Sunday 27 November 2011

chapter 8 : Mangrove Swamp





State the unsuitable conditions for habitation in the mangrove swamp. Describe the adaptation of  plants to survive in this environment.



                        Nyatakan keadaan-keadaan persekitaran yang tidak sesuai untuk kehidupan di paya bakau dan kemudian huraikan adaptasi  tumbuhan  untuk hidup dalam keadaan tersebut.



F1: Soft muddy // strong coastal winds pose support problems.

E1 : To  support themselves, mangrove trees such as the Avicennia sp. have long, highly branched underground cable root //the Rhizophora sp. have prop roots/ aerial roots to anchor the plants on to the muddy soil.                                                                                    



F2 : Waterlogged conditions of the soil reduce the amount of oxygen available

E2 : the Avicennia sp. has breathing roots called pneumatophores which grow vertically upwards.



F3 : Direct exposure to the sun/wind leads to a high rate of transpiration

E3: The leaves of the mangrove are covered by a thick layer of cuticle which reduces transpiration during hot days// the leaves are thick and succulent which able to store water.



F4:The high salinity of the sea water makes the surrounding water in the soil hypertonic when compared to the cell sap of the root cells.



E4: The cell sap in the roots cells of the mangrove trees has a higher osmotics pressure than the soil water that surrounds them.This ensures that the roots do not lose water by osmosis// the excess salt in the hypertonic solution of the soil the roots and then then excreted as crystalline salt from the hydathodes



F5: Seeds which fall onto the ground die because they are submerged in the soft and waterlogged soil.

E5: mangrove seeds are able to germinate while still attached to mother plant/viviparity (this phenomenon increases the chances of survival of the mangrove as the seedlings can float horizontally on the water and subsequently get washed up on the sand or mudflats where they settle to establish a new population.


Wednesday 23 November 2011

Chapter 8 : Nitrogen Cycle

  • All life requires nitrogen-compounds, e.g., proteins and nucleic acids.
  • Air, which is 79% nitrogen gas (N2), is the major reservoir of nitrogen.
  • But most organisms cannot use nitrogen in this form.
  • Plants must secure their nitrogen in "fixed" form, i.e., incorporated in compounds such as:
    • nitrate ions (NO3)
    • ammonia (NH3)
    • urea (NH2)2CO
  •        most plants can only take up nitrogen in two solid forms: ammonium ion (NH4+ ) and the ion nitrate (NO3- ).
  • Animals secure their nitrogen (and all other) compounds from plants (or animals that have fed on plants).
Four processes participate in the cycling of nitrogen through the biosphere:
                                        - biological fixation by certain microbes — alone or in
                                          a symbiotic  relationship with some plants and animals
                                           Nitrogen-fixing cyanobacteria -
                                         - industrial fixation

  • decay  : microorganisms of decay. They break down the molecules in excretions and dead organisms into ammonia.:
  • nitrification : most of the ammonia produced by decay is converted into nitrates ;accomplished in two steps:
    • Bacteria of the genus Nitrosomonas oxidize NH3 to nitrites (NO2).
    • Bacteria of the genus Nitrobacter oxidize the nitrites to nitrates (NO3).
    These two groups of autotrophic bacteria are called nitrifying bacteria.
  •  denitrification :To complete the cycle other bacteria in the soil carry out a process known as denitrification which converts nitrates back to nitrogen gas. A side product of this reaction is the production of a gas known as nitrous oxide, N2O. Nitrous oxide, also known as "laughing gas" .

Chapter 6: Ruminant Digestive system

Reticulum
The reticulum is a flask-shaped compartment with a "honeycomb" appearance. It moves ingested food (ingesta) into the rumen and the omasum. The reticulum also causes the regurgitation of ingesta during rumination, and acts as a collection compartment for foreign objects.

Rumen
The rumen is a large fermentation chamber (in adult cattle its volume is about 125 litres) which has a very high population of micro-organisms, mainly bacteria, but also protozoa.It is because the bacteria secrete the enzymes necessary for cellulose degradation that ruminants are able to utilize roughage. 
Omasum
The omasum, or "manyplies", contains numerous laminae (tissue leaves) that help grind ingesta. These folds assist in the removal of fluid from the ingesta on their way to the abomasum.

Abomasum
This compartment corresponds to the stomach of the non-ruminant, and is termed the true stomach. It secretes the gastric juices which aid in digestion. The pH of the abomasum is normally in the range of 2,0 to 2,5. This low pH facilitates initial protein breakdown, and kills the bacteria which have spilled over from the rumen.

Ruminants differ from monogastric animals in the following important ways:
  • They have no upper canine teeth, or incisors, and have long, thick and rough tongues.
  • They ruminate. Chewing the cud helps reduce feed particle size, and mixes saliva into the feed.
  • The ruminant digestive system includes a fermentation chamber, called the rumen. The rumen contains micro-organisms which serve some important functions: they make it possible for ruminants to digest fibre (especially those in roughages) and they synthesize nutrients (such as B complex vitamins), and also essential amino acids which become available to the animal when the micro-organisms die, and are digested



Tuesday 22 November 2011

LOCOMOTION N SUPPORT : AQUATIC PLANT

Aquatic plants are plants that have adapted to living in aquatic environments
Characteristics of aquatic plants:
  • A thin cuticle. Thick cuticles reduce water loss; thus most hydrophytes have no need for thick cuticles.
  • Stomata that are open most of the time, because water is abundant and there is no need for it to be retained in the plant. This means that guard cells on the stomata are generally inactive.
  • An increased number of stomata, which can be on either side of the leaves.
  • A less rigid structure: water pressure supports them.
  • Flat leaves on surface plants for flotation.
  • Air sacs for flotation.
  • Smaller roots: water can diffuse directly into leaves; thus large root systems are not required for water uptake.
  • Feathery roots: no need to support the plant.
  • Specialized roots able to take in oxygen.All floating plants
    • Either have air spaces trapped in their roots, or else air spaces in their bodies (aerenchyma) to help them to float, thus receiving adequate sunshine
    • Have hair on their leaves that traps air
    • Structural adaptations
    • Have hollow stems to float on water.

Paper3:TRANSPIRATION BY POTOMETER

A group of students carry out an experiment to study the effect of environmental factor on the rate of transpiration of a balsam plant. Design a laboratory experiment to determine the effect of the temperature on the rate of transpiration .

http://cd1.edb.hkedcity.net/cd/science/biology/resources/L&t2/practical/Practical-24.pdf

http://en.wikipedia.org/wiki/Potometer

TRANSPORT : Explain the mechanism of blood clotting

Mechanism of blood clotting

Blood Clotting For Minor Wound 
Connective tissue : located in a vessel wall is cut and exposed to the blood.

Platelets : The aggregation of platelets forms a plug. Platelet will stick rapidly.

Platelet Plug
: It can stop the blood loss completely if the damage to  the vessel is small.
Blood Clotting For Severe Wound :

Combination of :
  1. Clumped platelets
  2. Damaged cells
  3. Clotting  factors in the plasma
Form the activator called Thromboplastin

It converts Prothrombin( inactive plasma protein)
With the present of :
  1. Calcium ions
  2. Vitamin K
To Thrombin(active plasma and act as enzyme)
With the present of :
  1. Calcium ions
  2. Vitamin K

This thrombin catalyses Fibrinogen(soluble protein) Fibrin (insoluble protein) :
-  mesh over the wound, trapped the red blood cells and sealing the woundto
Problems Related To Blood Clotting
Haemophilia :
1.  An inherited disease cause by a lack of particular Clotting factors in the blood.

2. A person may die due to excessive bleeding from minor cuts and bruises and also can cause spontaneous  internal bleeding.
Thrombosis
1. A process of clot formation inside an unbroken blood vessel
 
                 2. The clot is called thrombus

                 3.  A blood clot that travels in the bloodstream is called an embolus
                  4. Blood flow in the blood vessel will stop if the embolus
                      lodged in an artery and it can’t pass through it.


    TRANSPORT IN PLANTS : TRANSPIRATION

    THE MOVEMENT OF WATER FROM THE SOIL TO THE LEAVES
    Movement of water through the root



    Root hair

    *TSA/V is big

    *Large surface for *absorption of water by osmosis

    *Absorption of ions is achived by active transport

    Cells in the cortex layer

    *the cellsbecome hypotonic compare to the adjacent cells

    *water diffuses through the cytoplasma, vacoule and cell wall of the parenchyma cells until it reaches the endodermis


    Endodermis cells
    *water diffuses through the cytoplasma andvacoule only
    *Casparian Strips lining the side of the cell wall is impermeable to water

    Xylem vessel
    *The gradient of water concentration resulting an inflow of water into the xylem vessels
    *ions is actively transported
    *osmotic pressure is increace causing a continous inflow of water –generating Root Pressure




    Movement of water through the stem
    Xylem vessel
    *long, narrow and continuos column generates capillarity
    Capillarity / capillary action involving
    *the cohesive forces (between water molecules) *adhesive  forces ( water molecules adhere to the xylem wall.)
    *forming acontinuos water column within the xylem vessel
    *Root Pressure- exerted by the root of a plant

    *Transpiration Pull due to the proses of transpiration ocuring at stomata.
    Continous upward movement of water in the stem
    .





    Transport : The various type of immunity

    The various type of immunity


    Active Immunity 
                                                            
    The body produces its own antibody in   response to stimulation by antigen.                            

    Passive Immunity

    The body receives antibody from an outside source.

    Active Immunity - two types : i) NaturallyAcquired Active Immunity
                                                    ii) Artificially Acquired Active Immunity

    Passive Immunity-- two types : i) NaturallyAcquired Passive Immunity
                                                      ii) Artificially Acquired Passive Immunity

    NaturallyAcquired Active Immunity -      obtained after recovers from the infection

    Artificially Acquired Active Immunity - obtained through vaccination or immunisation


    i) NaturallyAcquired Passive Immunity - obtained from the mother through
                                                                       breast milk(colostrum) or via placenta

    ii) Artificially Acquired Passive Immunity - Obtained through the injection of a serum
                                                                            contain specific antibody (antiserum)





                                                                                  

    Transport: The mechanism used by antibodies to destroy antigens

    Agglutination                                                              Neutralisation

    Antibodies clump pathogens together                       Antibodies neutralizes the toxin of

    Easier for phagocytes to capture & destroy               bact by binding to a toxin molecule.

                                                                                       Prevent the toxin attach to a cell.



    Opsonisation                                                                    Lysis

    Opsonins bind to antigens to act as marker.              Lysins bind to the antigen cause

    Antigen can be easily recognized & destroyed          antigen to rupture.

    by phagocytes.

    Transport :The Role of the Circulatory System in the Body’s Defence



    → 3 lines of defence mechanism

    the first line of defence :

       Physical and chemical barriers that prevent the pathogens from entering the body.

       (pathogens : disease-causing microorganism, e.g : bacteria, viruses, parasites)




    • e.g

       The skin                                            mucous membrane                  others

    • rough outer layer                              • line the trachea,                    • tears and saliva

    • impenetrable                                       respiratory passage ways,       (lysozyme), protect

    • secretes sebum ( acid & oils              digestive & urinary tracts,       eyes & mouth

      prevent bacteria growth)                   stop entry of microorganism  • HCl acid (stomach)

    • the sweat (lysozyme), breakg           • secretes mucus (lysozyme)      destroy pathogen

      down cell walls of certain bact.          traps & destroys bact.              entry via food @

                                                                                                                   drink consumed.

    * specific

    the second line of defence
      Phagocytic white blood cells (phagocytes) perform phagocytosis..
    • engulf and ingest m/o or other foreign particles such as cellular debris.
    • neutrophils & monocytes.
    • they enter the interstitial fluid by squeezg  through capillaries wall develop into macro-
      phages
    • when a phagocyte encounters the pathogen  it engulf & destroyed by lysozyme in the
      phagocyte.

    * non-specific
    • the third line of defence
    • involves in immune system. ( Immunity : the body resistance to the pathogen which
      causes a specific disease).
    • specific / targeted defence
    antigens :specific molecule (protein) at the external surface of an invading m/o. Immune
      system recognizes as foreign. E.g bacterial toxins, snake venom. When immune system
      identifies the antigen, antigen induce the lymphocytes to release antibody in the blood
      stream to destroy antigen.
    antibody :protein found on the surface of lymphocytes or protein released by lymphocy-
      tes into the blood plasma. Each antibody can only bind to a specific antigen.

    Paper 3 : The lCO2 concentration and the rate of photosynthesis.



         Figure shows an experiment set up to determine the relationship between

         the CO2 concentration and the rate of photosynthesis. The rate of photosynthesis

         is estimated by counting the number of gas bubbles releases per minute.      

         The reading is tabulated in Table 1 below.

    Sample Answer
    Aim : To investigate the effects of carbon dioxide on the rate of     photosynthesis of a plant.

    Variables :
    i.  Manipulated : carbon dioxide concentration
    ii. Responding : the distance of the water moved in a capillary tube/rate 
        of photosynthesis/number of bubbles released.
    iii Constant : time, temperature ,light intensity, plant used

    Hypothesis :
    The higher the concentration of carbon dioxide, the higher is the rate of
    photosynthesis.

    Technique :
    Counting the number of air bubbles released in a fixed time.

    Apparatus and material:
    Beaker, capillary tube, rubber tube, filter funnel, plastic ruler, retort stand,
    Thread, dropper, natrium bicarbonate solution of a different concentrations: 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, Hydrilla sp.

    Procedure:
    1. Cut 5 cm of hydrilla sp. And put it in a beaker.
    2. Pour a little sodium hydrogen carbonate solution into the beaker.
    3. Invert a filter funnel over the hydrilla sp. in a beaker. Place plasticine at
        its rim to support it.
    4. Connect the capillary tube to the filter funnel by using rubber tube and
        clip the metre ruler.


    5. Withdraw water till a quarter of capillary tube.
    6. Mark the initial water level in capillary tube.
    7. Record water level after 10 minutes.
    8. Repeat the experiment for solutions of sodium bicarbonate of 0.2%,
        0.3%,0.4% and 0.5%.

    Presentation of Data:

    Solution
    Concentrations
    (Natrium bicarbonate)

    0.1%


    0.2%

    0.3%

    0.4%

    0.5%

    Initial reading(cm)







    Final reading (cm)







    Difference(cm)







    Rate of
    Photosynthesis (cms-1)






    Conclusion:
    The increase in carbon dioxide concentration will increase the rate of photosynthesis. The hypothesis is accepted.


    6.12 :The factors of affecting the rate of photosynthesis

    The factors of affecting the rate of photosynthesis.

    1. The rate of photosynthesis which takes plant is affected by factors such as light intensity, concentration of carbon dioxide and temperature.


    i. Light is essential during the light reaction of photosynthesis

    ii. When the concentration of carbon dioxide  and temperature are controlled at constant levels, the rate of photosynthesis is directly  proportional to light intensity up to a certain point.

    ii. As the light intensity  increases ,the rate of photosynthesis increases up to  a maximum  rate .

    iv. A further increase in light intensity does not increase the rate of photosynthesis because of  limiting  factors such as the concentration of carbon dioxide and temperature.

    v. when the carbon dioxide concentration of the environment is raised, the rate of photosynthesis is higher the  rate of photosynthesis of the corresponding light intensity.
    vi. At very high light intensity, the rate of photosynthesis decreases because the pigment chlorophyll  is damaged by ultra-violet rays

    6.11: photosynthesis mechanism

    State in which part  of the chloroplast do the following reactions occur?

    (i)     light reaction …………> granum

    (ii) dark reaction …………> stroma                                             

    In which part of the chloroplast could the chlorophyll be found? ------------> granum








    (i) Ligt Reaction
                                        Light energy                            H+ + OH-
           (ii) water   -----------------------------> hydrogen ion + hydroxyl ion
                                        Chlorophyll
     
     Light energy absorbed by the chlorophyll for Generation of ATP and
     
    photolysis of water   to produce hydrogen atoms + oxygen (released to atmosphere)

      
                         
    ii)  Dark reaction does not required light  occurs at the stroma of the chloroplast
    during daytime
                                    carbon dioxide            + hydrogen ------------> glucose C6H12O6  -------------------> starch                          
               C02                          +   H
     
    The dark reaction is catalysed by enzymes     which are sensitive to low or high temperature.