drinking fluoridated water will also harden the bones
- adopt a good posture while standing, sitting, walking and while performing certain tasks to ensure that our body is always supported. This is important because bad posture will put undue pressure on our muscles and spine and this will in turn affect the functions of our internal organs (lungs, heart and stomach)
- 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
Muscular dystrophy- muscle destroying disorder- weakness/weaking of muscles- mostly in male- affect the heart muscle – heart attack- results in poor balance/wobbling/poor
movementOsteoporosis
- condition characterized by lost of normal density of bone
- resulting in fragile bone- bone fracture- no symptom before any bone fracture- consequences – fracture of
vertebrae//reduction of in height over time//stooped posture
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
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BIOLOGY FORM4&5 ikmal hafizah
Support system in woody plants differs from that of non-woody plants
Synapse – The event as a nerve impulse is transmitted across a synapse
Knee jerk
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 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
The transmission of information across a synapse involves the conversion of electrical signal into chemical signal in the form of neurotransmitter
Neurotransmitter is produced in vesicles in a swollen part of the axon terminal called synaptic knob
Synaptic knob contains abundant mitochondrion to generate energy for the transmission
When an impulse arrived at the synaptic knob, the vesicles release the neurotransmitters into the synapse
The neurotransmitters molecules diffuse across the synapse to the dendrite of another neurons
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
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BIOLOGY FORM4&5 ikmal hafizah
When the hand touches a hot object Roles of cerebellum and medulla oblongata - reflex action when finger being stung by a bee
Glomerular filtrate formed
- 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
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
- 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
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BIOLOGY FORM4&5 ikmal hafizah
Structure and the role of nephron - formation of urine
Formation of urine Consequences of kidney failure
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
- 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
- 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
Avoid drug and alcohol – why – affects - coordination systems
Geotropism is brought about in a plant root and shoot - advantages
Tips of shoot contribute to growth in oat seedlings
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BIOLOGY FORM4&5 ikmal hafizah
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 impulsesAlcohol
- 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
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
- *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
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