[Biology] GCSE Biology Topics

adapted from Pass My Exam.

Living Cells and Life Processes

1. Life Processes

• Movement
• Respiration
• Sensitivity
• Growth
• Excretion
• Reproduction
• Nutrition

2. Cells

• What are Cells?
• Structure of Animal and Plant Cell
• Similarities and Differences between Animal and Plant Cells
• Cell Specialisation– Animals
• Cell Specialisation– Plants
• Unicellular Organisms
• Multicellular Organisms
• Cells, Tissues and Organs

3. In and out of cells

• Diffusion
• Osmosis
• Active transport

4. Enzymes

• What are Enzymes?
• How Enzymes work
• Optimum conditions for enzymes

The Living body

1. Food and Digestion

• Why we need food?
• A Balanced Diet
• Carbohydrates
• Proteins
• Fat
• Fibre
• Vitamins and Minerals
• Water
• Digestion
• The Digestive System
• Animation of the Digestive System
• Enzymes and Digestion

2. Breathing and Respiration

• Breathing
• Respiration
• The Breathing System
• Gas Exchange
• Gas Exchange Animation
• Process of Respiration
• Types of Respiration, Aerobic and Anaerobic
• Breathing and Exercise
• Respiratory Diseases
• Smoking
• Asthma

3. Reproduction and Growth

• Asexual Reproduction
• Sexual Reproduction
• Male Reproductive System
• Female Reproductive System
• Menstrual Cycle and hormones

4. Blood and the Circulatory system

• Cardiovascular System
• Components of Blood
• Red Blood Cells
• White Blood Cells
• Platelets
• Plasma
• Arteries
• Veins
• Capillaries
• The Circulatory System
• The Heart
• The Cardiac Conduction System

The Plant World

• What is Photosynthesis?
• The structure of a Leaf
• Factors affecting the rate of Photosynthesis
• Light
• Temperature
• Carbon dioxide
• The importance of Photosynthesis
• Gas Exchange in Plants

[Biology] How Blood Pressure is Regulated

(10 marks essay)

Blood pressure is regulated by a negative feedback mechanism.

a) Blood pressure increases during strenuous exercise

1. Baroreceptor in the wall of the aorta and carotid arteries are stimulated.
2. Rate of nerve impulse increase, 
3. the impulse is sent at a faster rate 
4. to Cardiovascular centre in the medulla oblongata.
5. Nerve impulses (parasympathetic nerve) are sent to effectors
6. Causing relaxation (vasodilation) of smooth muscle in the blood vessel wall 
7. resistance of the blood flow in blood vessels reduces, 
8. weaker cardiac muscle contraction and 
9. decrease of heartbeat rate 
10. thus caused the blood pressure decreases and regulate to normal blood pressure.

b) Blood pressure decreases when in a state of shock

1. Baroreceptor in the wall of the aorta and carotid arteries are less stimulated.
2. Rate of nerve impulse decrease, 
3. the impulse is sent at a slower rate 
4. to Cardiovascular centre in the medulla oblongata.
5. Nerve impulses (sympathetic nerve) are sent to effectors 
6. Causing contraction (vasoconstriction) of smooth muscle in the blood vessel wall 
7. resistance of the blood flow in blood vessels increase, 
8. stronger cardiac muscle contraction and 
9. increase of heartbeat rate 
10. thus causing the blood pressure decrease and regulate the blood pressure to the normal blood pressure.

Baroreceptor

**to detect the pressure of blood 

@ arch of aorta & carotid arteries.

Biology Notes from Cikgu Naza

Happy 21.12.2012. LOL
See what I found on Cikgu Naza's blog?
NOTES FOR BIOLOGY!!!
although some of it isn't complete but the notes are pretty awesome.
Hope you enjoy! :) x

* I DO NOT OWN ANYTHING. 

Form 4

• Animal Cell & Plant Cell
• Being Multicellular
• Breathing Under Water
• Cell Division
• Cell Structure & Organisation
• Class Of Chemicals
• Diffusion
• Enzymes Extraordinaire
• Gaseous Transfer
• Human Respiratory System - The Network Within
• How to Synthesis Extracellular Protein
• Meiosis
• Meiosis - Process
• Meiosis - Phases
• Meiosis - The Significance & Nondisjunction
• Meiosis In Humans
• Mitosis
• Mitosis - Significance & Consequences Of Errors
• Movement Across The Plasma Membrane
• Nutrition
• Occurrence Of Meiosis In Eukaryotic Life Cycles
• Organelle 1
• Organelles And Its Function
• Phases Of Cell Cycle And Mitosis - Interphase
• Phases Of Cell Cycle And Mitosis - Preprophase
• Phases Of Cell Cycle And Mitosis - Prophase
• Phases Of Cell Cycle And Mitosis - Prometaphase
• Phases Of Cell Cycle And Mitosis - Metaphase
• Phases Of Cell Cycle And Mitosis - Anaphase
• Phases Of Cell Cycle And Mitosis - Telophase
• Phases Of Cell Cycle And Mitosis - Cytokinesis
• Plant & Growth
• Plasma Membrane
• Program Bestari Fasa 2 - Cell Division
• Program Bestari Fasa 2 - Chemical Composition Of The Cell
• Proteins
• Roles That Vary
• Single Cell
• Stage In Meiosis
• The Haploid Cells

Form 5

• Aquatic Adaptation
• Characteristics - Laws of Inheritance
• Clotting Helps!
• Crossing Variants
• Human Heart
• Meeting Gametes
• The Daily Transporter
• What's In Our Blood - Riddles

The Transport of Substances in Plants

Based on the Integrated Curriculum for Secondary Schools. KBSM.
Biology Form 5, Chapter 1-Transport,
1.7 The Transport of Substances in Plants

You must concentrate on these points:
☑ State the necessity for transport of substances in plants
☑ Identify the vascular tissue in stem, root and leaf.
☑ State the role of vascular tissue in the transport of substances
☑ Describe the structure of the vascular tissue
☑ Relate the structure of xylem to transport
☑ Relate the structure of phloem to transport
☑ Predict the effect of removing a ring of phloem tissue from a plant.

The necessity for transport of substances in plant? (answered by Pounds, thanks! x )
a) transport water and mineral salts absorbed from roots.
◎ water-solvent for biochemical reaction & reactant for cell metabolism (light reaction: photosynthesis)
◎ mineral salts / ions - synthesis chlorophyll, for healthy plant growth and development
b) be able to carry out photosynthesis. 
c) be able to synthesis organic substances.
d) transport carbohydrates (food) produced by leaves to stem and roots for respiration, growth and storage.

The problem that could be faced by plant in transporting substances and how it is overcome in plants?
Problems: 

◎ The roots absorb water and mineral salts which are transported upwards to the leaves and other parts of the plant several metres up.
◎ Plants are unable to pump necessary substances through great distances
◎ Sometimes requiring the need to defy gravity.
How is it overcome?
◎ Plants use a combination of root pressure, capillary action and transpiration to provide enough force to transport water to the shoot.

Transport in plant is provided by the vascular tissues. 

2 types of vascular tissues: xylem & phloem.

Vascular tissue in stem, root and leaf

is found in:-

◎ ROOTS

◎ STEMS

◎ LEAVES

Xylem

★ Transports water and dissolved mineral salts (absorbed in the roots, up the stem and to the leaves)

★ (in woody plants), provide mechanical support to the plant.

Phloem

★ Transport organic substances downwards (from the leaves to the storage organs), 

★ and also upwards (from the storage organs) such as the roots to the growing regions such as the buds.

THE STEM has an:

★ epidermis layer that helps maintain the shape of the stem.

✐ (in young plants) epidermis cells may secrete a waterproof cuticle.

✐ (in older plants) the epidermis may be absent, replaced by bark.

Just inside the epidermis is:

★ cortex layer 

✐ made up of parenchyma cells .

✐ which provide support and flexibility to the stem.

Inner part of stem (central region) consist of:

★ pith & vascular tissues

★ pith is: 

✐ used for food storage in young plants.

✐ may be absent in older plants.

In dicotyledonous plants, 

✿ the vascular tissues of the stem → grouped together → form vascular bundles.

✿ vascular bundles are arranged in a ring around the pith, the central region.

✿ in each bundle, the xylem is found towards the inside of the stem, phloem is found towards the outside.

✿ cambium ( a tissue) is found between xylem and phloem.

✿ cambium cells can divide resulting in an increase in the radius of the stem.

In monocotyledonous plants,

✿ the vascular bundles are scattered throughout the stem.

THE ROOTS

The cross section of a dicotyledonous root is shown in photograph below.
(Photograph found on: http://sci.waikato.ac.nz/farm/images/dicot%20stem_labelled_web.png)

★ The outermost layer is the epidermis.

✐ does not have waxy cuticles.

★ In one region of the root, specialised epidermal cells grow outwards to form root hairs.

✐ increase the surface area for water absorption.

✐ a single plant may have more than 10 million root hairs.

★ The region next to the epidermis is called the cortex. 

✐ made up of parenchyma cells ( which may store starch grains)

★ Located immediately after the cortex is a single layer of cells called the endodermis.

★ Inside the endodermis is the pericycle. 

✐ consists of sclerenchyma tissue which provides mechanical support for the root.

★ In roots, the vascular tissues are located in vascular cylinder.

✐  consists of the vascular tissues (xylem and phloem) and the pericycle.

✐  the vascular tissues in roots are continuous with the vascular tissues of stems.

✐  xylem radiates from the centre of the vascular cylinder, forming a star shape.

✐  phloem fills the area between the xylem.

The cross section of a monocotyledonous root is shown below

★ vascular cylinder has a central core called the pith.
✐ pith contains parenchyma cells
✐ vascular tissues form a ring around the pith with the xylem tissues alternating with the phloem tissues. 

THE LEAF

★ consists of a board portion called the blade

★ blade is connected to the stem by a leaf stalk called the petiole.

★ inside the petiole are vascular tissues of xylem & phloem that are continuous with those in the stem, root and blade.

★ the leaf blade contains leaf veins. 

★ vascular tissues are found in the leaf veins.

★ xylem forms upper part of a vascular bundle in the leaf

★ phloem forms lower part of the vascular in the leaf

The structure of xylem in relation to transport.

Xylem contains 4 types of cells:-

★  xylem vessels,

★  tracheids,

★  parenchyma (to store food substances) and 

★  fibres (to provide support) ( a type of sclerenchyma)

✐ xylem vessels and tracheids are water-conducting cells. 

✐ they are elongated cells arranged end to end.

Tips: make sure you also know the cross sections an longitudinal sections of xylem.

During development, 

✐ the walls of xylem vessels and tracheids are thickened with lignin deposits, making them woody and impermeable.

✐ mature xylem vessels and tracheids are perforated by a series of holes called pits (allow water and mineral salts to pass sideways between the cells)

Difference between xylem vessels and tracheids. 

✐ Tracheids are longer and have a smaller diameter compared to xylem vessels.

✐ Tracheids are pointed at the ends. 

✐ The end walls break down in pits that allow water to pass from cell to cell.

✐ The end walls of xylem vessels are open (so that the cells join end to form a continuous hollow tube)

✐ this allows water to flow upwards continuously. 

✐ The cell walls are thickened with lignin ( makes the xylem vessels strong, do not collapse under the tension created by the upward pull of water during transpiration) 

The structure of phloem in relation to transport.

Phloem is composed by 4 types of cells:-

★ Sieve Tube, 

✐ organic substances are transported along the sieve tube, 

✐ cylindrical column of long cells arranged end to end, 

✐ is a living cell, no nucleus and its cytoplasm is pushed to the sides of the cell when mature, 

✐ end walls of each cell are perforated by pores to form sieve plates, 

✐ each sieve tube cell is kept alive and supported in their function by one or more companion cells

★ Companion Cell, 

✐ is a normal cell with a nucleus and a large number of mitochondria, 

✐ indicating that it is very active metabolically

Tips: Check out the longitudinal sections of phloem showing sieve tubes and companion cells too.

★ Parenchyme, 

✐ to store food substances

★ fibres. 

✐ to provide provide support

What is the effect of removing a ring of phloem tissue from a plant? ( Bark Ringing) 

Aim: To carry out bark ringing to show the role of phloem in a plant.
Materials: A pot containing two woody plants (such as hibiscus) and petroleum jelly
Apparatus: Knife and ruler
Procedure:

1. A complete ring of bark including the phloem and cambium is removed from one of the hibiscus stems. The ring is about 4 cm wide and about 15 cm long from the ground.
2. The exposed xylem is covered with a layer of petroleum jelly.
3. The plants are watered regularly.
4. After four weeks, the parts above and below the ring are observed. 

Observation: 

Discussion:

1. Bark ringing is the removal of ring of tissue external to the xylem from around the trunk of a woody plant.
2. The ring is covered with petroleum jelly to prevent it from drying up.
3. Complete ringing affects the transport of organic substances from the leaves to the roots due to the roots due to the disconnection of phloem at the ring.
4. After a few weeks, there is swelling above the ring and reduced growth below the ring.
5. Prediction: Gradually the roots will die because they cannot get food from the upper part of the plant. When the roots die, there will be no absorption of water and mineral salts. Eventually, the whole plant dies.

Conclusion: Phloem transports organic substances manufactured in the leaves to the roots.

Questions:

Get yourself a piece of paper and ready to answer these questions.

You can get the answers from the notes above. :)

1. What is meant by the term vascular system in a plant?

2. Draw the cross sections of dicot stem and dicot root.

3. Predict the effect of removing a ring of phloem tissue from a woody plant.

4. How does the arrangement vascular bundles in dicotyledonous stems differ from the monocotyledonous stems?

5. State the main function of xylem. What are the common cells found in xylem and phloem tissues?

6. State one similarity between the phloem sieve tube and the xylem vessel.

The Role of the Circulatory System in the Body's Defence Mechanism

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Based on the Integrated Curriculum for Secondary Schools. KBSM.
Biology Form 5, Chapter 1-Transport,
1.5 The Role of the Circulatory System in the Body's Defence Mechanism.

Body's Defence Mechanisms 
Function: to protect body against disease-causing microorganisms- Pathogens.
Example of pathogens are bacteria, viruses, parasites.
Fever is part of the body's defence mechanism against infection. It increases the activity of phagocytes and combats invading microorganism.

1) State another function of circulatory system other than transport.
circulatory system also defends the body against disease-causing microorganisms. (Pathogens)

2) Three lines of defence
a) The first line of defence
b) The second line of defence
c) The third line of defence

a) The first line of defence ( Prevent pathogens from entering the body!) 

i) Physical barriers
ii) Chemical barriers

Example: 

Skin
- outer layer of the skin is tough (provides a physical barrier) that is impermeable to bacteria and viruses.
- continual shedding of dead skin cells, makes it difficult for bacteria to grow on it.
- secrets sebum, ( chemical barrier) which form a protective film over the skin.
- excreta sweat, contain an enzyme, lysozyme, which capable of breaking down the cell walls of certain bacteria.

Mucous Membrane ( that lines trachea, respiratory passageways, digestive and urogenital tracts)
- secret sticky fluid called mucus that contain lysozyme, trap and destroy bacteria.
- @nose, mucus-coated hairs, that traps and destroys pollutants from inhaled air.

Tears and saliva 
- contain lysozyme which helps protect the eyes and mouth form bacterial invasion.

WHERE can pathogens gain entry into our body?
The digestive tract. Pathogens present in the food and drinks that we consume can enter the alimentary canal. HOWEVER, stomach secrets hydrochloric acid which destroys most microorganism. 

b) The second line of defence (to prevent or overcome any invasion by pathogens!) 

Phagocytosis is a process by which phagocytic white blood cells engulf and ingest microorganisms or other particles such as cellular debris.

TWO main types of phagocytes
**Neutrophils @ blood
**Macrophages mostly found @ interstitial fluid

When infection occurs, 

1. Neutrophils and monocytes migrate to the infected area 
2. During migration, monocytes enlarge and develop into macrophages
3. They enter the interstitial fluid by squeezing through capillary walls
4. When a phagocytes encounters an invading pathogen, phagocyte ( neutrophils & macrophages) engulf the pathogen.
5. Enzyme lysozyme kills the pathogen.

Phagocytosis

c) The third line of defence (immune system)

Immune system, is a specific or targeted defence. It recognizes specific pathogens and defends the body against them.

Immunity,  mean the state in which the body is resistant to infection by a disease-causing pathogen.
For example, a virus. If you're exposed again to the particular virus, your body will recognize and destroy that virus before it can trigger symptoms of the illness. Hence, you acquire immunity after being infected by the pathogen.

Antigens, are large complex molecules ( normally a protein) that the immune system recognizes as foreign. Normally found on the outer layer of an invading microorganism. Some dissolved in blood plasma or interstitial fluid, like snake venom and bacterial toxin.

During an infection, 

1. immune system identifies the antigens invading body.
2. the antigens induce the lymphocytes to release antibodies into bloodstream to destroy particular antigen.

Antibodies, are proteins found on the surface of lymphocytes/ proteins released by lymphocytes into blood plasma.

Immune response,  the interaction between antibody and antigen which result in the antigen being eliminated from the body.

The mechanism used by antibodies to destroy antigens ( 4 types)

Agglutination 

1. Antibodies can clump pathogens together
2. The clumping makes the pathogens easy targets for phagocytes to capture and destroy.

Neutralisation

1. Antibody can neutralize the toxins produced by bacteria by binding to toxin.
2. Prevents the toxin from attaching to cells and causing damage.

Opsonisation

1. Opsonins are antibodies that bind with antigens to act as markers.
2. So that the phagocytes can recognize the antigens and destroy them.

Lysis 

1. Lysisns are antibodies that bind to antigens and cause the antigens to rupture or disintegrate.

3) State another function of lymphatic system other than returning excess interstitial fluid to the circulatory system.
Lymphocytes are distributed throughout the body in the blood and lymph. Lymphatic system also helps defend the body against invasion by pathogens  When a person has an infection, pathogens and white blood cells collect in great numbers in the lymph notes. The lymph notes may become swollen. The lymph notes contain macrophages that destroy bacteria, dead tissue, and other foreign substances by phagocytosis. They also contain lymphocytes that destroy antigens and foreign substances.

Antigen Receptor (antibody molecule antigen-binding site)
Each antibody can only bind to a specific antigen.

a) Antigen binds to the antigen-binding site of the antibody.

b) Each type of antibody can only bind to a particular type of antigen.

c) After binding to the antigen molecule, the antibody will destroy the antigen in different ways.

The Various Types of Immunity 

There two types of immunity, both types of immunity may develop either naturally or artificially:

1. Active Immunity ( means the body makes its own antibodies in response to stimulation by an antigen)
2. Passive Immunity ( means the body receives antibodies from an outside source)

Active Immunity

• does not offer immediate immunity against a disease.
• time lag between infection and a full immune response because the body needs time to make its own antibodies against a particular antigen
• usually a long-lasting immunity

Naturally acquired active immunity, once the person recovers from the infection, he will be immune if exposed to the particular pathogen again. Permanent immunity follow the infection.

Artificially acquired active immunity.

Immunisation is the process of inducing immunity by administering a vaccine. 

Vaccine is a preparation of weakened, dead or non-virulent forms of pathogen. When vaccine is injected into the body, it will activate the body to produce antibodies.Since the pathogen is modified or weakened, an individual gets mild or no symptoms of the disease. The body acquire immunity by vaccination. 

p/s: 

*For certain diseases, booster dose of the vaccine are to be given periodically. 

*1st dose usually result in the production of a low level of antibody concentration which is not sufficient to protect a person against the disease.

*The booster dose is necessary to increase antibody production to a level of immunity that protects the person against the disease.

The concentration of the antibodies in blood during first and second vaccinations

Passive immunity

Naturally acquired passive immunity

• Occurs when a foetus is still in the uterus. 
• Maternal antibodies cross the placenta to the foetal bloodstream.
• They protect the baby during the first few months after birth.
• babies can also acquire passive immunity from antibodies found in the mothers milk or colostrum during breastfeeding.

Artificially acquired passive immunity 

The difference between active and passive immunity

• involves the injection or transfusion of serum containing antibodies against the disease.
• serum which contains antibodies or antiserum from donors can be injected into a person who needs antibodies before he travels to a country in which a disease is widespread.
• these antibodies temporarily protect the person in the event of exposure to the pathogen that cause the disease.
• effective, but only lasts as long as the antibodies remain in the blood, usually about 3 months 
• short lived, offers only immediate, short term and temporary protection

AIDS

Human immunodeficiency virus (HIV) is a virus that attacks the immune system. 

Infection results in acquired immunodeficiency syndrome (AIDS).

AIDS is

• a condition in which a person who is infected experiences various infections. 
• may be symptom-free for many years (even when the virus is actively attacking the immune system)
• effects of disease may take 8-10 years to show
• due to the progressive destruction of the immune system cells

Effects of HIV on the body's defence system

• the virus reproduces inside the lymphocytes and kills them in process
• immune system is weakened, the body is prone to infections
• immune system collapses and the victim dies of an infection

Describe the transmission of HIV

• HIV enters the body through the transfer of body fluids such as blood and semen, or across placenta
• newborns can become infected with the virus from their infected mothers during delivery (usually preventable with proper medical treatment of the mother during pregnancy and delivery)
• teenagers and adults can get the disease from unprotected copulation with infected individuals
• by sharing contaminated needles used for injecting drugs or tattoo ink
• NO vaccine against HIV although certain drugs may stop the disease from progressing

HIV is not transmitted by:

• saliva, tears and sweat
• insects
• swimming in the same pool as someone who has AIDS
• shaking hands with someone who has AIDS
• sitting next to someone who has AIDS

Suggest ways to prevent the spread of AIDS 

The following answers is adopted from eHow Health, by an eHow Contributor.

1. Having protected sexual intercourse (using condoms) is about the single easiest way to protect yourself from HIV. Never have sex without one unless you are in a monogamous relationship where both partners have been tested twice. Spermicides and birth control pills are useless in preventing the spread of HIV.
2. Do not share needles. Drugs are never good, but when you share a needle, in addition to the harm the drug itself can cause, you are also putting yourself at a higher risk of catching HIV. Ending all drug use is the best possible solution.
3. A mother with HIV runs the risk of spreading the infection to her unborn child. This risk can be reduced by taking anti-retroviral drugs or a single dose of Nevrapine at delivery. Any mother with HIV should discuss the options with her doctor to help prevent spreading to her child.
4. Educate teens. The teenage years are the most susceptible to risky behavior. Talk to your teen about the dangers of unprotected sex. Answer questions they have honestly. Open communication will help your teen resist peer pressure when it comes to sex or drugs.
5. Get the whole family involved. Family activities keep the whole family busy and build strong relationships. A healthy family environment can keep teens from peer pressure by not only allowing an open door policy with mom and dad, but good ways to fill their free time.
6. Blood transfusions are another way HIV is spread. It is rare because the blood is tested, but unfortunately it can occur. Whenever possible, donate your own blood if you know you will be having a procedure that will require a blood transfusion.

The Role of the Circulatory System in the Defence Mechanism of the Body

1. Not only transport, circulatory system defends the body against foreign bodies, especially disease-causing microorganisms.
    < NOT lymphatic system, now we are talking about circulatory sys. >

2. There are 3 lines of defence mechanisms in our body:
- the first line of defence
- the second line of defence
- the third line of defence

The first line of defence

1. It consists of physical and chemical barriers that prevent pathogens from entering the body.

2. Pathogens are disease-causing microorganisms. e.g.: bacteria, viruses and parasites.

3. The barriers are non-specific defences, that is, they do not differentiate one pathogen from another.

4. The first line of defence : the skin, mucous membrane and others.

The Skin

1. The tough outer layer : provides physical barrier that is impenetrable (不能穿透的） to bacteria and viruses.

2. The continues shedding of dead skin cells makes it difficult for bacteria to grow on skin.

3. The skin is also a chemical barrier. [WHY?] --> secretes sebum that forms a protective film over the skin. The acids and oils in sebum prevent the growth of many microorganisms.

4. The sweat excreted contains lysozyme (F4 C2: :from lysosome), an enzyme capable of breaking down the cell walls of certain bacteria.

Mucous Membrane

1. They line the trachea, respiratory passageways, digestive and urinary tracts to stop the entry of potentially harmful microorganisms.

2. It secretes a sticky fluid called mucus that contains lysozyme which traps and destroys bacteria.

e.g.: nose  ->  mucus-coated hairs  ->  trap & filter microorganisms, dust and pollutants from inhaled air

Other first line of defences

1. Tears and saliva contain lysozyme -> protect eyes and mouth from bacterial invasion.

2. Hydrochloric acid (stomach) -> destroys most pathogens from food and drinks consumed.

3. Blood clotting mechanism -> prevents entry of pathogens by sealing the wound. (revise back)

** P/S : Most secretion contain lysozyme in first line of defence ** 

The second line of defence

1. also non-specific and functions to prevent or overcome any mocrobial invasion.

  

2. Phagocytocic white blood cells or phagocytes can perform phagocytosis.

3. Main phagocytes are neutrophils and monocytes.

4. Process of phagocytosis on infection part:

(a). When an infection occurs, they migrate to the infected area, attracted by chemicals released by damaged cells.

(b). They enter interstitial fluid by squeezing through capillary walls.

(c). During migration, monocytes enlarge and develop into macrophages. Macrophages are found mainly in interstitial fluid.

(d).When a phagocyte encounters an invading pathogen, it engulfs and ingests the pathogen in a process known as phagocytosis.

(e). Inside phagocyte, pathogen is destroyed by lysozyme.

(f). Figure.

The Third Line of Defence

1. It involves the immune system.

2. Specific or targeted defence = recognises specific pathogens, cancer cells and certain chemicals, and defends the body against them.

3. Immunity means the body resistance to the pathogen which causes a specific disease.

4. The external surface of an invading microorganisms contains specific molecules called antigens.

5. Antigens.

(a). They are substances, usually proteins, that the immune system recognises as foreign or not part of the body. Normally found on the outer surface of an invading microorganism. 

(b). Include snake venom and bacterial toxins.

6. When immune system identifies the antigens invading body, it is stimulated to defend body against those antigens. This type of defence is known as an immune response.

7. Each antigen induces certain lymphocytes to secrete specific antibodies that only react specifically with that antigen.

8. Antibodies are proteins found on surface of lymphocytes, or proteins released by lymphocytes into the blood plasma.

9. Interaction between antibody and antigen -> elimination of antigen from body -> immune response

10. An antibody molecule has an antigen-binding site or antigen receptor.

(a). The antigen-binding site is highly specific.

(b). 像enzyme, each binding site has particular shape that fits the one found on the antigen.

11. After it is bound to the antibody molecule, the antigen can be destroyed in several ways.

12. Figure : agglutination, neutralisation, organisation and lysis.

... to be continued ...

Appreciating a Healthy Cardiovascular System

Based on the Integrated Curriculum for Secondary Schools. KBSM.
Biology Form 5, Chapter 1-Transport,
1.6-Appreciating a Healthy Cardiovascular System

Disease that are linked to cardiovascular system takes usually years to develop) 
Some examples are:-

• coronary thrombosis
• atherosclerosis
• heart attack

Factor that contribute to cardiovascular disease
a) genetic factors

b) controllable factor (type of food we eat, lifestyle we lead)
-a diet in high fat, low in fibre
- lack of exercise
- obesity
- smoking
- stress
- high cholesterol levels
- deficiencies in antioxidant vitamins& minerals.

How to reduce the risk of cardiovascular diseases? 
- individuals have to be aware of the need of maintain a healthy cardiovascular system from young.
- leading a healthy lifestyle which include
*regular exercise, and
* proper diet.

The Lymphatic System

Printable Google Doc is now available click  here to get. :)

Based on the Integrated Curriculum for Secondary Schools. KBSM.
Biology Form 5, Chapter 1-Transport,
1.4-The Lymphatic System

1) Formation of interstitial fluid
Blood enters the arterial end of capillaries is under high pressure , the pressure is sufficient to cause fluid leak continuously from blood to spaces between cells.

**What is interstitial fluid? 
Fluid that fills the spaces between the cells.

2) Composition of interstitial fluid.

Interstitial fluid consists of:

• water
• dissolved nutrients
• hormones
• waste products 
• gases 
• small protein from blood 
• leucocytes ( that can ooze through the openings between the capillaries cells )

Interstitial fluid does not consists ( because they are TOO LARGE to pass through capillaries):

• plasma proteins ( albumin, fibrinogen, globulin )
• erythrocytes
• platelets

3) Importance of interstitial fluid 
a) Important to cell because through this fluid that exchanges material between blood capillaries & cells occurs.
b) Nutrient & oxygen diffuse through interstitial fluid into body cells.
c) Carbon Dioxide and waste product diffuse through interstitial fluid into the blood.

4) Fate of interstitial fluid

Where did the 15% of the fluid go?
-The fluid must be returned to the circulatory system to maintain normal blood volume.

For more understanding about the fate of interstitial fluid, please watch the following video. This video also explain breifly about the lymphactic system.
(Which uploaded by Rene LaMontagna on Aug 10, 2010 on YouTube.)

Starts from 1:35- 3:18


5) Structure of lymphatic system

What is lymph?
Interstitial fluid that are not absorb back to the bloodstream drains into the LYMPH CAPILLARIES. This collected fluid is known as Lymph. Lymph is a transparent yellowish fluid.

Lymph also contain tiny droplets of lipids.
-The intestinal lining of the small intestine is covered by villi
-villi contain lacteals
-lacteals are lymph capillaries (droplets of lipid and fat-soluble vitamins are transported to the bloodstream)

Lymphatic system?
-Collect most of the excess interstitial fluid (lymph) from the spaces between the cells and returns it to the circulatory system.
-is a network of lymph capillaries and larger vessels.

Lymph capillaries
- are blind-ended tubes or closed at one end.
- located in spaces between cells.
-interstitial fluid which is not absorbed into the bloodstream drains into these capillaries.

Lymphatic vessels
-lymph capillaries unite to form this lymphatic vessels.
-valves are found to
i) ensure the continuos flow of the lymph away from the tissues.
ii) prevent back flow of lymph

Lymph Nodes
-located at intervals along the lymphatic vessels.
- produce and store lymphocytes.
-defend the body against infection.

Lymphatic system does not have its pumps to move the lymph around through the lymphatic vessels.
It moves forward the subclavian veins with the help of:-
i) one-way valves,
ii) muscular contraction
iii) intestinal movements, and
iv) pressure changes that occur during inhalation& exhalation.

6) How lymphatic system complements the circulatory system?
According to an example in Wiki Answer, Cajohnson27 answered that:-

The lymphatic system is conected with circultion system by the body temp carring large blood vessels around the lymph.The lymphatic system is composed of lymphatic vessels, which are tubes that assist the cardiovascular system in the removal of tissue fluid, also known as lymph, from the tissue spaces of the body. The vessels then return fluid to the blood within the circulatory system.The circulatory system is composed of arteries, veins, and capillaries. This system allows the lymph to travel to lymph nodes where it is filtered of bacteria and other foreign particles. in general, the cardiovascular system and lymphatic system make up the circulatory system. (Johnson, A. 2010)

The following diagram shows the path of lymph in lymphatic system.

The following diagram shows the relationship between lymphatic system and circulatory.

From the lymphatic vessels, lymph will eventually passes one of two main channels which is either:
a) Thoracic duct, or
b) Right lymphatic duct.

7) Role of the lymphatic system in transport
- carry excessive interstitial fluid back to the bloodstream
-helps to maintain the balance of fluid in body
-the process is crucial because water, nutrients and other molecules continously leak out of blood capillaries into the surrounding body tissues.

8) If interstitial fluid not return to the circulatory system, will cause
-swollen of body tissues ( because too much fluid is retained)
-Oedema ( condition of excessive accumulation of interstitial fluid in the spaces between the cells, cause by a blocked lymphatic vessel)

Prepared by Emma.
Pictures and diagram from Google Image.