1. a) i) Define transport
Movement of substances from one part of the body to anotherii) Explain the necessity of transport in plants and animals
make nutrients move from one point to another
movement of respiratory gases i.e. oxygen and carbon IV oxide
elimination of metabolic wastes
movement of hormones
movement of water
movement of salts
movement of enzymesb) i) Describe the structure and function of root hair
root hairs are found near the root tip
they are cells with elongated finger-like projections which are in contact with soil particles
they are permeable to water and mineral salts hence are used to absorb Water and mineral salts
There large number offers a large surface area for absorption of water and mineral salts.ii) State ways in which the root hairs are adapted to their functions
the root hair is long/narrow/numerous to increase surface area for absorption of water and mineral salts
many mitochondria in cytoplasm to supply energy for active transport of mineral salts
are thin walled to speed up rate of absorption of Water and mineral saltsc) i) Compare the internal structure of a dicotyledonous root and a monocotyledonous root
Monocot root
ii) State the similarities and differences between a dicotyledonous and monocotyledonous root
Similarities
both used for anchorage and absorption of water and mineral salts
both have root hairs, epidermis, pericycle, cortex, endodermis and vascular bundles
(xylem and phloem)
both may be used to store food/storage organsDifferences
Monocotyledonous
phloem and xylem are arranged in ring form alternately
pith presentDicotyledonous
phloem lies between radial rays of central xylem(star shaped)
pith absentiii) Compare the internal structure of a monocotyledonous and dicotyledonous stem
Monocotyledonous stem
Dicotyledonous stem
i) Give the similarities and differences between a monocotyledonous and dicotyledonous stem
Similarities
both are used for protection
both conduct water, salts and food
both have epidermis, cortex, pericycle and vascular bundlesDifferences
Monocotyledonous
vascular bundles are many and scattered
some have hollow pith or pith is absent
no cambium layer therefore cannot
undergo secondary growth very
little cortexDicotyledonous
vascular bundles are few and arranged in a concentric ring near the epidermis
pith large and well developedState the differences between the internal structure of a root and a stem.
no cambium layer therefore cannot
undergo secondary growth
very little cortex
presence of cambium therefore
undergoes secondary growth
cortex has several layers of cellsc) i) Name the transport structures of a flowering plant
xylem vessels and tracheids transport water and mineral salts from the soil
Phloem vessels translocate manufactured food from leaves to other parts of the bodyii) State the ways in which xylem vessels are adapted to their function
lignified/thickened to prevent collapsing
narrow to facilitate capillary
no cross walls for continuous flow/column of water
have bordered pits for lateral movement of watera) i) Why do flowering plants need water?
photosynthesis
transport
turgidity w h helps in plant support
solvent i.e. medium for chemical reactions
cooling effect during transpiration
seed germinationii) Describe the movement of water from the soil to the leaves of a tall plant
Soil water exists as a thin film in the soil, between soil particles
the concentration of cell sap of root hair is greater than that of the surrounding solution in the soil, thus drawing the Water molecules across the cell wall and cell membrane into the root hair by osmosis
water drawn into the root hair cell dilutes the cell sap making it less concentrated than that in the adjacent cortex cells of the root
due to osmotic gradient water moves from the root hair cells into the cortex by osmosis, from cell to cell by osmosis, across the endodermis by active transport into xylem vessels of the root that conduct water into xylem vessels of the stem into xylem vessels of the leavesStem
Once in the stem water moves up the plant aided by the narrowness of the xylem vessels (capillary), root pressure, attraction of water molecules to each other (cohesion).
Attraction of water molecules to the Walls (adhesion) from the stem water enters the xylem of leaves
water moves in the xylem vessels of the stem in a continuous (uninterrupted) water column up to the tree leavesLeaves
once in the leaves water moves into the mesophyll cells by osmosis as water vaporizes from the spongy mesophyll cells their sap becomes more concentrated than the adjacent cells as the result water flows into the cell from other surrounding cells which in turn takes in water from xylem vessels within the leaf veins this creates a pull(suction force) called transpiration pull that pulls a stream of water from xylem vessels in the stem and roots .
The transpiration pull maintains a continuous column of water from the roots to the leaves.iii) Name the process by which mineral salts enter into a plant
active transport
diffusioni) Explain the forces that make water and mineral salts move through a plant
mineral salts are taken up due to diffusion because of the concentration gradient between the mineral ions in sap and those in soil solution
active transport involves energy in form of ATP due to respiration which forces mineral salts through a plant against a concentration gradient
water moves by osmosis through a semi-permeable membrane of root hairs and between cells of stem
in stem water moves by cohesion(attraction of water molecules to each other)
it also moves by adhesion(attraction of water molecules to walls)
capillarity is due to narrowness of xylem vessels
transpiration pull occurs When Water vapour evaporates from sub-stomatal chambers into the air
root pressure is a force that pushes Water up the stem from the roots and causes guttation /exudationii) Explain the uptake of mineral salts by plants
plants require mineral salts for metabolism and proper functioning of their bodies
mineral salts are taken up from the soil into the root hairs in form of solution by active
transport which requires energy
active transport involves substances called carriers taken up together with water and are then carried to the stems and leaves
the main process involved in uptake and movement of mineral salts is active transportb) i) What is transpiration?
loss of water from plant to the atmosphereii) Name the sites through which transpiration takes place in a plant
stomata (stomatal transpiration)
lenticels (lenticular transpiration)
cuticle(cuticular transpiration)iii) State the importance of transpiration to plants
cooling the plant
transport of water
transport of mineral salts
excretion of excess Water from plantsexcess transpiration causes wilting
i) Explain the structural factors that affect the rate of transpiration in plants
number of stomata i.e. the more the stomata the higher the rate and vice versa
turgidity of the guard cells which control the opening and closing of stomata when they are open transpiration rate is high
size of leaves where the larger the surface area the higher the rate of transpiration
leaf fall leads to lower rate of transpiration and also drying of leaves reduces rate of transpiration
Thin cuticle reduces distance through Which water vaporizes hence increase transpiration rate. Absence of cuticle also increase rate of transpirationii) Explain the environmental factors that affect rate of transpiration in plants
high temperature increases rate of transpiration and low temperature reduces the rate
humidity when high increases rate and when low reduces the rate
transpiration rate is higher in moving air (wind) than in still air
high light intensity increases internal temperature hence higher rate of evaporation leading to higher rate of transpiration
availability of water in the soil leads to more absorption hence more loss to the atmosphere
atmospheric pressure when high leads to more evaporation and when low leads to low rate evaporation of wateriii) State the structural differences between xylem vessels and sieve tubes
sieve tubes have cross wall while xylem vessels have none
xylem vessels are lignified while sieve tubes are not
Sieve tubes have cytoplasm elements while xylem vessels have none.iv) State the adaptations of plants which enable them to reduce water loss
thick waxy cuticle
reduced leaf size/thorns/spines
shedding of leaves
Sunken stomata. Water vapour accumulates in the depression of stomata lowering the water vapour concentration gradient leading to lower rate of evaporation
rolling of leavesv) State the factors that cause increase in the rate of transpiration from leaves
increased light intensity
low relative humidity
temperaturevi) Explain how drooping of leaves on a hot sunny day is advantageous to a plant
reduces surface area exposed to sun reducing cuticular transpirationc) Explain how aquatic and terrestrial plants are adapted to deal with problems of transpiration
a. Mesophytes
they grow in soils with enough water
water loss is perfectly balanced by absorption of more from the soil
no special adaptationsb. Xerophytes
they grow in dry conditions
root grow very deep to absorb water
succulent/fleshy leaves to store water
few stomata which are sunken
thickened waxy cuticle
leaves are hairy and often folding
some leaves are needle-like/spines or scales
leaf surfaces are reduced i.e. small leaves
all these adaptations are to reduce water lossc. Hydrophytes
plants that grow in water
presence of sclereids
leaves are broad
leaves have many stomata on upper side only (none on the lower surface)
some leaves float on water
absence or reduced leaf cuticle
large air spaces
some leaves are submerged
poorly developed or reduced vascular bundlesd) i) What is translocation
transfer of manufactured food substances to the parts where they are requiredii) Name the tissue which is responsible for translocation of manufactured food in flowering plants
phloem tissueiii) Name the processes that bring about the translocation of manufactured food
active transport
Diffusion
Mass flow
Cytoplasmic streamingiv) Draw a labeled diagram to represent phloem tissue
ii) State the functions of the labbeled structures cytoplasmic strands
translocationCompanion cell
supply nutrients to sieve tube element
supply energy for translocation
regulates activities of tube cells/elementsSieve tubes element
conduct food down the stemiii) name the compounds that are translocated in phloem
sugars
amino acids
hormones e.g auxins
oils/lipids
resins
vitaminsDescribe an experiment you would carry out in order to demonstrate that phloem transports manufactured food substances in a plant
a. Ringing experiment
cut a ring in the bark including the phloem from the stem of a woody plant
phloem is found next to or just beneath the bark
observe daily for some time(more than three weeks)
a swelling of the bark appears above the ring
this is due to accumulation of food from leaves
the bark of a second similar plant is removed carefully leaving the phloem intact
a swelling does not appearii) Use the radio-active tracers
plant is exposed to carbon containing radio-active carbon C14
C14 is found in the end products of photosynthesis
It is finally detected in phloem
C14 is found to move in both directionsiii) Collecting exudate from stylets of aphids
aphids feed on certain plant phloem using their stylets
aphid mouth parts are dissected using a sharp razor
exudes from the mouth parts are collected and then analyzed
sucrose is found to be a major component of the exudates
this proves that phloem translocates manufactured food substancese) Describe an experiment you would carry out to demonstrate that xylem transports water
i. Either
cut a stem of a young plant or twig of a tree under water
or else uproot a young herbaceous plant and wash the soil gently
put some water in a beaker and add a dye i.e. eosin or red ink and place the cut stem or young plant in a beaker
leave for time e. g. between 20 minutes and one hour
cut a thin section of stem or leaf
mount it on a slide and examine under a microscope
observe and note the distribution of the dye or ink
the dye appears only in the xylem vesselsii. OR
use radio-active tracers, C14 in form of carbon
ring a plant then put it in a container containing radio-active phosphorous solution
The radio-active phosphorus is later detected in the leaves.2. a) i)List the components of animal transport systems
system of blood vessels in which materials are circulated round the body
blood, a fluid medium which contains dissolved substances and cells
the heart, a pumping mechanism which keeps blood in circulationii) Distinguish between closed and open circulatory systems
closed system has blood vessels through which blood moves eg vertebrates
open system has no blood vessels hence blood is in direct contact with tissues e. g arthropodaiii) What are the advantages of the closed circulatory system over open circulatory system?
Closed system has continuous vessels hence able to generate high pressure
Circulates blood over longer distance
Circulates blood at a faster rate
Efficient transport of nutrients and waste products
Animals are more activeiv) Distinguish between single circulatory system and double circulatory system Single circulatory
blood passes through the heart once in a complete circuit of the body
Double circulation
blood enters the heart twice in a complete circulation
Pulmonary circulation from the heart to lungs and back
Systemic circulation from the heart to body systems and backb) i) Describe the general layout of the transport system in mammals
blood which is a fluid tissue of the body carrying food substances, oxygen, carbon IV oxide and metabolic wastes
arteries which are elastic tubes carrying blood from the heart to cells
veins which are blood vessels carrying blood away from the cells to the heart
capillaries which are extremely numerous and are microscopic channels connecting arteries to veinsii) Describe the structure and function of the mammalian heart
the heart is a four-chambered hollow muscle located in the thoracic cavity
it consists of two small receiving chambers, the atria(auricles) and two larger pumping chambers, the auricles
the left ventricles is the most powerful and has the thickest walls
this is because it is the chamber which pumps blood throughout the body
each time it contracts, blood is forced out into the elastic arteries(aorta)
blood moves on to the capillaries
from capillaries blood moves to veins and back to the heart through the vena cava
from vena cava it enters into right auricle which contracts and pumps blood into the right ventricle
right ventricle pumps blood into the lungs through the pulmonary artery
blood releases carbon IV oxide to lungs and picks oxygen then returns to left auricle
left auricle pumps blood into left ventricle
left ventricle then pumps blood into the aorta and into arteries, starting the process all over again
both auricles contract simultaneously while bothiii) Explain how the mammalian heart is adapted to performing its functions
the heart is made of muscles that contract and relax synchronously without requiring nervous stimulation
nerve supply however, determine contraction strength and frequency
the heart is divided into four chambers
The right atrium is connected to the right auricle. It receives blood from the whole body.
The blood is pumped from the left atrium to the right ventricle
To avoid flow back into the right atrium, a valve is present between the two chambersthe tricuspid valve
The right ventricle pumps blood to the lungs
This is facilitated by the presence of pulmonary artery
A valve is also present to avoid blood flowing back from the pulmonary artery to the right ventricle
Blood from the lungs enters the heart through the pulmonary vein into the left atrium.
When the left atrium contracts, blood flows into the left ventricle
Blood will not flow back into the left atrium because of the presence of bicuspid valve(mitral)
The left ventricle is connected with the aorta and when it contracts, blood flows into the aorta for distribution into the whole body
The heart muscle surrounding the left ventricle is thicker than that surrounding the right ventricle to be able to generate enough pressure to push blood to the whole body
A pace-maker is present in the heart muscle to initiate and synchronise contractions.
For the heart muscle to be well nourished and be provided with enough oxygen and carbon IV oxide removal, it is supplied with blood by the coronary arteries and drained by the coronary veinsiv) Explain why blood leaving the lungs may not be fully oxygenated
under ventilation of the lungs
blockage of alveoli (air sacs)
high cardiac frequency i.e. high rate of pumping of blood in the hearte) Describe the structure and functions of the blood vessels
i. Arteries
carry away blood from the heart
carry oxygenated blood except pulmonary artery which takes blood from the heart to lungs for oxygen
have thick, muscular walls
are elastic
have narrow lumen
all these adaptations are required to withstand high pressure caused by heartbeatii. Capillaries
link arterioles and venules to arteries and veins
small in diameter to increase pressure resistance for materials to filter out
thin walled as they consist of a single layer of cells to allow diffusion of substances e.g leucocytes to tissues
thin walled to allow presence of intercellular spaces
large number i.e. numerous to provide a large surface area for exchange of materials
have sphincter muscles at the junction of the arterioles and capillaries to control movement of blood into them
lie close to the body for easy exchange of materialsiii. Veins
carry blood back to the heart
all carry deoxygenated blood except pulmonary vein that carries blood from the heart to lungs
have thinner Walls than arteries
have valves to prevent back flow of blood
have wide lumenb) i) State the ways in which the composition of blood in the pulmonary arterioles differs from that in the pulmonary venules
pulmonary arterioles
deoxygenated
high carbon iv oxide
low oxygen
more nutrientspulmonary venules
oxygenated
low carbon iv oxide
high oxygen
less nutrientsii) Give the reasons why pressure of blood is greater in the arterioles than I the veins of mammals
blood is pumped to the arteries by the heart at high pressure
blood pressure in veins is reduced by capillary resistance
arteries have narrow lumen which maintains high pressure/veins have wide lumen which reduces pressure
arteries have more/thicker muscular walls which generate pressure/veins have less/thinner muscular walls which reduce pressureiii) Name the common heart diseases in humans
thrombosis
antheroma
arteriosclerosis
varicose veins
cerebral vascular thrombosisc) i) State the functions of mammalian blood
transport of substances
defense against diseases
clotting
temperature regulationii) Describe how mammalian blood components carry out their functions Plasma
transport dissolved food substances like glucose, amino acids, fatty acids and glycerol from small intestines to liver and other body tissues
transports hormones, enzymes from secretory glands to tissues when required
transports carbon IV oxide to lungs and urea from tissues to the kidneys
distributes heat
bathes the tissues allowing for exchange of materials
contains protein fibrinogen and pro-thrombin which take part in blood clottingRed blood cells (Erythrocytes)
transports oxygen from the lungs to body tissues in form of haemoglobin
transport carbon IV oxide from body tissues to the lungs in form of bicarbonatesWhite blood cells (leucocytes)
engulf foreign bodies
produce antibodies for defense against disease
produce antitoxins which neutralize bacterial toxinsBlood platelets (thrombocytes)
produce an enzyme called thrombokinase/thromboplastin necessary for blood clotting
prevents loss of blood, water and mineral saltsiii) State the Ways in which the red blood cells are adapted to their functions
many per unit volume hence carry more oxygen and carbon IV oxide
biconcave in shape to provide large surface area for absorption of oxygen and carbon IV oxide
absence of nucleolus hence more haemoglobin to carry sufficient oxygen and carbon IV oxide
alter shape to be able to pass through the narrow lumen of capillaries to deliver or supply oxygen and carry away carbon IV oxide
have haemoglobin with high affinity for uptake of oxygen and carbon IV oxideiv) State the structural differences between a red blood cell and a white blood cell.
Red blood cells
has hemoglobin
smaller size
lacks nucleusWhite blood cells
not pigmented
larger size
nucleatedv) State the functional differences between a red blood cell and a White blood cell
Red blood cell
Transports oxygen and carbon IV oxideWhite blood cell
Protects body against harmful pathogensHow does the heart increase blood flow to some parts of the body during exercise
stronger contractions
faster contractions/heartbeatExplain how oxygen and carbon Iv oxide are transported in the blood
Oxygen
oxygen concentration is higher in lungs(alveoli) that in blood
oxygen in the alveoli dissolves in the film of moisture and diffuses through thin epithelial and capillary walls into plasma and red blood cells
the oxygen combines with haemoglobin to form oxyhaemoglobin
blood then becomes oxygenated
blood from lungs then travels to all body tissues where the oxyhaemoglobin breaks down to form oxygen and haemoglobin
haemoglobin is transported back to the lungs to collect more oxygen while the oxygen in capillaries diffuses into body cells for respiration
respiration produces carbon IV oxideCarbon IV oxide
carbon IV oxide produced during respiration diffuses out of cells into blood plasma and red blood cells due to concentration gradient
carbon IV oxide and water fonn carbonic acid carbamino compounds with haemoglobin
in the presence of carboxyl anhydrase enzyme, hydrogen carbonate is carried in blood to the lungs
in the lungs the hydrogen carbonate dissociates to liberate carbon IV oxide which diffuses into alveolar cavity due to concentration gradient
from alveolar space carbon IV oxide is expelled during expirationMost carbon IV oxide is transported from tissues to lungs within the red blood cells and not in the blood plasma. Give the advantages of this mode of transport.
PH of blood is not altered/homeostasis is maintained
Within the red blood cell is an enzyme, carbonic anhyrase which helps in fast loading(combining) and offloading of carbon (iv) oxided) i) what is blood clotting?
process in which blood components clump together to prevent loss of blood from an injured/cut vesselii) Name a protein, vitamin, an enzyme and a mineral element involved in blood clotting
Protein — fibrinogen/prothrombin
Vitamin - k/quinine
Enzyme — thrombokinase/thromboplatin/thrombin
Mineral element — calciumiii) describe the blood clotting process
enzyme thromboplastin produced in the platelets of damaged tissues converts plasma
protein prothrombin into thrombin in the presence of calcium ions
thrombin converts another plasma protein fibrogen into fibrin in the presence of vitamin K
fibrin is insoluble
fibrin forms fibres which form a meshwork that forms a clot
prothrombin thromboplastin thrombin
calcium ion
Fibrinogen thrombin fibrin clot
vitamin Kiv) State the role of blood clotting on wounds
prevents blood/body fluids from being lost
conserves water and salts
prevents entry of microorganisms/pathogens
regulates body temperature
enables wound to heal fasterv) Explain why blood flowing in blood vessels does not normally clot
Presence of anticoagulant in blood
e) i. list the major types of human blood groups
O, with neither B nor A antigen
AB, with both A and B antigens
A, with type A antigen
B, with type B antigeniii. Explain the meaning of :
Universal donor
a person who can donate blood to any other blood group without agglutination/clumping
this is usually blood group O
however this person cannot receive blood from other blood groups except group OUniversal recipient
can receive blood from all blood groups without agglutination
this is usually blood group AB
however, can only donate blood to group ABiii) What is the difference between rhesus positive and Rhesus negative blood samples?
rhesus positive blood has the Rhesus (Rh) antigen
rhesus negative lacks the Rhesus antigenvi) What is blood transfusion?
Introduction of blood from one person to anotherv) Under what conditions would blood transfusion be necessary in people?
during accidents
during surgery in hospitals
bleeding mothers when giving birthvi) How can low blood volume be brought back to normal?
transfusion
taking fluids
eating iron rich food/taking iron tabletsHow may excessive bleeding result in death?
Anaemia/low blood volume/loss of iron/low red blood cells count/low haemoglobin leading to low oxygen, loss of nutrients and dehydration.State the precautions that must be taken before blood transfusion
blood must be disease free
sterilized equipment must be used
blood of the recipient and that of the donor must b compatible to both ABO and rhesus factor
Fresh blood must be used.j) i) What is immunity?
Resistance to disease by organismsii) Distinguish between natural and acquired immunity
natural immunity is inherited/transmitted from parent to offspring/inborn/innate
Acquired immunity is developed after suffering from a disease or through vaccination.iii) What are allergic reactions?
Excessive sensitivity and reaction of an individual to certain substances in environment e.g. dust, pollen, perfumes, smoke etc.vi) How does an allergic reaction occur?
the substances act as antigens
an antigen-antibody reaction occurs on surface of cells
the cells release a substance called histamine
the histamine causes irritation, itching and may stimulate nasal dischargeii) State the role of vaccination against certain diseases
protect body against infectious diseases
prevent spread/transmission of certain diseases
diseases for which vaccination is given include tuberculosis, poliomylitis,measles,
whooping cough, diphtheria3. a) i) What is gaseous exchange?
The continuous exchange of oxygen and carbon Iv oxide between the organism and environmentii) Why is gaseous exchange important to organisms?
to supply oxygen necessary for energy production
to remove carbon IV oxide produced during respiration
To remove Water vapour.b) i) name the structure used for gaseous exchange by plants
stomatal pores/stomata
lenticels
cuticle
pneumatophoresii) Briefly describe the structure of stomata
are minute pores found in leaf epidermis
each consists of a slit-like opening
Each is bordered by two large, bean-shaped guard cells.
Guard cells contain chloroplasts, unlike the other epidermal cells which enable photosynthesis to occur
Inner walls of guard cells are thicker than the outer cellsiii) State the factors which affect stomatal opening
water which when low stomata close and when high stomata keeps open
light as stomata open in bright light and close in darkness
temperatureiv) Name the theories suggesting the mechanism of opening and closing of stomata
interconversion of starch and sugar
pH theory
mineral ion concentrationv) Describe the mechanism of opening and closing of stomata
stomata close at night and open during daytime
This comes about due to changes in turgidity as a result of pH changes in guard cells.
In the dark carbon dioxide accumulates in the intercellular spaces
This raises concentration of carbonic acid
The pH drops (pH lowered)
Enzymes convert sugar into starch in guard cells
Osmotic pressure in guard cells is lowered
Water moves out of guard cells by osmosis making cells lose turgidity hence become flaccid
The stomata close
During day time there is photosynthesis hence the production of sugar, carbon IV oxide concentration is lowered, pH increases, guard cells become turgid causing stomata to open.
During the day potassium ions concentrate in guard cells, raising their osmotic pressure and causes then to open
In the night the concentration of potassium ions decreases increasing osmotic pressure in guard cells therefore causes stomata to open.i) What is the advantage of having stomata open during daytime and having them closed at night?
opening in the daytime allows diffusion of carbon IV into the leaf for photosynthesis to take place and allows diffusion of oxygen out of the leaf
transpiration also takes place, thus cooling the leaf and facilitating uptake of water and mineral slats
Closing in the night is to conserve water in the plant especially when there is not enough water available in the soil.c) i) State the ways in which leaves of plants are adapted to gaseous exchange
presence of stomata for faster gaseous exchange
intercellular spaces/air spaces in the leaf for movement/circulation of air
film of moisture around the surface of cells for easy diffusion
broad/flattened shape to increase surface area
thin lamina to reduce distance of diffusion
exposed to air for easy diffusionii) Describe how gaseous exchange takes place in terrestrial plants
Gaseous exchange takes place in spongy mesophyll
During the day air diffuses into large air spaces of spongy mesophyll through stomata
The carbon iv oxide in the air diffuses into the photosynthesis oxygen is produced
Some of the oxygen diffuses out of the leaf through stomata
During the night air diffuses out of air spaces of spongy mesophyll
The air dissolves into film of moisture
The oxygen in the air diffuses into cells and is used in respiration during which carbon iv oxide is produced
The carbon iv oxide diffuses out of the leaf through stomata due to diffusion/concentration gradient
At night carbon iv oxide accumulates in the leaf since photosynthesis does not take place
Some gaseous exchange also takes place through cuticle
Gaseous exchange occurs through epidermis of young leaves and stems
The cork cells at lenticels are loosely packed
Gaseous exchange takes place between cork and atmosphere within the loosely packed celliii) State the ways in which floating leaves of aquatic plants are adapted to gaseous exchange
stomata found only on upper dermis to allow efficient gaseous exchange
presence to aerenchyma tissues/large air spaces to enable it float/buoyancy/storage of air
absence of cuticle to enhance gaseous exchangeiv) How is aerenchyma tissue adapted to its function?
has large airspaces which store gases/for gaseous exchange/buoyancyv) Explain stomatal distribution in plants of different habitats
land plants have their stomata mainly on the lower side to reduce water loss but if on both sides then upper side has very few
water plants, floaters, have stomata on upper side to enhance water loss
in dry areas, plants have leaves with sunken stomata to reduce water loss by transpiration
Plants in wet areas have stomata equally distributed on both sides.d) i) List the types of respiratory surfaces of animals
cell membrane in unicellular organisms e. g. amoeba
gills in fish
tracheal system
skin, buccal cavity and lungs in amphibians
lings in mammalsii) State the characteristics of respiratory surfaces in animals
moist thin walled/thin membrane/thin surface
Highly/richly vascularised/numerous blood vessels/Well supplied with blood vessels.
Large surface areaiii) Describe gaseous exchange in protozoa
example is amoeba
small and have large surface area
oxygen diffuses into the organism and carbon IV oxide diffuses out into Water
simple diffusion of gases is enough to meet its respiratory requirementse) i) Make a labeled drawing of a fish gill
ii) How is a fish gill adapted to its function?
large surface area due to many filaments
extensive vascularisation due to capillaries, for gaseous exchange
thin filaments to facilitate diffusion of gases
presence of rakers to filter solid particles
gill bar is bony, hard and firm to support the filaments and rakers and for attachment of filaments and rakersiii) Discuss gaseous exchange in bony fish
example is tilapia
the mouth opens and the floor of the mouth is lowered so that the volume in the mouth is increased and pressure is lowered
water then enters into the mouth cavity
the mouth is closed and the floor of the mouth raised so that the volume is reduced this raises the pressure, forcing water over gills and out through the operculum
As water passes over the gills oxygen diffuses due to concentration gradient (partial pressure) into the blood stream.
In the body tissues, carbon IV oxide diffuses into the blood (due to concentration gradient, and is transported to the gills and diffuses out into the water.iv) What is counter-flow system?
Where water in which the fish lives flows in opposite direction across the gill.vi) What is the advantage of counter-flow system?
maintains a diffusion gradient so that there is maximum uptake of oxygen
oxygen continues diffusing into blood and carbon iv oxide into Waterf) i) Describe the mechanism of gaseous exchange in terrestrial insects
example is cockroach
air in the atmosphere contains oxygen
air is drawn into the body of the insect through the spiracles due to movement of abdominal muscles
these movements cause the opening of spiracles
air moves through the trachea to tracheoles
oxygen moves from the tracheoles into body cells by diffusion due to concentration gradient
carbon iv oxide in the tissues diffuses into tracheoles due to concentration gradient
From tracheoles carbon IV oxide moves into trachea and out through the spiracles into the air.ii) State how traceholes are adapted to gaseous exchange
thin walls of tracheoles
moist surface
large surface area due to numerous tracheolesg) i) What is breathing?
Any process which speeds up the rate of gaseous exchange between an animal and its surrounding.ii) Name the structures in humans that are used in gaseous exchange
nose
larynx
epiglottis
trachea
lungs
pleural membrane
pleural cavity
diaphragm musclesiii) Describe the mechanism of gaseous exchange in a mammal
Breathing in
external intercostals muscles contract while internal intercostals muscles relax, raising then ribcage upwards and outwards
muscles of the diaphragm contract hence it flattens
the volume of the thoracic cavity increases while pressure decreases
higher air pressure in the atmosphere forces air into lungs through the noseBreathing out
external intercostals muscles relax while internal intercostals muscles contract, moving the ribcage downwards and inwards
muscles of the diaphragm relax hence the diaphragm assumes dome shape
the volume of the thoracic cavity decreases while pressure increases
the higher pressure forces air out of the lungs through the noseiv) Explain how mammalian lungs are adapted to gaseous exchange
large number of alveoli that increase surface area
moist inner surface of alveoli for dissolving oxygen/gases to facilitate exchange of gases
through alveolar cavities and blood
thin walls of alveoli to allow efficient/faster diffusion of gases
rich capillary/blood supply on alveolar surface to transport oxygen away from the lungs and carbon IV oxide to the lungsv) Name the features of alveoli that adapt them to their function
have large surface area/spherical shaped
numerous/many to increase surface area
one cell thick
moist surface for air to diffuse
highly vascularised/numerous capillariesvii) How is the trachea of a mammal suited to its function?
has a ring of cartilage which keeps it open at all times
cilia that move mucus/particles to the top of the trachea i.e. into larynx for removal
mucus to trap dust, solid particles and microorganisms
hollow for passage of airviii) State the advantages of breathing through the nose rather than through the mouth
nose has hairs to filter solid particles
it has mucus lining to trap dust particles
the nose has cells sensitive to smell for survival
it warms the air before it reaches the lungsix) Give the conditions under which the carbon iv oxide level rises above normal in mammalian blood
vigorous exercise
emotions/stress
disease infectionx) Explain the physiological changes that occur in the body to lower the carbon iv oxide level back to normal when it rises
heartbeat/cardiac frequency increases to pump blood faster carbon iv oxide from the tissues and supply more oxygen
ventilation rate/rate and depth of breathing increases to take more oxygen and remove carbon iv oxide from the lungs
arterioles to take in more oxygen and remove carbon iv oxide from the lungs
arterioles dilate leading to faster flow of blood to and from body tissuesh) i)Describe the factors which control the rate of breathing in humans
breathing movements usually occur unconsciously
it is controlled by the medulla oblongata part of the brain situated at the breathing centre
medullar oblongata is in the brain
respiratory centre transmits impulses to the diaphragm through phrenic nerves
carbon iv oxide concentration in the blood determines the breathing rate
if carbon iv oxide is less, the brain is triggered to decrease breathing rate
cardiac frequency decreases and the arterioles constrict
therefore carbon iv oxide level is raised
this brings back to normal level of breathing and carbon iv oxide level increases/is more
the brain is triggered to increase breathing rate
cardiac frequency is increased
there is vasodilation of arterioles
carbon iv oxide level falls
therefore the normal level is attained and carbon iv oxide is removed fasterii) Name the respirator diseases
asthma
bronchitis
whooping cough
pneumonia
tuberculosis4. a) i) Define respiration
the oxidation/breakdown of food within cells to release energyii) Explain the significance of respiration in living organisms
it yields energy (ATP)
this energy enables organisms to move, grow, excrete and reproduceiii) Where does respiration take place?
in the mitochondriab) i) Draw and label a mitochondrion
ii) State the most important function of mitochondria
to produce Adenosine triphosphate (ATP) which is the energy source of the Whole celliii) Give the functions of the labeled parts
Outer membrane
controls what enters and What leaves mitochondrionCristae
also called inner membrane
increase surface are for attachment of enzymes
this is Where cellular oxidation reactions occurMatrix
enzymes are located here
other reactions occur herec) Explain the roles of enzymes in respiration
they catalyse reactions i.e. speed up respirationd) i) What is aerobic respiration
respiration in the presence of oxygenii) Give a word equation for aerobic respiration
glucose + oxygen - Water + carbon iv oxide + energyiii) What are the end products of aerobic respiration?
energy
carbon iv oxide
watere) i) What is anaerobic respiration
occurs in the absence of oxygen e. g. yeast and certain bacteria release energy in the absence of oxygenii) What are obligate anaerobes?
are completely independent of oxygeniii) What are facultative anaerobes?
can survive both in the presence and absence of oxygen also called partial anaerobesiv) State the Word equation representing anaerobic respiration in plants
Glucose ethanol + carbon (iv) oxide + energyv) Name the end products of anaerobic respiration in plants
alcohol/ethanol
carbon iv oxide
energyg) i) Give a word equation of anaerobic respiration in animals
Glucose —> lactic acid + energy
ii) Name the end products of respiration in animals when there is insufficient oxygen supply
lactic acid
energyiii) Why is there a high rate of lactic acid production during exercise?
the demand for oxygen is more than supply leading to anaerobic respirationiv) Why does lactic acid level reduce after exercise?
lactic acid is oxidized to form carbon iv oxide and water
some is converted to glucose
some is converted into glycogenv) State why accumulation of lactic acid during vigorous exercise lead to an increase in heartbeat
lactic acid is poisonous to tissues and must be removed
to increase supply of oxygen to tissuesState the economic importance of anaerobic respiration
brewing of alcohol
biogas production
compost manure formation
silage formation
baking bread
production of dairy products
fermentation of milk
sewage treatment
Fermentation of tea in industries.What is oxygen debt?
amount of oxygen required to convert accumulated lactic acid to water, carbon IV oxide and energyh) i) What is respiratory quotient(RQ)?
ration of carbon IV oxide produced to oxygen consumedRQ = volume of CO2 produced
volume of oxygen consumed
ii) Why are respiratory quotient important
their calculation assists in identifying the kind of substrate being used in respirationiii) Name the respiratory substrates
carbohydrates
fats
proteinsiv) Why does anaerobic respiration of a given substrate yield a smaller amount of energy than aerobic respiration?
Some energy locked up in intermediate products like ethanol in plants and lactic acid in animals
substrate is completely oxidized in aerobic respirationiv) Explain the disadvantages of anaerobic respiration
Less energy produced in anaerobic respiration since food is partially oxidized while in
aerobic respiration food is completely oxidized.
Some metabolic wastes accumulate in cells affecting cellular functions
Ethanol produced in plants poisons the tissues while lactic acid produced in animals
causes muscle fatigue/muscle cramp and may stop muscle contraction
Such intermediate wastes are not produced in aerobic respirationv) Mention the types of experiments carried out for respiration
germinating seeds which yield energy in form of heat
animals produced heat when they respire
yeast cells respire to produce heat5. a) i) Define the following terms
Excretion
the process by which organisms get rid of waste products which result from chemical process which occur in living cellsSecretion
the process by which organisms produce substances which are useful to the body, by glandsEgestion
removal of indigestive materials from the bodyHomeostasis
maintenance of constant internal environmentii) Explain Why excretion is necessary in plants and animals
-products of excretion are usually harmful while some are toxic
- if allowed to accumulate in the cells they would destroy tissues and interfere with normal metabolism
- They are therefore removed through excretion
b) i) Describe how excretion takes place in green plants
carbon IV oxide, oxygen and water diffuse through the stomata, lenticels and hydathodes
some toxic wastes are convened into non-toxic substances
these are deposited in certain tissues of the plant or stored in aging stmctures
resins and tannins are exuded through the bark of stem or lost during leaf fallii) Why do plants lack complex excretory structures like those of animals?
plants have lower rates of metabolism
plants excrete non-poisonous products derived from carbohydrate metabolism unlike animals which produce toxic wastes derived from protein metabolism
plants re-use some of their wastes like nitrogenous wastes used in protein synthesis
plants store waste products in roots, fruits and leavesii) State the excretory products of plants and some of their uses to humans
caffeine from tea and coffee is used in medicine and as a stimulant which is harmful to humans
quinine used for treating malaria
cocaine derived from leaves of cocoa plant used as a stimulant by addicts or as a local anesthesia, also causes damage to the brain, may cause addiction if not well used and is an illegal drug
Tannins derived from barks of acacia (wattle bark) trees are used to make ink and tanning (softening) of leather.
Nicotine got from leaves of tobacco plant stimulates the central nervous, may cause addiction if much is used or consumed. It is used to make cigarettes, cigars and is poisonous. It is a precursor of lung cancer
Cannabis sative(bhang) is used to make drugs
Gum derived from glues is used for sticking substances and making certain jellies
Rubber, a product of latex, got from rubber plant is sued to make tyres and synthetic fibres
Morphine from opium poppy plant is a narcotic and illegal drug as it causes addiction
Khat and miraa are used as stimulants
Colchicines used in inducing polyploidy, cancer therapy, treatment of gouts in small quantities
Papain used as meat tenderizerc) i) Describe excretion in unicellular organisms
-examples are amoeba and paramecium
-They have to remove waste products such as carbon IV oxide and nitrogenous substances e. g urea and ammonia
- These diffuse from the body surface into the surrounding Water
- Diffusion is due to large surface area
ii) List excretory organs and products of mammals
kidney excretes urea, water and salts
skin excretes Water, slats and urea
lungs excrete carbon IV oxide and water
liver excretes bile saltsd)i) Draw and label a mammalian skin
ii) Explain how the mammalian skin is adapted to its functions
the skin is made up of dermis and epidermis
Epidermis
it is made up of three layers
the outermost layer, comified layer is made up of dead cells that prevent entry of microorganisms, prevent physical damage and dessication
granular layer made of living cells gives rise to cornified layer
malpighian layer is made up of actively dividing cells that give rise to new epidermal cells/granular layer it contains melanin that protects the body against ultra violet rays(radiations)Dermis
has several components
Has sweat gland which produce sweat through sweat pores on the skin and the sweat evaporates cooling the body by lowering body temperature. When it is cold, no sweat is produced, conserving water
sweat contains water, sodium chloride, uric acid and urea hence the skin acts as an excretory organ
Has hair. The hair stands erect to trap air when temperature is low to reduce loss/insulation. It lies flat to allow heat loss when temperature is high.
Has nerve endings which are sensitive to stimuli such as heat, cold, pain, pressure and touch
Has subcutaneous fat/adipose fat that insulates the body against heat loss
Has arteries and capillaries (blood vessels) that supply food and oxygen and remove excretory products. Arterioles vasodilate when temperatures are high to lose heat by radiation, and convention. Arterioles constrict when temperatures are low to conserve heat i.e. reduce heat loss
Has sebaceous glands which secrete sebum, and antiseptic and water repellant that prevents drying and cracking the skin by making the skin supplee) What is the role of lungs in excretion?
during respiration oxygen is used up in the body cells to produce energy
carbon IV oxide is produced as a by-product
the carbon IV oxide must be eliminated from the body
elimination is through the lungs
also, water vapour is formed and must be removed
this removal is through the lungs
the lung is therefore considered as an excretory organ as it removes carbon IV oxide and water vapour which are by-products of respirationf) State the functions of the liver
i. Excretion
in this function the liver is aided by the kidney
deamination i.e. excess amino acids converted into urea and uric acid which is transported to skin and kidney for removal
detoxification where harmful substances are converted into harmless ones in the liver and transported to kidneys for removal
breakdown of worn out blood cells and haemoglobin and the residue excreted through the
kidney to give urine a yellow tinge
Breakdown of sex hormones after they have performed their function and the wasted are
released through the kidney and bile.ii) Homeostasis
regulation of blood glucose
the normal amount of glucose in blood is about 90mg/ 100
increase in blood sugar is detected by cells of the pancreas which secrete insulin
insulin stimulates the liver to convert excess glucose to glycogen
further excess glucose is converted to fats until the normal blood sugar level is attained
Excess glucose is oxidized to carbon IV oxide, water and energy. Excess glucose is also used in respiration
decrease in blood sugar level below normal level is detected by the pancreas, which secretes glucagon which stimulates the liver to convert glycogen to glucose until the normal sugar level is attained
fats, amino acids are converted to glucose
it also leads to reduced oxidation of glucoseDeamination
excess amino acids are deaminated by the removal of amino group
the amino group is converted to ammonia
ammonia combines with carbon IV oxide to form urea
urea is excreted in urine through the kidney
Detoxification
poisonous substances are converted to less harmful compounds
Thermal regulation
maintenance of body temperature
heat is generated in the liver by chemical activities
the heat is distributedg) i) Draw a labeled diagram of mammalian nephrone
ii) Describe how the human kidney functions
the afferent arterioles, which is a branch of the renal artery, supplies blood to the glomerulus
the afferent arteriole has a wider diameter than the efferent arteriole
this difference in diameter of afferent and efferent vessels causes high pressure leading to ultra filtration
the walls of the blood capillaries are one cell thick hence glucose, amino acids, vitamins,
hormones, salts, cratinine, urea and water filter into Bowman’s capsule to form glomerular filtrate
white blood cells, red blood cells, plasma proteins (such as globulin) and platelets are too large to pass through the capillary walls hence remain in blood capillary
the filtrate flows into proximal convoluted tubule where amino acids, vitamins and all glucose are selectively reabsorbed back into the blood stream
many mitochondria provide energy for reabsorption of these substances against a concentration gradient by active transport
the glomerular filtrate flows into the loop of Henle
water in the descending loop moves by osmosis into the blood capillaries
sodium chloride is actively pumped from the ascending arm of the loop of Henle into the blood capillaries
the glomerular filatrate flows into the distal convoluted tubule
water and salts are reabsorbed from distal convoluted tubule into blood capillaries
the glomerular filtrate flows into collecting tubule (duct) from where more Water is reabsorbed into blood stream
antiduretic hormone influences the amount of Water reabsorbed depending on osmotic pressure of blood
the glomerular filtrate from collecting duct, now referred to as urine, is emptied into pelvis and ureter into bladder and out of body through urethra
urine consists of excess water, slats and nitrogenous wastesiii) State the adaptations of proximal convoluted tubule to its function
folded to increase surface area for absorption thin epithelium to reduce distance of diffusion micro-villi on inner
lining to increase surface area for absorption folded to reduce speed of flow for efficient absorption numerous mitochondira to provide energy for reabsorption dense capillary network to transport reabsorbed productsiv) Name the common kidney diseases
nephritis
kidney stones(renal calculi
cystitis
oedema
kidney failure6. a) i) Why is homeostatic control necessary?
this provides a constant internal environment so that the cells of the body have the optimum (best) condition for their survivalii) What is internal environment?
immediate surrounding of body cells
refers to tissue fluid within an organismb) i) Why is constant body temperature maintained by mammals?
most enzymes in the body function within a narrow range of temperature
high temperature denatures enzymes
low temperature inactivates and inhibits enzymesii) Explain the advantage gained by possessing a constant body temperature
animals remain active despite fluctuations in environmental temperature
higher chances of survival in various environments ie they colonize various environments
chemical processes in their body continues at an optimum rateiii) How do mammals regulate body temperature?
the body temperature of a mammal is kept constant
to maintain this temperature the mammal must be able to balance its heat loss against the heat gain
body temperature is controlled by the hypothalamus, a specialized part of the brain
changes in the temperature within the body and the surrounding are detected by the hypothalamus it transmits impulses to the skin and the blood stream in response to temperature changes hypothalamus acts as a thermostat for the body
a mammal loses heat by breathing out, urine, feaces, skin by radiation and by evaporation of sweat.
A mammal generates heat by the activity of its muscles, by general metabolism in respiration, or chemical activities
In hot conditions the hypothalamus stimulates responses that increase heat loss from the body hence lowering the body temperature
Such responses include sweating, vasodilation, keeping its hair flat on the surface of skin and reduction of metabolic rate
In cold conditions the hypothalamus stimulates responses that generate heat gain in the body and reduce heat loss to the environment
Such responses include shivering, vasoconstriction, raising its hair to trap a layer of air around the skin because still air is a good insulator of heat and by generation of heat by increasing metabolic rate.iv) Why does body temperature of a healthy person rise up to 37 C on a hot humid day?
sweat evaporation is reduced hence cooling is less therefore more heat is retained in the body causing temperature to risev) Name the structures in the human body that detect external temperature changes
temperature receptors (end bulb corpuscles e. g. bulb of Krause (warmth) and organ of Ruffinni (cold)
heat (thermal) receptorsvi) State the advantages that organisms with small surface area to volume ratio experience over those with larger
heat loss slow hence their body temperature can increase to intolerable levels
Heat gain from surrounding slower hence may remain inactive for a long time.
Need specialized and complex transport system and also gaseous exchange systemExplain why individuals with smaller sizes require more energy per unit body weight than those with larger sizes.
surface area to volume ratio is higher in smaller individuals than larger ones, therefore smaller heat is lost faster by smaller ones than larger ones
they therefore require more energy per unit body weight to maintain body temperaturec) i) What is the meaning of osmoregulation?
mechanism which regulates osmotic pressure of internal environment of an organism
the regulation/maintenance of salt/solute-water balance of an internal environmentii) State the importance of osmoregulation
Maintenance of constant level of water and slats (osmotic pressure) for optimum/suitable conditions for metabolism suitable for cellular functionsiii) State the ways by which desert mammals conserve water fewer glomeruli longer loop of Henle
excretion of dry feaces or concentrated urine
hump for fat to be metabolized to give metabolic water for use
nocturnal, burrowing, aestivate or hibernate
sweat glands few or absent
more ADH (vasopressin)iv) Explain why some desert animals excrete uric acid rather than Water
uric acid is less toxic than ammonia, hence elimination of uric acid requires less water
than ammonia therefore more water conserved
uric acid being less toxic is safer to excrete where there is less water/desertv) Explain why eating a meal with too much salt leads to production of a small volume of concentrated urine
the concentration of salts in the blood rises leading to production of more ADH hence higher rate of water reabsorption by kidney tubulesvi) Explain how marine fish regulate their osmotic pressure
swallow plenty of sea water to increase amount of water in the body
have chloride excretory cells in their gills to remove excess salts
eliminate nitrogenous wastes in form of trimethalamine oxide which requires little water for elimination
few/small glomeruli thus slow filtration rate in the kidneys
retain nitrogenous wastes in form of urea to raise osmotic pressure of body fluidsd) i) What is the biological significance of maintaining a relatively constant sugar level in a human body?
body cells are surrounded by tissue fluids that are isotonic/same osmotic pressure as cytoplasm
if sugar level is high/hypertonic, cell will lose water by osmosis to the surrounding, thus increasing the concentration of the contents
this changes the physiology of the cell
if the blood sugar is lower than the normal, the cytoplasm gains water by osmosis,
diluting the cell contents, thus altering the physiology of the cellii) Discuss the role of the following hormones in blood sugar control
Insulin
insulin is produced when there is increase in blood sugar concentration
it converts glucose to glycogen which is in the liver or muscle thus lowering sugar levelGlucagon
when glucose level decreases glucagon is produced, which causes the breakdown of glycogen to glucose thus raising blood sugar levele) Explain the part played by antidiuretic hormone in homeostasis
Produced when there is less water (high osmotic pressure above normal level of salt concentration) in the blood.
It acts on kidney tubules (nephron) thus increasing water reabsorption from tubules to the blood stream, thus restoring osmotic pressure
When there is more water(lower osmotic pressure) or decreased salt concentration in blood, little or no ADH is produced, less water reabsorbed hence water loss in urine (more dilute urine) hence raising the osmotic pressure in body fluids/bloodf) What is the role of blood clotting in homeostasis?
when a blood vessel is cut, there is exposure of blood platelets to the air
this triggers fibrinogen to be converted to fibrin
the fibrin forms a clot that prevents body fluids e. g. blood from being lost
therefore the clot conserves water and salts in the bodyg) Describe the role of the following hormones in homeostasis
i. Aldosterone
concerned with regulation of ionic balance
secreted by the cortex of adrenal glands
it increases sodium ion uptake by the gut and promotes the reabsorption of sodium ions (and therefore water) in the kidneys)
this is accompanied by elimination of potassium ions
this raises the overall level of sodium and lowers the overall level of potassium in the blood
as sodium ions are absorbed in the blood, chlorine ions follow so as to neutralize the effect of sodium ions
the production of aldosterone is regulated by the concentration of sodium ions which has an inhibiting effect, and a fall in sodium ions has a stimulating effect on the adrenal cortex
the flow of aldosterone is stimulated by the adreno-cortic-tropic hormone (ACTH) produced in the anterior of the pituitary gland however, the main method of control is dependent on the fact that adrenal cortex itself is somehow sensitive to the relative concentration of potassium and sodium in the bloodii. Adrenaline
produced by adrenal glands
in high concentrations, it increases hydrolysis of glycogen and increases blood sugar
it is usually released in emergency cases to increase glucose level for respiration
this releases energy for the emergencyh) i) Distinguish between diabetes mellitus and diabetes insipidus
diabetes mellitus is a condition resulting from insufficient production of insulin causing hyperglucaemia and presence of glucose in urine
diabetes insipidus is a condition whereby less or no antidiuretic hormone is secreted hence a high volume of water is passed out in urine in a condition called diuresisii) How can high blood sugar level in a person be controlled?
administer insuliniii) Why does glucose not normally appear in urine even though it is filtered in the mammalian Bowman’s capsule?
glucose molecules are actively reabsorbed in the proximal convoluted tubulesiv) When is glycogen which is stored in the liver converted into glucose and released into the blood?
after activity/when blood sugar (glucose) falls below normal
when glucagon
stimulates the liver/when glucagon is produced
after strenuous/vigorous activity
during starvationv) How would one find out from a sample of urine whether a person is suffering from diabetes mellitus?
test or react urine in Benedict’s solution
positive result i.e. orange or red precipitate
Positive result is an indication of diabetes mellitus
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