Post on 16-Jan-2016
Importance of WaterImportance of Water It acts as:
solvent / reaction medium
medium for transport (e.g. blood)
metabolite (e.g. photosynthesis)
others like act as cooling agent (e.g.
sweating in hot weather)
as supporting agent (e.g. turgidity in
young plant)
for sexual reproduction
Water as a SolventWater as a Solvent dissolve most organic and
inorganic substances
needed for all biochemical reactions
remove excretory products such as urea and excess salts
in plants, root hairs absorb mineral salts present in soil in solution form
Water as a Water as a Medium of Medium of TransportTransport human blood plasma consists
mainly of water (90%)
carry many dissolved substances
like excretory wastes, hormones
and gases around the body
in plants, sugar and mineral salts
are transported in solution in
vascular bundles
Water as a MetaboliteWater as a Metabolite
in plants during photosynthesis,
carbohydrates are synthesized from
carbon dioxide and water
essential in hydrolytic reactions,
e.g. digestion
Ways of Gaining Water in Ways of Gaining Water in AnimalsAnimals
drinking
eating
from respiration occurs in cells
which the water formed is called
metabolic water
Ways of Losing Water in Ways of Losing Water in AnimalsAnimals
evaporation from body
surfaces
sweating
exhalation
urination
defaecation
Hypotonic, Hypertonic and Hypotonic, Hypertonic and Isotonic Solutions Isotonic Solutions
Hypotonic solution
- a solution has a higher water
potential than the reference
solution
Isotonic solution
- a solution has the same water
potential as the reference solution
Hypertonic solution
- solution has a lower water
potential than the reference
solution
Animal Cells Response to Animal Cells Response to Different SolutionsDifferent Solutions
tissue cells
water move in by
osmosisin hypotonic
solutio
n cells burst
tissue cells
water move out by
osmosis
in hypertonic solution
cells shrink
Animal Cells Response to Animal Cells Response to Different SolutionsDifferent Solutions
Importance of Importance of OsmoregulationOsmoregulation
osmoregulation is the maintenance of
correct levels of water in the body
any excessive gain or loss of water will
upset the proper functioning of cells in
an organism
metabolic reactions are affected and
organisms may die
Investigation of the Investigation of the Effects of Different Salt Effects of Different Salt Concentration on Concentration on
Red Blood Red Blood CellsCells
Which of the five saline solutions most closely resembles the blood plasma in salt concentration ?Ans: The one in 0.8% saline solution is the most
resembles the blood plasma concentration.
red blood cell swells and is about to burst
red blood cell shrinks
red blood cell remains unchanged in appearance
In hypotonic saline solution
In hypertonic saline solution
In isotonic saline
solution
What evidence supports your answer ?Ans: Red blood cells in 0.8% saline solution
remain unchanged in appearance indicating that the solution is isotonic to blood plasma …
red blood cell swells and is about to burst
red blood cell shrinks
red blood cell remains unchanged in appearance
In hypotonic saline solution
In hypertonic saline solution
In isotonic saline
solution
What evidence supports your answer ?Ans: Fewer red blood cells can be observed in
0.6% saline solution and even fewer in 0.2% saline solution. This shows the two solution are hypotonic to the red blood cells …
red blood cell swells and is about to burst
red blood cell shrinks
red blood cell remains unchanged in appearance
In hypotonic saline solution
In hypertonic saline solution
In isotonic saline
solution
What evidence supports your answer ?Ans: The 1.6% and 3.2% saline solutions are
hypertonic to the red blood cells as a net movement of water out of the red blood cells into the saline solution is noticed.
red blood cell swells and is about to burst
red blood cell shrinks
red blood cell remains unchanged in appearance
In hypotonic saline solution
In hypertonic saline solution
In isotonic saline
solution
Human Urinary SystemHuman Urinary System
kidney
ureter
urinary bladder
urethra
Human Urinary Human Urinary SystemSystem
aorta
renal arteryureter
urinary
bladder
left kidne
y
renal vein
right kidne
ysphincter muscle
urethra
Inferior vena cava
Human Urinary Human Urinary System System - Location of - Location of KidneysKidneysmammals have two kidneys which
are reddish and bean-shaped
they are situated at one on each side
of the vertebral column, below the
ribs and are not protected by any
part of the skeletal system
renal artery brings blood to kidney
while renal vein takes blood away
from it
Human Urinary Human Urinary System System - Ureter - Ureter
carries urine from kidney down to urinary bladder where stores urine temporarily
valves are present in ureter to prevent urine from flowing upwards
back flow of urine may happen when urinary bladder empties if valves do not close properly.This may lead to infection and damage kidney
Human Urinary Human Urinary System System - Urinary Bladder - Urinary Bladder
a muscular bag situated towards the
bottom of the abdominal cavity
urethra is led out from it
on the top of urethra is surrounded
by ring of sphincter
Urination Urination normally, the sphincter muscle is
tightly contracted, so no urination
occurs when urinary bladder is full
sphincter muscle relaxes +
wall of urinary bladder contracts
urination occurs
Adults can control the sphincter muscle but children cannot, it relaxes automatically when the bladder is full
Structure of Structure of Mammalian Mammalian
Kidney Kidney cortex
medulla
renal arteryrenal vein
ureterpelvis
nephron
Structure of Structure of Mammalian Kidney Mammalian Kidney
made up of three parts:
- a light outer
region - cortex
- a dark inner region - medulla
- a whitish central region leads to
kidney - pelvis
contain numerous tiny tubules called
nephrons
Structure of Nephron Structure of Nephron consists of a swollen end called
Bowman’s capsule which is connected
to a narrow
tubulethe tubule begins in
cortex
after leaving the capsule, it coils up
(proximal convoluted
capsule)
It is then descends into the medulla and
becomes U-shaped (loop of Henle)
It goes back into the cortex and coils up
again (distal convoluted tubule)
Finally, it drains into a collecting duct
which goes through the medulla and
down to pelvis
NephronNephron
renal artery
renal veinproximal
convoluted tubule (first convolution)
capillaries around nephron
Loop of Henle
afferent arteriole
glomerulusefferent arteriole
collecting duct
distal convoluted
tubule (second convolution)
How Nephron is How Nephron is Connected with Blood Connected with Blood
VesselVesselrenal
arteryenters
Bowman’s
capsule
Glomerulus (a tightly
bunched group of
capillaries)
afferent arteriole
(branches from renal
artery)
efferent arteriole
(capillaries join up)…...
How Nephron is How Nephron is Connected with Blood Connected with Blood VesselVessel
leaves Bowman’s
capsule
capillaries (spread out
and wrap around
tubule)venule
(capillaries join
up)renal vein
Bowman’s capsule(with glomerulus)
afferent arteriole
efferent arteriole
loop of Henle
Structure Structure of of
NephronNephron
collecting duct
first & second convolution
venule
How Nephron Works ?How Nephron Works ?
By two ways, one is
ultrafiltration and the other
is reabsorption
UltrafiltrationUltrafiltration
diameter of tiny artery leading to
the glomerulus is larger than the
leaving one so increase in pressure
is resulted as blood tries to force its
way out of the smaller tube
the high hydrostatic pressure forces
small molecules through the walls of
capillaries and Bowman’s capsule
into the capsular space
fluid which filtered into the nephron is
glomerular filtrate
glomerular filtrate has the same
composition as that of blood except
that it hasn’t got red blood cells, blood
proteins & blood platelets
Reabsorption reabsorption is the process of
absorbing useful substances into
capillaries which wrapped around
tubule
as in glomerular filtrate, some
substances like glucose and amino
acid are useful to human so they are
absorbed back while fluid travels
along the tubule
those urea which remains in the fluid
pass the whole nephron and finally
drains into collecting duct which
leads to pelvis and form urine
urine contains mostly water, with
urea and excess mineral salts
reabsorption of glucose, amino acids
and some salts begins in the first
convolution and finished when the fluid
reaches loop of Henle
useful substances are reabsorbed by
diffusion down the concentration
gradient and active transport against
concentration gradient in collecting duct, water is mainly
reabsorbed by osmosis but the first
convolution actually reabsorbs the
largest amount of water
Functions of KidneyFunctions of Kidney
kidney mainly has three functions:
osmoregulation
removal of excess salt
excretion
Functions of Kidney Functions of Kidney - -
OsmoregulationOsmoregulationdrink a lot of
water
blood becomes
diluted
dilute urine
produce
small proportion of
water is reabsorbed
Amount of water in blood:
CONSTANT
after sweating
blood becomes
concenrtratedlarge proportion of
water is reabsorbed
concentrate urine produce
Amount of water in blood:
CONSTANT
Functions of Kidney Functions of Kidney - -
OsmoregulationOsmoregulation
Functions of Kidney Functions of Kidney - Removal of - Removal of
Excess SaltExcess Saltafter eating a salty meal
salt enters blood, concentration of salt
in blood increase
volume of urine increase
concentration of urine is higher
man feels thirsty drink water
Functions of Kidney Functions of Kidney - Excretion - Excretion
protein cannot be stored in human
body, excess protein are broken
down in liver
removing of amino groups from
amino acids is called deamination
amino groups are incorporated into
urea molecules and then excreted in
urine
Kidney Failure and Kidney Failure and Artificial Kidney Artificial Kidney
some kidney diseases can lead to
kidney failure which kidney can no
longer function properly
toxic substances will accumulate in
blood and patient will die
artificial kidney is a bulky machine
attached to patient which is used to
filter and clean patient’s blood
artificial kidney make use of the
principle of dialysis. It has a filter
made of cellophane which acts as a
selectively permeable membrane
along one side of the membrane is
the patient’s blood while the other
side is dialysis fluid which has the
same contain as plasma except urea
only urea diffuses from patient’s
blood into dialysis fluid through
cellophane filter
blood without urea will return to
patient through his vein
dialysis fluid flows in direction
opposite to that of blood flow to
increase the efficiency of diffusion of
urea into dialysis fluid other than using artificial kidney,
kidney transplant is another possible
method but only few people are
willing to donate their kidneys after
death
Excretion in HumanExcretion in Human metabolism are reactions take place
inside cells of an organism
most of the by-products of
metabolism are toxic and should be
removed once they are produced by
excretion
there are four major excretory
organs in human body: Lungs,
Kidneys, Liver and Skin
Excretory Organs - Excretory Organs - LungsLungs excrete carbon dioxide which is
produced by cells during respiration
and is carried by blood to lungs
carbon dioxide diffuses out of the
blood capillaries surrounding the
lungs and passes into the air sac
it is excreted when people breathe
out. Water is lost during respiration,
too
Excretory Organs - Excretory Organs - KidneysKidneys
deamination (break down of excess
amino acids) in liver forms urea and
uric acid
urea and uric acid are called
nitrogenous wastes
the wastes are carried by blood to
kidneys which excrete them from the
body in form of urine
Excretory Organs - Excretory Organs - LiverLiver old red blood cells are destroyed in
liver and haemoglobin are
released
haemoglobin will turned into bile
and excreted with bile into small
intestine
finally, haemoglobin will expel with
faeces and leave the body
Excretory Organs - SkinExcretory Organs - Skin skin is the largest excretory organ
in human body
it carries out its function through
sweating
sweat contains water, salts and
urea, and sweating can excrete
these substances from the body
Plants CellPlants Cell
cell wall cytoplasm
cell membrane
vacuole
cell wall freely permeable so it lets
most of molecules to go
through
osmosis does not occur
cell membrane
beneath cell wall
selectively permeable
Water Relations of Plant Water Relations of Plant - Turgor - Turgor
plant cell put in distilled water
plant cell contains solutes
water potential lower than pure
water
net water movement into the cell by osmosis
vacuole and cytoplasm swells
cell wall is rigid and strong, cell bursting is
prevented
turgor is present because: turgor
hydrostatic pressure develops inside the cell
cytoplasm is pushed against cell wall
tendency of the cell to give out water increases
water potential increases When water potential of cell
= water potential of waterTurgor occur (cell cannot take in
any water) the cell is turgid
Water Relations of Plant Water Relations of Plant - Plasmolysis - Plasmolysis
plant cell in concentrated
solution
net water movement out of the cell by
osmosis
vacuole and cytoplasm shrink
cytoplasm is torn away from cell wall
flaccid
The whole phenomenon is called plasmolysis and
cell is plasmolysed
Turgidity of Plant CellsTurgidity of Plant Cells
turgid cell(in hypotonic sol.)
plasmolysed cell(in hypertonic sol)
cell wall
cytoplasm
vacuoleenlarged
solution here is the same as the external solution
cell membrane separated from cell wall vacuole
very small
Cells in Different Cells in Different SolutionsSolutions
Solution Concentration
animal cells(e.g. RBC)
plant cells
hypotonic hypertonic
haemolysis
turgid
shrink
plasmolysis(cell is flaccid)
To Investigate the Effects To Investigate the Effects of Sucrose Solution and of Sucrose Solution and Tap Water on Epidermal Tap Water on Epidermal Cells of Red Onion Scale Cells of Red Onion Scale Leaf or Leaf or Rhoeo Discolor Rhoeo Discolor
LeafLeaf
fleshy scale leaf of red onion
bulb forceps
filter paper
epidermis
What do you observe when the epidermal strip is placed in the concentrated sucrose solution ?Ans: The coloured cytoplasm shrinks.
Explain your observation.Ans: When the piece of epidermis is placed in
concentrated solution, cells lose water by osmosis as the cells have a higher water potential than the sugar solution.
fleshy scale leaf of red onion
bulb forceps
filter paper
epidermis
What has happened to the cells in tap water ?Ans: The coloured cytoplasm swells and cells
become turgid.
fleshy scale leaf of red onion
bulb forceps
filter paper
epidermis
Explain your answer.Ans: When the piece of epidermis is placed in
tap water, cells gain water by osmosis as the surrounding tap water has a higher water potential than the cells.
fleshy scale leaf of red onion
bulb forceps
filter paper
epidermis
Effects of Effects of Concentrated Concentrated
Sucrose Solution and Sucrose Solution and Tap Water on Raw Tap Water on Raw
Potato StripsPotato Strips
What has happened to the potato strips ?Ans: Potato strip A increases in both weight
and length while potato strip B decreases in both weight and length.
petri dish
water20% surcose solution
raw potato strips
A B
Explain your answer.Ans: For potato strip A, it gains water by
osmosis so both of its weight and length increase but for potato strip B, it loses water by osmosis so its weight and length decrease.
petri dish
water20% surcose solution
raw potato strips
A B
TranspirationTranspiration
an evaporation of water in form of
water vapour from the surface of
plant to atmosphere
it mainly takes place in leaves
where there are some openings
called stomata
more water loses from the lower
surface of the leaf than the upper
one as more stomata present on
the lower surface it also happens in lenticels and
cuticle
Transpiration in LeavesTranspiration in Leaves
a thin film of moisture is covered
with each mesophyll cell
the moisture evaporates from
mesophyll cells into intercellular
spaces and diffuses out of stomata
into atmosphere
water potential of cells losing water
decreases so they draw water from
deeper cells in the leaf by osmosis.
This in turn, draws water in xylem
vessels into leaf to replace the loss
Experiment to Show Experiment to Show that Water is Given that Water is Given
Off During Off During TranspirationTranspiration
polythene bag
What do you observe in the polythene bags ?Ans: The one enclosing plant A becomes
misty while nothing can be noticed in the one enclosing plant B.
How can you show that it is water ?Ans: We can use anhydrous cobalt chloride
paper to test it. It will turn the paper from blue to pink or we can use anhydrous copper sulphate. Water will turn it from white to blue.
polythene bag
What conclusions can you draw from the results ?Ans: We can conclude that a leafy shoot gives
off water during transpiration.
polythene bag
To Measure the Rate To Measure the Rate of Transpiration by of Transpiration by
Using a Simple Using a Simple PotometerPotometer
What are the environmental conditions under which transpiration occurs quickly ?Ans: It is under dry, warm and windy
conditions.
air/water meniscus
graduated capillary tube
reservoir
leafy shoot
tap
Does this apparatus give you an accurate measurement of the rate of transpiration ?Ans: No. It is because it only measures the rate
of water uptake by the leafy shoot … Ans: In addition, it is too small to fit the whole
root system and this may affect the rate of water uptake.
air/water meniscus
graduated capillary tube
reservoir
leafy shoot
tap
Sometimes you may introduce an air bubble into the capillary tube. State the advantage of this method.Ans: Movement of the air bubble is easier to
observe than that of air/water meniscus.
air/water meniscus
graduated capillary tube
reservoir
leafy shoot
tap
Sometimes you may introduce an air bubble into the capillary tube. State the disadvantage of this method.Ans: Friction between the capillary wall and
the bubble may affects the movement of bubble.
air/water meniscus
graduated capillary tube
reservoir
leafy shoot
tap
Environmental Factors Environmental Factors Affecting the Rate of Affecting the Rate of
TranspirationTranspirationThere are five environmental factors
which affect the rate of transpiration.
They are:
(I) Light Intensity
(II) Temperature
(III) Humidity
(IV) Wind Speed
(V) Water Supply
Light IntensityLight Intensity
stomata open in light, so plants can
get enough carbon dioxide from
atmosphere for carrying out
photosynthesis
light will increase temperature so
increases the rate of transpiration
TemperatureTemperature
temperatur
erelative humidity of air outside
leaf
rate of evaporation of
water from mesophyll cells
rate of diffusion of water vapour from intercellular space in leaf to outside
HumidityHumidity
humidity
outside
rate of
transpiration
it makes the diffusion gradient of
water vapour from moist
intercellular space of a leaf to the
external atmosphere steeper
Wind Speed & Water SupplyWind Speed & Water Supplywind
blows
water vapour around
the leaf sweeps
awaytranspiration
rateINCREASES
lack of water
soil dries, plant wilts
and stomata
close
transpiration
rateDECREAS
ES
StomataStomata stomata are pores in the epidermis
which gaseous exchange takes
place during photosynthesis (or
respiration)
find mainly in lower epidermis of
dicotyledonous leaves and stems
Guard CellsGuard Cells each stomata is surrounded
by two guard cells
which possess
chloroplasts
its inner wall is thicker than
outer wall
it is kidney-shaped
guard cell
stomata
Distribution of Stomata Distribution of Stomata in Leaves in Leaves
normal plants
mainly on the lower surface of leaves
floating plants
mainly on the upper surface
leaves may also have air sacs to keep them afloat so they can carry out gaseous exchange
submerged aquatic plants
no stomata (not required since gaseous
exchange can be carried out by
diffusion though the leave surface)
no cuticle (the primary function of
cuticle is to prevent excess water
transpiration which is not present in
aquatic plants)
Experiment to Experiment to Investigate Stomatal Investigate Stomatal Distribution in a Leaf Distribution in a Leaf
by Using Cobalt by Using Cobalt Chloride PaperChloride Paper
Which piece of cobalt chloride paper turns pink first? Ans: The piece of cobalt chloride paper
attached to the lower epidermis of the leaf turns pink first.
cobalt chloride paper
sellotape
Explain your answer.
Ans: It is because more stomata are present in the lower epidermis.
cobalt chloride paper
sellotape
Why is it important to handle cobalt chloride paper with forceps? Ans: It is because there is moisture on human
fingers so the paper may turn pink before sticking onto the surfaces of leaves.
cobalt chloride paper
sellotape
To Observe the To Observe the Release of Air Release of Air
Bubbles from Leaves Bubbles from Leaves placed in Hot Waterplaced in Hot Water
Which surface has more air bubbles coming off?Ans: There are more air bubbles appear on
the lower surface of the leaf.
forceps
hot water
leaf
Where does the air come from?Ans: It is in the air spaces between the
mesophyll cells in leaf which expands on heating and passes out through stomata of the leaf.
forceps
hot water
leaf
What does the result show?Ans: The result shows that more stomata are
present on the lower epidermis of the leaf.
forceps
hot water
leaf
Structure of RootStructure of RootRoot Cap
a protective layer at the very tip of root
to protect the delicate cells of root from being damaged as the root grows down through the soil
Epidermis
cover the rest of root
absence of cuticle so water can enter
Growing Point
behind root cap
cells are capable of active division
Region of Elongation
more elongated than cells in growing
point and have large vacuoles
Region of Root Hair
little way behind root tip
root hair are thin-walled extension
of epidermal cells of root
increase surface area for uptake of
water and mineral salts
Vascular Tissue
further from the tip of root
contain xylem and phloem
xylem transport absorbed water to
every part of plant
Absorption of Soil Water Absorption of Soil Water by Root Hairs by Root Hairs
soil water is a dilute solution of salts
which is more dilute than cell sap and
cytoplasm in root hair
water will pass by osmosis into root hair
through cell wall and cell membrane
transpiration occur in leaves so water is continuously removed
from the plant
flow of water through plant: transpiration stream tension produced to draw up water:
transpiration pull
reduction of effective pressure at the top of xylem vessel
water flows upwards from roots continuously
Transverse Transport Transverse Transport of Water to of Water to
Xylem Xylem epidermal cells gain water by
osmosis
NOTE: some water may travel inwards along or between cell walls without entering cytoplasm or vacuole of each cortical cell
cytoplasm and cell sap have higher water
potential than neighbouring cortical cells
water travels by osmosis
inwards from cell to cell
~ ~ End End ~~