Science Final Exam Summary
Cells, PHS and Cell respiration
Cells
Definition: the unit of live, is the smallest fraction of a living organism
Cell parts:
Definitions:
Nucleus: the nucleus is a small sac containing the genetic material.
Cell membrane: the cell membrane surrounds the cytoplasm
Cytoplasm: the cytoplasm is the liquid that fills most cells
Cell wall: the cell wall is layer that surrounds the cell and provides the shape and protection. It is made of
cellulose.
Chloroplasts: the cells reorient them selves so the can be exposed to the sun and the photosynthesis can carry
out.
Central Vacuole: transport and get rid of unwanted material and waste products also make the cell change
shape and protect the cell form material could harmful. They also contain toxins
Diffusion: is a spontaneous movement (flow) of particles from high concentration to an area of low
concentration (down the concentration gradient). Diffusion can be affected by temperature, the size of the
molecule and by the steepness of the concentration gradient.
Diagram:
Osmosis: is the diffusion of water through a cell wall or semi−permeable membrane in wich the water
molecules passes from low concentartion to high concentartion.
Hypertonic Solutions: contains high concentration of solute in comparison with another relative solution.
Hypotonic solutions: contains low concentration of solute in comparison with a relative solution.
When you put a cell into a Hypertonic solution the cell will shrivel because the water will diffuse out of the
cell, when you put a cell into a hypotonic solution the cell will collapse because water will diffuse into the cell
causing the cell collapse.
Diagram:
Tissue, Organ system, Organ and Organism
Definitions:
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• Tissue: A group of similar cells, joined to do a similar job.
• Organ system: A group of organ working together in a common job.
• Organ: A group of different tissues joined together to accomplish a function.
• Organism: A set of organ system working together coordinatel
PHS
Nitrogen (N)
Oxygen (02)
Carbon dioxide (C02)
79 %
20%
0.04%
Definition:
Photosynthesis is the process by which plants cells produce their own food, it takes place in the mesophyll
tissue, where the chloroplast is found
Word equation: Carbon dioxide + water Glucose + Oxygen
Cross section of a leave:
Plant cell:
Some Questions:
Where does Carbon Dioxide come from and how does it reach the mesophyll cells?
Carbon dioxide comes from air, and it reaches the mesophyll by the stoma.
Where does water come from and how does it reach the mesophyll cells?
The water it taken by the earth and it reach the mesophyll cell by little pipes called xylem vessels, they take
nutrients and water from the roots to the cells.
Where does the oxygen produced go to, and how?
The oxygen produce goes to the mesophyll cell and the, the oxygen enters the mesophyll cells by the stoma
where all the gases enter.
Transpiration: is the loss of water through the leaves by evaporation.
Transpiration stream: Flow of water through the xylem vessel
The water diffuses into the routs and goes up the xylem vessel due to capillary and evaporation of water form
the leaves.
Factors limiting the PHS
• Without enough light a plant cannot photosynthesise very fast, even if there is plenty of water and
carbon dioxide. Increasing the light intensity will make photosynthesis faster.
• Sometimes photosynthesis is limited by the level of carbon dioxide. Even if there is plenty of light a
plant cannot photosynthesis if it has run out of carbon dioxide.
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• Temperature can be a limiting factor too. If it gets too cold the rate of photosynthesis will slow right
down; equally, plants cease to be able to photosynthesis if it gets too hot.
Science
• The heart
• The muscles are the only type of tissue that generate movement, by contracting and relaxing.
• Blood will carry supplies to the cells, pick up waste from the cells, get rid of it and reload supplies.
• Blood will supply the cells with oxygen, collect carbon dioxide from the cells, get rid of it at the lungs
and reload oxygen at the same site.
• Valves in the heart: Between the Atria and Ventricles: Tricuspid (R) Bicuspid (L), between
Ventricles and Arteries: Semi−lunar valves
• The pacemaker: controls the heart rate by chemical impulses.
• Adrenaline: increases the heart rate pumping more blood to the body and also the stroke volume
increases also it increases glucose and breakdown the lipids in fat cells.
• Electrical system: The S−A node produces an electrical; which spreads through the right and left atria,
the signal causes the atria to contract, the electrical signal reaches the A−V node were it pauses
briefly, before continuing through the His bundle to the left and right ventricles and all the way to the
Purkinje fibers the signal causes the ventricles to contract and blood is pumped to the lungs and body.
• Blood vessels
♦ These would be the pipes of our transport system. We have to consider that blood flows
around the body under different conditions.
♦ Vessels which carry blood away from the heart have thick mucular walls that contract and
relax to push the blood forwards. These are the ARTERIES.
♦ The arteries will divide as they go along forming smaller arteries (arterioles) and of course
their walls will become thinner as they give out more branches.
♦ Microscopic vessels of one cell thick walls called CAPILLARIES.
♦ Through these capillaries nutrients and oxygen will diffuse into the cells and carbon dioxide,
urea and other waste materials will diffuse into the blood.
♦ Capillaries will start getting together to form bigger vessels that will take back the blood to
the heart called VEINS this will transport blood at a very lower pressure. Because much of it
was used in pushing the blood through the different tissues and organs so the blood vessels
carrying back blood to the heart do not have to stand a high pressure and so do not need thick
walls.
Arteries:
◊ Carry blood away form the heart
◊ Thick muscular walls
◊ Blood travels through them at high pressure
◊ Have pulse that pushes blood forwards
◊ Narrow lumen
Capillaries:
◊ One cell thick that makes diffusion easy
◊ Blood travels through them at low pressure
◊ Take nutrients and oxygen to tissues
Veins:
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♦ Blood
◊ Carry blood to the heart
◊ Thin, elastic walls
◊ Have valves to prevent back flow of blood
◊ Blood travels at low pressure
◊ Usually run in between muscles
◊ Wide lumen
◊ The Blood is the liquid means in which nutrients, oxygen and waste are carried to and
from cells.
◊ Liquid fraction (plasma): accounts for 55% of the total volume. Mainly made of
water. In it nutrients such as glucose, mineral salts, amino acids, proteins, etc., are
carried to the cells. Also, waste such as urea and carbon dioxide are carried away
from cells.
◊ Solid fraction (blood cells): account for 45% of the total volume. There are three
main types of cells, all of which carry out different functions.
◊ Transport needs three basic things, a vehicle, a pathway or network and motion.
◊ Oxygen needs to be carried into the cell and carbon dioxide needs to be carried out of
the cell.
◊ The best way of transporting thins is by the capillary network, or through the blood,
every cell Is near a capillary so diffusion and gaseous exchange occurred with more
facility
◊ The arteries have thick walls that would resist bloods high pressure and contracting
and relaxing will make blood flow forward, when its necessary the flaps will prevent
blood going back.
Red blood cell
◊ Contain haemoglobin
◊ Red pigment which has bug affinity for oxygen
◊ No nucleus
◊ Biconcave disk
◊ Normal amount 3 and 5 million per mm^3
White blood cells
◊ Phagocytes: From Phagos (Eat) and Cytos (Cell); cells that eat. These will eat and
digest bacteria and some other organisms or substances strange to the body.
◊ Lymphocytes: specialized white blood cells that produce ANTIBODIES. These are
proteins that act as "poisons" to specific micro organisms (virus) or chemicals
(toxins).
Platelets: small cell fragments that have the property of "sticking" together to form a clot.
Their function is to stop bleeding whenever a wound is made and to help repair tissue
together with the protein fibrin which is in the plasma
Transport system in plant
◊ Transpiration is the loss of water from the leaves by evaporation
◊ Water is taken from the soil via the roots
◊ The roots have tiny root hairs cells which have a large surface area so the plant can
absorbed enough water from the soil.
◊ Water is absorbed into the roots by osmosis
◊ On the underside of the leave are tiny holes called stomata which allows the plant to
breath.
◊ When water reaches the leave it evaporates and escapes through the stomata
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◊ As the water is escaping more water is drawn up the xylem suctions structure
The transport system is made by 2 types of tubes:
⋅ Strong, thick pipes called Xylem vessels
⋅ They consist of dead cells with no end walls, which contains lignin to form
stiff structure, they are impermeable and are strength with fibres
⋅ Thin tubes called Phloem vessels
⋅ They consist of living cells lined with cytoplasm, with walls made of
cellulose and perforated end walls called plates, they are permeable
surrounded by companion cells
What is taken where?
◊ Water is taken up the plant from the roots the roots to the leave (for photosynthesis
and transpiration) in the xylem vessels.
◊ Minerals dissolve in water are taken up the plant to the shoots leaves in the xylem
vessels.
◊ Food (the product of photosynthesis) is taken from the leaves and moved up and
down the plant to any part which needs it (for growth or for storage) in phloem
vessels.
Respiratory system
◊ Alveolus − tiny, thin−walled air sac at the end of the bronchiole branches where gas
exchange occurs (plural − alveoli).
◊ Bronchioles − numerous small tubes that branch from each bronchus into the lungs.
They get smaller and smaller.
◊ bronchus − a branch of the trachea that goes from the trachea into the lung (plural −
bronchi)
◊ diaphragm − muscle at the base of the chest cavity that contracts and relaxes during
breathing
◊ epiglottis − a flap of tissue that closes over the trachea when you swallow so that
food does not enter your airway
◊ intercostals muscles − muscles along the rib cage that assist in breathing
The pleural membranes reduce frication between lungs and ribs, and seal the lungs from the
outside.
◊ Larynx: vocal cords
◊ Trachea, bronchi, bronchioles}pipes made of c shape cartilage rings
◊ All the air way is made out of cartilage
◊ NO GASEOUS EXCHANGE
Gaseous exchange
◊ Gaseous exchange occurs in the alveoli
◊ There are millions of alveoli's in each lung presenting a massive surface area for
exchange to occur over.
◊ Each alveolus is very closely associated with a network of capillaries containing
deoxygenated blood from the pulmonary artery
⋅ The capillary and alveolar walls are very thin, allowing rapid exchange of
gases by passive diffusion along concentration gradients.
⋅ CO2 moves into the alveoli and O2 moves into the red blood cell
Alveolus
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◊ Large surface area
◊ One cell thick walls to make easier diffusion
◊ A capillary network around them
◊ Moist inside to facilitate diffusion
Breathing
◊ The air is inhaled by either the nose or the mouth then it passes through the larynx
then through the trachea goes to the bronchus to go to the lungs, the intercostals
muscles push the ribs so you can get more air volume so the pressure its lower than
outside so air come in, then the intercostals muscles relax the lungs have more
volume for air so all the CO2 gets out.
Clean up system
Our respiratory system gests clean by the mucus that produces the bronchiole, this mucus
traps all the dirt particles that your respiratory system, then the microscopic cilia moves the
mucus up and up until it gets outside the respiratory system.
Physics
(Turning) Moments (of a force)
(Perpendicular) Distance (from pivot) X Force = Turning movements
Meters = m, Newton's = N, Newton−metres = Nm
Conditions for equilibrium
♦ Forces are balanced
◊ Up to left = Downwards forces
◊ Forces to the left = Forces to the right
◊ No resultant moments
⋅ Clockwise moments = Anti−clock−wise moments
Anti−clockwise = clock wise moments
5F=(5X5)+(1X15)
5F=25+15
5F=40
F=40/5
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F=8
Hooke's Law
The extension of a spring a spring is directly proportional to the load on it;
provide the elastic limit is not exceed
Vectors and Scalars
All physical quantities have a magnitude if they only have a magnitude we
call, them Scalars.
Some physical quantities also have direction. If they have a magnitude and a
direction, we call them Vectors
Scalars
Vectors
Displacement
Distance
Velocity
speed
acceleration
Temperature
Force
Time
Friction
Mass
Weight
Length
Representative Vector quantities
Vectors are represented by arrows. The length of the arrow represents the
magnitude. The direction of the arrow represents the direction.
E.g. a 4N force to the right and 3N force downwards:
Adding vectors
Vectors are added graphically, i.e. using diagrams.
Example
Add an 8N force downwards to 6N force to the right what is the resultant
force?
Kinetin theory
Tries to explain the behaviour of gases such as pressure, temperature, or
volume, by considering their molecular composition and motion.
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Density
Mass/volume = density
Units:
• Kg/m³
• g/cm³
• g/ml
Item
Mass (g)
Volume(cm3)
Density
Rock
66.7
25.4
2.63
Glass
97.4
37.0
2.63
Aluminium
193.8
8
60.0
3.23
Wood
41.6
60.0
0.7
Iron
166.7
20.0
8.34
Motion
Speed = Distance
Time
V=s
t
M/S = meters
Seconds
Acceleration = Change in speed
Time taken
A = v = v−u
tt
y = mx+c
yv
ma
xt
czero
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therefore v = at
When U is = to 0
S = 1 at²
2
S = 1vt
2
but
v = at
therfore:
s = 1 at²
2
example
a car starts from rest and accelerates at a rate of 2m/s² for 8 seconds.
a)What is it its final speed? V = at (a= 2m/s²) and (t=8s)
b)What distance has it traveled? S = ½ at² = ½ x 2 x 8² = 64 m
Friction
Frication is a force that opposes motion. It cannot be bigger than force that
generates it.
Weight = mg
M = mass (kg)
G = 10M/s²
The objects starts to move with an acceleration of 5m/s²
Frication has not changed. What is:
⋅ the resultant force (Fr) on the object
⋅ the size of the resultant force pulling the object
answers: a) Fr = ma
= 2 x 5 = 10N
10
⋅ Fr = F−f = 10
F = 10 + f = 10 + 5
= 15 N
Newton first law
Conditions for equilibrium
⋅ No resultant Force
• Upward farce = downward force
• Forces to left = forces to right
• NO RESULTANT MOMENTS
♦ Clockwise moments = clockwise moments
Law: if there is no reluctant force on an object it will:
a) If stationary, remain stationery;
b) If moving, it will continue to move with a constant
velocity (constant speed in a straight line)
Example: The object in the diagram is being swirled at
constant speed v. The string break at point P. What is the
speed and direction at which object O continues to travel
Force and Motion
F=a
F=k a
F=ma
Force = mass x acceleration
Newton's = kilograms x meters per second per second
N Kg m/s²
Energy transfer
Energy is measured in joules (J)
Energy is equivalent to work
Work is also measured in joules (J)
Work = force x distance (in the same direction as force)
Pierre is very romantic. He carries his girlfriend form the
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street level to the top of the Eiffel tower (300 m) his girl
friend, Justine has a mass of 35 kg how much work does
Pierre have do.
Answer
Work = force x distance
= mg x s
= 35 x 10 x 300
= 105, 000
105 kj
Gravity
G = 10m/s²
S = ½ at² h = ½ gt²
V = at v = gt
A mouse of mass 0.001 falls of a do distance of 5m.
♦ How long does it takes to hit the ground?
H = ½ gt² 5 = ½ x 10t² 5 = 5t² t = 1s
♦ At what speed does it hit the ground?
V = gt 10 x 1 = 10m/s
Chemistry
C.1. THE ELEMENTS OF CHEMISTRY
Changes of state:
The
The
When
particles
Solid to
particles
start to
Liquid
Melting
something
liquid
get more
move
is heated
energy
more feely
The
particles
When
The
stop
Liquid to
liquid
particles
Evaporation
moving
Gas
Gas
get more
except for
is heated energy
a little
vibration
Condensation
Liquid
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Gas to
Liquid
Liquid to
Freezing
Solid
When its
hot
When is
hot so it
melt
Particles
lose
energy
Particles
The
stop
particles moving
looses except for
energy a few
vibrations
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