Biología, Botánica, Genética y Zoología


Science Final Exam Summary

Cells, PHS and Cell respiration


Definition: the unit of live, is the smallest fraction of a living organism

Cell parts:


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.


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.


Tissue, Organ system, Organ and Organism


  • 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


Nitrogen (N)

79 %

Oxygen (02)


Carbon dioxide (C02)



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.

  • 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.


  • 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


        • One cell thick that makes diffusion easy

        • Blood travels through them at low pressure

        • Take nutrients and oxygen to tissues


        • 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

      • Blood

        • 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

        • 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


        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


        • Large surface area

        • One cell thick walls to make easier diffusion

        • A capillary network around them

        • Moist inside to facilitate diffusion


        • 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.


        (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

          • 'Science'

            Anti-clockwise = clock wise moments






            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















            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.


            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.



            Mass/volume = density


            • Kg/m³

            • g/cm³

            • g/ml

            • Item

              Mass (g)
























              Speed = Distance


              V = s


              M/S = meters


              Acceleration = Change in speed

              Time taken

              A = v = v-u

              t t

              y = mx+c

              y v

              m a



              therefore v = at

              When U is = to 0

              S = 1 at²


              S = 1vt



              v = at


              s = 1 at²



              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


              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

            • 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=k a


                  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 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.


                  Work = force x distance

                  = mg x s

                  = 35 x 10 x 300

                  = 105, 000
                  105 kj


                  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


                  C.1. THE ELEMENTS OF CHEMISTRY

                  Changes of state:


                  Change of State

                  Name of Process

                  When does it occur?

                  Describe energy of particles

                  Movement of particles

                  New State?

                  Solid to liquid


                  When something is heated

                  The particles get more energy

                  The particles start to move more feely


                  Liquid to Gas


                  When liquid

                  is heated

                  The particles get more energy

                  The particles stop moving except for a little vibration


                  Gas to Liquid


                  When its hot

                  Particles lose energy


                  Liquid to Solid


                  When is hot so it melt

                  The particles looses energy

                  Particles stop moving except for a few vibrations

                  Enviado por:Sebastian Petrozzi
                  Idioma: inglés
                  País: Perú

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