Organelle Found Abundantly In

8/4/2019 Organelle Found Abundantly In

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Organelle found abundantly in

Sperm cells contain a high density of mitochondria because they require energy to propel themselves

towards the uterus and fallopian tube, to fertilize the ovum during fertilization. Mitochondria are also

found abundantly in flight muscle cells of insects and birds to generate energy for movement and flight.

Meristematic cells also have a high density of mitochondria. These cells need energy to undergo activecell division to produce new cells.

The golgy apparatus are found abundantly in the goblet cells in the intestinal epithelium and respiratory

tract to secrete mucus which acts as lubricant.

Smooth endoplasmic reticulum is found abundantly in the intestinal epithelial cells to produce digestive

enzymes.

Why is it a semi permeable membrane?

d the plasma membrane is semi permeable because it only allows the movement of certain

molecules and limits the movement of other molecules

d the plasma membrane consist of two layers of phospholipids with protein molecules scattered

in them.

d Therefore, molecules that are able to pass through the plasma membrane easily are those that

are small, can dissolve in lipids, and uncharged molecules.

d Molecules which cannot move through the plasma membrane but require help include large

molecules that do not dissolve in lipids, large charged molecules.

Concepts of diffusion and osmosis are applied in food preservations

d Food can be stored for a longer period if the surrounding conditions inhibits the activity ofdecomposers.

d This can be done by preserving the food with vinegar, salt or sugar.

d This allows water from the food to diffuse into the surrounding hypertonic solutions.

d At the same time, sugar or salt ions diffuse into the food.

d The dry conditions and unsuitable pH inhibit the growth of the decomposers in the food.

d The hypertonic condition of the solution causes the microorganisms to lose water and die

eventually.

Changes that could be made to an enzyme-catalyze which would results in a decrease of the rate of

reaction (factors effecting enzyme activity)

d When the temperature is increased to 100oC, the enzyme is denaturated.

d The hydrogen bonds break, the shape of the active site changes so that the substrate cannot

bind to the active sites.

d The addition of the strong acid or alkali alters the changes of the enzyme. As a result, substrate

cannot bind to the active site


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d The decrease in the amount of the enzyme or substrate used also result in a decrease in the rate

of reaction as there are less collisions between the enzyme and the substrate molecules for the

reaction to take place.

d The addition of heavy metal can reduce or completely stops enzyme activity.

d An enzyme helps speed up biochemical reactions in a cell

d Biochemical reactions occur simultaneously in cells at all times in a controlled an systematic

conditions.

d In the cell, biochemical reactions must occur at fast rate to protect living processes

d Biochemical reactions occur rapidly in cells because enzymes help speed up the reactions.

d Enzymes are organic catalyst made up of proteins and produce by living cells in organisms. As

organic catalyst, enzymes control and speed up biochemical reactions in the cell.

d Many reactions in living cells have high activation energy

d Activation energy is the energy required to break the bond in the substrate molecules before

reactions can take place.

d In the presents of enzymes, activation energy is reduced.

d Enzymes functions by reducing the activation energy of the substrate molecules before a

reaction occurs. With that the rate of biochemical reaction in the cell is increased.

The tissue culture technique.

d The production of tomato hybrids can be carried out within a short period of time for

commercial purpose using the tissue culture technique.

d Tissue culture technique is the in vitro technique of maintaining fragments of cells or parts of

plant tissues in such a way that they are kept alive after their removal from the parent plant.

d Conditions for the success of this technique include suitable pH, use of sterile instruments and a

correct balance of nutrients.d the culture medium and other essential substances necessary for the growth of cells or tissues

must be included.

d A cross section of the tomato plant root is cut. The section is then further sliced to obtain pieces

of cells or tissues.

d The pieces of cells or explants are cultured in a conical flask containing a suitable culture

medium for growth, for example a culture containing growth hormone.

d After a few days, the cell in the suspension start to divide to form a callus, which is a group of

tissues that have not, differentiates into stems, leaves, and roots.

d The callus is then transferred into an agar medium and when the roots sprout, they were

transfer into the soil.d After approximately two weeks, a new tomato clone similar to the parent plant is produced.

d Hundreds of similar plant can be produced from a single plant. These plant are planted at the

same time and therefore, the fruits can be picked for sale at the same time.

Mitosis


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1. Interphase

d The DNA replicates and the chromosomes duplicate.

d At the end of interphase, the nucleus appears big, and the chromosomes resemble fine

and long chromatin threads.

2. Prophase

d The chromosomes become condense, thick and short.

d The chromosomes are made up of two identical threads known as chromatids. Both the

chromatids are joined at the centromere.

d At the end of prophase, the nuclear membrane disappears and the spindle fiber starts to

form in the cytoplasm.

3. Metaphase

d The spindle fibers attached themselves to the centromeres.

d The chromosomes are arrange in the metaphase plate

4. Anaphase

d The spindle fibers shorten, contract and pull the chromatids opposite poles.

d Anaphase ends when the chromosomes reach the poles. Each pole now consist of a

complete set of identical chromosomes.

5. Telophase

d The nuclear membrane is formed and surrounds the chromosomes to forms two

daughter cells.

6. Cytokinesis

d Telphase is followed by cytokinesis (cytoplasmic division).

d Cytokinesis produce two daughter cells. In this way, the number of cells at the apical meristem

increases and this brings growth to a plant.

Cloning

d Cloning is the process of producing clones or genetically identical organisms of a cell or an

organism to asexual reproduction.

Advantage Disadvantage

The best traits can be chosen to produce to

produce offspring (clones) of high quality.

The side effects and long-term effects of using

clones are still not known.

Cloned plants flower and bear fruits within a

much shorter period compared to those

planted from seedlings.

Clones do not show genetic variation.

Therefore, any changes in the environmental

conditions might wipe out all the clones.

Cloning does not depend on pollination and

dispersal agents.

All clones possess resistance to a similar type

of disease. All the clones might possibly die if anew disease breaks out.

The rate of growth of clones is faster and

clones reach maturity faster. Therefore, less

care is needed when compared to those

planted by conventional techniques.

Cloning prevents the process of natural

selection from taking place.

Ruminants (cows)


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d a stomach with four chambers : rumen, reticulum, omasum and abomasum.

d Rumen and reticulum contains bacteria which produce the enzyme cellulase.

d Partially chewed food is passed into the rumen where cellulose is hydrolyzed by cellulase.

d Further hydrolysis takes place in the reticulum. The food now forms a cud which is then transfer

back into mouth for further chewing into smaller particles.

d The cud is then swallowed and enters into the omasum where further breakdown by peristalsis

occurs. Water is reabsorbed from the cud.

d The food moves into abomasums where digestion of protein occurs and finally it moves into the

small intestines for final digestion and absorbtion.

Rodents (rabbit)

d At the junction between the ileum and the colon, there is large sac with closed-off ending called

caecum

d The caecum contains bacteria which produce cellulase.

d Rabbit passed their food twice through alimentary canal to ensure they get the maximum

benefit from the food eaten.

d At night they passed out soft creamy white feaces that are eaten again for further digestion and

absorption of the nutrients in the alimentary canal.

d Finally the undigested food is passed out as hard faecal pellets.

Comparison between ruminants and rodents

d Similarity: both organisms do not produce cellulase to digest cellulose.

Ruminants (cow) Rodents (rabbit)

Has four stomach chambers. Has one stomach

Does not have a large caecum. Has a large caecum

Cellulose-producing bacteria are present in the

stomach.

Cellulose-producing bacteria are present in the

caecum

Does not ingest digested food that is passed out

of the alimentary canal.

Semi-digested food that is passed out of the

alimentary canal is ingested for the second time.

Digestive system in human

d Digestion is the physical and chemical breakdown of complex substance into smaller molecules

that can be absorbed by our body.

d Food digestion starts in mouth with the cutting and chewing of food with the aid of the teeth.

dMouth contains saliva which contain enzyme amylase. Amylase breakdown starch into maltose.This reaction is known as hydrolysis of starch.

d The food now moves into esophagus which peristalsis occurs.

d In the stomach, food is mixed with gastric juices and formed a paste called chyme.

d Gastric juice is acidic. It contains hydrochloric acid. It stops the action of enzyme amylase and

kills bacteria in the food.


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d Gastric juices also contain proteases-pepsin which breakdown protein into polypeptides. This

reaction is known as hydrolysis of proteins.

d Rennin converts the soluble milk protein caseinogens into insoluble casein.

d Stomach also contains mucus that protects the stomach wall from the acid and enzyme.

d Duodenum: bile that contains bile salts is secreted. Bile is produce by liver but is stored in gall

bladder. It is alkali.

d Bile salt emulsifies fats into smaller droplets to increase surface area for enzyme to act.

d Pancreas secrets pancreatic juice which contain amylase, trypsin and lipase.

d Amylase converts starch into maltose. (hydrolysis of starch) trypsin converts polypeptides into

peptides(hydrolysis of protein) lipase converts lipid droplets into fatty acid and

glycerol.(hydrolysis of fat)

d Small intestine secretes intestinal juice which contains maltase, sucrose, lactase and erepsin.

d Maltase breakdown maltose into glucose. Sucrase breakdown sucrose into glucose and fructose.

Lactase breakdown lactose into glucose and galactose. Erepsin breakdown peptides into amino

acid.

If carbon dioxide increased

d Carbon dioxide dissolves in blood plasma to form carbonic acid which dissociates into

bicarbonate and hydrogen ions.

d This increases the acidity of the blood, that is the blood pH drops.

d The drops in blood pH stimulates the central chemoreceptors to send nerve impulses to the

respiratory centre which, in turn, send nerve impulses to the diaphragm and intercostals muscle

to contract and relax faster.

d This increases the breathing rate and the rapid removal of carbon dioxide.

Photosynthesis

d Photosynthesis is a process carried out by green plants to synthesize organic compounds

(carbohydrates) from raw organic substances (co2 and h2o) in the presence of sunlight and

chlorophyll.

d It involves two main stages:

o Light reaction which occurs only in the presence of sunlight.

o Dark reaction which occurs in the presence or absent of sunlight and result in the

production of starch.

d Light reaction:

o Chlorophyll traps light energy which excites the electron of chlorophyll molecules to higher

levels.

o In the excites state, the electrons can leave the chlorophyll molecules.


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24H2O 24H+ + 24OH-

24H+

+ 24e-

24H

24OH-

- 24e-

24OH

24OH 12H2O + 6O2

6CO2 + 24H 6(CH2O) + 6H2O

6(CH2O) C6H12O6

o Light energy is also used to split water molecules into hydrogen ions and hydroxyl ions. This

reaction is known as photolysis of water.

o The hydrogen ions combine with the electron released by chlorophyll to form hy drogen

atoms.

o At the same time, each hydroxyl ion loses an electron to form a hydroxyl group. This

electron is receive by chlorophyll.

o The hydroxyl group combine to form water and oxygen.

d dark reaction:

o the hydrogen atoms are used to fix carbon dioxide in the series of reaction catalyzed by

photosynthetic enzymes.

o The overall reactions results in the reduction of carbon dioxide into glucose.

o (C6H2O) is the basic unit of glucose. Six units of CH2O combine to form one molecule of

glucose.

o The glucose monomers the undergo condensation to form starch which is temporarilystored as starch granules in the chloroplasts.

The process of gaseous exchange in the leaf.

d Gaseous exchange between plant cells and the environment occurs by diffusion mainly through

the stomata and lenticles.

d When stomata are open, they connect the air spaces inside a leaf with atmosphere.


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d Oxygen from the atmosphere diffuses into the air spaces and then dissolve in the film of water

that surrounds the mesophyll cells.

d Oxygen is then used in aerobic respiration.

d The concentration of oxygen in the cells becomes lower than the concentration of oxygen in the

air spaces. This allows the oxygen to diffuse continuously into the air spaces through the

stomata.

d Carbon dioxide which is produce during aerobic respiration diffuse into the air spaces and then

through the stomata into the atmosphere.

Differences between photosynthesis and respiration

aspect photosynthesis respiration

occurrence Occurs in all green plants Occurs in all living organism

purpose Stores energy Released energy

Raw materials Water and carbon dioxide Glucose and oxygen

products Glucose, water, oxygen Energy, water, carbon dioxide

energy needed Not needed

The process of gaseous exchange and the differences in the rate of reaction and the rate of

photosynthesis.

d in the dark:

o photosynthesis can only occurs during daylight. During the night, plants only carried out

respiration.

o Carbon dioxide is released to the atmosphere.

d in low light intensity (gelap):

o photosynthesis occurs and uses the carbon dioxide produced by respiration. Photosynthesis

produces oxygen needed for respiration.

o The rate of photosynthesis is the same as the rate of respiration.

o Exchange of gases between the atmosphere and the leaf does not occur.

o The plant has reached the compensation point.

o At this point, there is no net gain or loss in carbon dioxide by the plant and no net gain or

loss in the sugar produce.

d In high light intensity (terang):

o The rate of photosynthesis is higher than the rate of respiration.

o Carbon dioxide produce during respiration is no longer sufficient for the plant.

o The plant must take in carbon dioxide from the atmosphere to supplement the need for a

higher concentration of carbon dioxide for photosynthesis.

o At the same time, the plant releases the excess oxygen into the atmosphere.

Industrial development

d Good economics effects.


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o the development provides job opportunities and improves the economic status of the

residents in the area.

o Land for building infrastructure such as schools and clinics. This improves the quality of life.

o Better living conditions.

o A convenient transport system to save travelling time.

d Bad environmental effects.

o Heavy rain washes away soil particles to the river and this leads to flash floods.

o The habitats of many flora and fauna species are destroyed.

o The population of various species in the area is greatly reduced.

o The released of pollutants such as sulphur dioxide and oxides of nitrogen into the

environment leads to air pollution and health problem.

Colonization and succession

d Colonization is a process whereby a species colonises in a newly formed environment.

d Succession is a process whereby the activities of one species of organisms change the

environment. This results in the species being replaced/succeeded by another species which is

well adapted to the new condition.

d The activities of thepioneer species (submerge plants) change the conditions of the

environment and make them more suitable for other species.

d The remains of the submerge plants decompose and are deposited on the pond base.

d The water level in the pond drops. The pond becomes shallower.

d This favours the growth offloating plants which is succeed the pioneer species.

d Floating plants cover the water surface and prevent light from penetrating the water. This

reduce the rate of photosynthesis in submerged plants.

dMore submerge plants die and they remain sink to the bottom of the pond.

d This raised the pond bed further and makes the pond shallower. This condition is not suitable

for floating plants.

d Floating plants are gradually replace by emergent plants.

d The successor causes further changes to the pond, making it unfavorable for the emergent

plants.

d Emergent plants are replaced by terrestrial plants.

d Finally, a primary forest which is the climax community is formed after hundreds of years.

Eutrophication

d Fertilizers from farms run off into the river during heavy rainfall.

d Fertilizers containing nitrates and phosphate are nutrients needed for growth of plants including

green algae. Excess nutrients in the water encourage rapid growth of algae resulting in a

population explosion known as algal bloom.

d Eutrophication is the artificial nutrient enrichment of an aquatic system with inorganic nutrients

causing excessive plant growth. During the night, the high respiration rate in algae increased the

demand for oxygen.


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d The excessive growth of algae restricts the penetration of sunlight into the water. The rate of

photosynthesis in other aquatic plants decreases and this further reduce the supply of oxygen.

d The algae grow faster than the consumers. As a result, most of the algae die without being

consumed.

d The mass of organic material is broken down by decomposing microorganisms, specifically

aerobic bacteria.

d The aerobic bacteria used up oxygen at a faster rate than it can be replenished. An increase in

biological oxygen demand (BOD) results in the depletion of oxygen supply.

d The low level of oxygen concentration kills larger aerobic aquatic animals such as fish which

require higher oxygen levels to survive.

events on earth that cause temperatures to rise:

d When sunlight enters the earths atmosphere, some of its solar radiat ion is reflected back to

space.

d Heat energy that is reflected back into the atmosphere by the earths surface is in the form of

infrared rays.

d Heat energy that is reflected back is absorbed by carbon dioxide, methane, carbon monoxide,

water vapour, nitrous oxide, and chlorofluorocarbons (CFCs) in the atmosphere.

d The increase in the levels of greenhouse gases as a result of human activities causes more heat

energy to be absorbed and trapped in the atmosphere.d Human activities include the burning of fossil fuels (coal, petrol) in motor vehicles and

generation of electrical energy, large-scale deforestation, mining activities, heavy industries and

open burning.

d Trapping of excessive heat increases earths temperature. This eventually leads to global

warming and the earth becomes hotter.

How air pollution effect photosynthesis

d Combustion of fossil fuels (coal, air and gas) in power stations, domestic boilers and internal

combustion engines releases large quantities of sulphur dioxide and oxides of nitrogenwhich

causes air pollution.

d Sulphur dioxide and oxides of nitrogen combine with water vapour in the atmosphere to form

sulphuric and nitric acid respectively.

d These fall back to the earth as acid rain.

d Soil becomes very acidic and unsuitable for cultivation of crop plants.

d Acid rain causes leaching of minerals such as potassium, calcium and magnesium ions. Trees die

because of a lack of minerals in the soil.


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d Photosynthetic tissues are destroyed. Plant leaves turn yellow and fall off.

d Plant roots are damage and cannot absorb minerals from the soil.

d Smoke emitted by factories and vehicles contains tiny particles of carbon called soot.

d Haze is formed when smoke, dirt and particulate matter combine with water vapour in the air.

d Smoke and haze can reduce the penetration of sunlight.

d Smoke particles (soot) also deposit on leaves and prevent gaseous exchange.

d Both these effects lead to reduce photosynthesis and reduce crop yields.

d As a result, plants cannot carry out photosynthesis efficiently and die. Absence of carbon sinks

leads to the greenhouse effect and reduced oxygen levels in the atmosphere. The balance of

nature therefore is disturbed.

the importance of anaerobic respiration in humans during vigorous activity.

d In humans, anaerobic respiration occurs in muscle cells. This allows the muscles cells to continue

carrying out vigorous activities although the oxygen supplied to them is not enough to meet the

demand for oxygen.

d As a result, glucose is not completely oxidize and is broken down into lactic acid.

d The muscle cells are said to have incurred in oxygen debt.

d The oxygen debt is paid back after the vigorous activity has stopped, that is, when a person

breathes deeply and rapidly inhales more oxygen.

d Oxygen that is inhaled is used to oxidize the accumulated lactic acid into carbon dioxide, water

and energy.

*if the lactic acid concentration continues to increase in the muscles and may finally become

high enough to cause muscle cramps and fatigue. A person need to rest and recover.d Therefore, anaerobic respiration enables human muscles to carry out activities for a longer

period, when the supply of oxygen is unable to meet the high demand for oxygen.

Physiological changes during chased by a dog (scared), in rock concert (exited) during interview

(nervous)

d The secretion of the adrenaline hormone increases. This increases the rate of respiration and

heartbeat, and simulates the conversion of glycolgen to glucose.

d The rate of respiration increases so that oxygen can be inhaled.

d The rate of heartbeat so that oxygen can be transported by the blood circulatory system to the

muscles rapidly.

d The rate of ventilation, that is, gaseous exchange between the blood and air in alveoli increases.

d The rate of cellular respiration increases. This provides additional energy for Ali to run fast.

d Cellular respiration increases to produce a large amount of heat energy. The heat produced is

released through effectors such as sweat to remove the excess heat energy.

Comparison between filaments in fish and alveoli in humans


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d Similarities

o both are numerous and therefore, provide a large surface area for gaseous exchange.

o both are made up of thin membranes (one-cell thick) to facilitate of diffusion of gases easily

o both are covered by an extensive network of blood capillaries to enable the rapid transport

of respiratory gases.

o both structures are constantly moist to allow gases to dissolve in them.

o both organisms have a blood circulatory system that transport oxygen to every part of the

body.

d Differences

o the respiratory structures of fish are in close contact with the external medium (water) but

human lungs (alveoli) are not directly in contact with the medium (air)

o human lungs/alveoli are protected by the rib cage while fish gills are not protected when the

operculum is open.

o Ills are easily damage by toxic substance/heavy metals because they are exposed to the

medium. In most circumstances, human alveoli are protected and not exposed to external

harmful gas.

The formation of gall stone

d Gall stone are formed through the hardening of cholesterol in the bile duct and gall bladder.

d Usually occur in obese people.

d A diet high in fatty food can lead to the formation of gallstones.

d Since gall stones block the bile duct, bile cannot be channeled out. Therefore, lipids cannot be

emulsified and digested in small intestine.

The importance of preservation and conservation

d the biodiversity in our country has to be preserve and conserved so that the fauna and flora in

our country can be preserved.

d Preservation involves efforts to increase the number of individuals of an endangered species so

that its number can be increased to a reasonable level.

d Conservation refers to the efforts to return an affected ecosystem to its natural equilibrium. For

example, carrying out replanting programmes.d Preservation and conservation are important to:

o ensure that the flora and fauna species are not extinct

o ensure that the quality of the environment does not deteriorate as result of a result of an

imbalance nature.

o Preserve the sources of genetic information


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o Ensure that energy flow and food sources in a food web are not affected as a result of the

extinction of a certain species.

o Ensure the survival of natural resources such as plants that have high medicinal value.

Regulation of heartbeat

d The sinoatrial node generates electrical impulses which spread rapidly over the walls of both

atria.

d Causing them to contract rhythamically.

d The impulses are then relayed to the atrioventricular node which sends electrical impulses to

the ventricles.

d Causing them to contract

d From the AV node, impulses are sent to the bundle of his, bundle branches and purkinje fibres.d Then, send nerve impulses to the apex of the heart and throughout the walls of the ventricles.

d The ventricles contact and pump blood out to the lungs and other parts of the body.

Blood clotting.

d The platelets clump together and produce thromboplastins.

d Thromboplastins eith the aid of vitamin k and calcium ions, convert prothrombin to thrombin.

d Thrombin converts fibrinogen to fibrin.

d Fibrin form a mesh of fibres across the wound to trap the erythrocytes.

d Blodd clot hardens to form a scab.

Comparison between fish and human circulatory system

d similarities

o Both have closed circulatory system

o Both have a heart

o The heart pumps blood throughout the circulatory system

d Differences

fish human

Has a single circulatory system Has a double circulatory system

The heart is divided into two chambers The heart is divided into four chambers

The septum in absent The septum is present

Deoxygenated blood flow from heart to gills Deoxygenated blood flows from heart to lungs

Oxygenated blood flows from gills to body cell Oxygenated blood flows from lungs to the heart.

Then, pimped to the rest of the body.


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Human circulatory system

d A double circulatory system means that in one complete circulation of the body, blood flows

through the heart twice.

d In the pulmonary circulation, deoxygenated blood is pumped into the pulmonary arteries from

the right ventricle of the heart and returns to the left atrium of the hearts.

d In the systemic circulation, blood id carried between the hearts and the other parts of the body

except the lungs.

d Blood is pumped into the systemic circulation via aorta.

Transpiration

d When water is absorbed by roots from the soil, the water is transported through the xylem

vessel through the mesophyll cells of the leaves.

d Heat from the sun causes water on the external surface of the mesophyll cells to evaporate,

thus saturating the air spaces in the mesophyll eith water vapour.

d The concentration of water vapour in the atmosphere is lower than the concentration of water

vapour in the air spaces.

d Hence, water vapour from the plant cell evaporates and the water vapour diffuses from the

plant cells through the stoma.

d The movement of air carries water vapour away from stoma.

d The loss of water from mesophyll cell makes the cell hypertonic to to the adjacent cell.

dWater from adjacent cell diffuses into mesophyll cell by osmosis. Water continue to diffuse intoadjacent cell from neighboring cells.

d A pulling force is created for pulling water up the xylem vessel due to the evaporation of water

from mesophyll cells.

d This pull is called transpirational pull.

Movemet of water from soil to leaves.

d


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Organelle Found Abundantly In