Tugas biologi 12 ipa1

Evaluasi  METABOLISME

Lengkapi pernyataan di bawah ini !

Metabolisme  dibedakan menjadi (1)...... dan  (2)...... Metabolisme dipengaruhi oleh enzim, dengan cara (3)............. energi aktivasi yaitu energi (4)....... Enzim Katalase  mengubah (5)..... menjadi air dan (6).....  Pada PH  1 maka  aktivitas katalase (7) ...... sehingga tidak terbentuk (8).... dalam air, sementara itu  pada kondisi asam, enzim....(9)  akan mengubah protein menjadi pepton. Disamping  itu Enzim katalase memiliki ciri kas antara lain (10).....(11) dan (12).....

Glikosis  terjadi  di. (13)..... dengan  mengubah  2 molekul glukosa menjadi(48)...... asam piruvat dan menghasilkan (14)... ATP   dan  (15)......   NADH. Sementara itu dalam siklus krebs, (16)...... bereaksi dengan (17) ....... membentuk asam sitrat, dengan hasil akhir berupa (18)....ATP  dan (19).... NADH serta  (20)..... FADH2, untuk tiap  3 molekul glukosa. Dengan demikian, hasil bersih ATP jika   2 molekul glukosa dipergunakan sebagai substrat respirasi adalah  sebesar (21)..... ATP. Diantara enzim yang terlibat dalam respirasi aerob pada manusia adalah (22)....... mengubah  (23)..... menjadi (24)........Pada Fermentasi asam cuka substratnya berasal  dari (25).......menghasilkan (26).....ATP dengan bantuan bakteri  (27).....dan memerlukan oksigen. Sedangkan Fermentasi alkohol menghasilkan (28).....ATP dan (29)....NADH2. Penambahan soda kue dapat (30) .........hasil fotesintesis, terbukti dari  (31) .......pada percobaan Ingenhoze. Reaksi terang fotosintesis  terjadi pada (32)....menghasilkan  (33)....., (34) dan oksigen yang berasal dari (35)......... Sedangkan reaksi gelap terjadi di (36).......... Untuk tanaman C3 Senyawa stabil pertama yang terbentuk setelah CO2 diikat oleh ribulose diposhat adalah (37)....., sedangkan untuk tanaman C4  senyawa stabil pertama setelah CO2 diikat oleh PEP adalah  (38)......Pada tanaman C3,  glukosa dibentuk oleh senyawa (39)........Tanaman C4 memiliki   tiga keunggulan pokok dibanding tanaman C3 yaitu (40).....(41).......dan (42)...

Thiotrix adalah salah satu bakteri yang dapat melakukan kemosintesis dengan sumber energi yang berasal dari (43)......, Sedangkan Nitrosomonas menggunakan sumber energi yang berasal dari (44) ........menghasilkan (45) ..... dan memerlukan oksigen.

46. Gambarkan  rangkaian  alat untuk membuktikan Fermentasi yang dilakukan oleh sel khamir !Berikan keterangan secukupnya !

47. Gambarkan prosedur kerja untuk membuktikan  fotosintesis menghasilkan amilum!berikan keterangan secukupnya !

Cleavage and Blastocyst Formation

Cleavage and Blastocyst Formation

The product of fertilization is a one-cell embryo with a diploid complement of chromosomes. Over the next few days, the mammalian embryo undergoes a series of cell divisions, ultimately leading to formation of a hollow sphere of cells known as a blastocyst. At some point between fertilization and blastocyst formation, the embryo moves out of the oviduct, into the lumen of the uterus. The images below demonstrate major transitions in structure during early embryogenesis in cattle. Note that in all of the the early stages, the embryo is encased in its zona pellucida. Embryos from other mammals have a very similar appearance, and the general sequence of stages is seen in all mammals.

Unfertilized oocytes typically fill the entire space inside the zona pellucida, but after fertilization, the one-cell embryo usually is somewhat retracted from the zona pellucida surrounding it. Although not visible in this image, one or two polar bodies are often visible in the perivitelline space, the area between the embryo and the zona pellucida.
The one cell embryo undergoes a series of cleavage divisions, progressing through 2-cell, 4-cell, 8-cell and 16 cell stages. A four cell embryo is shown here. The cells in cleavage stage embryos are known as blastomeres. Note that the blastomeres in this embryo, and the eight-cell embryo below, are distinctly round.
Early on, cleavage divisions occur quite synchronously. In other words, both blastomeres in a two-cell undergo mitosis and cytokinesis almost simultaneously. For this reason, recovered embryos are most commonly observed at the two, four or, and seen here, eight-cell stage. Embryos with an odd number of cells (e.g. 3, 5, 7) are less commonly observed, simply because those states last for a relatively short time.
Soon after development of the 8-cell or 16-cell embryo (depending on the species), the blastomeres begin to form tight junctions with one another, leading to deformation of their round shape and formation of a mulberry-shaped mass of cells called a morula. This change in shape of the embryo is called compaction. It is difficult to count the cells in a morula; the embryo shown here probably has between 20 and 30 cells.
Formation of junctional complexes between blastomeres gives the embryo and outside and an inside. The outer cells of the embryo also begin to express a variety of membrane transport molecules, including sodium pumps. One result of these changes is an accumulation of fluid inside the embryo, which signals formation of the blastocyst. An early blastocyst, containing a small amount of blastocoelic fluid, is shown to the right.
As the blastocyst continues to accumulate blastocoelic fluid, it expands to form - you guessed it - an expanded blastocyst. The blastocyst stage is also a landmark in that this is the first time that two distinctive tissues are present. A blastocyst is composed of a hollow sphere of trophoblast cells, inside of which is a small cluster of cells called the inner cell mass. Trophoblast goes on to contribute to fetal membrane systems, while the inner cell mass is destined largely to become the embryo and fetus. In the expanded blastocyst shown here, the inner cell mass is the dense-looking area at the botton of the embryo.
Eventually, the stretched zona pellucida develops a crack and the blastocyst escapes by a process called hatching. This leaves an empty zona pellucida and a zona-free or hatched blastocyst lying in the lumen of the uterus. Depending on the species, the blastocyst then undergoes implantation or elongates rapidly to fill the uterine lumen.

As mentioned, the developmental progression depicted above for bovine embryos is essentially identical to what all mammalian embryos go through, including humans. For example, the image to the left shows an expanded blastocyst from a dog. This embryo was stained to accentuate the trophoblast and inner cell mass.

The length of time required for preimplantation development varies somewhat, but not drastically, among species. The zona-intact bovine blastocysts shown above were collected 5-6 days after fertilization. The same stages would be seen in mice at about 3.5 days after fertilization.

In addition to the morphological changes in the embryo described here, preimplantation development is associated with that might be called an awakening of the embryonic genome. There is, for instance, little transcription in the embryos of most species prior to the 8 cell stage, but as embryos develops into morulae, then blastocysts, a large number of genes become transcritionally active and the total level of transcription increases dramatically.

How Cells Make ATP

by PHOSPHORYLATION... adding a phosphate to ADP ADP + P ------> ATP

a) substrate level phosphorylation... where a substrate molecule ( X-p ) donates its P to ADP making ATP b) chemiosmosis - [Oxidative Phosphorylation via Electron Transfer Chain]... food substrates donate e- & protons to acceptor molecules [NADH], i.e., oxidation. NADH gives up electrons & protons are pumped out of mitochondria (or the chloroplasts in photosynthesis); protons diffuse back into mito thru an enzyme - ATP synthase, the ATP synthase enzyme makes ADP + P --> ATP figure * c) photophosphorylation.... e- of light energy, instead of food covalent bonds, are captured by chlorophylls to make a proton gradient across the chloroplast membranes... figure* protons move through a chloroplast ATP synthase enzyme to make ATP

Oxidative Metabolism... (cell respiration)
occurs in heterotrophic organisms that consume foods
... we say organisms oxidize (consume) foods (often glucose) to make energy
because they remove & capture electrons...
... where is energy in foods? it's in the covalent bonds (e-)
Thus - METABOLISM is cells capturing e- via REDOX reactions.


REDOX REACTION...
e- passed from one molecule to another [PGAL --> NAD⁺] in a chemical rx
energy is transferred into the new molecule (a redox couple) by holding e-

OXIDATION = removal of electron &/or proton from food covalent bond

REDUCTION = gaining electron &/or proton; adds an electron to an acceptor molecule

a model redox reaction...

A-H + B-O <---> A + B-O-H
donor acceptor (:H) acceptor donor
PGAL NAD+ 1,3-bisphosphoglycerate NADH

reducing oxidizing becomes becomes
agent agent oxidized reduced

Oxidation state* and energy relationship --> the more reduced = the more energy it holds

an example using acceptor coenzyme (redox couple) NAD⁺ <--> NADH*

Thus : metabolism becomes the stepwise oxidation of foods

if aerobic - requires oxygen as electron acceptor

if anaerobic - requires no oxygen (uses other e- acceptors)

Cell RESPIRATION... is Concept Activity 9.1 - Overview of Cellular Respiration
Investigation chapter 9.1 - How Rate of Respiration is Measured

1. oxidation of GLUCOSE --> CO₂ + H₂O
& 2. reduction O₂ to H₂O

C₆H₁₂O₆ + 6O₂ <----> 6 CO₂ + 6 H₂0 + e- ---> 36-38 ATP
DG = -686 Kc/mole 263Kc = 38%

called oxidation... because e- are removed from glucose

called reduction... because e- passed to O₂ making water
& 3. phosphorylation of ADP (thus oxidative phosphorylation)

a more complete definition of cell respiration :

- series of enzyme rx's (biochemical pathways) in the cytoplasm & mitochondria that,

- remove e- (oxidation) from covalent bonds of substrates (as glucose), and

- pass e- to acceptor molecules [coenzymes] such as NAD⁺ & FAD*
which become reduced [ NADH & FADH₂ ]

- the reduced coenzymes [ NADH & FADH₂ ] pass e- to other acceptors...
a series of protein electron carriers called cytochromes,

- the electron carriers [cytochromes] pass e- to O₂ --reduction--> H₂O

- cytochromes also pump protons [H⁺] out of mitochondria into peri-mito space,

- protons move back into mito thru a special enzyme (ATP synthase*) & make ATP

the Enzyme Pathways* of Cell Respiration...
Glyco-lysis : converts 1 glucose (C6) to 2 pyruvate (C3) produces : 2 pyruvate, 2 NADH, & 2 ATP (net) occurs in : cytoplasm [anaerobic] may include : alcoholic fermentation = glucose --> alcohol lactic acid fermentation = glucose --> lactic acid
KREBS Cycle : oxidizes : 2 pyruvate to CO2 + H2O produces : 8 NADH, 2 ATP, 2 FADH2 releases : 6 CO2 occurs in the mitochondria [aerobic]
ETC - Electron Transport Chain : uses carrier proteins (cytochromes, etc...) and passes e- & H+ from NADH & FADH2 to O2 to make H2O generates a proton gradient (chemiosmosis) across the inner mitochondria membranes
& ATPsynthase : the enzyme of the inner mitochondrial membrane end that lets H+ back into mitoplasm & makes ATP directly

Glycolysis... don't memorize the pathway, but learn the...
KEY REACTIONS of GLYCOLYSIS... Concept Activity 9.2 - Glycolysis
1. substrate level phosphorylation* [occurs twice in glycolysis]
2. redox reaction step 6* involving NAD⁺
3. reactions --> investment phase* & payoff phase* - Summary of glycolysis*
Quicktime movie animation of glycolysis*^{view for homework}

FATE of NADH - need to regenerate NAD+: mito membranes is impermeable to NADH alcoholic fermentation* "history of wines" lactic acid fermentation* also called anaerobic respiration shuttles* malate shuttle (liver, kidney, heart) = NADH c --> NADH m glycerol-P shuttle (muscle/brain) = NADH c --> FADH2m Purpose: to move electrons captured in cytosolic NADH c into mitochondria
FATES of PYRUVATE (figure*) Concept Activity 9.5 - Fermentation if anaerobic alcoholic fermentation & lactic acid respiration if aerobic pyruvate dehydrogenase + Krebs Cycle

SUMMARY GLYCOLYSIS figure*

- 2 ATP to initiate

- 2 substrate level phosphorylation steps = 4 ATP gross

thus Glycolysis makes: what goes in & come out*
2 ATP (net),
2 NADH, and
2 PYRUVATES

remember the role of the ... Fermentations & Shuttles

Heterotrophic Metabolism in Aerobic Organisms...
Krebs Cycle [Sir Hans Krebs] the Fate of Pyruvate*

PYRUVATE DEHYDROGENASE Reaction... in mitoplasm (Fig 9.10)* oxidizes PYR --> acetyl-CoA a multienzyme complex of 60 proteins and 5 coenzymes involves CoASH* -----> acetyl coenzyme A [Fritz Lippman] reactions: 1. decarboxylation (-CO2), 2. reduction of NAD+ --> NADH, 3. acylation & synthesis of AcoA*
KEY Reactions of KREBS CYCLE 1. NAD+ is reduced (NADH) and FAD is also reduced (FADH2) 2. substrate level phosphorylation occurs (GTP <--> ATP) 3. decarboxylation occurs [-COOH] 4.* an acylation reaction via coenzyme-A (forms Acetyl-coA) SUMMARY Reactions: [Krebs Cycle Quicktime Movie*] Summary figure* full cycle
--> how many actual ATP have we made so far? Activity 9.3- The Citric Acid (Krebs) Cycle

OXIDATIVE PHOSPHORYLATION & ELECTRON TRANSFER CHAIN...
Concept Activity 9.4 - Electron Transport*
the coupling of oxidation of substrates (-e) to the phosphorylation of ADP to make ATP
µ remember, most of the energy of glucose's bonds is now carried in NADH & FADH₂
e- passed from NADH/FADH₂ to O₂ via "carrier molecules"* names*
these series of electron carrier proteins occur in 4 membrane subunits fig 9.16*
I) NADH Reductase, II) Succinate Dehydrogenase
III) Cytochrome Reductase, IV) Cytochrome Oxidase
Virtual Cell - ETC animation*


CHEMIOSMOSIS (fig 9.16*) & ATP Synthase (fig 9.14* & EM)
creation of a hydrogen ion gradient (H⁺) by e- flow thru the ETC
- some e- carriers release protons to outside (into perimitochondrial space)
- H⁺ diffuse back into mitoplasm thru ATP synthase ---> ATP via a molecular motor*
- Boyer hypothesis* & animation of ATP synthase of mechanism by D. Nicholson*
- bacteriorhodopsin* provides experimental proof of H⁺ gradient making ATP

A-level Biology/Human Health and Disease/immunity

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Contents [hide] 1 Disease Defense 1.1 Cells of the immune system 1.1.1 Phagocytes 1.1.2 Phagocytosis 1.1.3 Lymphocytes 1.1.3.1 B Cells 1.1.3.2 T Cells 1.1.4 Antibodies 2 Immunity 2.1 Active and Passive 2.2 Vaccination 2.2.1 Problems 2.3 Smallpox 2.4 Measles 3 Allergies

[edit] Disease Defense

Our front line defense consists of a few things, and our overall defense has physical, chemical and cellular elements. The front line defense could be considered our skin, which provides an effective blocking mechanism for disease, combined with blood clotting that prevents pathogens entering through wounds. If pathogens reach the airway, the epithelial that cover the airways should prevent their entry, as should the mucus stop them, hydrochloric acid in the stomach kills the bacteria we ingest with our food.

Our immune response is helped massively by lymphocytes, which produce a special type of protein known as an antibody which acts against a certain antigen (foreign molecule), and is specific to this antigen. These antibodies are only secreted when the appropriate antigen is encountered and this may take several weeks to build up enough first time this happens (which is why you feel ill the first time you get chickenpox for example), but if the pathogen is spotted again there is a very rapid response that prevents even symptoms appearing.

[edit] Cells of the immune system

Bone marrow provides the cells of our immune system, and they are seperated into two groups;

• Phagocytes (including neutrophils and macrophages)
• Lymphocytes

See this light micrograph for a blood smear showing a monocyte (develops into a macrophage), a neutrophil and a lymphocyte. : [1]

[edit] Phagocytes

Phagocytes are constantly produced throughout a humans lifespan by the bone marrow and are stored there before being distributed in the blood. Their function is to remove any dead cells or invasive microorganisms.

Macrophages are a type of phagocyte that are more often found in organs - they leave the bone marrow and travel as monocytes, developing into macrophages once they settle into organs. They are long-lived cells and are vital in initiating the immune response since they do not destroy pathogens but cut them up to display antigens for lymphocytes to recognise.

Neutrophils are also type of phagocyte, smaller than macrophages and are around 60% of the bodies white blood cells - they patrol the body looking for invasion and can leave the blood by going through the capillaries into the tissues. During infection they are released en masse by have a short-lived cells.

[edit] Phagocytosis

When under attack large moble cells (mast cells) release histamine, and also the chemicals released by the pathogens attract passing neutrophils to the site - these neutrophils then destroy the pathogens via phagocytosis. Neutrophils recognise antibody molecules on the surface of the pathogens and attach to them, and the neutrophils plasma membrane then engulfs the pathogen and traps it in a vacuole, digestive enzymes take care of the rest. Neutrophils die shortly after and usually collect at the site of an infection in the form of pus.

[edit] Lymphocytes

Lymphocytes are smaller than phagocytes, but have a large nucleus that fills most of the cell (see the picture above). The two types are B and T lymphocyte cells. Only mature lymphocytes partake in the immune response, and many different types will develop - each type is specialised to respond to one antigen. The immune response depends on B and T cells interacting with each other to provide an effective defence. T cells are the coordinators, and they stimulate B cells to divide and secrete antibodies into the blood - these antibodies destroy on the antigenic pathogens and the T cells then seek out and kill any of the body's own cells.

• B lymphocyte cells (sometimes known as B-Cells) remain in the bone marrow until they are mature and then spread throughout the body, concentrating in the spleen and lymph nodes.

• T lymphocyte cells (sometimes known as T-Cells) leave the bone marrow and collect in the thymus gland until they mature.

[edit] B Cells

One B cell can make an antibody for only one type of pathogen - it is thought up to 8 million B cells can develop in each of us. Each immature B cell in the bone marrow divides to give a small number of cells able to make the same antibodies, called, appropriately, clones. They go to the plasma membrane of the bone marrow and form protein receptors, which combine specifically with one type of antigen. If this antigen enters the body, there will be mature B cells that can recognise it.

On the first invasion by the pathogens, i.e. the first time they are seen by the body, the primary response occurs -some are taken by macrophages to lymph nodes, with the macrophages exposing the pathogens antigens to the B cells in the lymph nodes. The B cells with the matcing receptor respond by dividing repeatedly by mitosis, producing huge numbers over a few weeks.

Some of these many become plasma cells, producing antibodies at a rate of several thousand a second, destroying the pathogens. The other B cells become memory cells, remaining in the body for a long time, providing a rapid immune response (the secondary response) by developing plasma cells much quicker than before, destroying the pathogen before it can affect the host. This is know as the immunological memory - these memory cells often last a lifetime, explaining why we get disease such as chickenpox once and never again - however diseases such as the common cold and influenza constantly mutate, meaning that our bodies defenses constantly have to be ready to deal with a new disease.

[edit] T Cells

T cells have specific receptors much like B cells that have a structure similiar to antibodies and are again specific to one antigen. T cells are activated when their antigen is found in contain with a host cell - sometimes a macrophage exposing the antigens or an invaded body cell.

T helper cells release cytokines that stimulate the appropriate B cells to divide, and they also stimulate macrophages to carry out phagocytosis more vigorously. Killer T cells (cytotoxic cells) search the body for invaded cells (it recognises them because they display the invaded molecules antigens on its plasma membrane's surface). Killer cells attach themselves to infected cells and secrete toxic substances to kill them and the pathogens inside. Memory T cells are produced which remain in the body and are used in the secondary immune response.

[edit] Antibodies

Antibodies (also known as immunoglobulins) are globular glycoproteins that are found in blood and are used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses. An antibody always consists of four polypeptide chains, two heavy, two light - disulphide bonds hold these chains together. Each molecule has two identical antigen binding sites, formed by two types of chains, and the sequences of amino acids in these regions are known as the variables, since they determine the antigen specificity.

The hinge section (see picture) provides flexibility for the antibody molecule to bind around the antigen. Some antibodies are known as antitoxins whose job it is to block the toxins released by bacteria.

Functions:

• Combine with viruses/toxins to prevent them from invading cells
• Attach to flagella of bacterium, restricting their movement
• Multi-binding to many bacteria at once, causing them to accumulate and prevent movement around the body
• Bursting bacteria cell walls
• Attach to bacteria making it easier for phagocytes to ingest them.

The black section of the picture is 'Di-Sulphide bonds, hinge area'. For some reason, it has not rendered correctly.

[edit] Immunity

Immunity as thus far described occurs during an infection, and is known as active immunity since lymphocytes are activated by antigens that have invaded the body.

[edit] Active and Passive

Active immunity can be natural or artificial. Natural active immunity is as described - when an organism invades the body and lymphocytes are activated by antigens to deal with it - artificial active immunity (in other words, vaccination) is the same except we are injected with active antigens (possibly weakened to ensure we are not infected) so that we do not get the disease in the future.

Passive immunity can also be natural or artificial. Artificial passive immunity is injecting human antibodies designed to deal with a specific disease, and is usually given to someone infected to said disease, so that they can fight it off and survive. This is a temporary protection, as they are foreign and will be removed by macrophages themselves, hopefully after they have destroyed the tetanus, for example, infection.

Natural passive immunity is designed to protect newborns, since their immune system is not fully developed - it is antibodies passed across the placenta, immunising (for a time), the baby against everything the mother is immunised against. Colostrum, produced by the mothers breasts is rich in antibodies and some will remain in the infants gut to prevent bacteria and viruses.

[edit] Vaccination

A vaccine is antigenic material, which could be a live, dead or harmless microorganism, or perhaps a harmless form of a toxic or simply surface antigens. This allows our immune system to produce the requisite B and T cells without actually suffering the disease, mimicking natural immunity.

[edit] Problems

Viruses are constantly mutating and changing - the reason we cannot create a vaccine against the common cold or influenza- by the time we have, it'll have mutated and the vaccine will not be effective. These mutations are known as antigenic shift or drift. Also, diseases like malaria are eukaroytic in nature and have far more genes and thus antigens on their cell surfaces.

Also, people sometimes do not respond well to vaccinations, maybe because their immune system cannot handle it, or they do not have enough protein to make antibodies - and thus the vaccination attempt may infect them. Also, people infected with a live virus may pass it out in their faeces during the primary response, potentially infecting others. This is why we vaccinate everyone at the same time, known as herd immunity.

Some viruses evade attack by the immune system by living inside cells - plasmodium (causes malaria) enters the liver and red blood cells, protected against antibodies in the plasma. Some parasites cover their bodies in host proteins, so that the immune system cannot see them. Vaccines cannot be easily produced against these because there is a very short period of time for the immune response to occur before the pathogen hides.

[edit] Smallpox

Smallpox was eradicated from the world in 1980 due to an incredibly successful program from the World Health Organisation (WHO ). Smallpox is characterised by red spots containing fluid appearing all over the body, swelling the victims eyelids and sometimes 'glueing' them together - it very often scarred and blinded people. It killed 12-30% of people.

The eradication program had two main aspects - vaccination and surveillance. Surveillance included watching for smallpox reports, and the vaccination section meant vaccinating everyone in the household and 30 surrounding households, aswell as all relatives and contacts in the area. This is known as ring vaccination, containing the transmission of the disease, destroying it at the source.

The program worked so well for a number of reasons.

• The program was particularly aggressive, and was helped by 16-17 year old 'enthusiastic vaccinators'.
• It was only a human disease, meaning it was easier to control
• One disease, one vaccine - cheap to produce.
• Easy to administer and very effective. It was a live virus, which is a very effective vaccination type.

[edit] Measles

Measles is a disease that causes a rash and fever, with potentially fatal complications. Measles is no longer common in the UK or most developed countries since most children are vaccinated. It and most commonly affects developing countries in places where conditions are overcrowded and insanitary. It can cause childhood blindness and severe brain damage, and is the ninth leading cause of death worldwide.

Unlike smallpox, measles requires several booster shots to develop full immunity, and in large cities with high birth rates, it can be difficult to give boosters or even follow up cases of measles. Refugees from these areas can spread the disease around, which makes it much more difficult to treat than smallpox. Measles is highly infectious.

[edit] Allergies

Allergies are caused by the immune system responding inappropriately to harmless substances which can lead to severe illness. Asthma and hay fever are examples of allergic reactions - reacting to allergens that are antigenic but shouldn't cause harm. When these allergens are inhaled, B cells produce antibodies and these coat the mast cells that are found in the lining of the airways, sensitising the body to these allergens.

Now, every time this allergen enters the body, the antibodies are stimulated to release histamine, causing the blood vessels to widen and become leaky - fluid and white blood cells leave capillaries. The area where histamines are released because hot, red and inflamed. In the case of hay fever the inflammation is in the eyes nose and throat.

Asthmatics have a more serious problem - their airways are nearly always inflamed, but during an asthmatic attack this inflammation worsens. Fluid leaks from the blood into the airways and the goblet cells secrete large amounts of mucus, blocking the smaller airways with fluid. This forces the muscles to contract, narrowing the airways and increasing air flow resistance. This makes breathing very difficult and can have fatal consequences. Asthma is a condition that is currently getting worse, 1/7 children in the UK have asthma. It has been linked to increased air pollution and passive smoking.

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Category: A-level Biology

Kinerja Guru Kunci Sukses

KINERJA GURU KUNCI SUKSES UJIAN NASIONAL

Pendidikan adalah usaha sadar dan terencana untuk mewujudkan suasana belajar dan proses pembelajaran agar peserta didik secara aktif mengembangkan potensi dirinya untuk memiliki kekuatan spiritual keagamaan, pengendalian diri, kepribadian, kecerdasan, akhlak mulia serta keterampilan yang diperlukan dirinya, masyarakat, bangsa dan negera (UU Sisdiknas No 20 Tahun 2003, psl. 1). Sejak Undang-Undang tersebut mulai diberlakukan, berarti ketentuan itu perlu senantiasa menjadi nafas setiap upaya pendidikan pada tiap jenjang dan jenis pendidikan di negeri ini.

Secara empiris guru adalah orang yang akan membawa dan mewujudkan suasana belajar dan proses pembelajaran yang inovatif, kreatif dan produktif di dalam kelas. Apa yang direncanakan, disajikan dan diperbuat guru dalam pembelajaran akan sangat mempengaruhi tingkat keterlibatan dan macam kemampuan yang dapat dimiliki siswa. Paling tidak bukti empiris itu ditunjukkan oleh signifikansi kotribusi guru terhadap prestasi belajar siswa di 16 Negara berkembang dan 13 negara maju. Menurut Supriadi (1998 : 178), di negara berkembang, kontribusi guru terhadap prestasi belajar siswa sebesar 34 %, sedangkan manajemen 22%, waktu belajar 18 % dan sarana fisik 26 %. Sedangkan di 13 negara maju (industri), termasuk Amerika dan Jepang kontribusi guru terhadap prestasi belajar sebesar 36 %, manajemen 23 %, waktu belajar 22 % dan sarana fisik 19 % . Oleh karena itu tidak berlebihan kiranya, jika Ronald Brandt (dalam Educational leadership (1993)) menyatakan bahwa “hampir semua usaha reformasi dalam pendidikan seperti pembaharuan kurikulum dan penerapan metode mengajar baru akhirnya tergantung kepada guru. Tanpa mereka menguasai bahan pelajaran dan strategi belajar mengajar, tanpa mereka dapat mendorong siswanya untuk belajar sungguh-sungguh guna mencapai prestasi yang tinggi, maka segala upaya peningkatan mutu pendidikan tidak akan mencapai hasil yang maksimal”.

Beberapa fakta dan deskripsi itu, menunjukkan bahwa guru memiliki peranan yang sangat penting dalam pendidikan. Apa yang disiapkan dalam pendidikan berupa sarana prasarana, biaya dan kurikulum, hanya akan bermakna jika diberi arti oleh seorang guru. Guru dapat tampil sebagai sosok yang menarik sebagai virus needs for achievement, dan dapat pula membawa siswa berfikir divergen, atau bahkan sebaliknya tidak menutup kemungkinan dapat tampil sebagai sosok membosankan, instruktif dan tidak mampu menjadi idola siswa pada proses pembelajaran, yang justru dapat mematikan kreativitas, menumpulkan daya nalar serta mengabaikan aspek afektif bagi siswa-siswanya.

UJIAN NASIONAL

Ujian Nasional adalah kegiatan pengukuran dan penilaian kompetensi peserta didik secara nasional pada jenjang pendidikan dasar dan menengah . Ujian nasional bertujuan untuk menilai pencapaian kompetensi lulusan secara nasional pada mata pelajaran tertentu dalam kelompok mata pelajaran ilmu pengetahuan dan teknologi. Hasil Ujian nasional digunakan sebagai salah satu pertimbangan untuk (a) pemetaan mutu satuan dan atau program pendidikan (b) seleksi masuk jenjang pendidikan berikutnya (c) penentuan kelulusan peserta didik dari program dan atau satuan pendidikan (d) pembinaan dan pemberian bantuan kepada satuan pendidikan dalam upaya peningkatan mutu pendidikan (Permen Diknas RI No. 34 tahun 2007).
Sukses ujian nasional akan diperoleh jika semua siswa di sekolah dapat memenuhi criteria kelulusan ujian nasional seperti yang ditetapkan Pemerintah. Kabupaten/Kota dan atau satuan pendidikan dapat menentukan standar kelulusan UN lebih tinggi dari yang ditetapkan pemerintah

UJIAN NASIONAL SEBAGAI SALAH SATU BENTUK HASIL BELAJAR DAN FAKTOR YANG MEMPENGARUHINYA

Menurut Sudjana ( 1989 : 39) hasil belajar siswa di sekolah, 70 % dipengaruhi kemampuan siswa dan 30 % dipengaruhi oleh lingkungan. Dijelaskannya (40) salah satu lingkungan belajar yang dominan yang mempengaruhi hasil belajar di sekolah adalah kualitas pengajarannya. Kemampuan siswa dan kualitas pengajaran berbanding lurus dengan hasil belajar siswa. Artinya makin tinggi kemampuan siswa dan kualitas pengajaran, makin tinggi pula hasil belajar siswa. Keberhasilan siswa menempuh ujian nasional dipengaruhi oleh berbagai faktor Menurut Djamarah (2002 : 123) “Faktor-faktor yang mempengaruhi keberhasilan belajar adalah tujuan, guru, anak didik, kegiatan pengajaran, alat evaluasi, bahan evaluasi dan suasana evaluasi”. Sedangkan menurut (Arikunto, 1993: 21; Dimyati dan Mujiyono, 1999: 43) “faktor yang mempengaruhi hasil belajar dapat dibedakan menjadi factor internal (faktor yang bersumber dari dalam diri manusia yang belajar) dan factor eksternal (faktor yang bersumber dari luar diri manusia yang belajar)”. Dijelaskannya factor internal mencakup faktor biologis ( usia, kematangan, dan kesehatan) dan psikologis (kelelahan, suasana hati, motivasi, minat dan kebiasaan belajar). Faktor eksternal meliputi faktor manusia (human) dan faktor non manusia seperti alam benda, hewan dan lingkungan fisik. Ditambahkan Slameto (2003) factor-faktor intern meliputi (1) faktor jasmaniah (kesehatan dan cacat tubuh) (2) factor psikologis (Inteligensia, Perhatian, Minat, Bakat, Motif, Kematangan, dan kesiapan) dan (3) Faktor kelelahan (kelelahan jasmani dan keleahan rokhani). Sedangkan factor ekstern mencakup (1) faktor keluarga (cara orang tua mendidik, relasi antar anggota keluarga, suasana rumah, keadaan ekonomi keluarga, pengertian orang tua dan latar belakang kebudayaan), (2) faktor sekolah (metode mengajar, kurikulum, relasi guru dengan siswa, relasi siswa dengan siswa, disiplin sekolah, alat pelajaran, waktu sekolah, standar pelajaran, keadaan gedung, metode belajar dan tugas rumah) (3) Faktor masyarakat (kegiatan siswa dalam masyarakat, mass media, teman bergaul dan bentuk kehidupan masyarakat). Sementara itu menurut Sumadi Suryabrata (1983) keberhasilan belajar dipengaruhi oleh (1) Bahan yang harus dipelajari (2) Faktor – faktor lingkungan (3) Faktor – faktor instrumental (4) Kondisi individu siswa.

Hasil penelitian Soedijarto (1981: 74) menunjukkan bahwa tingkat partisipasi pelajar secara signifikan memperngaruhi mutu hasil belajar, baik secara kognitif maupun secara afektif. Ditambahkan Boediningsih (1995 : 5) bahwa proses belajar yang dialami siswa mempengaruhi jumlah pengetahuan yang dikuasai siswa (tabel 1 ).

Tabel 1 : Tabel Hubungan Proses Belajar dengan Jumlah Pengetahuan yang Dikuasai Siswa

No	Proses belajar yang dialami siswa	Jumlah pengetahuan yang dikuasai
1	Membaca	10 %
2	Mendengarkan	20 %
3	Melihat	30 %
4	Melihat dan Mendengarkan	50 %
5	Mengungkapkan sendiri	80 %
6	Mengungkapkan sendiri dan mengulang pada kesempatan yang lain	90 %

Berdasarkan uraian itu diketahui bahwa hasil belajar siswa, termasuk hasil ujian nasional dipengaruhi oleh berbagai faktor. Dan diketahui bahwa faktor guru merupakan faktor yang dominan yang menentukan keberhasilan siswa dalam belajar. Karena itu upaya untuk meningkatkan peran kepala sekolah dalam meningkatkan kinerja guru pengampu mata pelajaran ujian nasional menjadi kebutuhan yang tidak dapat ditunda.

PERAN KEPALA SEKOLAH

Kepala sekolah yang berhasil antara lain dilihat dari kemampuannya sehubungan dengan perannya sebagai pendidik (educator), manajer (manager), administrator, penyelia (supervisor), pemimpin (leader), dan pencipta iklim sejuk (climate maker). Berdasarkan cakupan peran itu, dapat disampaikan bahwa terhadap berbagai proses dan hasil pendidikan termasuk prestasi Ujian Nasional, seorang kepala sekolah mempunyai makna yang strategis.

Sejalan dengan dinamika yang demikian cepat, Kepala sekolah dituntut juga untuk mengembangkan diri secara dinamis menuju peran kepala sekolah yang lebih produktif dan efektif dalam pengembangan sekolah. Hal itu sesuai dengan pernyataan John Henry Newman (1801-1890) yang menyatakan bahwa ”hidup itu perubahan. Kesempurnaan hidup muncul apabila terus diiringi perubahan”. Ditambahkan Ovid, Penyair Roma ternama (43 SM – 18 M), ” siapapun yang berubah tidak akan punah” (Kompas, 7 April 2003) Oleh karena itu seorang kepala sekolah harus dinamis, dan bahkan harus dapat berperan sebagai Agent of change dalam dinamika sekolah dan masyarakatnya.

Sebagai Agent of change, Kepala sekolah dapat berperan sebagai (1) calatist (2) solution givers (3) process helpers dan (4) resources linkers . sebagai catalist kepala sekolah harus dapat meyakinkan orang lain tentang perlunya perubahan menuju kondisi yang lebih baik. Solution givers berperan untuk mengingatkan akan tujuan akhir dari perubahan yang dilaksanakan. Cara boleh berubah, tetapi tujuan akhir harus tetap dipertahankan. Process helpers, Kepala sekolah dapat berperan dalam membantu kelancaran proses perubahan, khususnya menyelesaikan masalah yang muncul dan membina hubungan antara pihak-pihak yang terkait. Dan sebagai Resource linkers Kepala sekolah harus dapat berperan untuk menghubungkan orang dengan pemilik sumber dana / alat yang diperlukan.

Untuk dapat berperan sebagai agent of change maka diperlukan kerja keras kepala sekolah untuk berfikir dan bertindak secara dinamis, produktif, reflektif dan inovatif. Tenggelam pada tantangan masa kini tanpa melihat keteladanan adalah buta, namun tanpa antisipasi terhadap tantangan masa depan akan segera ketinggalan jaman

Di era otonomi daerah dan otonomi sekolah, Kepala sekolah dan segenap komunitas sekolah perlu memiliki kesamaan komitmen untuk mewujudkan sekolah yang efektif dengan tetap berpegang teguh pada budaya mutu. Guru semakin profesional dalam menjalankan tugasnya, mampu mengembangkan pendidikan sebagai suatu proses yang berkesinambungan, dan terus mengembangkan diri agar semakin dapat membantu keberhasilan belajar siswa. Guru mampu mengintegrasikan kecakapan hidup (life Skill) dengan melakukan reorientasi pembelajaran sehingga mampu (1) mengkaitkan bahan ajar dengan lingkungan terdekat siswa dalam kehidupan sehari-hari (2) memilih pendekatan dan atau metode pembelajaran yang variatif sehingga mampu melatihkan kecakapan hidup. Dengan demikian learning to know, learning to do, learning to live together dan learning to be dapat terjadi dalam pembelajaran di sekolah bukan sekedar wacana.

PENINGKATAN KINERJA GURU DALAM UJIAN NASIONAL

Nilai rata-rata Ujian nasional SMA Negeri 1 Klaten dalam dua tahun terahir meningkat. Diakui berbagai kalangan bahwa kualitas input siswa SMA Negeri 1 Klaten sudah baik, sehingga para pemerhati pendidikan menilai wajar jika output yang diperoleh cukup menggembirakan. Namun perlu pula disadari bahwa mempertahankan dan meningkatkan perolehan nilai yang tinggi bukanlah persoalan yang mudah, karena itu manajemen kinerja guru dalam kerangaka manajemen peningkatan mutu berbasis sekolah tetap menjadi sesuatu yang penting. Demikian pula jika kita menyadari bahwa guru merupakan faktor yang belum tergantikan dalam menentukan kualitas pembelajaran dalam pendidikan formal, maka upaya-upaya yang sistemik untuk meningkatkan kinerja guru perlu terus diupayakan.

Upaya peningkatan kinerja guru dapat dilakukan melalui berbagai cara diantaranya melalui Pendidikan/Pelatihan dan peningkatan kesejahteraan. Pembinaan melalui proses pendidikan dapat dilakukan melalui berbagai seminar, pelatihan dan lokakarya, workshop, simposium, seminar, penelitian, dan melanjutkan studi lanjut di perguruan tinggi. Pendidikan dapat pula dilakukan melalui pembinaan oleh atasan langsung (kepala sekolah) atau petugas khusus yang memiliki kewenangan untuk melakukan supervisi pendidikan yang dikenal dengan sebutan pengawas sekolah (supervisor). Melalui pelaksanaan supervisi yang efektif seorang supervisor dapat mengontrol, membina, mendorong dan memotivasi guru untuk melaksanakan tugasnya secara berkualitas.

Peningkatan kinerja guru dapat dilakukan juga melalui peningkatan kesejahteraan. Kesejahteraan dapat berupa kesejahteraan material (gaji, honorarium, insentif, bonus, tunjangan, dan fasilitas fisik) dan non material yang mengarah kepada kepuasan kerja. Dengan demikian pemberian kompensasi kerja yang berupa gaji, insentif ataupun tunjangan atas prestasi kerja seorang guru dapat mempengaruhi kinerja guru. Paling tidak, hal itu ditunjukkan oleh hasil penelitian Lasa (2006) menunjukkan bahwa pelaksanaan supervisi dan kompensasi kerja berpengaruh positif dan signifikan terhadap kinerja guru SMA Negeri 1 Klaten.

Secara umum upaya yang dilakukan SMA Negeri 1 Klaten untuk meningkatkan kinerja guru dan perbaikan kualitas pembelajaran antara lain (1) melengkapi sarana dan prasarana pendidikan yang sesuai dengan kebutuhan,antara lain buku referensi,komputer di ruang guru, laptop, Scanner dll. (2) memacu guru untuk mengembangkan pembelajaran berbasis ICT (3) Mengirimkan semua guru untuk mengikuti pendidikan dan pelatihan ICT (Microsoft Office) (4) mengirimkan guru dan tenaga pendidikan untuk mengikuti kursus bahasa inggris (5) Mengadakan IHT (6) menghadirkan pakar (7) Mengirimkan guru pada forum ilmiah (8) Mengadakan Workshop pengelolaan sekolah pada awal tahun pembelajaran (10) Memberikan Honorarium sesuai dengan tugas dan tanggungjawabnya (11) Menyediakan akses internet 24 jam di ruang guru. (12) Mengadakan ulangan umum secara mandiri, dengan LJK dan dikoreksi dengan Scanner. Dan direncanakan untuk mengembangkan penilaian on-line. (13) Melakukan supervisi klinis dan supervisi akademis

Disamping upaya yang dilakukan secara makro seperti di atas, untuk memperoleh sukses ujian nasional, maka secara khusus SMA Negeri 1 Klaten (1) Membentuk tim sukses ujian nasional, berdasar hasil evaluasi tahun dan semester sebelumnya (2) mengoptimalkan pembelajaran untuk mata pelajaran Ujian Nasional di kelas XII dan membuat pelajaran yang kondusif untuk mata pelajaran yang lain (menciptakan iklim sejuk) (3) memberikan tambahan jam pelajaran (4) Mengadakan klinis bidang studi (5) melakukan try out minimal 3 kali (6) Melakukan monitoring dan evaluasi secara terencana, terpadu dan berkesinambungan (8) Memberikan tambahan insentif kepada personel yang terlibat dalam kegiatan tambahan pelajaran (9) Memberdayakan segenap potensi yang ada untuk pengembangan pembelajaran untuk mata pelajaran yang diujikan (10) menambah sarana dan prasarana pendukung pembelajaran, alat dan bahan praktikum laboratorium dan buku latihan soal ujian nasional (11) melakukan konsultasi, koordinasi dan studi banding dengan pihak terkait.

Akhirnya jika kita ingin sukses dalam ujian nasional, menginginkan pendidikan yang benar untuk mencerdaskan kehidupan bangsa, kiranya kualitas proses pembelajaran formal di kelas dan sekolah perlu diupayakan. Peningkatan kemampuan profesional dan penghargaan terhadap guru perlu terus dilakukan.

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