Index
Cell Structure
1
Movement of molecules
Enzymes
12
19
- The Characteristics of Living Organisms
28
- Biodiversity
- Biotechnology & Genetic Engineering
35
- Nutrients & Diet
52
-Plant nutrition "Photosynthesis"
60
-Transport in plants
74
-Sexual reproduction in flowering plant
83
-Plant Sensitivity
93
45
CHAPTER 1
1
THE CELL
The cell is the structural and functional unit of all living organisms
Cell part
Structure
cell wall
Made of cellulose
(non-living)
Function
Inelastic, gives the cell its shape
Protects the cell from bursting
Fully permeable
Partially permeable
(controls entry & exit of substances in the cell)
Barrier; separating inside the cell from external
environment
cell membrane
Thin layer
made of protein and fat
cytoplasm
Clear jelly
Made of water (70%) and
dissolved substances
Chloroplasts
Disc like structure containing
chlorophyll
Absorbs sunlight to perform photosynthesis
Stores starch grains
Sap Vacuoles
Stores cell sap
filled with water
It keeps the cell turgid by being filled with
water to support the plant
Nucleus
Has chromosomes
Made of DNA
Mitochondria
rod like structures
found in all living cells except
bacteria(prokaryotes).
Rough
endoplasmic
reticulum
Ribosomes
Network of membranes
ribosomes are attached
Found in all types of cells.
They are tiny organelles
It is the site of chemical reactions in the cell
It contains all cell organelles
Controls cell activities
Carries genetic information
Aerobic respiration and energy release.
Muscle cells, liver cells, sperm cells and nerve
cells need to have many mitochondria to release a
lot of energy
Protein Synthesis by its ribosomes
Protein synthesis (check in genetics).
2
animal cell
nucleus
cell membrane
mitochondria
cytoplasm
10 µm
1
mm)
(1 µm =
1000
Compare between an animal cell and a plant cell:
P.O.C
Plant cell
Animal cell
Call wall
Present
Absent
Chloroplasts
Present
Absent
Sap vacuole
Present
Absent
Food store
Starch grains
Glycogen granules
Animal cell is also irregular in shape but plant cell is regular in shape
2-Similarities:
Both have cell membrane, cytoplasm, nucleus, mitochondria ribosomes and
rough endoplasmic reticulum.
3
Modification in cell structure for specific function
TS through a
red blood cell
1- Red blood cell:
cell surface membrane
Function → transports oxygen from lung to all body cells
Adaptations "structure and function"
haemoglobin solution in
cytoplasm (no nucleus,
mitochondria or ER)
1- Biconcave disc → to increase surface area to absorb
more oxygen.
2- Has hemoglobin → combines with oxygen giving
oxyhemoglobin.
7 μm
3- No nucleus → to give more space, to carry more hemoglobin,
they are unable to divide and lives a short time (120-days).
4- Small, and has elastic membrane → to be able to squeeze itself into narrow blood capillaries
2- Muscle cell:
Function → contract for movement.
Adaptation → Has contractile filaments in its cytoplasm to contract to help movement.
3- Root hair cell:
Function → absorbs water and mineral ions from soil.
Adaptation:
finger like projections → to increase surface area to absorb more water & mineral ions.
Thin cell wall → to shorten distance for faster diffusion
Many mitochondria → to release more energy for active transport
thin, permeable,
cellulose cell wall
partially
permeable
cell surface
membrane
dilute soil solution
"higher water
potential"
more concentrated
solution in cytoplasm
and vacuole
"lower water potential"
osmosis –
water
diffusing
down the
water
potential
gradient
4
5-Xylem vessel
Function → Transports water and salts from Source (root) to Sink (leaves.)
Adaptation
continuous hollow tube → nonliving ( no cell membrane, no cytoplasm no nucleus)
no end walls → to allow transportation of water and salts from roots to leaves upward
has lignin → which is impermeable to water → to support plant.
→ Thick → to avoid collapse
has pits → to allow lateral movement of water.
thick lignified
secondary wall
lumen
empty lumen
no living contents
pit
simple pit
no intercellular air
spaces present
Source of water &salts:roots sink of water and salts: leaves
5- Ciliated epithelial cell
Function → Found in trachea, bronchus & bronchioles
Adaptations
Has cilia → to beat upward to push mucus with trapped
dust and bacteria out of the lungs to to the throat → to
purify air entering the lungs.
6- Intestinal epithelial cell with microvilli
inside of tubule
Function → Found in small intestine.
Adaptation
Has microvilli → to increase the surface area to
absorb more digested food.
Many mitochondria → to release more energy for
active transport.
movement
of glucose
nucleus
mitochondria
blood
5
Microscopic
structure
Nutrition
BACTERIA
FUNGI
Prokaryotic cell
- unicellular:
yeast
- multicellular:
Unicellular
small and can be
only seen by the
light microscope
Murein cell wall
Has cell membrane
No nucleus, only a
circular DNA free
in the cytoplasm
Has glycogen
granules
Has no vacuole
Some has capsule
for protection
Some has flagellum
for movement
Reproduction
Asexual
reproduction by
fission
mushroom, Penicillium
Small and can be
only seen by light
microscope
Chitin cell wall
Has cell membrane
Has nucleus or
nuclei with
DNA inside
Has glycogen in
granules
Has vacuoles
VIRUSES
Not a cell
no nucleus,
no cell wall
no cytoplasm no
cell membrane
no organelles
Smallest, only
seen by electron
microscope
None
None
None
None
None
None
None
None
None
Asexual reproduction
by spore formation or
budding
Only in host cell. A
virus can direct the
host cell to make new
copies for its nucleic
material and the
protein coat.
6
Fungus
Prokaryotic cells {Bacteria}
Unicellular Yeast Cell
cell wall
cell
membrane
nucleus
cytoplasm
mitochondrion
Binary Fission
7
Multicellular Fungus
Virus
Viral Replication
8
Practical work
How to observe a plant cell under the microscope?
1- Cut a small piece of onion.
2- Get off the inner epidermis using forceps.
3- Get a slide and put a drop of water on its surface.
4- Cover the slide gently with a cover slip
5- Observe the slide under the microscope.
How to observe an animal cell?
12345-
Cut a very small piece of liver.
Put it on a slide with a drop of water.
Cover it with a cover slip.
Gently tap on it to spread the liver.
Observe under the microscope.
Magnification
Exercises given to the students.
Measurements should be in mm
or micrometer.
1cm = 10mm
1mm = 1000µm
Magnification = Image length
Actual length
Levels of organization
1-Tissue: group of cells that are similar in structure and function.
2-Organ: group of different tissues grouped together-forming a structure with specific functions.
3-Organ system: group of different organs with related functions.
9
e�deLmis
fi.�of water
cortex
;.,-P
�--;:
·-
f watu
Xylem�-!NII
Vasc�ar"'ff"""�
cambium
Endodermis
Pericycle -,--�A
Casparian strip
endodermis
xylem
pericyde
Venules
Tissue capillaries
Pulmonary artery
LUNG$ ____
Pulmonary vein
----Artery
Vein ___--,
------Urethra
Venules
Tissue capillaries
Arterioles
--- Arterial circulation
___ Venous circulation
10
brain
oesophagus
trachea
lungs
heart
kidneys
(behind gut)
skin
liver
pancreas
stomach
intestine
bladder
ovaries (in female)
testes (in male)
Some of the main organs of the human body.
11
CHAPTER 2
Movement of Molecules
12
Diffusion
Active transport
random movement
of water molecules
due to their kinetic
energy
Osmosis
partially larger sucrose molecules
permeable cannot pass through
membrane
membrane
water molecules
attracted to
sucrose
molecules
water
It is the net movement of
molecules / ions from the
region higher
concentration to region of
lower concentration down
concentration gradient
due to random
movement. It is a passive
process; needs no energy
and depends on the
kinetic energy of particles
sucrose
solution
arrows show amount of water
movement in each direction
It is the movement of
It is the net movement of water
molecules from the region of
molecules from the region of
lower concentration to the
higher water potential to the
region of higher
region of lower water potential
concentration through
down water potential gradient
specific protein carriers
through a partially permeable
changing their shape,
membrane. It is a passive
against concentration
process.
gradient using energy from
respiration. It is an active
process.
Importance
Importance
Importance
1- absorption of salts
(minerals) from soil by root
hair cells.
2- absorption of digested
food by villi in the small
intestine.
3- gas exchange in plant
through stomata in leaves
and in animals through
alveoli
Does not consume energy
1- Active uptake of ions by
root hair cell.
2- Active uptake of
glucose by epithelial
cells of villi and kidney
tubules
1- absorption of water from the
soil by the root hair cell.
2-movement of water across the
root to the xylem vessel in the
root centre.
3- supports the plants by
filling the sap vacuoles and
making them turgid.
consumes energy
does not consume energy
13
Distinguish between diffusion and active transport:
Diffusion
Active transport
down concentration gradient
against concentration gradient
Does not need energy
Needs energy
Does not need a cell membrane
Needs a cell membrane
Factors affecting rate of diffusion:
1- Concentration gradient; the higher the concentration gradient, the faster the rate of diffusion
2- Temperature; the higher the temperature, the faster the rate of diffusion
3- Surface area; the larger the SA, the faster the rate of diffusion
4- Size of molecules; the larger the molecules the slower the diffusion
5- Thickness of the membrane; the thicker the membrane the slower the diffusion
14
The effect of osmosis on animal cell
In dilute solution
(higher water potential)
In isotonic solution
(same water potential)
In concentrated solution
(lower water potential)
Cells swell and may burst
as water moves by osmosis
from region of higher
water potential (outer
solution) to the region of
lower water potential
(inside the cell) through
partially permeable
membrane
No change in size as water
potential inside cell =
water potential outside,
water gained by the cell
equals water lost ; net
movement of water is zero
Cells shrink as water moves
by osmosis from the region
of its higher water potential
(inside the cell) to the
region of lower water
potential (outer solution)
through partially permeable
membrane.
15
The effect of osmosis on plant cell
In dilute solution (turgidity)
In concentrated solution
Plant cells become turgid as there is
as a cell wall that can withstand the
inner pressure due to turgidity. Cell
wall is inelastic.
Cells become flaccid, &
plasmolysed
Water moves by osmosis from the
region of higher water potential
(outer solution) to the region of lower
water potential (sap vacuole) through
a partially permeable membrane
Water moves by osmosis from the
region of higher water potential (sap
vacuole) to the region of lower water
potential (outer solution) through a
partially permeable membrane
16
Features of plasmolysis:
1- Sap vacuole & cytoplasm shrinks
2- Cell membrane pulled away from the cell wall
3- A space between the cell membrane and the cell wall containing the outer solution
(as the cell wall is fully permeable)
4- No change in the cell wall
Practical work
Cell Membrane / Dialysis tubing / Visking tubing → Partially permeable membrane →
allow molecules to pass according to size.
Small: Pass
Glucose, amino acids, fatty acids, glycerol, water, iodine
Large: Don’t pass
Starch, proteins, fats, sucrose, maltose.
17
concentrated ---t�•
sugar solution
10g mass
potato strip A
support
10g mass
support
potato strip B
concentrated
----+� sugar
solution
potato strip A
support
support
potato stri�
An experiment was carried out to investigate the effect of different concentrations of
sucrose solution on the length of potato strips.
Five test-tubes were set up, each containing a different concentration of sucrose solution.
Another tube was set up containing the same volume of distilled water.
A strip of potato tissue was placed in each tube. The strips were of equal size
Fig. 2
These strips were completely covered by the solutions and were left in the tubes for 30
minutes. The potato strips were removed and measured. The results are shown in Table 2
Table 2
concentration of
sucrose solution
–3
(mol dm )
initial length
(mm)
final length
(mm)
0
0.2
0.4
0.6
0.8
1.0
70
70
70
70
70
70
73.0
71.5
69.0
67.0
66.0
64.5
change in length
(mm)
18
CHAPTER 3
Enzymes
19
Definitions:
• Enzymes: are protein that act as biological catalysts, they are specific in their action.
• Biological catalysts: they are chemicals made in the body that speed up the rate of chemical
reactions without being used up or chemically changed.
• Substrate: it is a substance upon which an enzyme works and fit like a lock & key.
Examples:
amylase
Starch + water → maltose
protease
Protein + water → amino acids
lipase
Fats/oil (or lipids) + water
→ fatty acids + glycerol
Substrate
Starch
Protein
Fats/oil
Product
Maltose
Amino acids
Fatty acids & glycerol
Enzyme
Amylase
Protease
Lipase
20
Role of enzymes in chemical reactions:
Enzymes act as a catalyst and speed up the chemical reaction.
Enzymes are specific in their action as each enzyme has a specific shape of active site, only
complementary to its substrate substrate fits and binds to the active site like lock & key,
forming enzyme-substrate complex products no longer fit to the active site and will be
released & enzymes can be reused.
Enzymes lower the activation energy
Factors affecting the enzyme activity:
1-Temperature:
Rate of
reaction
enzyme
becoming
denatured
0
optimum
temperature
10
20
30
40
50
Temperature / °C
60
enzyme
completely
denatured
Describe and explain the graph shown:
Describe: On increasing temperature from 0-60 oC, enzyme activity increases then
decreases, no activity above 60 oC, Peak activity of 100 au at 37 oC. steepest decrease in
activity above 37 oC
Explain: As on increasing temperature KE of enzyme & substrate molecules increases,
more chance of successful collisions, more enzyme-substrate complex formation.
37 oC is the optimum temperature where enzymes worked best,
Above 37 oC, enzymes are getting denatured, changing shape of active site, so no longer
complementary to substrate, enzymes lost their function, fully denatured at 60 oC.
21
2- Effect of pH:
pepsin (a protease
in the stomach)
Rate of
reaction
At extreme
pHs the
enzyme is
denatured
and
inactivated.
2
4
6
pH
8
10
Optimum pH
pH
Describe and explain effect of pH on Trypsin:
Describe: No activity below pH 5.5, & above 10, on increasing pH, from 5.5 to
10, enzyme activity increases then decreases, Peak activity at pH 7.6 of 100 au.
Explain: pH 7.6 is the optimum pH, where enzymes worked best, as enzymes had
their proper shape of active site, more chance of successful collisions with substrate,
more enzyme substrate complex formation. Changing pH denatures enzymes,
changing their shape of active site, so active site is no longer complementary to
substrate, enzymes lost their function. Fully denatured at pH 5.5, & 10
22
The role of enzymes in seed germination
1- The absorption of water activates the enzymes in the seed.
2- The amylase enzyme:
- Breaks down stored starch into simple soluble sugar.
- The soluble sugar is translocated through the phloem to the embryo to be broken down for
respiration and energy release, also used to make cellulose to form cell wall.
3- The protease enzyme:
- Breaks down protein into soluble amino acids.
- The soluble amino acids is transported through the phloem to the embryo to be used
by other enzymes to build protein needed for growth.
water uptake initiates
germination by
activating enzymes
embryo
amylase
starch
protein
protease
maltose
Amino acid
endosperm tissue
containing starch
reserves
23
Practical work: Food test
a- Iodine test for starch:
1.
2.
3.
4.
Crush food with water
Take a sample in attest tube.
Add drops of iodine solution.
The color changes from yellow brown to blue
black showing the presence of starch.
b- Benedicts test for reducing sugar(glucose):
1.
2.
3.
4.
As before
As before
Add Benedicts solution and shake well.
Put the tube in a boiling water bath (to avoid
splashing of the food sample)
5. observe the change in color from blue to
brick red showing the presence of glucose.
c- Biuret test for proteins:
1.
2.
3.
4.
As before
As before
Add Biuret reagent
observe the change in color from blue to
mauve (or violet, lilac, purple) showing the
presence of protein.
d- Ethanol emulsion test for fat:
1. Crush food sample with ethanol
(If liquid as oil, then dissolve in ethanol)
2. As before
3. Add drop few drops of water.
4. Observe color change from clear to milky showing
the presence of fat.
e- DCPIP test for vitamin C:
DCPIP is blue in colour and decolorises itself as a
result of dropping vitamin C. the number of drops or
volume of a fruit used to decolorise it determines the
concentration of vitamin C in this fruit.
N.B. If the food sample is liquid then don’t crush food.
24
Describe an experiment to show effect of temperature on the activity of amylase enz.
1. Get three test tubes with equal volumes & concentrations of starch solutions, three other test
tubes with equal volumes & concentrations of amylase enzyme.
2. Add a buffer to keep pH constant
3. Set three water baths at 10, 30, & 50 °C, put a test tube of amylase & starch in each.
4. After 5 minutes, for temperature equilibration, add amylase to starch in each water bath.
5. Prepare a white tile with drops of iodine solution, & every minute take a sample from each
water bath to test for starch.
6. Record time when there is no color change.
7. Repeat experiment 2 more times & take average to be more reliable.
(6 marks)
transfer sample
every 30 seconds
spots of iodine
solution
water
amylase
solution
starch
suspension
starch and amylase
mixture
spotting tile
Temperature / °C
Time /
min
20
30
40
50
60
0.0
blue-black
blue-black
blue-black
blue-black
blue-black
0.5
blue-black
blue-black
brown
blue-black
blue-black
1.0
blue-black
blue-black
yellow
blue-black
blue-black
1.5
blue-black
blue-black
yellow
blue-black
blue-black
2.0
blue-black
blue-black
yellow
brown
blue-black
2.5
blue-black
blue-black
yellow
brown
blue-black
3.0
blue-black
blue-black
yellow
brown
blue-black
3.5
blue-black
blue-black
yellow
yellow
blue-black
4.0
blue-black
blue-black
yellow
yellow
blue-black
4.5
blue-black
blue-black
yellow
yellow
blue-black
5.0
blue-black
blue-black
yellow
yellow
blue-black
5.5
blue-black
blue-black
yellow
yellow
blue-black
6.0
blue-black
brown
yellow
yellow
blue-black
6.5
blue-black
brown
yellow
yellow
blue-black
7.0
blue-black
yellow
yellow
yellow
blue-black
7.5
blue-black
yellow
yellow
yellow
brown
8.0
blue-black
yellow
yellow
yellow
brown
8.5
brown
yellow
yellow
yellow
yellow
25
Describe an experiment to show the effect of pH on the activity of catalase enzyme
1. Get filter papers of the same size, & dip into potato extract for the same time
2. Get three test tubes with equal volume & concentration of H2O2
3. To the first add acidic buffer pH 5, to the second neutral buffer, pH 7, to the third,
alkaline buffer. pH 9, of equal volumes.
4. Put the three test tubes in a water bath at 35 °C, to keep temperature constant & optimum
5. Get a filter paper & sink in the first test tube, use a stopwatch to record the time it
takes to rise, repeat this for the other test tubes.
6. Repeat experiment 2 more times & take average to be more reliable.
7. Make control using boiled potatoes to compare with results.
(6marks)
Control:
Why do we need a control in all our experiment?
To compare with results, to show that enzyme X caused result Y
How to make a control?
By repeating the experiment, the same way and under the same conditions and replacing
the factor of investigation …………
- If the factor of investigation is liquid replace it with distilled water of the same volume
(sometimes boiled enzyme is used instead of an enzyme).
- If the factor of investigation is solid replace it with glass beads (sometimes boiled seeds
are used instead of germinating seeds).
26
Describe an investigation to estimate the energy found in food:
This experiment is not accurate… Why?
1- Much of the heat produced by burning food is lost in the
surrounding air.
2- The needle gains an amount of this heat and is not
recorded by the thermometer.
3- Incomplete combustion of food.
water
thermometer
burning food held
on mounted needle
27
CHAPTER 4
The Characteristics of Living Organisms
28
All living organisms must have the following characteristics
1- Nutrition
2- Respiration
3- Excretion
5- Growth
6- Sensitivity
7- Movement
4- Reproduction
1- Nutrition
It is the obtaining of organic substances and mineral ions to get energy and raw
materials for growth and tissue repair.
Autotrophic nutrition
Heterotrophic nutrition
(producers)
(consumers)
1- organisms make their own organic 1- organisms obtain their food from
food form inorganic materials
other organisms
2- their source of carbon is inorganic 2- their source of carbon is organic
(CO2)
3- they have chlorophyll to trap sun 3- they have no chlorophyll and do
light for photosynthesis
not perform photosynthesis
Heterotrophic nutrition:
1- organisms that ingest, digest and egest:
a- Herbivores………only eat plant e.g. horses.
b- Carnivores………only eat meat e.g. lions.
c- Omnivores………only eat plant & meat e.g. human
2- Decomposition:
Decomposers (bacteria of decay and fungi) feed on dead and decayed
remains of animals and plants in a liquid form. They do this by secreting
extra cellular enzymes that digest large insoluble complex molecules into
small soluble ones (liquid) and absorb them into their body by diffusion &
active transport.
Role: 1.
2.
29
2- Respiration
It is the release of energy from breaking down carbohydrates inside the living cells;
it may be aerobic in presence of oxygen or anaerobic (in absence of oxygen).
Types of respiration
Aerobic respiration
Anaerobic respiration
Glucose + oxygen → carbon dioxide + water
a- In yeast:
glucose → ethanol + carbon dioxide + energy
+ energy
b- In bacteria or in muscle cells:
glucose → lactic acid + energy
releases more energy
complete breakdown of food to CO2 and
H2O
takes place in mitochondria
releases less energy
Incomplete break down of food, lactic acid
still contains energy
takes place in the cytoplasm
b- Similarities; they both break down food and release energy and takes place inside the cell.
Fate of energy released
The energy released will be used, stored as chemical energy, lost as heat energy.
The uses of the released energy:
1-growth and tissue repair
2-Performing all chemical reactions in the cell
3-Muscle contraction for movement, heartbeat, breathing, peristalsis
4-Active transport in roots, intestine and in kidney.
5-Transmission of nerve impulses
6-Heat energy to maintaining constant body temperature in mammals.
30
The disadvantages of anaerobic respiration in animals compared
to aerobic respiration
1- Releases less energy
2- Gives lactic acid (poisonous) which lead to Oxygen Debt:
During exercise, O2 supply is insufficient → muscles performed anaerobic
respiration to release energy, but also produced lactic acid → after exercise,
lactic acid is taken to the liver to be broken down to CO2 & H2O → this needs
more O2 → this is the O2 debt
rest
exercise
oxygen deficit
2.5
Oxygen uptake / dm3 min–1
recovery
2.0
post-exercise
oxygen uptake
(oxygen debt)
1.5
1.0
0.5
0
0
1
2
3
4
5
6
7
8
Time / min
9
10
11
12
13
30
31
Practical work
How to find the rate of respiration in yeast?
By counting the number of bubbles per minute
Is this accurate, & why?
No; as:
1. Bubbles have different size
2. Miscounting bubbles
How to make it accurate?
By measuring the volume of co2 gas produced per minute, using a gas
syringe or graduated measuring cylinder
Respirometer
32
HCO3 (red) pH indicator
CO2 is acidic (low pH)
If CO2 increased → colour becomes yellow, if decreased → colour becomes purple,
if normal → colour remains red
3- Movement:
4- Reproduction:
Action by an organism or part of an organism
causing a change of position or place.
Ability to produce offspring, may
be sexual or asexual.
a- Sexual reproduction:
Gametes: they are reproductive cells, made by meiosis, in reproductive organs, their nuclei
are haploid (n).
Fertilization: It is the fusion between a male gamete and a female gamete nuclei
(haploid) to give a zygote (diploid).
Male gametes
Female gametes
Smaller in size
Bigger in size
Has a little cytoplasm and no food store. Has much cytoplasm and food store.
Has an acrosome full of enzymes.
Has a jelly coat that changes after fertilization.
Has tail to moves to female gamete
Has no tail and do not move
Large in numbers
Small in numbers
1- Why are mitochondria found in large numbers in sperm?
To release energy for their swimming.
33
formation of new potato tubers
Sexual reproduction
Needs two parents
Asexual reproduction
Needs only one parent
Genetically identical offspring, to each
other and to parents
Faster
Gives large number of offspring
Offspring show variation
Slower
Gives fewer offspring
Needs presence of male and
female reproductive system
Does not need
Advantages and disadvantages of sexual and asexual reproduction
Advantages
Asexual reproduction
Sexual reproduction
Offspring shows variation, new better
forms, adapt more to changing environment,
survive more, reproduce more, pass alleles
of good features to offspring, increasing in
frequency
A genetic disease in one parent does not
necessarily ass to the offspring
Offspring retains alleles of good features
from parents, so more chance to survive in
their environment
only one parent needed, so more chance of
species to continue
Needs less energy
rapid
Disadvantages
Sexual reproduction
Two parents needed, a complex
process
Slow
Asexual reproduction
offspring shows no variations → no
new better form adapt less to changing
environment → survive less, reproduce
less → may become extinct
needs a lot of energy
Offspring doesn't retains alleles of good A disease in the parent will always
pass to the offspring.
features from parents
34
CHAPTER 5
35
Classification of living organisms before DNA:
study → similarities & differences in morphology "appearance, shape" as presence
or absence of wings
study → similarities & differences in, anatomy "internal structure of organisms" as
skeleton / organs /ones /teeth.
The five main kingdoms:
1) Prokaryotes (bacteria)
2) Protoctist (protozoa and algae)
3) Fungae (yeast and molds)
4) Plant (ferns, & flowering plants)
5) Animalia (arthropods, vertebrates)
kingdom is divided into phylum, classes, order, family, genus and species.
Species:
A group of similar living organisms that can interbreed & produce fertile offspring.
The binomial nomenclature (two-names):
It is a method of giving every organism two Latin names; the first is the genus
name with first letter in capital, followed by the species name. Both names are
underlined or printed in italics.
Example:
Genus
species name
Musca
domestica
Name two species that are related to each other, explain your results.
36
Structure of the DNA:
Chromosomes are found inside the nucleus. They are made of DNA, it contains
four different bases called A, C, T, & G.
DNA is a double helix made of two strands held together by many hydrogen
bonds according to base pairing A with T and C with G.
DNA differs from an organism to another according to their base sequence →
each organism has a specific sequence of bases which identifies him →the more
similar the base sequence the more the organisms are closely related to each other.
The DNA carries the gene, which is a length of DNA determined by a specific
sequence of bases → & codes for a specific protein which makes organisms
look different .
What makes proteins vary?
Proteins are built up from amino acids. There are twenty different amino acids.
Their sequence makes the protein molecules differ from each other. The base
sequence in the DNA of a gene is translated into a sequence of the amino acids by
ribosomes found in the cytoplasm and result in the formation of a specific protein.
Using DNA to help with classification of species:
The evolution of different species from a common ancestor comes due to natural
selection. DNA is used to prove evolutionary relationships→ to show if the
organisms share a more recent ancestor (they are more closely related) by having
more similar genes in DNA between them or a distant ancestor by having less
similar genes.
37
I- Plant kingdom
Phylum ferns and phylum flowering plants
Phylum flowering plant
P .D.C
Seeds
Leaf
Class Monocotyledonous
Class Dicotyledonous
Has one cotyledon
Has two cotyledons
1- Narrow & Long
1- Broad
2- Has parallel veins
2- Has branching veins.
3- Has stomata on upper & lower 3- Has stomata on lower epidermis
only
epidermis
1- Flower parts in threes
Flower
2- not differentiated into sepals
and petals
1- Flower parts in fours or fives
2- Differentiated into sepals & petals
Root
Fibrous
Tapering
e.g.
Grasses & cereals
Lupin & bean
Ferns:
Ferns have leaves called fronds → they don't
produce flowers → they reproduce by spores
found on the lowers surface of fronds.
38
I- Animal Kingdom
1- Phylum Arthropods (Invertebrates)
General characteristics:
1- Body is segmented (for flexibility)
2- Jointed legs (for movement)
3- Hard exoskeleton (to reduce water loss)
3- Invertebrates (no back bone)
P.O.C
1- the body is
divided into:
2- Jointed legs
movement
3- Antennae:
for sensation
4- Eyes;
for sensation
5- Wings:
6- Other
adaptations:
Insects
Three segments;
head, thorax &
abdomen
Three pairs of
jointed legs
Arachnids
Two segments;
cephalothorax
& abdomen
Four pairs of
jointed legs
One pair
Compound; to
sense light and
movement
Two pairs, or one
pair, or none
mouth parts: e.g.
Some arachnids
- sucker needle,
to suck blood
(mosquito)
- tube to feed on
nectar (bees,
butterfly).
- biter, to eat
plants (beetles,
locust)
Crustaceans
Myriapods
Many segments
Many
segments
One pair to
each segment
One pair to
each segment
in centipedes
& two pairs to
each segment
in millipedes
None
Two pairs
One pair
Simple, to sense
movement
Compound…
Simple
None
None
None
Some arachnids
have poison
fangs to kill
enemies
(scorpions)
Some
crustaceans
have claws to
hold and kill
their prey
Centipedes
have poison
claws to kill
their prey as
they are
carnivores.
Millipedes are
herbivores.
Water (most
are aquatic)
Crab, shrimp,
lobster
Ground
7- Habitat
Ground
Ground
Examples
Ants, housefly
flea
Spider, scorpion
Garden
centipede
39
40
6- Phylum Vertebrates.
Class
1- Fish
Main external features
1- Moist scaly skin
2- fins used to change direction,
forward movement & keep
balanced in water
3- gills (operculum may be found)
4- lateral lines for sensation
1- Moist skin
2- tadpoles live in water, adults on land
but return to water to reproduce.
2- Amphibians 3- eggs are laid in water and they are
surrounded with a gelatinous coat
4- four limbs with webs between
fingers
5- ear drum.
3- Reptiles
4- birds
5- mammals
1- dry scaly skin
2- eggs have hard shell to reduce water
loss as they are laid on land
3- four legs except for snake
4- third transparent eye lid to protect
the eyes in desert from storms &
allows vision
1- skin with water proof feathers
2- beak
3- two wings
4- Scaly legs
5- 3rd eye lid
1- skin with hair / fur
2- external ear pinna
3- mammary glands, breast feed their
babies
4- give birth
5- tail, except in man
N.B. bats have wings. Bear ,
Whales, dolphins are all mammals
41
Adaptive Features:
They are features in an organism that help him to survive and reproduce in its environment, it
increases fitness
Fitness (fitness with the environment):
Probability of organism to survive & reproduce in its environment
Examples:
Fish have gills to extract oxygen from water.
Fish living on sand in shallow water have flat sand colored bodies camouflage from
predators.
Predator fish have teeth to kill their prey & streamlined body for fast swimming Adaptation of
root, stem & leaf of plants to different environment:
environment
Xerophytes
Roots
• Long, branching in most, to get deep water.
• Superficial in some, to collect the rare rain.
Stems:
• Strongly supported, to stand the wind
• Have thick cuticle, to reduce water loss
• fleshy store water
Leaves:
• Thin or needle like, to reduce surface area so reduce water loss
• Have thick cuticle, to reduce water loss
• Stomata are few & sunken, to reduce water loss.
• Rolled leaves to trap moist air to reduce water loss by
transpiration
Cold windy
environment
Stem
Strongly supported, to stand the wind have thick cuticle, to reduce
water loss
Leaves:
• Thin or needs like, to reduce surface area so reduce water loss &
reduce water loss & reduce snow on leaf [coniferous]
Or
• Broad, to get as much light as possible in summer, but shed off
their leaves before winter season [deciduous]
• Have thick cuticle, to reduce water loss
• Stomata are few & sunken, to reduce water loss
Hydrophytes
Roots:
• Small or absent, as plant absorbs water from all it’s surface
Stems:
• Flexible, to withstand water currents
Leaves:
• Thin & long, to be flexible so as not to be destroyed by water
currents [immersed plants: Elodea]
Or
• broad with stomata on upper surface [floating plants: Hyacinth]
42
on upper eidermis
to absorb CO2
·· Thin flexible
submerged
leaflets
Large air spaces to foat
buoyancy
Rolled lea, ves to trap moist
air1 to reduce water loss
Pallisaide Cells
/
...____ Spongy Mesophyl
Cells
43
Simple dichotomous Key
It is a way of giving two descriptions at a time to choose from.
Example
Joined in pairs
rod-like
in clusters
rod-like in chain
spiral
1. bacteria with rod-shaped cells ................................................................2
bacteria with spherical or spiral-shaped cells .........................................4
2. cells in short chains .......................................................................Anthrax
cells single ...............................................................................................3
3. cells with many thread-like projections......................................Typhoid
cells without projections .......................................................Tuberculosis
4. bacteria with spiral-shaped cells ...................................................Syphilis
bacteria with spherical-shaped cells .......................................................5
5. cells joined in pairs .................................................................Pneumonia
cells joined in large groups .....................................................................6
6. cells in chain ...........................................................................Sore throat
cells in cluster ...................................................................................boils
Bacteria
A
B
C
D
E
Diseases
44
CHAPTER 6
BIOTECNOLOGY &
GENETIC ENGINEERING
45
1. Describe the role of anaerobic respiration in yeast during production
of ethanol for biofuels:
• Maize is soaked in water amylase will digest the stored starch to glucose.
• yeast is then added yeast respire anaerobically giving ethanol.
• ethanol is extracted by distillation. Although alcohol burns well it should be
mixed with gasoline ( petrol ) to give enough energy.
• yeast must be added from time to time as ethanol accumulation kills yeast cells.
Advantages of biofuels:
Sustainable; produced as fast as it is removed from the environment, so doesn't
run out (can keep growing maize to make more fuel)
• Less CO2 added to atmosphere as CO2 produced is absorbed by plants grown
•
Disadvantages:
•
•
•
Less energy released per liter, so normally mixed with gasoline to make fuel
Using fertile land for maize agriculture, rather than agriculture of food for people, so
less food for people
Maize prices will rise as large quantities are used
2. Role of anaerobic respiration of yeast in making bread:
Mix flour and water to get dough. Add yeast to the dough and leave it in a warm
place. Yeast secretes enzymes that will break down starch in the flour to soluble
sugars and use it in its respiration.
Enzymes from yeast
Starch + water → soluble sugar.
yeast fermentation
Soluble sugar
→ ethyl alcohol + carbon dioxide
during baking in the oven;
carbon dioxide makes bubbles (gas) which will raise the dough
alcohol will evaporate due to oven heat & yeast will be killed by oven heat.
3. Investigate and describe the use of pectinase in fruit juice production:
Pectin is a substance which helps to stick plant cells together. If pectin is
broken down, it will be much easier to squeeze juice from the fruit. Pectinase
is used in the extraction of juice from fruit and in making the juice clear rather
than cloudy. Apple and orange contains a lot of pectin
Precautions: use the scalpel to cut the fruit on the bench..
46
Lactose intolerance:
Some babies can't produce lactase enzyme, so unable to digest lactose (milk
sugar), this causes stomach ache, diarrhea, & vomiting
47
6- Describe the role of the fungus Penecillium in the production of the
antibiotic penicillin
Penecillium is a fungus that secretes the antibiotic penicillin if they are
growing in a medium which lacks food (glucose).
The use of the fermenter to extract penicillin:
Uses of the fermenter:
4- Production of enzymes for
1- production of penicillin.
2- production of insulin
3- production of antibodies.
pressure
release valve
washing powder.
5- Production of SCP such as
pruteen and quorn.
motor
probes
nutrients
sample tube
sterile air
cooling
water
water-filled
jacket
cooling
water
stirrer
tap
How to sterilize fermenter ?
Using UV radiations & steam
Why to sterilize ?
• To avoid contamination
• To reduce competition
for nutrients & space.
Feed Stock?
Glucose, source of carbon for
respiration ammonia, source of
nitrogen to make amino acids, to
make proteins for growth
products
name
water jacket
stirrer
nutrient inlet
Probe
function
Maintain constant optimum,temperature;
stirs, maintains a suspension
supplies glucose, & ammonia nutrients for respiration
& energy release for growth & reproduction
monitors, temperature / pH
air supply
supplies oxygen for aerobic respiration;
outlet
allows collection of the liquid containing penicillin
after fermentation
48
Genetic engineering.
What is meant by genetic engineering:
Changing the genetic material of an organism by removing, changing or
inserting individual genes.
Uses of genetic engineering:
1. insertion of human insulin genes into bacteria to produce insulin
2. insertion of genes into crop plants to provide vitamin A
3. insertion of genes into crop plants to confer resistance to insect pests.
Outline the use of genetic engineering in producing human insulin:
• Extract the insulin gene from the chromosome in the pancreas using
restriction enzyme that cuts forming sticky ends
• Cut the plasmid (vector) using the same restriction enzyme forming
complementary sticky ends.
• Insert the insulin gene into the plasmid using ligase enzyme to obtain
a recombinant DNA
• Insert the plasmid into the bacteria using heat shock & Ca++.
• Put the bacteria in a fermenter → filter the product and extract insulin
from the filtrate.
bacterial
chromosome
plasmid
s
plasmids
isolated
Plasmids are isolated from a
bacterium.
The gene to be transferred is cut from the donor DNA
using the same restriction enzyme.
DNA to be transferred
The plasmids are
opened with a specific
restriction enzyme.
two strands
plasmid
of
DNA
sticky
on
ends
plasmid
sticky ends on
DNA being
transferred
donor
cell
The opened-up plasmids and
the isolated gene are mixed with
a DNA ligase enzyme to create
recombinant plasmids.
Bacteria are incubated with
the recombinant plasmids.
recombinant
plasmid
bacterium containing recombinant
plasmid
Some bacteria will
take up the
plasmids.
The bacteria that have taken up the
plasmid now contain the gene from the
donor cell. This could be a gene controlling
the production of human insulin.
49
Advantages of using human insulin produced fromgenetic engineering:
1. Identical to human insulin rapid response and less allergy
2. less transmission of animal diseases.
3. large products available to all patient and cheap
4. No ethical concerns, doesn't harm animal health
Advatages of genetically modified crop plant such as maize, soya &rice:
1. GM crops resistant to herbicides herbicides are sprayed to kill weeds
GM crop plants will not be harmed
this increases the crop yield.
2. GM crops resistant to pests as BT maize/cotton GM crops secrete
toxins such as BT toxin to kill pests less use of pesticides
3. Adding food value to crop plant, as vitamin
A in Golden rice lessvitamin A deficiency
less night blindness
4. Cheaper crops as it needs less labour
50
Disadvantages of genetically modified crop plant:
BT toxin they is specific may kill other animals such as bees.
Pests may become resistant to pest resistant crops "BT toxin
resistance"
Seeds are expensive to buy by the farmers as they have to be bought
yearly.
The development of super-weeds that will resist the herbicides.
People are afraid to eat genetically modified seeds thinking that it
may harm their health..
Explain why bacteria are used in biotechnology and genetic engineering:
They reproduce rapidly.
They have the ability to make complex molecules
Lack of ethical concern
Their genetic code is the same like all other organisms and will code
for the same amino acid.
Presence of plasmids.
51
CHAPTER 7
Nutrients & Diet
52
Nutrients include six classes;
1- Carbohydrates
2- Fats
5- Vitamins
6- Water
3- Proteins
+
Building unit
Roughages (fibers)
Carbohydrates
P.O.C
Elements in them
4- Minerals
Carbon, hydrogen and oxygen
Glucose
Monosaccharides
Chemically
Disaccharides
glucose
Maltose
sucrose
Polysaccarides
glucose sub-units
Main sources
"part of a starch molecule"
Monosacch sweet drinks, fruits
Disacch sugar cane, honey
Polysacch bread, potatoes, cereals
1. Used in respiration and energy release in animals and
in plant.
Importance
2. Excess stored in animals as glycogen and in plants as
starch.
3. Glucose is used in plants to make proteins needed
for growth, cellulose needed for the formation of cell
wall, chlorophyll needed for photosynthesis oils and
vitamins needed for growth
-
How can a plant synthesize protein? Glucose formed due to
photosynthesis reacts with nitrate ions giving amino acids that will combine
together giving protein.
- How can plant synthesize chlorophyll? …. Glucose reacts with
magnesium ions giving chlorophyll.
53
P.O.C.
Elements
Fats and oil (lipids)
Proteins
Carbon, hydrogen, oxygen, nitrogen
Carbon, hydrogen, oxygen + sulphur
Building unit
Fatty acids& glycerol
Main sources
Oils found in plants &
known as vegetable oils.
It is liquid.
Meat, eggs, beans, wheat, milk
Fats found in animals
such as cheese, butter.
It is solid.
Amino acids
1- Provides energy fat
releases more energy
than carbohydrates.
2- Used in the formation
Importance
1- For growth and tissue repair as it
enters in the formation of cell
membrane, cytoplasm,
chromosomes..
2- Formation of enzymes that act as
of cell membrane.
biological catalyst
3- Insulation of heat fat
under the skin is an
3- Formation of antibodies needed
insulator that reduces
for immunity.
heat loss.
4- Formation of haemoglobin
4- Fat under the skin
needed to combine with oxygen.
changes to vitamin D 5- Formation of hormones needed
on exposure to ultra
for coordination.
violet rays.
glycerol
3 fatty
acids
chain of amino acids forming
part of a protein molecule. Each
shape represents a different
amino acid.
A computer model of a protein
in the blood that is involved in
forming a blood clot. The
coloured bands represent
different amino acids in a chain.
• There are twenty different amino acids, their
sequence gives different shapes to protein molecules.
• This gives many different specific enzymes that differ from each other in their
specific shape of active site determined by the sequence of amino acids
• Gives many different specific antibodies each with a specific binding site to
bind to a specific antigen of a pathogen (bacteria or virus)
54
4- Minerals
Animals and plant get these elements from food in simple inorganic ions
Plant
Inorganic ions
Source
Importance
If deficient
Nitrate ions
Soil
For protein synthesis
Poor growth
Magnesium ions
Soil
For making
Yellow leaves and
chlorophyll
poor growth
Animals
Inorganic ions
Source
Importance
Iron ions
Liver,
kidney,
eggs, green
vegetables
(spinach)
Formation of
haemoglobin in the
red blood cells. It
carries oxygen
from the lungs to
body organs
If deficient
Anemia: less oxygen
carried to the body cells
less respiration Less
energy release shortness
of breath & easy fatigue
• Children Rickets
Milk, cheese, • formation of
"soft, bent bones,
bones and teeth
green
especially lower limb
Calcium ions vegetables, • blood clotting
due to weight, & poor
teeth development
bread
• Adults fragile bones
"osteomalacia"
55
Vitamins
"Inorganic & needed in small amounts"
Vitamin
Sources
Citrus fruits as
Vitamin C
orange, fresh
fruits,
vegetables
Importance
If deficient
Scurvy: bleeding from
- maintains healthy
gums, loss of teeth,
gums and teeth
reduced resistance to
- increase resistance to
diseases. It only
diseases
occurs if fresh food is
- healthy skin
not taken for a long
time
Liver, fishVitamin D
liver oil, milk,
exposure to
sunlight
Helps absorption of
calcium from the small
Rickets
intestine and deposits it
Fragile bone
in bones and teeth, to
harden them
56
Water
Importance:
a)Act as a solvent for all chemical reactions inside the cell
b) Act as a solvent to help transport of solutes such as glucose, amino
acids, salts, urea, vitamins, hormones…………
c) Used in photosynthesis, digestion...(write equations)
d) Act as a coolant. Water vapour lost in transpiration in plant and in sweat
in animals.
e) Support plant by filling the sap vacuoles and making the cells turgid.
Roughages (fibers, mainly cellulose)
It is not a real nutrient and never seen our cells but is essential in our diet.
Importance:
Prevents constipation and colon disease such as colon cancer; How?
1- Roughages stimulate peristalsis.
2- It retains water, so keep remains soft and easy to be expelled.
Deficiency:
Causes constipation and colon cancer.
Sources in the diet: Bran, green vegetables, grains, bread..
Balanced diet
It is a diet that contains all the necessary nutrients in their right amounts
and supplies the body with the amount of energy needed
It depends on
1- age
2- gender
3- occupation or activity.
- 55 -
57
Malnutrition
When a balanced diet is not eaten and there is a decrease or an increase of a
particular type of food
Over nutrition (excess)
Under nutrition (deficiency)
Too much food causes obesity
(over weight) higher risk of:
Protein deficiency
• Poor growth
• Weak immune
response
• kwashiorkor &
marasmus
disease
heart attack
high blood pressure
diabetes
Vitamins/Minerals deficiency
Vit. C scurvy
Calcium/vit. D rickets, bad teeth
in children, fragile bones in adults
(vit D).
Iron Anemia
Roughages deficiency
and colon cancer
constipation
Too much fat leads to obesity
Too much sugar
obesity
tooth decay
Starvation
I It is to deprive completely nutrients for a long period of time.
58
The problem of world food supplies; Famine
There is Famine in some parts of the world as they are unable to get enough food.
Causes of these problems and thfe factors contributing to famine are:
1. Over population increase of population faster than increase in
the food production.
2. Unequal distribution of food some countries have more than they
need others do not.
3. Drought and flooding make agriculture impossible.
4. Lack of money farmers are unable to buy machines, fertilizers,
pesticides
5. Cash crop using good lands for cultivating cash crops
(e.g. tea, coffee) Which have no food value, but are exported for money
gain.
6. Deforestation leads to soil erosions, & decrease rain fall drought &
desertification.
7. Over cultivation/over grazing which decreases soil fertility, & lead to
soil erosion.
8. Wars people cannot cultivate their land.
Solutions:
• Birth control to avoid over
population.
• Avoid cultivating cash crops
• Aids to poor countries must be
given from rich countries.
• Economic development
• A void over cultivation, over
grazing, deforestation.
• Using modem technology to increase
food production: as "single cell
protein"
59
CHAPTER 8
Plant nutrition "Photosynthesis"
Autotrophic nutrition
60
Photosynthesis:
It is the process by which green plant makes carbohydrates "glucose" from
raw materials "CO2 & water", converting light energy into chemical energy.
Equation:
Sunlight energy
Carbon dioxide + water
→ glucose + oxygen
Sunlight energy
6CO2 + 6H2O
→ C6H12O6 + 6O2
Raw materials needed:
Products given:
1- carbon dioxide
1- glucose
2- water
2- oxygen
61
How photosynthesis occur:
1- Carbon dioxide in air diffuses through the stomata to air spaces in the
leaf to mesophyll cells to chloroplasts.
2- Water absorbed from the soil through the root hair cells by osmosis,to
cortex cell, rises up in the xylem vessels to the mesophyll cells to
chloroplasts.
3- Chlorophyll absorbs sun light energy and uses it in photosynthesis.
sunlight
Carbon dioxide
diffuses through
air spaces.
Carbon dioxide
diffuses through
stomata from
the atmosphere.
Water travels
to chloroplasts
by osmosis.
acer is
brought from
the roots in
xylem vessels.
How the raw materials for photosynthesis get into a palisade cell.
How a plant uses the products of photosynthesis
1- Oxygen used in respiration and energy release.
2- Glucose a. used in respiration and energy release.
b. changes to other substances; cellulose, starch, protein,
chlorophyll and other pigments, vitamins.
N.B. starch will be stored in chloroplasts, roots, stem, tubers.
62
Glucose +
From
photosynthesis
enzymes
enzymes
nitrates → amino acids → protein
absorbed from soil by
diffusion and active
transport and
transported to the leaves
by the xylem vessels
63
Factors affecting rate of photosynthesis
I- limiting factors: It is any external factor given in a short supply and
limiting the effect of the other factors.
1. Light intensity.
2. Carbon dioxide concentration.
3. Temperature.
In curve A
1-Between a and b: light is the limiting factor. As you increase light
intensity, the rate of photosynthesis increases.
2-Between b and c: Light intensity is no more a limiting factor. The
limiting factor may be carbon dioxide concentration or temperature.
experiment 3
25 °C; 0.4% CO2
Rate of photosynthesis
How can you prove that the limiting
factor is carbon dioxide?
By giving plant more CO2 & repeating
the experiment from the start.
If the rate of photosynthesis increases
(the curve rises), then carbon dioxide
was deficient in the first experiment.
If the rate of photosynthesis does
not increase, then temperature is the
limiting factor.
If the CO2 & temperature increase &
the rate of photosynthesis is the same
then all the chloroplasts are occupied.
- 61 -
experiment 1
25 °C; 0.04% CO2
experiment 2
15 °C; 0.04% CO2
Light intensity
The rate of photosynthesis at different temperatures and
different carbon dioxide concentrations.
(0.04% CO2 is about atmospheric concentration.)
64
II- Stomata:
1. During day light light opens stomata light is absorbed by
chlorophyll CO2 diffuses into the leaf and increases the rate of
photosynthesis.
2. During night no light energy absorbed, so CO2 is not needed stomata
close to reduce water loss and avoid wilting CO2 does not diffuse into
the cell no photosynthesis
3. On a very hot sunny day stomata close to reduce water loss & avoid
wilting no CO2 absorbed from atmosphere less photosynthesis as CO2
released from the cells due to their respiration is used in
photosynthesis.
What does a plant need for its growth:
1- Light
3- Nutrient (water and salts)
2- Carbon dioxide
4- Temperature
Differentiate between respiration and photosynthesis
Respiration
Photosynthesis
continuous
only during day light
uses glucose
gives glucose
gives CO2
uses CO2
Find the similarities
1 ____________________________________
2 ____________________________________
65
The Green House
It is a closed place where plants are cultivated,
Reduces the negative effect of limiting factors on the rate of photosynthesis
Green houses are made of glass to allow light and heat energy to pass, a light
source is used to provide light energy at night.
High carbon dioxide concentration by burner.
Heater to provide optimum temperature.
Humidifier to increase humidity so reduce water loss.
Sprinklers to give water.
Fertilizers as nitrates & magnesium.
"By this the green house provides CO2, optimum light intensity,
optimum temperature, nutrients (salts and water)"
Importance:
• Reduce negative effect of shortage of limiting factors, provides optimum light-intensity,
temperature & carbon dioxide concentration, so more yield.
• To obtain fruits and vegetables at any time of the year.
66
Leaf structure
nucleus
chloroplast
upper
epidermis
palisade
mesophyll
mesophyll
layer
vein
spongy
mesophyll
stoma
air space
1- Cuticle It is transparent & waxy to allow light to pass through & reduce water loss
2- Epidermis it is found at the upper and lower surface of the leaf to keep the shape of the
leaf. It is transparent to allow light to pass through.
67
Structure
P.O.C
Distribution.
Funct.
Palisade cells
Spongy cells
• Tightly packed cells,
• Perpendicular to upper
epidermis
• Many chloroplasts
Below the upper epidermis
Photosynthesis
• Loosely packed cells,
• Wide inter-cellular air
spaces
• Few chloroplasts
Near to the lower epidermis
-Circulation of CO2 in air spaces
to be able to diffuse into the
chloroplast in the palisade cells
-Photosynthesis (less)
Vascular bundles vein
Xylem vessels (non living)
Phloem cells (living)
• Continuous hollow tube with no
• Hollow with a thin layer of
cell membrane, no cytoplasm, no
cytoplasm at the periphery to
nucleus, no end walls to allow
allow translocation of sucrose
transportation of water & salts
and amino acids from Source
from roots to leaves
(leave) to Sink (root)
• has lignin to support the plant
• Has sieve plates with pores to
• has pits to allow lateral movement
allow translocation.
of water & salts
xylem
vessel
lumen
pit
nucleus
68
Stomata
A stoma is made of two guard cells
around a stomatal pore
Structure of guard cell:
1. They are sausage shaped.
2. They are joint at ends.
3. They have uneven thickness of cell
wall.
4. Contain chloroplasts unlike the other
cells in the epidermis.
"N.B. If the guard cells are turgid
the stomata will open, but if they
are flaccid the stomata will close"
cell wall
epidermal cell
cytoplasm
nucleus
QO
��
,. Q
di
Function of stomata:
• Transpiration (loss of water vapour)
• Gas exchange
stoma
cytoplasm
nucleus chloroplast
guard cell
Surface view of the lower epidermis of a leaf.
69
Gaseous exchange in a leaf
No photosynthesis
Only respiration
respiration = photosynthesis
photosynthesis rate > respiration rate
Compensation point
Adaptations of a leaf to it's function
1- Broad to increase the surface area, to trap more light & make more photosynthesis
2- Thin to increase the surface area to volume ratio to shorten the distance for faster
diffusion.
3- Cuticle i. transparent -----------4- Epidermis transparent to allow light to pass through -----
ii. waxy -----------
5- Chloroplasts
• found more in the palisade cell that lie just below the upper epidermis to absorb more
light
• found very close to the cell wall to shorten the distance to absorb more light & more
CO2 by diffusion.
6- has guard cells to open and close to allow transpiration and gas exchange
7- has air spaces between the spongy cells -----8- has a wide network of veins to bring water and salts and to take food to the growing
part of the plant.
70
Practical work
Destarching leaving a plant in a dark place (or in a dark cupboard) for
two days
How to ensure that the plant has been destarched?
1- detach a leaf and put it in boiling water to kill the cytoplasm and
denature the enzyme.
2- remove the leaf and place it in ethyl alcohol. Put the tube in a boiling
water bath till it becomes white alcohol dissolves the chlorophyll.
3- remove the leaf from alcohol and place it in warm water to soften it.
4- remove the leaf and drop few drops of iodine solution.
If the color changes to blue black --- starch is not completely digested in
the leaf and the plant should be kept more in the dark. If the color does not
change then the plant has been destarched.
Destarching
testing for starch
Boiling water
bath
denature
enzymes
Damage
memb.
dissolve
cuticle
Boiling water bath
with ethanol
warm/cold
water to
soften
add drops of iodine
to test for starch
to remove
chlorophyll
to see colour
change clearly
71
To show that light is necessary for photosynthesis
1. destarch the plant
2. get a black paper as shown in the figure and place the plant in a front of the
sunlight and leave for few hours
3. Test the leaf for the presence of starch the covered part will not change
the color of the iodine solution as it reflects the light while the uncovered part
will be changed to blue black.
To show that CO2 is necessary for photosynthesis
1. Destarch the plant
2. Set up the apparatus as shown
3. Use KOH or NaOH "soda lime" to
absorb carbon dioxide from air of
one pot .
4. Put both pots in light for two days,
then test the presence of starch
To show that chlorophyll is necessary for photosynthesis:
1. Use a plant with variegated leaves
2. Test it for starch after removing
chlorophyll & using iodine solution
3. The green area will turn blue black while
the white one will take the yellow brown
color of iodine solution showing the
absence of starch.
72
To prove that light intensity is a limiting factor
1. set up the apparatus shown.
2. use a heat filter to avoid the effect of temperature as a limiting factor.
3. darken the room and place a source of light in front the plant with a
constant distance.
4. count the number of bubbles produced with in 3min and record it.
5. increase the light intensity, & count the number of bubbles & record it.
6. put the results in a table and plot a graph.
"N.B. counting the number of bubbles is inaccurate as the size of the
bubbles differs from each other. By this it is better to measure the volume of
gas produced using a graduated cylinder or a gas syringe"
sodium hydrogen
carbonate solution
source of CO2
movable lamp
thermometer
Heat filter
water bath
ruler
0
cm
15
pond plant
Changing distance to
change light intensity
Precautions:
• Darken the room →so that the only light available is light energy from
light source
• Use a heat filter →to keep temperature constant & optimum, as light
intensity is a controlled variable
• On changing light intensity → wait 5 min before recording results so the
chlorophyll will work at the new light intensity.
73
CHAPTER 9
Transport in plants
74
Transpiration.
loss of water as water vapour from leaves through open stomata by diffusion down
water potential gradient.
Mechanism of transpiration:
1- Water in the cell wall of the spongy mesophyll cells absorbs heat from the
surrounding air spaces and evaporates. This sets a water potential gradient between
the leaves and air water vapor diffuses out the leaf through open stomata down
water potential gradient by transpiration.
2- The mesophyll cells have to replace waterwater moves from the xylem vessels to
the mesophyll cell walls by apoplast pathway. This lowers the hydrostatic pressure
at the top of the xylem vessels than the pressure at the bottom (in the root) this
creates a pressure gradient, so water with dissolved salts move up the xylem vessels
to the leaves by transpiration pull. "helped by cohesion & adhesion by hydrogen
bonds that makes water rise as a continuous uninterupted column"
1. Water vapour diffuses from air spaces in
leaf through open stoma, a process called
transpiration.
Water vapour is carried away from the leaf
surface by air movements.
This reduces water potential inside the leaf.
2. Water evaporates from a mesophyll cell
wall into the air space.
3. Water moves through mesophyll cell wall
or out of the mesophyll cytoplasm into the
cell wall.
4
5
3
mesophyll
cell
3
2
xylem
vessel
air space
in spongy
mesophyll
4. Water leaves a xylem vessel through pits.
It may enter the cytoplasm or cell wall of a
mesophyll cell.
5. Water moves up the xylem vessels to
replace the water lost from leaf.
1
1
stoma
guard cells
lower epidermis
N.B. Most of the water absorbed is lost from the plant by transpiration. Very
little is used in photosynthesis, solvent, & turgidity of cells.
75
Factors affecting the rate of transpiration:
1. Temperature: the more the temperature the more the evaporation of water, the
more the transpiration.
2. Air movement: the more the air movement the more the removal of humid air
touching the leaves which sets a water potential gradient and increase water lost by
transpiration
3. Light intensity: the more the light intensity the more the transpiration
4. Humidity: the more the humidity the less the water potential gradient, the less the
transpiration
5. Stomata / surface area: the more…, the more…
The uptake of water
phloem
I- Transport of water from the soil into the
root hair cell by osmosis
II- Transport of water from the root hair cell to
the xylem in the center;
xylem
vessel
a- from the cytoplasm of a cell to cytoplasm
of another cell.
direction
of water
movement
b- from the cell wall of a cell to the cell wall
of the other cell. .
III- Transport in the xylem from the roots to the
leaves by transpiration pull helped by
cohesion & adhesion forces
pericycle
endodermis
cortex
epidermis
root hair
2. Water passes across the root,
from cell to cell. by osmosis. It also
seeps between the cells.
3. Water is drawn up the xylem vessels,
because transpiration is constantly
removing water from the top of them.
1. Water enters the root
hairs by osmosis.
•;
soil particle · -·
film of water
xylem vessel
76
Leaves have a
lower water
potential.
2
water potential
gradient
3
water moves
from xylem
to leaf cells
water moves up xylem
4
xylem tissue
higher water
potential
water
in root
evaporation of water
into leaf air spaces
1
transpiration of water
vapour through open
stomata into air (mainly
from underside of leaf)
water movement down
water potential gradient
water
in leaf
lower water
potential
water enters xylem
5
Roots have a higher
water potential.
6
water uptake
near root tips
The distribution of xylem & phloem in different plant parts
root hairs
cortex
Vascular
bundle
epidermis
collenchyma
tissue
parenchyma
xylem
pith
phloem
lignified fibres
xylem
phloem
endodermis
T.S of a young dicotyledonous root to show the distribution of tissues.
TS of a young sunflower stem to show the distribution
of tissues. The sunflower is a dicotyledonous plant.
The uptake of minerals
I. Uptake from the soil by diffusion & active transport
II. Movement from the root hair cell to the xylem by diffusion
III.movement in the xylem from the root to the leaves transpiration pull
77
cortex
Translocation
It is the transport of sucrose and amino acids from Source (leaves ), to sink (roots)
in the phloem
How to prove that food produced by leaves moves up & down in the phloem ?If
the leaf is supplied with radioactive carbon in carbon dioxide, radiations will be seen
from carbon in sucrose in the phloem
How to prove that translocation is an active process that uses energy ?
By using respiratory poison respiration stops no energy released for translocation
so it stops
source e.g. leaf
processes
carbon dioxide + water
photosynthesis
sucrose
water
companion sieve
cells
tube
loading
aphid stylet has moved
between cortical cells
stylet penetrates a
single sieve tube in
a vascular bundle
aphid
mouthparts
mass flow
sink growing or storage point
water
sucrose
unloading
vascular
bundle
cortex
epidermis
glucose + fructose
respiration storage
carbon dioxide starch
+ water
growth
anaesthetised
aphid removed;
phloem sap
exudes from
broken stylet
cellulose
Using an aphid to collect phloem sap.
why source & sink may change?
during seed germination
the source is the
cotyledon, the sink is the
embryo, when the plant
develops leaves, the
source becomes leaves &
the sink becomes roots
during spring & summer,
the source is the leaves &
the sink is the roots where
starch is stored, during
winter, leaves fall of,
source becomes roots, &
sink becomes branches
78
Summer the leaves photosynthesise
and produce sucrose
Winter search is stored in
the tubers
Spring sucrose is sent to the
new shoots
sink sucrose is used by the
new shoots as they grow
produce sucrose
Sucrose is sent
from the tubers to
the new shoots.
Sucrose is sent
from the leaves
to the cubers.
sink sucrose is
converced into
starch in the
tubers
-11--- source starch
is converted into
sucrose in the tubers
Potato plants in summer and spring.
1. used as glucose as it is
very soluble
very reactive
2. stored as starch as it is
less reactive
insoluble
3. transported as sucrose as it is
more soluble than starch
less reactive than glucose
Wilting
When transpiration rate exceeds the rate of water absorption from the soil
cells cannot replace their lost water from xylem cells in the leaves will
be plasmolysed plant wilts.
Causes of wilting:
lack of water
Wind
high temperature
over use of fertilize
low humidity / dry air
frozen water
Advantages of wilting:
"N.B. If plant is in salty water, root hair cells Guard cells become flaccid, stomata
close to reduce further water loss
will lose water instead of absorbing it "
- 77 -
79
The Potometer
reservoir containing water
airtight seal
shoot of plant, with its
cut end in contact with
the water inside the tubing
water
air–water meniscus
capillary tubing
It is designed to measure the rate of water uptake in a cut leafy shoot under
different conditions.
Performing the experiment:
1- Cut a stem of a leafy shoot under water to prevent air from entering the
xylem and blocking it. (stops transpiration pull).
2- Set up the potometer & ensure an air tight seal using petroleum jelly or
vaseline to prevent evaporation of water.
3- Close the clip again and make sure that the air/water meniscus reaches zero.
4- As the plant transpires the water lost by transpiration is replaced by water
taken up by the stem.
5- Record the position of the meniscus every two minutes for 30 minutes.
6- Repeat the experiment but with the potometer in different conditions.
blowing it with a fan
changing the light intensity
putting it in a refrigerator
cover the sheet with a plastic-bag
7- After changing the condition, take 3 readings of the rate of uptake & notice
whether they represent an increase or a decrease in the rate of transpiration.
80
Limitations of the potometer:
Not all the water up taken
will be transpired; some of it
will be used in photosynthesis
and turgidity of the cell but
since this water is of negligible
amount and most of the water
is lost in transpiration it can
be considered that the rate of
absorption equals the rate of
transpiration.
How to find surface area?
using a grid with squares,
count the number of squares
that are half or more covered
& multiply by the SA of one
square
How to make it more accurate?
use a grid with smaller squares
Explain how the internal structure of leaves results in
the loss of large quantities of water in transpiration?
xylem supplies water ;
air spaces ;
large (internal) surface area ;
water evaporates from surface of mesophyll cells ;
guard cells, open / close, stomata ;
water vapour, diffuses out through stomata ;
Epidermal impressions:
Impressions (or replicas) of the epidermal surface can
be made with clear nail varnish. The surface of the leaf
is coated with a thin layer of nail varnish which is
allowed to dry. It can then be carefully peeled off using
fine forceps and mounted dry or in water on a slide.
You will be able to see whether stomata are open or
closed at the point in time the peel was made. Stomatal
densities can be estimated as with epidermal peels.
81
To find which surface of the leaf has stomata
1- Use a paper with cobalt chloride and fix it ob both surfaces the color
changes from blue to pink if it is moistened with water, this shows the
presence of stomata.
If the color does not change then there is no / less stomata.
2- Put the leaf in hot water bubbles will be seen getting out of the
surface that has stomata. The bubbles emerge due to the expansion of air
inside the leaf.
To show which part in the stem transports water and solutes
Ringing experiment
82
CHAPTER 10
Sexual reproduction in flowering plant
83
Structure and Function of a named dicotyledonous flower
• The flower is an organ.
• It is responsible for sexual reproduction & forms seeds
stigma
petal
carpel
anther
ovary
filament
ovule
receptacle
A flower has:
nectary
"N.B. flowers may be bisexual (male &
female reproductive organs) or unisexual"
1. Sepals "small and green"
to protect the flower in bud
2. Petals "large, bright colored and scented & have guide lines"
to protect the reproductive organs
to attract insects
3. Stamens "anther & filament" .
anther has four pollen sacs full of pollen grains. "male gamete"
4. Carpel "stigma, style & ovary"
stigma receives the pollen grains.
ovary carries the ovule "has female gamete" where fertilization
takes place
5. Nectary a gland at the base of the petals that has sugar liquid on which
insects feed.
6. Guide lines they guide the insects to the base of the petals
84
--pollen grains
stigma
lines along which
the anther will
split
pollen sac. containing
developing pollen grains
caught by stigma
style
anther
filament
A young flower anther
T.S. through a young
flower anther
placenta
mature pollen grains
Section through the female part of
a flower.
Trans verse section through a
mature flower anther
Pollination
It is the transfer of pollen grains from anther to stigma.
It may be self pollination if the pollen grains are transferred to the
stigma of the same flower or another flower on the same plant, or
cross pollination if the pollen grains are transferred from a flower
of a plant to a flower on another plant of the same species.
Types of pollination
Self pollination
Cross pollination
- bisexual flower
- unisexual or bisexual
- have anther higher than stigma
- have anther lower than stigma
- anther & stigma mature together - don't
- not self sterile
- self sterile
Agents of cross pollination
1- Wind
2- insect
Anther splits pollen grains will Insects visit the flower to get food
be carried by wind. e.g. grass
e.g. lupin, bean, pea
85
Method of insect pollination:
Insects bees, butterflies
1- Insect is attracted to the flower by its bright colorlarge petals and scent.
2- It pushes in its body shaking the anther so pollen grains fall and stick to
the insect's body.
3- When the insect visit an older flower, pollen grains stick to the stigma
Advantages of self pollination
more chances of pollination
more chances of fertilisation
prevents extinction / enables
survival of species
no need for pollinators as
bees
useful if plants are on their own
"geographically isolated"
parent plants that are adapted to this
environment, pass alleles to offspring
It is still sexual reproduction so still offspring
shows some variation that increases chances
of survival than asexual reproduction.
Advantages of cross pollination
• Gametes have different Genes "from
different plants "
• Offspring will show more Variation
• May develop resistance to diseases
• more chance to adapt, survive &
reproduce
• Pass alleles of good features to
offspring
• Allows evolution to occur
Diadvantages of self pollination
• Less chances of pollination
• More wastage of pollen & energy
• Depends on pollinators
86
Structural adaptation of flowers to pollination
P.O.C
1- Petals
2- Anthers
3- Stigma
4- Pollen
grains
Wind pollinated flowers
Insect pollinated
Small, inconspicuous, green, no
Large, conspicuous, bright
nectar, no scen, no guide lines.
colored, scented and have nectar
Large, loosely attached to
filament & hangs out of flower.
Large has many pollen grains
Loosely attached to be easily
shaken by the wind
Hangs out exposed to wind
Small, firmly attached to the
filament, inside the flower Small
has less pollen grains Firmly
attached and hangs inside the
flower does not need to be
exposed to wind.
Feathery, hangs out of flower
Feathery to Increase the
surface area to catch more
pollen grains
Hangs out to be exposed to
wind
Flat
or lobed
, inside the
flower.
Flat/lobed to receive
pollen grains.
Inside does not need to be
shaken by the wind.
Pollen grains are
smooth, numerous, smaller.
Smooth so that they do not
stick or else wind cannot carry
them.
Numerous more chance of
loss
Small easily carried by wind
Pollen grains are sticky
or spiky, less numerous, larger.
Sticky or spiky to stick to
insect's body
Less numerous less chances
of loss
87
Fertilization and Fruit formation
A- Fertilization
1- Pollen grains on stigma absorbs water,
this activated enzymes that start to
digest through stigma, style, & ovary
forming a pollen tube.
2- The pollen tube grows down the style
and ovary towards the ovule with the
male nucleus "male gamete" at the tip.
3- The pollen tube enters through
micropyle into the ovule.
4- Pollen tube splits, male & female
nuclei fuse giving a diploid zygote.
"fertilization"
"N.B. fertilization will not take place unless
the flowers are of the same species"
Fruit and seed formation after fertilization:
• Zygotebecomes an embryo
• Ovule becomes seed
• Walls of ovulebecomes
testa of seed
• Walls of ovarybecomes
pericap of fruit
• Ovarybecomes the fruit
• Petals, sepals and stamen
fall down
• Micropylremains in the
seed.
Function of the fruit:
1- Protects the seed
2- Helps dispersal of seeds
88
Structure of a broad bean & its germination:
Whole bean seed
swelling
over the
radicle
Bean seed split
plumule
embryo
radicle r
micropyle
micropyle
hilum
cotyledon
testa
Germination of seeds
• The seed absorbs water through the
micropyle.
• It swells and its testa bursts.
• Enzymes area activated " continue as in
enzymes"
• Radical comes out of the testa, moves
downward to give root.
• The plumule merge after the radical, it
moves upward, it gets above the surface
of the soil to give shoot with developing
leaves.
testa
radicle emerges
from cesta
lateral roots
begin to grow
root system forms
plumule grows
into a shoot
cotyledons come
above ground, turn
green and stare to
photosynthesise
Conditions necessary for seed germination:"WOW"
1. Warm temperature for enzyme activity
2. Oxygen for respiration and energy release
3. Water activates enzymes
acts as solvent for all chemical reactions.
4. of the testa:
Role
Role of micropyle:
• Protects the embryo from
being damaged
• Allows fertilization as pollen tube
with male gamete passes through it
• protects the seed from bacteria
& fungi.
• Allows germination as water is
absorbed through it.
89
Growth
Permanent increase in size & dry mass by an increase in number of cells, size of
cells or both.
Why do we use dry mass as an accurate indicator for growth
Answer: total (fresh) (wet) mass is not used to indicate growth because it includes
water gain & water loss, which fluctuates depending on the surrounding environment.
How to get dry mass:
Get 100 seeds of the same species, same size
Find initial mass by taking ten seeds, & putting in oven at 100 °C,
weigh frequently till there is no decreased in mass "dry mass"
Plant them in same type of soil, give same volume of water.
Leave them under the same environmental conditions
(same humidity, warm temperature)
Every 2 days take 10 seeds & dry them in an oven.
Repeat the experiment 2 more times & calculate average
Record the dry mass and plot a graph.
How does the dry mass change during germination:
At the beginning:
Dry mass decreases. Why ?
starch digested into soluble
maltose,
used by embryo in respiration
& energy release releasing CO2,
water & energy used by embryo for
mitosis.
CO2 evolves, water evaporates.
By this the dry mass will decrease.
Few days later:
Dry mass increases Why ?
Leaves developed, they make photosynthesis, & build up starch.
This makes the dry mass increases.
90
Growth shown in a longitudinal section of a root:
Xylem
Phloem
Zone of absorption and
development
Root hair cell
zone of elongation; most
growth; as the cells expand
due to the formation of sap
vacuole arid absorption of
water
zone of cell division; cells
divide by mitosis giving
daughter cells that show
no variation and are
identical to each other
Development
An increase in complexity: cells specialize,
form tissues, form organs.
91
Practical work
1- Distinguish between fruit (1) and fruit (2):
Remains of
style
Stalk
Receptacle
Seeds
Pericarp
Seeds
Pericarp
Sepals
Fruit (1)
Fruit (2)
2- Make an investigation to determine which color is most attractive to
insects. (same…………).
92
CHAPTER 11
Plant Sensitivity
93
Sensitivity is the ability to detect &
respond to a change in the external or
internal environment (stimulus)
Tropism "tropic response"
Plant growth in response to unidirectional
stimuli."light or gravity"
Auxin hormone is growth regulator
produced at the tips of shoot & roots.
Phototropism
Shoot's response +ve phototropism / Root's response -ve phototropism
When light comes from one direction:
Shoot
+ve Phototropism
auxins made, in tip of shoot
moves down the stem from cell to cell by
diffusion & active transport.
auxins collect in the dark side away from
light in zone of elongation.
greater cell elongation at side in the dark,
as cells absorbs water by osmosis, become
turgid stretching cell walls.
Root
-ve Phototropism
auxins made, in tip of root
moves up the root from cell to cell by
diffusion & active transport.
auxins collect in the dark side away from
light in zone of elongation.
Less cell elongation at side in the dark.
root grows & bends away from light.
shoot grows & bends to light.
94
2- If light comes from above
Plant grow vertically upward
3- When plant is left in darkness:
"Etiolation"
Plant grow faster this makes the plant
long, thin, weak, yellow and finally die.
95
2- Gravitropism
Shoot's response -ve gravitropism / Root's response +ve gravitropism
More auxins accumulate towards gravity "When placed horizontally in the absence of light"
In shoot
-ve Gravitropism
auxins made, in tip of shoot
moves down the stem from cell to
cell by diffusion & active transport.
due to gravity, auxins collect in the
lower part in zone of elongation.
greater cell elongation at lower part,
as cells absorbs water by osmosis,
become turgid stretching cell walls.
shoot grows & bends upwards.
Root
+ve Gravitropism
auxins made, in tip of root
moves up the root from cell to cell
by diffusion & active transport.
due to gravity, auxins collect in the
lower part in zone of elongation.
Less cell elongation at side in the
lower part
root grows & bends downwards.
96
Advantages of tropism
(1) +ve phototropism in shoots places the leaves in the best position to absorb
more light and perform more photosynthesis
(2) +ve gravitropism in roots allows plant to grow downward, absorb more
water and salts and fix the plant to the soil
The use of auxin in food industry
1- Auxin is sprayed on plant to help ripening of fruits
2- used to stimulate root growth in stem cutting as the end of the stem is dipped into auxin.
3- Used as a synthetic weed killer; 2,4-D is a synthetic type of auxin hormone
sprayed on crops & weeds, more absorbed by (broad leaved) weeds "selective for
weeds", less absorption by (narrow leaved) crops
increase growth of weed
weeds can't produce enough glucose "Respiration > Photosynthesis" finishing food
reserves.
weeds cannot maintain rate of growth so they die.
_...---......
97
