Biology Essay Points

7/30/2019 Biology Essay Points

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BIOLOGY FORM4&5 ikmal hafizah

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COLLECTION OF BIOLOGY

ESSAYS FOR SPM

PREPARED BY :

- MOHD IKMAL BIN ASMUNI- NUR HAFIZAH BINTI SAZALI

A+ALLAH HELPS THOSE

WHO HELP THEMSELVES

YOU AND ME A+ BIOLOGY


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Facilitated Diffusion Active Transport Animal and plant cells in an isotonic solution

y For water soluble molecules//moleculeswhich are not soluble in lipids (ions,

nucleic acid, amino acids and glucose)

y Carrier Proteiny The carrier protein function by

binding to the molecules to pass

through the plasma membrane.

y The molecules move to the carrierprotein which is specific for themolecules.

y Molecules bind with the carrierprotein at the active site.

y Carrier protein changes its shape andpass the molecules through the

plasma membrane.

Movement of molecules or ions againstthe concentration gradient across the

plasma membranes.

Requires both carrier proteins andexpenditure of energy.

Energy from ATP (adenosinetriphosphate) that is generated during

respiration in the mitochondria.

Has active sites which bind to the ATPmolecules.

The carrier protein changes shape whenthe phosphate group from the ATP

molecule binds to it

Then the solute is moved across theplasma membrane.

y Solution in which the solute concentrationis equal to that of the cytoplasmic fluid.

y Water diffuse in and out of the cells atequal rate.

y No net movement of water.y Cells retain its normal shape.

Phagocytosis Simple Diffusion Osmosis: the diffusion of water

y The pseupodia are also used for feeding.y Amoeba sp. engulfs food by phagocytosis.y Amoeba sp. is a holozoic organisms which

feed on microscopic organisms such as

bacteria.

y The presence of food causesAmoebasp.to advance by extending its pseupodia.

y The pseupodia encloses the food which isthen packaged in food vacoule.

y The food vacoule fuses with lysosome andthe food is digested by hydrolitic enzymecalled lysozyme.

y The resulting nutrients are absorbed intothe cytoplasm.

y Net movement of molecules or ions froma region of higher concentration to aregion of lower concentration.

y Going down concentration gradient untilan equilibrium is achieved.

y The particles are distibuted equallythroughout the system.

y The concentration gradient providesenergy to move the molecules into and

out of the cells.

y Net movement of freely moving waterfrom a region of lower soluteconcentration to a region of higher solute

concentration through a semi-permeable

membrane.//

y Net movement of water from regionhigher water concentration to a region of

lower water concentration.//

y Net movement of water from hypotonicregion to hypertonic region.

**Choose any one


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Hypotonic solution Hypertonic solution Preservation of fish and vegetables

Concentration of solute outside a cell is lower

than concentration of solute inside cell.

Animal cells

y Is said to be hypotonic solution.y Cell placed in hypotonic solution.y Net movement of water into the cells via

osmosis.

y Cell swells up.y When extremely hypotonic, cells will

eventually burst

y Cannot withstand the osmotic pressurebecause of thin plasma membrane.

y E.g : red blood cells (haemolysis)Plant cells

y Do not bursty Rigid cell wall.y Water diffuse into vacoule of cell via

osmosis.

y Cell swells up and becomes turgidy Tugor pressure in plant.y Supporting the plant.

The concentration of solute in the solution is

higher than the concentration of solutes withinthe cell.

Animal cells

y Net movement of water from inside tothe outside of the cell.

y Cells shrink//shrivel, internal pressuredecrease.

y Red blood cells immersed in hypertonicsolution , the cell shrink and the plasma

membrane crinkles up.

y Cell undergone crenation.Plant cells

y Water diffuse out via osmosis.y Vacoule and cytoplasm shrink and plasma

membrane pulls away from the cell wall.

y This process called plasmolysis.y Cell becomes flaccid.

Fish

y Fish is covered by salt solution which ishypertonic to body fluid/cell/tissue.y More water diffuses out from tissues into

salt solution via osmosis.

y Fish becomes hydrated.y Prevents bacterial growth in fish tissues.y Bacteria cells are also

plasmolysed//crenated.

y Prevent decay/last longer.Vegetables

y Vegetables are immersed in vinegar whichis acidic//has low pH.

y Vinegar diffuses into vegetables tissues.y Vegetables tissues becomes acidic//has

low pH.

y Prevents bacterial growth in tissues.y Preventing decay//last longer.


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Differences between facilitated diffusion and active transport

Facilitated diffusion

But

Active transport

D1

E1

Down the concentration gradient

Molecules moves from higher concentration to lower

concentration

Against the concentration gradient

Molecules moves from lower concentration to

higher concentration

D2

E2

Molecules move in both direction across the plasma

membrane

Molecules can move through pore protein or/and carrier

protein

Molecules move in one direction across the plasma

membrane

Molecules move through carrier protein

D3

E3

No ATP/energy used

Molecule can move through pore protein without binding

ATP/energy is used

Energy needed for binding/bind with active siteD4 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 accumulation

D6 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

y Both (ways of transportation)need carrierprotein.

y To bind withmolecules/ion/substrate/examples

y Both transport specific molecules only.y Because the carrier protein have specific

site to certain molecules.

y Both processes occur in living cell.y Because carrier protein need/can change

shape to allow substances to move across.

y Water is a polar molecule and act as asolvent.

y Transport medium in the blood,lymphatic, excretory and digestive

systems and in the vascular tissues of

plant.

y As a medium for biochemiocal reaction.y Helps in lubricant.y Regulates/maintaining body temperature.y Providing support to the cell.y High surface tension and cohesion.y Providing miosture (respiratory surfaces

such as alveoli).

y Maintaining osmotic balance andturgidity.

y Alter or speed up the rates of chemicalreactions

y Remain unchanged at the end of reaction.y Do not destroyed by reactions they

catalysed.

y Have specific sites called active site tobind with specific substrates.

y Needed in small quantities.y Reaction are reversibley Can be slowed down or stopped by

inhibitors. E.g: lead and mercury

y Require helper molecules, calledcofactors.

y Inorganic cofactor : ferum, coppery Organic cofactor: water soluble vitamins,

B vitamins .


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Digestion in mouth Digestion in stomach Digestion in small intestine

y Secretion of saliva by three pairs ofsalivary glands

y Saliva contains the enzyme salivaryamylase

y Begins the hydrolysis of starch to maltose.

Starch + water maltose

yAn additional digestive process occursfurther along the alimentary canal to

convert maltose to glucose.

y pH is maintained at 6.5-7.5

y Epithelial lining of the stomach containsgastric glands.

y These glands secrete gastric juice.Consists of mucus, HCL and enzyme

pepsin and renin.

y HCL make the pH around 2.0.y High acidity destroy bacteria.y Acidity stop the activity of salivary

amylase enzyme.

Protein + water polypeptides

y Renin coagulate milk by converting thesoluble milk protein, caseinogen into

soluble caesin.

y Stomach contents become a semi-fluidcalled chyme.

y Chyme gradually enter the duodenum.

y Duodenum received chyme from stomachand secretion from the gall bladder andpancreas.

y Starch, protein and lipids are digested.y Bile which produced by the liver and

stored in the gall bladder enter the

duodenum via the bile duct.

y Bile helps neutralise the acidic chyme andoptimise the pH for enzyme action in

duodenum.y Bile salts imulsify lipids, breaking them

down into tiny droplets.

y Providing high TSA for digestion.y Pancreas secrete pancreatic juice into

duodenum via pancreatic duct.

y Pancreatic juice contains pancreaticamylase, trypsin and lipase.

y Pancreatic amylase complete thedigestion of starch to maltose.

y Trypsin digests polypeptides intopeptides.

y Lipase complete the digestion of lipid intofatty acid and glycerol.

y Glands in the ileum (small intestine)secrete intestinal juice which contain

digestive enzyme needed to complete the

digestion of peptides and disaccharides.y Peptides digested by erepsin into amino

acids.

y Maltose digested by maltase into glucose.y Disaccharides digested by its own enzyme

into monosaccharides and glucose.

Salivary amylase

pepsin


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Digestion of cellulose by ruminant Digestion of cellulose by rodent Digestion

y Partially chewed food is passed to therumen (largest compartment of thestomach).

y Cellulose is broken down by cellulaseproduced by bacteria.

y Part of the breakdown products areabsobed by bacteria, the rest by the host.

y Food enters the reticulum.y Cellulose undergoes further hydrolysis.y The content of the reticulum, called the

cud, is then regurgitated bit by bit into the

mouth to be thoroughly chewed.

y Helps soften and break down cellulose,making it more accessible to further

microbial action.

y The cud is reswallowed and moved to theomasum.

y Here, the large particles of food arebroken down into smaller pieces byperistalsis.

y Water is removed from the cud.y Food particles moved into obamasum, the

true stomach of the ruminant. (e.g : cow).

y Gastric juice complete the digestion ofprotein and other food substances.

y The food then passes through the smallintestine to be digested and absorbed inthe normal way.

y Caecum and appendix are enlarged tostore the cellulose

-

digesting bacteria.y The breakdown products pass through the

alimentary canal twice.

y The faeces in the first batch are usuallyproduced at night.

y Faeces are then eaten again. To absorbthe products of bacterial breakdown.

y The second batch of the faeces are harderand drier.

y Allows rodent (give example) to recoverthe nutrients initially lost with the faeces.

y Protein-

In stomach, pepsin breakdownprotein into polypeptides.

- HCL being secreted to provide acidicmedium for the digestion to occur.

- In duodenum, trypsin breakdownpolypeptides into peptides.

- In small intestine, arepsin break dwonpeptides into amino acids.

y Fats- Bile salts breaking up fats into small

fat droplets in the duodenum.

- In duodenum/small intestine, lipasebreaks lipids into fatty acids and

glycerol.

y Carbohydrates-

In mouth, salivary amylase hydrolysestarch into maltose.

- In duodenum, pancreatic amylasehydrolyse starch into maltose.

- In small intestine, maltase hydrolysemaltose into glucose.


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Absorption of digested food Assimilation of digested food Formation faeces

y Absorption of digested food occur in theileum.

y Glucose/amino acids initially diffuse intoblood capillaries.

y The remaining of the glucose/amino acidsactively transport into blood capillaries.

y All blood capillaries converge into hepaticportal vein, which lead to the liver (and

transport to all parts o fthe body).

y Glycerol and fatty acids diffuse to theepithelial cell which lining the ileum) andcombine to form fat droplets.

y Fatty acids and glycerol then enter thelacteal (lymphatic system).

y Return back to the blood stream at leftsubclavian vein.

Explain the assimilation of glucose and amino acid

in body cells.

y Glucose is oxidised to produce energy,carbon dioxide and water by cellular

respiration.

y Amino acid is used to synthesisprotoplasm (the component of cell). By

this way new cells will be synthesised

causing growth.

y Amino acid also can be used to synthesisenzyme, hormone or antibody.

y Faeces which contain dead cells that areshed from intestinal linings, toxicsubstances and bile pigments enter the

colon by action of peristalsis.

y In colon, more water is absorbed. Theundigested food residues harden to

become faeces.

y Faeces contain undigestible residues thatremain after the process of digestion and

absorption of nutrients that take place in

the small intestine.


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Photosynthesis mechanism Photosynthesis mechanism Uses of enzyme (Chapter 4)

y The formation of starch in plants is by theprocess ofphotosynthesis which occurs in

chloroplasts.

y The two stages in photosynthesis are thelight and dark reactions.

y Light reaction:y P3:Takes place in grana.y P4: Chlorophyll captures light energy

which excites the electrons of chlorophyll

molecules to higher energy levels.

y P5: In the excited state, the electrons canleave the chlorophyll molecules.

y P6: Light energy is also used to split watermolecules into hydrogen ion (H+) and

hydroxyl ions (OH-) (Photolysis of water).

y P7: The hydrogen ions then combine withthe electrons released by chlorophyll to

form hydrogen atoms.

y P8: The energy from the excited electronsis used to form energy-rich molecules of

adenosine triphosphate /ATP.

y P9: Hydroxyl ion loses an electron to forma hydroxyl group. This electron is then

received by chlorophyll.

y P10: The hydroxyl groups then combine toform water and gaseous oxygen.

y Dark Reaction:y P11: Take place in stroma.y P12: Do not require light energy.y P13: The hydrogen atoms are used to fix

carbon dioxide in a series of reactions

catalysed by photosynthetic enzymes

y P14: and caused the reduction of carbondioxide into glucose.

y P15: The glucose monomers then undergocondensation to form starch which is

temporarily stored as starch grains in thechloroplasts.

y Enzymes are used as biologicaldetergents.

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.

y Enzymes are used in the baking industry. Protease is used in the breakdown ofproteins 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.

y Enzymes are used in the medical field.T

rypsin is used to remove blood clotsand to clean wounds.

Various other enzymes are used in

biosensors.

y 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 Anaerobic respiration in human muscle Anaerobic respiration in yeast

y Continuous supply of oxygen.y

Glucose molecules are oxidised byoxygen.

y Complete breakdown of glucose in thepresence of oxygen.

y A large amount of energy released.y Carbon dioxide and water are produced as

waste products.

y Most of the nergy released is used tosynthesise adenosine triphosphate (ATP)

from adenosine diphosphate (ADP) andinorganic phosphate.

y ATP acts as instant energy source.y ATP consists of phosphate bonds which

can be easily broken down to release

energy.

ATP ADP + phosphate + energy

y During a vigorous exercise (running), thebreathing rate is increased.

y This is to supply more oxygen to themuscles for rapid muscular contraction.

y However, the supply of oxygen to musclesis still insufficient.

y and the muscles have to carry outanaerobic respiration to release energy.

y The glucose is converted into lactic acid,with only a limited amount of energy

being produced.y An oxygen debt builds up in the body,

when no oxygen use in energy production.

y High level of lactic acid in the musclescause them to ache.

y After running, the athlete breathes morerapidly and deeply than normal for

twenty minutes.

y There is recovery period after 10 minutesuntil it reaches 20 minutes when oxygen ispaid back during aerobic respiration.

y About 1/6 lactic acid is oxidized to carbondioxide, water and energy.

y Yeast normally respires aerobically.y U

nder anaerobic condition, yeast carryout anaerobic respiration.

y Produces ethanol.y Process known as fermentation.y Catalysed by the enzyme zymase.

- Ethanol produced can be used inmaking wine and beer.

- In bread making, the carbon dioxidereleased during fermentation of yeastcauses the dough to rise.

Similarities between the sturucture of digestive and digestion process of ruminants and rodents

S1 y Both alimentary canal contains bacteria/protozoaP1 y To secrete extracellular enzyme//to digestP2 y To digest cellulose into glucoseS2 y Both have large surface areaP1 y To increase rate of diffusion //hydrolysed food

Energy released


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Transport ofO2 and CO2 in human body

(continuation)

Explain how energy flows through the food chain

and how it is lost to the environment.

Colonisation and succession in mangrove

swamps

y Oxyhaemoglobin dissociates to releaseoxygen.

y Carbon dioxide released by repairingcells can be transported by dissolve

carbon dioxide in the blood plasma.

y Bind to the haemoglobin.y As carbaminohaemoglobin.y In form of bicarbonate ions.y Carbon dioxide is expelled with water

vapour from the lung.

y Energy flows through the food chain in onedirection .

y 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.

y 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.

y Energy is transferred from one trophic levelto another trophic level.

y When energy is transferred from one trophiclevel to another level as much as 90% of thechemical energy in the food consumed by

primary consumer is used for its metabolic

activities and lost as heat.

y Only 10% of the energy in an organism ispassed on to the organism at the next trophic

level.

y The pioneer species of a mangroveswamp are the Sonneratia sp. and

Avicennia sp.

y The presence of this species graduallychanges the physical environment of

the habitat.The extensive root systems

of these plants trap and collect

sediments, including organic matter

from decaying plant parts.

y As time passes, the soil becomes morecompact and firm. This condition

favours the growth ofRhizophora sp.

Gradually the Rhizophora sp. replaces

the pioneer species.

y The prop root system of the Rhizophorasp. traps silt and mud, creating a firmer

soil structure over time.

y The ground becomes higher. As a result,the soil is drier because it is less

submerged by sea water.

y The condition now becomes moresuitable for the Bruguiera sp., which

replaces the Rhizophora sp.

y The buttress root system of theBruguiera sp. forms loops which extend

from the soil to trap more silt and mud.

y As more sediments are deposited, theshore extends further to the sea. The

old shore is now further away from the

sea and is like terresterial ground.

y Over time, terrestrial plantslike nipah palm and Pandanus sp. begin

to replace the Bruguiera sp.


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Green house effects Explain brieflywhy humans carry out the activity

as shown in diagram above

Explain the impacts of the activity shown above

on the environment

y Green house effect.y 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.

y Heat or infrared radiation cannot bereflected back to the atmosphere.

y Because it is trapped by green housegases such as CO2, nitrogen dioxide and

methane.y Heat/infrared warmed the surface of

earth.

y Earth temperature increases.y The human population grows rapidly. The

demands for food and housing areas have

increased.

y Vast areas of forest are cleared foragricultural and commercial purposes.

y Urbanization and industrialization havecaused more forests to be cleared for

road construction and housing areas.y Deforestation is also caused by the

demands for timber and fuel wood.

y Deforestation causes soil erosion ,landslides, flash floods and global

warming.

y Causes the soil to become loose and lessstable.

y Without the protection of green plants,the soil is exposed to the forces of wind

and rain.

y The top layer of soil is washed awaygradually by the rainwater.

y This is known as soil erosion.y Soil erosion causes the depletion of

minerals from the soil, therefore the soil

becomes infertile and unsuitable for

agriculture.

y Landslides may happen on steep hillsidesduring heavy rain.

y It is because rainwater flows quickly andcauses the top layer of the soil tocrumble.

y Rivers and drains are silted and the flowof water is blocked.

y Therefore, water flows inland and thiscauses flash floods in the lower areas

during rainy seasons.


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Human blood vessels Circulatory system in fish and human Blood clotting

Arteries

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 lumen

Capillaries

thin walled blood vessels allow rapid gaseous exchange via diffusion nutrients, wastes and hormones are alsoexchanged across here one cell thick

Veins

blood returns from capillaries to heartthrough 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 Human

Has single circulation Has double circulation

Heart 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, clottingfactors form activators (thromboplastins)

- activators together with calcium ions andvitamin K, converts prothrombin to

thrombin

- thrombin catalyses the conversion ofsoluble protein fibrinogen into insoluble

fibrin.

- fibrin is a fibrous protein which combinesto form a mesh of long threads over the

wounds, trapping red blood cells andsealing the wound.

- blood clot hardens when exposed to airforming scab

Difference between blood and lymph Type of immunity Phagocytosis

- lymph has a large numbers of lymphocytecompare to blood

- lymphocyte is produced by lymph nodesin lymph system

- lymph has lower content of oxygencompare to blood

active immunity, body produces its ownantibodies in response to stimulation by

an antigen

passive immunity, body receive anantibodies from outside source

- the phagocyte is attracted by chemicalsproduced 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 bedestroyed by lysozyme

- phagocyte releases the digested productsfrom cell

Lymph formed - brought back into the blood

circulatory system.

Respiratorygases Active immunity Passive immunity


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- when blood flows from arteries intocapillaries, there is higher hydrostatic

pressure at artial end of capillaries

- high pressure causes some plasma to passthrough capillary walls into intercellular

spaces

- interstitial fluid fills the spaces betweencells and constantly bathes the cells

- 90% of interstitial fluid diffuses back intoblood capillary

- 10% of interstitial fluid goes into the lymphcapillaries and known as lymph

- lymph capillaries unite forming largerlymphatic vessels

- from lymphatic vessels, lymph eventuallypasses 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 bydifferent of partial pressure of both

gaseous

partial pressure of oxygen in alveoli ishigher than partial pressure of oxygen in

blood capillaries

oxygen diffused in cytoplasm of red bloodcell oxygen combines with haemoglobin

forming oxyhaemoglobin

oxyhaemoglobin then sent to all parts ofbody

heart pumped the oxygenated blood to allbody cells

oxygen diffused from blood capillaries tocell because partial pressure of oxygen in

blood capillaries is higher than in cell

carbon dioxide diffuse from cell to bloodcapillaries because partial pressure of

carbon dioxide in cell is higher than in

blood capillaries

deoxygenated blood going back to heartby vena cava and to lungs by pulmonary

artery

Active immunity

- obtained by vaccination (artificiallyacquired)

- vaccine contains dead/weakenedbacteria/pathogen/virus

- white blood cells stimulated to produceantibodies against pathogen

- also obtained when an individual hasrecovered from certain diseases(naturally

acquired)

- a ready made supply of antibody will giveimmunity towards the disease

Passive immunity

- obtained by injectingantibodies/antiserum (artificially

acquired)

- no antigen is put into body, so body doesnot produce its own antibodies

- obtained by a baby when antibodies frommothers blood plasma diffuse into foetus

through placenta (naturally acquired)


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Movement of water froom root toleaves Movement of water from root toleaves 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

y cell sap of root hair(usually) hypertonic tosurrounding soil solution

y water diffuses into root by osmosisy cell cap becomes more dilute compared

to neighbouring celly water moves to these adjacent cells which

become more diluted themselves, so

osmosis continues across the cortex

y (at the same time) ions from soil areactively secreted into xylem vessels and

causes osmotic pressure to increase

y Water flows continuously into xylem andcreate a pressure(root pressure)

y Root pressure gives an initial upwardforce to water and mineral ions in xylem

Capillary action

y water moves up through xylem in stemsby capillarity

y capillary action is due to combined forceof cohesion(water molecules have

attraction for each other) and

adhesion(water molecules are attracted

to the side of vessels)

y water molecule form a continuous watercolumn in xylem vessel (due to cohesionand adhesion)

y the cohesion of water prevent the watercolumn in xylem breaking apart

y the adhesion of water prevents gravityfrom pulling the water down the column

Transpirational pull

ythe lost of water from mesophyll cellsduring transpiration is replaces by water

which flows in from xylem vessels in

leaves

y this creates a tension/suction force inwater column because water has cohesive

properties called transpiration pull

y the transpiration pull draws water fromxylem in the leaves/stem/roots

y the continuous flow of water throughplant is known as transpiration stream

y lignin is important to make tissue xylemstrong

without lignin, tissue xylem will collapse therefore, it cannot form a continuous

hollow tube

to allow water to flow upwardscontinuously

y lignin makes the tissue becomeimpermeable

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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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

y F1- from 0500 to 0170(time/hours), rateof water loss increases

y E1- light intensity increasesy E2- stimulates photosynthesis in guard

cells

y E3- this makes energy available forpotassium to move into guard cells by

active transport

y E4- guard cells becomehypertonic(compared to cell sap) ofepidermal cells

y E5- water molecules from epidermal cellsdiffuse into guard cells by osmosis

y E6- causing guard cells to bend outwardsy E7- stoma opens (allows water to escape)y F2- from 0170 to 0300(time/hours) rate of

water loss decreases

y E8- lisght intensity decreases/rate ofphotosynthesis decreasesy E9- guard cells become flaccid and bend

inwards

y E10- stoma closes, prevents water fromescaping

y Notes: (F1 + any 5Es) + (F2 + 3Es)

the skeletal muscle consist of bundles ofmuscle fibres and a large supply of nerves

and blood vessels

a muscle fibre is made up of bundles ofsmaller units called myofibrils

each myofibril is made up of 2 types ofprotein filaments: the actin and the

myosin which interact and cause muscle

contractions

the muscles nerve endings control itscontractions

Muscle

quadriceps femoris contract while bicepsfemoris muscles relax (leg straightened)

biceps femoris contract while quadricepsfemoris 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 elasticJoints

a hinge joint allow the movement of leg toswing 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 andstrong

provide support to body weight


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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 (plantsbecome more lighter)

have air spaces/air sacs (becomes moreeasy to float)

have big and swell stem/petiole (increasethe air to help plant floating)

have fine and many roots (trap gasbubbles)

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 setof muscles

o an outer layer of circular musclesrunning around the body causes the

worm to become long and thin when

they contracto an inner layer of longitudinal muscles

causes the worm to get short and

thick when they contract

as the circular muscles contract, thelongitudinal muscles will relax

simultaneously in antagonistic action

causes the hydrostatic pressure to betransferred 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, rightmyotome will relax in antagonistic action

causes the vertebral column to curvetoward 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)//smallskull to reduce weight

streamlined body shape reduce airresistance

waterproof feather avoid increase inbody weight during rainingFish

streamed lined body reduce waterresistance

myotome muscle are W/V shaped whichact antagonistically

air sac maintain buoyancy in water fins

o dorsal and ventral fin prevent/helps in yawing and

rolling

o tail fin provides thrust andcontrols direction

o pelvin and pectoral fin act asbrakes/to slow down


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Support is achieved in submerged and floating

plants

Osteoporosis and osteoarthritis happen -

prevented

Important to have healthymusculoskeletal

system - ways maintaining a healthy

musculoskeletal

Submerged plants

posses air sacs within the leaves and thestem 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 littleresistance 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 reducedand the boned become porous and lighter

occurse most often in old people, partiallywomen who have gone menopause

bodies of postmenopausal women do notproduce sex hormone, oestrogen

causes more bone minerals to be lost thandeposited

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 vitaminD

o takin in vitamin C, increase bonemass

o refraining from smokingOsteoarthritis

Osteoarthritis is part of ageing processdue to wear and tear of cartilage between

bones at certain joints

Patient has painful, swollen stiff kneeswhich restrict daily activities (walking,

climbing)

If treatment fails to relieve the pain, asurgeon can replace the damaged jointswith 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 ourbody

if any part of system injured, we willexperience discomfort, pain and loss of

mobility it also affect othe organs and physiological

processes in body (respiration/digestion)


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Important to have healthymusculoskeletal

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 inproteins, 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 performingcertain 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. Womanwearing 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 vigorousactivities

practice correct and safe techniques whenexercisingto prevent serious injuries tothe 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

movement

Osteoporosis

condition characterized by lost of normaldensity 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) providedby the turgidity of

parenchyma/collenchyma cells

(when there is enough warm in theground) the cells take in water by osmosis

and become turgid

The turgor pressure of fluids in thevacuoles pushes the cell contents/plasmamembrane 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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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 specializedtissues/sclerenchyma tissues/xylem

vessels.tracheids to give them support

these tissues have cellulose walls whichhave 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 isto provide support

Xylem vessels have thick walls of ligninwhich are deposited during the plants

secondary growth

The lignified xylem vessels form thewoody tissues of the stem

This makes the plant stronger and alsoprovides support for the plant

Tracheids are also dead cells with thickwalls and very small diameters

They are found with xylem vessels andtogether they support the plants

Synapse is a narrow gap between an axonterminal and a dendrite of anotheradjacent neuron. A chemical is used by

neuron to transmit an impulse across a

synapse. The chemical is called

neurotransmitter

The transmission of information across asynapse involves the conversion of

electrical signal into chemical signal in theform of neurotransmitter

Neurotransmitter is produced in vesiclesin a swollen part of the axon terminal

called synaptic knob

Synaptic knob contains abundantmitochondrion to generate energy for the

transmission

When an impulse arrived at the synapticknob, the vesicles release theneurotransmitters into the synapse

The neurotransmitters molecules diffuseacross the synapse to the dendrite of

another neurons

The dendrite of another neurons isstimulated to trigger a new impulse which

travel down a long neuron

the knee jerk action involves two types ofneurons named afferent and efferentneurons

when a hammer hits a tendon thatconnect to quadriceps muscle in the thigh

to a bone in the lower leg

as the hammer strike, the force stretchesthe 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 legforward, it indicates that the patients

nerve system is still functioning

if there is no response, it shows that thepatients nervous system fails to function

properly


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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 thenerve endings (receptors) in skin

impulses are triggered impulses travel along the sensory/afferent

neuron to spinal cord

in spinal cord, the impulses aretransmitted first across a synapse to the

interneurone and then across another

synapse to the motor/efferent neurone

At synapse

when an impulse reach a presynapticmembrane, it triggers the synaptic

vesicles to release neutrotransmitter into

the synaptic cleft

the neurotransmitter diffuse across thesynaptic cleft

and bind to receptors which are attachedto the postsynaptic membrane

the binding of the neurotransmitter to thereceptors leads to the generation of a

new impulse

impulses leave the spinal cord along themotor/efferent neurone to the effector

the effector is the biceps muscle whichthen 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 detectspain

nerve impulse is generated in painreceptor

electrical impulses are sent via theafferent(sensory) neurone to spinal cord

impulses are transferred to theinterneurone in the spinal cord

interneurone sents impulses to theefferent neurone

efferent neurone sents impulses tobiceps/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 thenephron/glomerulus at high pressure

and due to the different artiole andefferent arteriole

the high pressure forces fluid through thefiltration membrane into capsular space

forming glomerular filtrate


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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 Bowmans capsule a long narrow tube called the renal

tubule, which made up of proximal

convoluted tubule, loop ofHenle and

distal convoluted tubule

the distal convoluted tubules of severalnephrons join to a common collecting

duct

the loop oh Henle is a long hairpin-shapedregion 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, forcesfluid to filter through the filtration

membrane into the lumen of Bowmans

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 reabsorbedinto the blood by osmosis

increase the concentration of urea in theconvoluted tubule

glomerular filtrate then flow into loop ofhenle and distal convoluted tubule

more water and minerals beingreabsorbed back into the blood

take place in the distal convoluted tubule

urea/toxins/ammonia/ect being secretedby passive diffusion and active transport

from blood capillary into distal convoluted

tubule

filtrate reaches the collecting duct (nowcalled urine). flows down the ureter, the

bladder and urethra and is finally excreted

if both kidneys stop functioning, the bloodosmotic pressure and blood volumecannot be maintained

the built up of toxic wastes in the bodycan 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 Essay Points