martes, 30 de noviembre de 2010

jueves, 25 de noviembre de 2010

Components of the Human Diet

miércoles, 24 de noviembre de 2010

3.6 Enzymes (Core and C2/7.6)

martes, 2 de noviembre de 2010

miércoles, 20 de octubre de 2010

Water properties for IB one

Water Properties
States of Water
Adhesion and Cohesion
Surface Tension
Capillary Action


The States of Water

Water has three states. Below freezing water is a solid (ice or snowflakes), between freezing and boiling water is a liquid, and above its boiling point water is a gas. There are words scientists use to describe water changing from one state to another. Water changing from solid to liquid is said to be melting. When it changes from liquid to gas it is evaporating. Water changing from gas to liquid is called condensation (An example is the 'dew' that forms on the outside of a glass of cold soda). Frost formation is when water changes from gas directly to solid form. When water changes directly from solid to gas the process is called sublimation.

Gas

Liquid

Solid

Most liquids contract (get smaller) when they get colder. Water is different. Water contracts until it reaches 4 C then it expands until it is solid. Solid water is less dense that liquid water because of this. If water worked like other liquids, then there would be no such thing as an ice berg, the ice in your soft drink would sink to the bottom of the glass, and ponds would freeze from the bottom up!

Water is found on Earth in all three forms. This is because Earth is a very special planet with just the right range of temperatures and air pressures. Earth is said to be at the triple point for water.

Adhesion and Cohesion

Water is attracted to other water. This is called cohesion. Water can also be attracted to other materials. This is called adhesion.
The oxygen end of water has a negative charge and the hydrogen end has a positive charge. The hydrogens of one water molecule are attracted to the oxygen from other water molecules. This attractive force is what gives water its cohesive and adhesive properties.

Surface Tension

Surface tension is the name we give to the cohesion of water molecules at the surface of a body of water. Try this at home: place a drop of water onto a piece of wax paper. Look closely at the drop. What shape is it? Why do you think it is this shape?

What is happening? Water is not attracted to wax paper (there is no adhesion between the drop and the wax paper). Each molecule in the water drop is attracted to the other water molecules in the drop. This causes the water to pull itself into a shape with the smallest amount of surface area, a bead (sphere). All the water molecules on the surface of the bead are 'holding' each other together or creating surface tension.

Surface tension allows water striders to 'skate' across the top of a pond. You can experiment with surface tension. Try floating a pin or a paperclip on the top if a glass of water. A metal pin or paper clip is heavier than water, but because of the surface tension the water is able to hold up the metal.

Surface tension is not the force that keeps boats floating. If you want to know why a boat floats look here: Why do boats float?

Capillary Action
Surface tension is related to the cohesive properties of water. Capillary action however, is related to the adhesive properties of water. You can see capillary action 'in action' by placing a straw into a glass of water. The water 'climbs' up the straw. What is happening is that the water molecules are attracted to the straw molecules. When one water molecule moves closer to a the straw molecules the other water molecules (which are cohesively attracted to that water molecule) also move up into the straw. Capillary action is limited by gravity and the size of the straw. The thinner the straw or tube the higher up capillary action will pull the water (Can you make up an experiment to test this?).

Plants take advantage of capillary action to pull water from the into themselves. From the roots water is drawn through the plant by another force, transpiration. Click here for more information about transpiration.

jueves, 14 de octubre de 2010

Defence against infectious diseases

6.3.1 Define pathogen.
Pathogen: an organism or virus that causes a disease.

6.3.2 Explain why antibiotics are effective against bacteria but not against viruses.
Antibiotics are produced by microorganisms to kill or control the growth of other microorganisms by blocking specific metabolic pathways within the cell. Since bacteria are so different to human cells, antibiotics can be taken by humans to kill bacteria without harming the human cells. Viruses on the other hand are different as they do not carry out many metabolic processes themselves. Instead they rely on a host cell (a human cell) to carry out these processes for them. Therefore viruses cannot be treated with antibiotics as it is impossible to harm the virus without harming the human cells.

Summary:


Antibiotics block specific metabolic pathways in bacteria.
Bacteria are very different to human cells so human cells are not affected.
Viruses require host cell to carry metabolic processes for them and so antibiotics cannot be used to treat viruses.
Harming the virus would harm the human cells.
6.3.3 Outline the role of skin and mucous membranes in the defence against pathogens.
The skin forms a physical barrier that prevents pathogens from entering the body as the outer layer is very tough. In addition the skin contains sebaceous glands which secret lactic acid and fatty acids which creates an acidic environment on the surface of the skin preventing the growth of pathogens.

Mucous membranes form another type of barrier against pathogens. Mucous membranes are soft and moist areas of skin found in the trachea, nose, vagina and urethra. These membranes are not strong enough to create a physical barrier but they do have mucus which contain lysozyme enzymes that digest the phagocytes. Also, the mucus can be sticky such as in the trachea, and trap the pathogens which are then expelled up the trachea and out of the body by muscles within the trachea.

Summary:

Skin:

Forms a physical barrier.
Sebaceous glands secret lactic acid and fatty acids.
Mucous membranes:

Mucous contains lysozyme enzymes.
Mucous can be sticky and trap pathogens.
6.3.4 Outline how phagocytic leucocytes ingest pathogens in the blood and body tissues.
Phagocytes are found in the blood and ingest pathogens. They do so by recognising pathogens and engulfing them by endocytosis. Enzymes within the phagocytes called lysosomes then digest the pathogens. Phagocytes can ingest pathogens in the blood but also within body tissue as they can pass through the pores of capillaries and into these tissues.

6.3.5 Distinguish between antigens and antibodies.
Antibodies are proteins that defend the body against pathogens by binding to antigens on the surface of these pathogens and stimulating their destruction. Antigens are foreign substances which stimulate the production of antibodies. Antibodies usually only bind to one specific antigen.

6.3.6 Explain antibody production.
Lymphocytes are a type of leukocyte which make antibodies. Each lymphocyte makes only one specific antibody. A large amount of different lymphocytes are needed so that the body can produce different types of antibodies. The antibodies are found on the surface of the plasma membrane of these lymphocytes with the antigen-combining site projecting outwards. Pathogens have antigens on their surface which bind to the antigen-combining site of the antibodies of a specific lymphocyte. When this happens the lymphocyte becomes active and starts to make clones of itself by dividing by mitosis. These clones then start to make more of this specific antibody needed to defend the body against the pathogen.

Summary:


Each lymphocyte makes one type of antibody.
Antibodies are found on the surface of the lymphocyte.
Pathogen have antigens on their surface.
The antigens bind to the antibodies.
Lymphocyte becomes active and makes clones of itself.
The clones make more of the specific antibody.
6.3.7 Outline the effects of HIV on the immune system.
The HIV virus (which causes AIDS) destroys a type of lymphocyte which has a vital role in antibody production. Over the years this results in a reduced amount of active lymphocytes. Therefore, less antibodies are produced which makes the body very vulnerable to pathogens. A pathogen that could easily be controlled by the body in a healthy individual can cause serious consequences and eventually lead to death for patients affected by HIV.

6.3.8 Discuss the cause, transmission and social implications of AIDS.
Cause: HIV causes AIDS (acquired immunodeficiency syndrome). A syndrome is a group of symptoms that are found together. HIV destroys a type of lymphocyte which is vital for antibody production. Over the years, less active lymphocytes are produced which leads to a fall in the amount of antibodies. Pathogens that would normally be easily controlled by the body in healthy individuals can cause serious consequences and eventually lead to death for patients affected by HIV. The immune system is considerably weakened.

Transmission: HIV is transmitted through body fluids from an infected person to an uninfected one. This can occur through vaginal and anal intercourse as well as oral sex if there are cuts or tears in the vagina, penis, mouth or intestine. It can also be transmitted by hypodermic needles that are shared by intravenous drug abusers. The small amount of blood present on these needles after their use may contain the virus and is enough to infect another person. Another way of transmission is through the placenta from mother to child, or through cuts during childbirth or in milk during breast feeding. Finally there is a risk of transmission in transfused blood or with blood products such as Factor VIII used to treat hemophiliacs.

Social implications: Relatives and friends suffer grief. Families can also suffer from a loss of income as the person infected by HIV can lose their wage if they are unable to work and are refused life insurance. Also, HIV patients may find it hard to find partners, employment and even housing. Finally, AIDS can cause fear in a population and reduce sexual activity.

Summary:

Cause:

HIV causes AIDS.
HIV destroys a type of lymphocyte vital for antibody production.
Overtime there are less active lymphocytes.
The body becomes very vulnerable to pathogens.
Transmission:

Through vaginal and anal intercourse as well as oral sex if cuts or tears are present.
Through hypodermic needles shared by drug users.
Through placenta from mother to child.
Through cuts during child birth or in milk during breast feeding.
Through transfused blood.
Through blood factors such as Factor VIII used to treat hemophiliacs.
Social Implications:

Grief suffered by relatives and friends.
Families can get poorer.
Can be hard to find a partner, employment and housing.
Can reduce sexual activity in a population.

miércoles, 22 de septiembre de 2010

Surface area to volume ratio

SIZES OF ORGANISMS: THE SURFACE AREA:VOLUME RATIO
Introduction: Two- and three-dimensional parameters of organisms (i.e., surface area and volume) do not necessarily increase or decrease proportionally to increases or decreases in one-dimensional, or linear, parameters (i.e., length). For example, the greater the diameter of a single-celled organism, the less surface area it has relative to its volume. The surface area to volume ratio is a way of expressing the relationship between these parameters as an organism's size changes.

Importance: Changes in the surface area to volume ratio have important implications for limits or constraints on organism size, and help explain some of the modifications seen in larger-bodied organisms.

Question: How is the surface area to volume ratio calculated, and how exactly does it change with changing size? What modifications do larger organisms exhibit to get around this problem?

Variables: S surface area (units squared)
V volume (units cubed)
l length (units)
r radius (units)


Methods: For a single-celled organism (or a cell in a multicellular organism's body, for that matter), the surface is a critical interface between the organism/cell and its environment. Exchange of materials often occurs through the process of diffusion, in which dissolved molecules or other particles move from areas of higher concentration to areas of lower concentration (although some exchange is mediated by cellular mechanisms). This type of exchange is a passive process, and as a result imposes constraints upon the size of a single-celled organism or cell. Materials must be able to reach all parts of a cell quickly, and when volume is too large relative to surface area, diffusion cannot occur at sufficiently high rates to ensure this.

We'll begin with a reminder of some basic geometric formulae. The surface area and volume of a cube can be found with the following equations:

and

where S = surface area (in units squared), V = volume (in units cubed), and l = the length of one side of the cube.












The equations for the surface area and volume of a sphere are:

and

where r is the radius of the sphere.






Notice that for any increase, x * l or x * r, in length or radius, the increase in surface area is x squared (x2) and the increase in volume is x cubed (x3). For example, when length is doubled (i.e., x = 2) surface area is quadrupled (22 = 4) not doubled, and volume is octupled (23 = 8) not tripled. Similarly when length is tripled (x = 3) surface area is increased ninefold (32 = 9) and volume is increased twenty-sevenfold (33 = 27). The increase in volume is always greater than the increase in surface area. This is true for cubes, spheres, or any other object whose size is increased without changing its shape.

Interpretation: Each point on the graph below represents the surface area and volume for cubes that are increasing by one unit in length, starting with a cube with l = 1. The larger orange dot is the size of the cube (l = 6) at which surface area and volume have equal values (although the units are differentó one is units2 and one is units3). For cubes smaller than this, surface area is greater relative to volume than it is in larger cubes (where volume is greater relative to surface area).













Sometimes a graph that shows how the relationship between two variables changes is more instructive. For example, a graph of the ratio of surface area to volume,

,

clearly illustrates that as the size of an object increases (without changing shape), this ratio decreases. Mathematically, that tells us that the denominator (volume) increases faster relative to the numerator (surface area) as object size increases. The star on the line (at l = 6) represents the same point mentioned above: this is the size of the cube where S and V have equal values, and so the surface area to volume ratio is equal to one.













Conclusions: Organisms exhibit a variety of modifications, both physiological and anatomical, to compensate for changes in the surface area to volume ratio associated with size differences. One example of this is the higher metabolic rates found in smaller (homeothermic) animals. Because of their large surface area relative to volume, small animals lose heat at much higher rates than large animals, and therefore must produce more heat to offset the effects of thermal conductance. Another example is the variety of internal transport systems that have developed in plants and animals for actively moving materials throughout the organism, thus enabling them to circumvent the limits imposed by passive diffusion. Many organisms have developed structures that actually increase their surface area: the leaves on trees, the microvilli on the lining of the small intestine, root hairs and capillaries, and the convoluted walls of arteries, to name but a few.

Additional Questions: Calculate and graph the surface area to volume ratio for spheres increasing in one unit increments (beginning with r = 1). Compare the S:V ratio of spheres and cubes of comparable sizes (2r, or diameter, = l).

Extra credit: Graph the surface areas (x axis) and volumes (y axis) of these spheres on a standard plot and a log-log plot. What happens to the line? Why?

Sources: Schmidt-Nielson, K. 1984. Scaling: Why is Animal Size so Important? Cambridge University Press, New York, NY.

Vogel, S. 1988. Life's Devices: The Physical World of Animals and Plants. Princeton University Press, Princeton, NJ.



--------------------------------------------------------------------------------

copyright 2000, M. Beals, L. Gross, S. Harrell

Welcome to my New students!!

To the new people of International School of Verona, please make yourself fan of the blog so I can communicate with you!! And Welcome again! This has its own order, please forgive me!

jueves, 17 de junio de 2010

S1 Digestion study questions.


Digestion Study Questions

1. Why do you have a digestive system? (Hint: why do you need to break down the food you eat?)

2. What organs are found in the digestive system, and where are they located? How long does food spend in each of these organs?

3. What are six basic functions of the digestive system? Where does each of them take place?

4. What are carbohydrates, proteins and lipids and what are the different types of each? What foods are they found in?

5. What are the basic layers of the gut tube? Which tissues make up each layer?

6. Describe the oral cavity. What role does each anatomical structure you have described play in processing food in the oral cavity? Which foods are digested in the mouth, and to what extent?

7. What structures are involved in the swallowing reflex? How is the reflex triggered? Describe the movements of the structures and how a bolus of food is directed into the esophagus. What parts are voluntary and which involuntary?

8. What structural modifications of the basic layers characterize the esophagus? What is the functional significance of these modifications? How is food propelled down the esophagus?

9. What structural modifications of the basic layers characterize the stomach? What substances are included in gastric juices? What is the function of each component? How does the stomach protect itself against acid?

10. What is acid reflux (heartburn)? What are ulcers? Who is at risk for developing ulcers? What is the anatomical/physiological basis for each condition?

11. Which foods are digested in the stomach? What are the end products of that digestion? What substances are absorbed in the stomach?

12. What are gastritis and diaphragmatic hernias? What is reverse peristalsis and why does it occur?

13. What structural modifications of the basic layers of the gut tube characterize the small intestine? Which structural adaptations of the small intestine increase surface area? Why is increased surface area important?

14. What digestive substances does the small intestine secrete?

15. What other substances are added to chyme in the small intestine?

16. Where does bile come from and where is it stored? What role does it play in digestion? What are gallstones?

17. What substances are in pancreatic juices? What role do they play in digestion?

18. Why is the pancreas such a critical organ? How would the process of digestion be affected if the pancreas did not function?

19. What is an enzyme?

20. What digestive enzymes digest carbohydrates? Where is each produced, and what are it the products of each? What are the end products of carbohydrate digestion?

21. What digestive enzymes digest proteins? Where are they produced? Why are there so many types of protein digesting enzymes? What are the end products of protein digestion?

22. What substance emulsifies lipids? What enzyme breaks down simple lipids? What are the end products of lipid digestion?

23. Where are the end products of digestion absorbed? Which products move into epithelial cells by active transport, which by diffusion? Where do they go from the epithelial cells?

24. What other substances ingested with your meal are absorbed in the small intestine?

25. What substance cannot be digested? What kind of organic molecule is it?

26. What structural modifications of the basic layers of the gut tube characterize the large intestine? What is the major role of the large intestine?

27. What do intestinal bacteria do? Why is their relationship with humans considered mutually beneficial instead of parasitic? Why can antibiotic treatment affect the ability of your large intestine to function properly? Why can diarrhea be a serious problem?

28. What are feces? Describe the nervous reflex which controls the process of elimination. Is this reflex under voluntary or involuntary control?

29. What is diverticulitis? What are the risk factors for this disease and what are its effects on the digestive system?


Sample Questions

What is the role of bile in digestion?



Salivary amylase breaks down

a. carbohydrates b. fatty acids
c. protein d. none of the above

Bacteria in the large intestine produce

a. fats b. digestive enzymes
c. mucus d. vitamins

Gastric juice contains all of the following except

a. HCl b. mucus
c. pepsin d. bicarbonate ions

S2 Lung dissection


The purpose of this activity is:
• to find out about the structure of the lungs
• to find out how our lungs move as we breathe
• to relate the structure of the lungs to how they work when we breathe
Procedure
SAFETY:
• Wear eye protection whenever there is a risk to the eyes, for example, when changing scalpel blades, cutting cartilage or if the dissection material has been preserved.
• Take care with sharp dissecting tools and report any cuts to your teacher.
• Do not breathe directly into the lungs.
• At the end of the practical, disinfect the work area and wash your hands thoroughly using soap and hot water.


If you prefer not to work with the animal lungs your teacher has provided, you could research the lungs using books, models, or the internet. You could search for more information in this way after the practical.
Investigation
a Describe the look, feel and colour of the lungs.
b Identify the trachea and explore the texture of its wall.
c Explore the tubes that enter the lungs and see how they divide.
d If the heart is still attached, identify the main blood vessels leaving and entering the lungs. If not, try to identify large blood vessels anyway.
e Identify any membrane surrounding the lungs.
f Inflate the lungs (following your teacher’s instructions) and observe how they behave.
g Cut a piece of lung tissue and observe the cut surface and how the tissue behaves when you drop it into water.

viernes, 4 de junio de 2010

jueves, 27 de mayo de 2010

S3 How to extract DNA for the lab report!!!

Here you have more information for your lab report that has to be handed in on thursday 3 June 2010

http://learn.genetics.utah.edu/content/labs/extraction/howto/

http://www.umbi.umd.edu/~scitech/pdf/DNA.pdf

miércoles, 19 de mayo de 2010

Lab report on the heart, for S2

http://eduspace.free.fr/vs_pages/heart_dissection.htm

martes, 18 de mayo de 2010

Excellent Science Blog from Spain!!!

Ihttp://biodeluna.wordpress.com/2010/04/26/evolution-4eso/
ts over your level but have a look at it cause is fun!!!!Its mostly for Ib students but you´ll find some resources.Specially S2

S2 Circulatory System Excellent site!!!!

http://sixthsense.osfc.ac.uk/biology/biology_excellence/circulatory_system.asp

jueves, 13 de mayo de 2010

Amazing revision for IGCSE

http://www.carmel.org.uk/media/revision/GCSEBiologyRevision.ppt#256,1,GCSE Biology Revision
Have a look at it!!!!!

miércoles, 12 de mayo de 2010

Circulatory system S2

http://www.youtube.com/watch?v=D3ZDJgFDdk0&feature=PlayList&p=FD5B3F061F7DB890&playnext_from=PL&playnext=1&index=42

jueves, 6 de mayo de 2010

S1 Watch this presentation on enzymer and we will discuss

http://www.clickbiology.com/wp-content/uploads/2009/11/enzymes-video.ppt#256,1,Diapositiva 1

S2 Do this as an excercise!

Complete the word fill exercise below and table on the next sheet:

The male part of the flower is called the _______________consists of the ____________ and ____________ . The female part of the flower is called the _____________ consists of the ______________, ______________ and _______________. The male gamete is made in the ______________ and is found inside the _____________ grain. The female gamete is found in the _____________ and is called an ______________.
Pollination:

What is pollination: ___________________________________________________________

___________________________________________________________

___________________________________________________________


There are two mechanisms for pollination: wind and insect. Flowers are adapted to suit the mechanism by which they are pollinated.

Identify which flower below is wind-pollinated and which is insect-pollinated:


Name three flowers that are insect-pollinated:

_____________________________________________________________________


Give an example of a type of plant that is wind-pollinated:

_____________________________________________________________________
Explain the difference between self-pollination and cross-pollination:

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

Plant reproduction S2

http://www.clickbiology.com/igcse-plant-reproduction-powerpoint-presentation-worksheets/

In this adress you will find everything you need for plant reproduction

martes, 20 de abril de 2010

See enzymes in this website

http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/enzymes/enzymes1.shtml

jueves, 15 de abril de 2010

Flowering plants for S2


An Introduction to Vegetative Reproduction


Vegetative Reproduction

is a form of asexual reproduction in plants. It does not involve flowers, pollination and seed production. Instead, a new plant grows from a vegetative part, usually a stem, of the parent plant. However, plants which reproduce asexually almost always reproduce sexually as well, bearing flowers, fruits and seeds. Vegetative reproduction from a stem usually involves the buds. Instead of producing a branch, the bud grows into a complete plant which eventually becomes self-supporting. Since no gametes are involved, the plants produced asexually have identical genomes and the offspring form what is known as a clone. In some cases of vegetative reproduction, the structures involved also become storage organs and swell with stored food, e.g. potatoes.

The principal types of vegetative reproduction structures are bulbs, corms, rhizomes and runners.

Bulbs

Bulbs consist of very short stems with closely packed leaves arranged in concentric circles round the stem. These leaves are swollen with stored food e.g. onion. A terminal bud will produce next year’s flowering shoot and the lateral (axillary) buds will produce new plants.


Corms

Corms also have a short stem but in this case it is the stem itself which swells and stores food. The circular leaves form only papery scales. As with bulbs, the terminal bud grows into a flowering shoot and the lateral buds produce new plants.


Rhizomes

Rhizomes are stems which grow horizontally under the ground. In some cases the underground stems are swollen with food reserves e.g. iris. The terminal bud turns upwards to produce the flowering shoot and the lateral buds may grow out to form new rhizomes.


Runners

Runners are also horizontal stems growing from the parent plant, but they grow above ground. When their terminal buds touch the ground they take root and produce new plants.


Advantages of vegetative reproduction

Since food stores are available throughout the year and the parent plant with its root system can absorb water from quite a wide area, two of the hazards of seed germination are reduced. Buds are produced in an environment where the parent is able to flourish, but many seeds dispersed from plants never reach a suitable situation for effective germination.

Vegetative reproduction does not usually result in rapid and widespread distribution of offspring in the same way as seed dispersal, but tends to produce a dense clump of plants with little room for competitors between them. Such groups of plants are very persistent and, because of their buds and underground food stores, can still grow after their foliage has been destroyed by insects, fire, or cultivation. Those of them regarded as weeds are difficult to eradicate, since even a small piece of rhizome bearing a bud can give rise to a new colony (clone).

Bulbs - Snowdrop

In the snowdrop and daffodil, the bulb is formed by the leaf bases which completely encircle the short, conical stem. The part of the leaf above ground makes food by photosynthesis and sends it to the leaf bases which swell as they store the food. In the following year the stored food is used for the early growth of the bulb.

Life cycle of Daffodil
In the spring, adventitious roots grow out of the stem, and the leaves begins to grow above ground, making use of the stored food in the fleshy leaf bases which consequently shrivel. During late spring some of the food made in the leaves in the daffodil is sent to the leaf bases which swell and form a new bulb inside the old one.

Life cycle of Tulip and Onion
In these bulbs, the food is not sent to the leaf bases but to the lateral buds. As these buds enlarge they form two or more ‘daughter’ bulbs inside the old bulb. The leaves of the old bulb shrivel and dry out forming the dry scales which surround the daughter bulbs. In both cases, when the daughter bulbs grow, they form a clump, together with the parent bulb.

Corms - Crocus
Plants with bulbs store food in special leaves or leaf bases. Plants with corms store food in the stem, which is very short and swollen. When the foliage has died off, the leaf bases, where they encircle the short stem, form protective scaly coverings. A familiar corms is that of the crocus, and the wild arum corm is illustrated on p.1. Since the corm is a stem, it has lateral buds which can grow into new plants. The stem remains below ground all its life, only the leaves and flower stalk coming above ground.

Life Cycle of Corm
In Spring, the food stored in the corm enables the terminal bud to grow rapidly and produce leaves and flowers above ground. Later in the year, food made by the leaves is sent back, not to the old corm, but to the base of the stem immediately above it. This region swells and forms a new corm on top of the old, now shrivelled, corm. Some of the lateral buds on the old corm have also grown and produced new plants with corms.

Contractile Roots
The formation of one corm on top of another tends to bring the successive corms nearer and nearer to the soil surface. Adventitious roots develop from the base of the new corm. Once these have grown firmly into the soil, a region near their junction with the stem contracts and pulls the new corm down, keeping it at a constant level in the soil. Wrinkles can be seen on these contractile roots where shrinkage has taken place. Bulbs also have contractile roots which counteract the tendency in successive generations to grow out of the soil.

Rhizomes

In plants with rhizomes, the stem remains below ground but continues to grow horizontally. The old part of the stem does not die away as in bulbs and corms, but lasts for several years. In the iris, the terminal bud turns up and produces leaves and flowers above ground. The old leaf bases form circular scales round the rhizome, which is swollen with food reserves. Lateral buds grow into new rhizomes.

Life Cycle of Rhizome
The annual cycle of a rhizome is similar to that of a corm. In late spring/early summer, food from the leaves passes back to the rhizome, and a lateral bud uses it, grows horizontally underground, and so continues the rhizome. Other lateral buds produce new rhizomes which branch from the parent stem. The terminal buds of these branches curve upwards and produce new leafy shoots and flowers. Contractile, adventitious roots grow from the nodes of the underground stem and keep it at a constant depth.

Runners
Plants such as the strawberry have a very short stem, called a rootstock, with thin scale leaves,. Foliage leaves and flowers grow from the buds in the axils of the scale leaves. Some of the lower buds produce shoots which grow horizontally over the surface of the ground and bear scale leaves and buds. The terminal buds of these runners turn up and produce daughter plants some distance away from the parent, the new plants developing adventitious roots. Later, the runner shrivels away. The runner does not store food but conducts it from the parent plant to the daughters, until they are well developed.

Stem tubers - potato
In the potato plant, lateral buds at the base of the stem produce shoots which grow laterally at first and then down into the ground. These are comparable to rhizomes, as they are underground stems with tiny scale leaves and lateral buds. They do not swell evenly along their length with stored food.

Annual cycle - potato
Food made in the leaves passes to the ends of these rhizomes, which swell and form the tubers we call potatoes. Since the potato tuber is a stem, it has leaves and lateral buds; these are the familiar ‘eyes’. Each one of these can produce a new shoot in the following year, using the food stored in the tuber. The old tubers shrivel and rot away at the end of the season

Stolons
Blackberry stems form a rather different type of runner in which the main shoot forms the new individual. When the growing end of a shoot arches over and touches the ground, the terminal bud curves up, producing a new shoot which soon develops adventitious roots.

Grafting
A bud or shoot from one plant is inserted into a cleft or under the bark on the stem of a closely related variety. The rooted portion is called the stock; the bud or shoot being grafted is the scion. The stock is obtained by growing a plant from seed then cutting away the shoot. The scion is a branch or a bud cut from a cultivated variety with the required characteristics of flower colour, fruit quality, etc.

Rose plants grown from seed would produce a wide variety of plants, only a few of which would retain all the desirable features of the parent plant. Most of them would be like wild roses. Similarly, most of the apple trees grown from seed would bear only small, sour ‘crab-apples'. By taking cuttings and making grafts, the inbred characteristics of the plant are preserved and you can guarantee that all the new individuals produced by this kind of artificial propagation will be the same.

Cuttings
It is possible to produce new individuals from certain plants by putting the cut end of a shoot into water or moist earth. Roots grow from the base of the stem into the soil while the shoot continues to grow and produce leaves.

In some cases the cut end of the stem may be treated with a rooting 'hormone' to promote root growth. Evaporation from the shoot is reduced by covering it with polythene or a glass jar. Carnations, geraniums and chrysanthemums are commonly propagated from cuttings.

Tissue culture
Once a cell has become part of a tissue it usually loses the ability to reproduce. However, the nucleus of any plant cell still holds all the 'instructions' (genes) for making a complete plant and in certain circumstances they can be brought back into action. In laboratory conditions single plant cells can be induced to divide and grow into complete plants. One technique is to take a small piece of plant tissue from a root or stem and treat it with enzymes to separate it into individual cells The cells are then provided with particular plant 'hormones’ which induce cell division and, eventually the formation of roots, stems and leaves.

An alternative method is to start with a small piece of tissue and place it on a nutrient jelly (agar). Cells in the tissue start to divide and produce many cells forming a shapeless mass called a callus. If the callus is then provided with the appropriate ‘hormones’ it develops into a complete plant.

miércoles, 31 de marzo de 2010

S3 Genetics Game

http://www.what2learn.com/games/play/12505/

martes, 23 de marzo de 2010

Definition,puberty, Psychology, Sexuality

Adolescence (from the Latin: adolescere meaning "to grow up") is a transitional stage of physical and mental human development that occurs between childhood and adulthood. This transition involves biological (i.e. pubertal), social, and psychological changes, though the biological or physiological ones are the easiest to measure objectively. Historically, puberty has been heavily associated with teenagers and the onset of adolescent development.[1][2] In recent years, however, the start of puberty has had somewhat of an increase in preadolescence (particularly females, as seen with early and precocious puberty); adolescence has had an occasional extension beyond the teenage years (typically males). These changes have made it more difficult to rigidly define the time frame in which adolescence occurs.[3][4][5]

The end of adolescence and the beginning of adulthood varies by country and by function, and furthermore even within a single nation-state or culture there can be different ages at which an individual is considered to be (chronologically and legally) mature enough to be entrusted by society with certain tasks. Such milestones include, but are not limited to, driving a vehicle, having legal sexual relations, serving in the armed forces or on a jury, purchasing and drinking alcohol, voting, entering into contracts, completing certain levels of education, and marrying.

Adolescence is usually accompanied by an increased independence allowed by the parents or legal guardians and less supervision, contrary to the preadolescence stage.

Puberty

Upper body of teenage boy. The structure has changed to resemble an adult form.Main article: Puberty
Puberty is a period of several years in which rapid physical growth and psychological changes occur, culminating in sexual maturity. The average onset of puberty is at 10 for girls and age 12 for boys.[6] Every person's individual timetable for puberty is influenced primarily by heredity, although environmental factors, such as diet and exercise, also exert some influence.[6][7][8] These factors can also contribute to delayed puberty.

Puberty begins with a surge in hormone production, which in turn, causes a number of physical changes.[6] It is also the stage of life in which a child develops secondary sex characteristics (for example, a deeper voice and larger adam's apple in boys, and development of breasts and more curved and prominent hips in girls) as his or her hormonal balance shifts strongly towards an adult state. This is triggered by the pituitary gland, which secretes a surge of hormonal agents into the blood stream, initiating a chain reaction. The male and female gonads are subsequently activated, which puts them into a state of rapid growth and development; the triggered gonads now commence the mass production of the necessary chemicals. The testes primarily release testosterone, and the ovaries predominantly dispense estrogen. The production of these hormones increases gradually until sexual maturation is met. Some boys may develop gynecomastia due to an imbalance of sex hormones, tissue responsiveness or obesity.[9][10] Put simply, puberty is the time when a child's body starts changing into an adult's body.[6]

Facial hair in males normally appears in a specific order during puberty: The first facial hair to appear tends to grow at the corners of the upper lip, typically between 14 to 16 years of age.[11][12] It then spreads to form a moustache over the entire upper lip. This is followed by the appearance of hair on the upper part of the cheeks, and the area under the lower lip.[11] The hair eventually spreads to the sides and lower border of the chin, and the rest of the lower face to form a full beard.[11] As with most human biological processes, this specific order may vary among some individuals. Facial hair is often present in late adolescence, around ages 17 and 18, but may not appear until significantly later.[12][13] Some men do not develop full facial hair for 10 years after puberty.[12] Facial hair will continue to get coarser, darker and thicker for another 2–4 years after puberty.[12]

The major landmark of puberty for males is the first ejaculation, which occurs, on average, at age 13.[14] For females, it is menarche, the onset of menstruation, which occurs, on average, between ages 12 and 13.[7] The age of menarche is influenced by heredity, but a girl's diet and lifestyle contribute as well.[7] Regardless of genes, a girl must have certain proportion of body fat to attain menarche.[7] Consequently, girls who have a high-fat diet and who are not physically active begin menstruating earlier, on average, than girls whose diet contains less fat and whose activities involve fat reducing exercise (e.g. ballet and gymnastics).[7][8] Girls who experience malnutrition or are in societies in which children are expected to perform physical labor also begin menstruating at later ages.[7]

The timing of puberty can have important psychological and social consequences. Early maturing boys are usually taller and stronger than their friends.[15] They have the advantage in capturing the attention of potential partners and in becoming hand-picked for sports. Pubescent boys often tend to have a good body image, are more confident, secure, and more independent.[16] Late maturing boys can be less confident because of poor body image when comparing themselves to already developed friends and peers. However, early puberty is not always positive for boys; early sexual maturation in boys can be accompanied by increased aggressiveness due to the surge of hormones that affect them.[16] Because they appear older than their peers, pubescent boys may face increased social pressure to conform to adult norms; society may view them as more emotionally advanced, despite the fact that their cognitive and social development may lag behind their appearance.[16] Studies have shown that early maturing boys are more likely to be sexually active and are more likely to participate in risky behaviors.[17]

For girls, early maturation can sometimes lead to increased self-consciousness, though a typical aspect in maturing females.[18] Because of their bodies developing in advance, pubescent girls can become more insecure.[18] Consequently, girls that reach sexual maturation early are more likely than their peers to develop eating disorders. Nearly half of all American high school girls' diet is to lose weight.[18] In addition, girls may have to deal with sexual advances from older boys before they are emotionally and mentally mature.[19] In addition to having earlier sexual experiences and more unwanted pregnancies than late maturing girls, early maturing girls are more exposed to alcohol and drug abuse.[20] Those who have had such experiences tend to perform less well in school than their "inexperienced" age peers.[21]

By ages 15-17, girls have usually reached full physical development.[18][22] By age 16, boys are close to completing puberty,[18] which is usually achieved by ages 17 or 18.[22] Teenage and early adult males may continue to gain natural muscle growth even after puberty.[16]
Psychology
Main article: Adolescent psychology
Adolescent psychology is associated with notable changes in mood sometimes known as mood swings. Cognitive, emotional and attitudinal changes which are characteristic of adolescence, often take place during this period, and this can be a cause of conflict on one hand and positive personality development on the other.

Because the adolescents are experiencing various strong cognitive and physical changes, for the first time in their lives they may start to view their friends, their peer group, as more important and influential than their parents/guardians. Because of peer pressure, they may sometimes indulge in activities not deemed socially acceptable, although this may be more of a social phenomenon than a psychological one.[23] This overlap is addressed within the study of psychosociology.

The home is an important aspect of adolescent psychology: home environment and family have a substantial impact on the developing minds of teenagers, and these developments may reach a climax during adolescence. For example, abusive parents may lead a child to "poke fun" at other classmates when he/she is seven years old or so, but during adolescence it may become progressively worse. If the concepts and theory behind right or wrong were not established early on in a child's life, the lack of this knowledge may impair a teenager's ability to make beneficial decisions as well as allowing his/her impulses to control his/her decisions.

In the search for a unique social identity for themselves, adolescents are frequently confused about what is 'right' and what is 'wrong.' G. Stanley Hall denoted this period as one of "Storm and Stress" and, according to him, conflict at this developmental stage is normal and not unusual. Margaret Mead, on the other hand, attributed the behavior of adolescents to their culture and upbringing.[24] However, Piaget, attributed this stage in development with greatly increased cognitive abilities; at this stage of life the individual's thoughts start taking more of an abstract form and the egocentric thoughts decrease, hence the individual is able to think and reason in a wider perspective.[25]

Positive psychology is sometimes brought up when addressing adolescent psychology as well. This approach towards adolescents refers to providing them with motivation to become socially acceptable and notable individuals, since many adolescents find themselves bored, indecisive and/or unmotivated.[26]

Adolescents may be subject to peer pressure within their adolescent time span, consisting of the need to have sex, consume alcoholic beverages, use drugs, defy their parental figures, or commit any activity in which the person who is subjected to may not deem appropriate, among other things. Peer pressure is a common experience between adolescents and may result briefly or on a larger scale. If it results on a larger scale, the adolescent needs medical advice or treatment.[27]

It should also be noted that adolescence is the stage of a psychological breakthrough in a person's life when the cognitive development is rapid[28] and the thoughts, ideas and concepts developed at this period of life greatly influence one's future life, playing a major role in character and personality formation.[29]

Struggles with adolescent identity and depression usually set in when an adolescent experiences a loss. The most important loss in their lives is the changing relationship between the adolescent and their parents. Adolescents may also experience strife in their relationships with friends. This may be due to the activities their friends take part in, such as smoking, which causes adolescents to feel as though participating in such activities themselves is likely essential to maintaining these friendships. Teen depression can be extremely intense at times because of physical and hormonal changes but emotional instability is part of adolescence. Their changing mind, body and relationships often present themselves as stressful and that change, they assume, is something to be feared.[30]

Views of family relationships during adolescence are changing. The old view of family relationships during adolescence put an emphasis on conflict and disengagement and thought storm and stress was normal and even inevitable. However, the new view puts emphasis on transformation or relationships and maintenance of connectedness.

[edit] Sexuality
Main article: Adolescent sexuality
Adolescent sexuality refers to sexual feelings, behavior and development in adolescents and is a stage of human sexuality. Sexuality and sexual desire usually begins to intensify along with the onset of puberty. The expression of sexual desire among adolescents (or anyone, for that matter), might be influenced by family values and the culture and religion they have grown up in (or as a backlash to such), social engineering, social control, taboos, and other kinds of social mores.


Teenage couples at a fair in the American West.In contemporary society, adolescents also face some risks as their sexuality begins to transform. Whilst some of these such as emotional distress (fear of abuse or exploitation) and sexually transmitted diseases (including HIV/AIDS) may not necessarily be inherent to adolescence, others such as pregnancy (through failure or non-use of contraceptives) are seen as social problems in most western societies. In terms of sexual identity, all sexual orientations found in adults are also represented among adolescents.

According to anthropologist Margaret Mead and psychologist Albert Bandura, the turmoil found in adolescence in Western society has a cultural rather than a physical cause; they reported that societies where young women engaged in free sexual activity had no such adolescent turmoil.

In a 2008 study conducted by YouGov for Channel 4, 20% of 14−17-year-olds surveyed revealed that they had their first sexual experience at 13 or under.[31]

The age of consent to sexual activity varies widely between international jurisdictions, ranging from 12 to 21 years.[32]

lunes, 22 de marzo de 2010

poli 2 Transport in plants

See this adress for more information http://www.jochemnet.de/fiu/BSC1011/BSC1011_9/index.htm

martes, 16 de marzo de 2010

Classification!!


Classification of Organisms

Organismal diversity is the product of evolution. Evolutionary paths are branched and numerous, though most arrive at dead ends with organisms which do not survive in the face of environmental change. In this lecture we consider these evolutionary paths (called lineages), ignoring for the moment the processes that carry organisms along them.
While the lineage of any given organism may have twisted repeatedly according to the whims of chance and change, key nodes may nevertheless be tracked retrospectively. These nodes consist of times of identifiable change, particularly points of divergence between two lineages (speciation events). The delineation of these nodes in organismal lineages is accomplished through fossil reconstruction of the past as well as by comparing extant organisms, looking for similarities and differences in anatomies, physiologies, genes, behaviors, etc. From this information classification and phylogenetic reconstruction is accomplished. Classification according to similarity:
Carolus Linnaeus developed a system of classification of every (then) known organism.
This system is based on creating and differentiating groups in terms of structural (and other) similarities and differences.
Linnaeus also invented binomial nomenclature to keep track of group members.
Systematics
Systematics is the study of the diversity of organisms and their evolutionary relationships.
Science of classification:
Systematics is the science of the classification of organisms.
The main goal of systematics is the discovery and codification of phylogenetic relationships between organisms.
"The term systematics often is used for taxonomy. However, many taxonomists define it in more general terms as 'the scientific study of organisms with the ultimate object of characterizing and arranging them in an orderly manner.' Any study of the nature of organisms, when the knowledge gained is used in taxonomy, is a part of systematics. Thus (systematics) encompasses disciplines such as morphology, ecology, epidemiology, biochemistry, molecular biology, and physiology." (p. 391, Prescott et al., 1996)
Taxon [sing., taxa, pl.]
A taxon is a phylogenetic grouping of organisms.
Taxonomy
Identification and classification:
Taxonomy is the science concerned with the:
identification
classification
nomenclature
of organisms.
"Taxonomy [Greek taxis, arrangement or order, and nomos, law, or nemein, to distribute or govern] is defined as the science of biological classification. In a broader sense it consists of three separate but interrelated parts: classification, nomenclature, and identification." (p. 391, Prescott et al., 1996)
Note that the terms systematics and taxonomy can often be used semantically in a nearly indistinguishable manner.
Identification
Identification is "the practical side of taxonomy, the process of determining that a particular (organism) belongs to a recognized taxon." (p. 391, Prescott et al., 1996)
Classification
Classification is "the arrangement of organisms into groups or taxa." (p. 391, Prescott et al., 1996)
Nomenclature
Name assignment:
Nomenclature is "the branch of taxonomy concerned with the assignment of names to taxonomic groups in agreement with published rules." (p. 391, Prescott et al., 1996)
Note that ideally names have taxonimic meaning, i.e., they give clues to phylogenetic relationships.
Hierarchical classification
Hierarchy of designations:
The full description of a given organism's place among all the world's organisms does not end with its binomial designation.
There exists a hierarchy of designations only the last of which describe genera and species denomination.
"A category in any rank unites groups in the level below it based on shared properties." (p. 391, Prescott et al., 1996)
The major designations, listed in terms of increasing specificity, include:
domain (empire/super-kingdom)
kingdom
phylum
class
order
family
genus
species

Various mnemonics exist to help you remember these designations from kingdom through species
Did King Peter Came Over From Geneva Switzerland?

lunes, 15 de marzo de 2010

Dichotomus key Senior 1

Activity
Create a dichotomous key using the following list of specimens: pine tree, clam, rock,
robin, tin can, deer, oak tree, mouse, dandelion, Paramecium, bicycle, ant
Here's an example in written form using these items:
1. a. Organism is living........................................................go to 4.
1. b. Organism is nonliving..................................................go to 2.
2. a. Object is metallic........................................................go to 3.
2. b. Object is nonmetallic..................................................ROCK.
3. a. Object has wheels......................................................BICYCLE.
3. b. Object does not have wheels......................................TIN CAN.
4. a. Organism is microscopic...................................PARAMECIUM.
4. b. Organism is macroscopic............................................go to 5.
5. a. Organism is a plant.....................................................go to 6.
5. b. Organism is an animal.................................................go to 8.
6. a. Plant has a woody stem..............................................go to 7.
6. b. Plant has a herbaceous stem.................................DANDELION.
7. a. Tree has needle like leaves.....................................PINE TREE.
7. b. Tree has broad leaves............................................OAK TREE.
8. a. Organism lives on land................................................go to 9.
8. b. Organism lives in water...............................................CLAM.
9. a. Organism has 4 legs or fewer......................................go to 10.
9. b. Organism has more than 4 legs...................................ANT.
10 a. Organism has fur........................................................go to 11.
10 b. Organism has feathers................................................ROBIN.
11 a. Organism has hooves.................................................DEER.
11 b. Organism has no hooves............................................MOUSE.

miércoles, 3 de marzo de 2010

WELCOME TO SCIENCE BIOLOGY




WELCOME TO SCIENCE BIOLOGY

TEACHER ING.LIZZIE VALERIANI

I WISH YOU A FUN AND PRODUCTIVE YEAR

LAB SAFETY RULES


When you study Biology you would probably have to do experiments. It is important to know what you're doing as to avoid doing something silly like poisoning yourself or blowing up the lab!

Therefore you should first read and understand the below rules about working and behaving in the laboratory before doing any experiments.

1. Never enter the laboratory unless a teacher is present.

2. Never run or play in the laboratory.

3. Never remove anything from the laboratory without your teacher's permission.

4. Never use your bare hands to transfer chemicals. Use a spatula instead.

5. Never leave experiments unattended.

6. Never smell gases directly - fan a little of the gas towards the nose instead.

7.Never look directly down the test tube or poing the mouth of a test tube towards anyone when heating.

8. Never taste anything without your teacher's permission.

9. No eating or drinking in the laboratory.

10. Never put solids in the sink.

11. Always follow strictly the instructions given.

12. Wear safety glasses whenever necessary.

13. Always read the label on a reagent bottle carefully to make sure it contains the chemical you want. Put the bottle in its original place immediately after use.

14. Always handle flammable liquids with great care and keep them away from naked flames.

15. Always handle concentrated acids and alkalis with great care.

16. Report all accidents and breakage to your teacher. If any chemicals get onto your skin or clothing, wash the affected area with a large amount of water and then report it to your teacher.

17. Always adjust the Bunsen burner to give a luminous flame when not using it (or just simply turn it off)

18. Always tie up your tie or long hair.

19. Always wash hands after experiments.

20. Don't eat anything you find in the laboratory or in the laboratory freezer!

lunes, 1 de marzo de 2010



The definition of science:

Science is not merely a collection of facts, concepts, and useful ideas about nature, or even the
Systematic Investigation of nature, although both are common definitions of science. Science is a method of investigating nature—a way of knowing about nature—that discovers reliable knowledge about nature. So science is a method of discovering reliable knowledge about science.
Reliable knowledge is a knowledge that has high probability of being true , because its veracity has been justified by a reliable method.
The method used to justify scientific knowledge and thus make it reliable, is called scientific method.
When one uses the scientific method to study or investigate nature of the universe, one way is practicing scientific thinking to deduce and analyze something and the other is through observing and experimenting.
REASONING IN SCIENCE
Learning about the scientific method is almost like saying that you are learning how to learn. You see, the scientific method is the way scientists learn and study the world around them. It can be used to study anything from a leaf to a dog to the entire Universe.

The basis of the scientific method is asking questions and then trying to come up with the answers. You could ask, "Why do dogs and cats have hair?" One answer might be that it keeps them warm. BOOM! It's the scientific method in action. (OK, settle down.)
QUESTIONS AND ANSWERS
Just about everything starts with a question. Usually, scientists come up with questions by looking at the world around them. "Hey look! What's that?" See that squiggly thing at the end of the sentence? A question has been born.

So you've got a scientist. When scientists see something they don't understand they have some huge urge to answer questions and discover new things. It's just one of those scientist personality traits. The trick is that you have to be able to offer some evidence that confirms every answer you give. If you can't test your answer, other scientists can't test it to see if you were right or not.

As more questions are asked, scientists work hard and come up with a bunch of answers. Then it is time to organize. One of the cool things about science is that other scientists can learn things from what has already been established. They don't have to go out and test everything again and again. That's what makes science special: it builds on what has been learned before.

This process allows the world to advance, evolve, and grow. All of today's advancements are based on the achievements of scientists who already did great work. Think about it this way: you will never have to show that water (H2O) is made up of one oxygen (O) and two hydrogen (H) atoms. Many scientists before you have confirmed that fact. It will be your job as a new scientist to take that knowledge and use it in your new experiments.
EXPERIMENTAL EVIDENCE
Experimental evidence is what makes all of the observations and answers in science valid (truthful or confirmed). The history of evidence and validations show that the original statements were correct and accurate. It sounds like a simple idea, but it is the basis of all science. Statements must be confirmed with loads of evidence. Enough said.

Scientists start with observations and then make a hypothesis (a guess), and then the fun begins. They must then prove their hypothesis with trials and tests that show why their data and results are correct. They must use controls, which are quantitative (based on values and figures, not emotions). Science needs both ideas (the hypothesis) and facts (the quantitative results) to move forward. Scientists can then examine their data and develop newer ideas. This process will lead to more observation and refinement of hypotheses.
THE WHOLE PROCESS
There are different terms used to describe scientific ideas based on the amount of confirmed experimental evidence.

Hypothesis
- a statement that uses a few observations
- an idea based on observations without experimental evidence
Theory
- uses many observations and has loads of experimental evidence
- can be applied to unrelated facts and new relationships
- flexible enough to be modified if new data/evidence introduced
Law
- stands the test of time, often without change
- experimentally confirmed over and over
- can create true predictions for different situations
- has uniformity and is universal

You may also hear about the term "model." A model is a scientific statement that has some experimental validity or is a scientific concept that is only accurate under limited situations. Models do not work or apply under all situations in all environments. They are not universal ideas like a law or theory

Introduction to science

The definition of science:

Science is not merely a collection of facts, concepts, and useful ideas about nature, or even the
Systematic Investigation of nature, although both are common definitions of science. Science is a method of investigating nature—a way of knowing about nature—that discovers reliable knowledge about nature. So science is a method of discovering reliable knowledge about science.
Reliable knowledge is a knowledge that has high probability of being true , because its veracity has been justified by a reliable method.
The method used to justify scientific knowledge and thus make it reliable, is called scientific method.
When one uses the scientific method to study or investigate nature of the universe, one is practicing scientific thinking to deduce and analyze something and the other is through observing and experimenting.
REASONING IN SCIENCE
Learning about the scientific method is almost like saying that you are learning how to learn. You see, the scientific method is the way scientists learn and study the world around them. It can be used to study anything from a leaf to a dog to the entire Universe.

The basis of the scientific method is asking questions and then trying to come up with the answers. You could ask, "Why do dogs and cats have hair?" One answer might be that it keeps them warm. BOOM! It's the scientific method in action. (OK, settle down.)
QUESTIONS AND ANSWERS
Just about everything starts with a question. Usually, scientists come up with questions by looking at the world around them. "Hey look! What's that?" See that squiggly thing at the end of the sentence? A question has been born.

So you've got a scientist. When scientists see something they don't understand they have some huge urge to answer questions and discover new things. It's just one of those scientist personality traits. The trick is that you have to be able to offer some evidence that confirms every answer you give. If you can't test your answer, other scientists can't test it to see if you were right or not.

As more questions are asked, scientists work hard and come up with a bunch of answers. Then it is time to organize. One of the cool things about science is that other scientists can learn things from what has already been established. They don't have to go out and test everything again and again. That's what makes science special: it builds on what has been learned before.

This process allows the world to advance, evolve, and grow. All of today's advancements are based on the achievements of scientists who already did great work. Think about it this way: you will never have to show that water (H2O) is made up of one oxygen (O) and two hydrogen (H) atoms. Many scientists before you have confirmed that fact. It will be your job as a new scientist to take that knowledge and use it in your new experiments.
EXPERIMENTAL EVIDENCE
Experimental evidence is what makes all of the observations and answers in science valid (truthful or confirmed). The history of evidence and validations show that the original statements were correct and accurate. It sounds like a simple idea, but it is the basis of all science. Statements must be confirmed with loads of evidence. Enough said.

Scientists start with observations and then make a hypothesis (a guess), and then the fun begins. They must then prove their hypothesis with trials and tests that show why their data and results are correct. They must use controls, which are quantitative (based on values and figures, not emotions). Science needs both ideas (the hypothesis) and facts (the quantitative results) to move forward. Scientists can then examine their data and develop newer ideas. This process will lead to more observation and refinement of hypotheses.
THE WHOLE PROCESS
There are different terms used to describe scientific ideas based on the amount of confirmed experimental evidence.

Hypothesis
- a statement that uses a few observations
- an idea based on observations without experimental evidence
Theory
- uses many observations and has loads of experimental evidence
- can be applied to unrelated facts and new relationships
- flexible enough to be modified if new data/evidence introduced
Law
- stands the test of time, often without change
- experimentally confirmed over and over
- can create true predictions for different situations
- has uniformity and is universal

You may also hear about the term "model." A model is a scientific statement that has some experimental validity or is a scientific concept that is only accurate under limited situations. Models do not work or apply under all situations in all environments. They are not universal ideas like a law or theory

jueves, 25 de febrero de 2010

IGCSE BIOLOGY SYLLABUS AIMS AND ASSESSMENT

AIMS
The aims of the syllabus are the same for all students. These are set out below and describe the
educational purposes of a course in Biology for the IGCSE examination. They are not listed in
order of priority.
The aims are to:
1. provide, through well designed studies of experimental and practical science, a worthwhile
educational experience for all students, whether or not they go on to study science beyond this
level and, in particular, to enable them to acquire sufficient understanding and knowledge to
1.1 become confident citizens in a technological world, to take or develop an informed interest
in matters of scientific import;
1.2 recognise the usefulness, and limitations, of scientific method and to appreciate its
applicability in other disciplines and in everyday life;
1.3 be suitably prepared for studies beyond the IGCSE level in pure sciences, in applied
sciences or in science-dependent vocational courses.
2. develop abilities and skills that
2.1 are relevant to the study and practice of Biology;
2.2 are useful in everyday life;
2.3 encourage efficient and safe practice;
2.4 encourage effective communication.
3. develop attitudes relevant to Biology such as
3.1 concern for accuracy and precision;
3.2 objectivity;
3.3 integrity;
3.4 enquiry;
3.5 initiative;
3.6 inventiveness.
4. stimulate interest in, and care for, the environment.
0610 BIOLOGY IGCSE 2010
2
5. promote an awareness that
5.1 scientific theories and methods have developed, and continue to do so, as a result of the
co-operative activities of groups and individuals;
5.2 the study and practice of science is subject to social, economic, technological, ethical and
cultural influences and limitations;
5.3 the applications of science may be both beneficial and detrimental to the individual, the
community and the environment;
5.4 science transcends national boundaries and that the language of science, correctly and
rigorously applied, is universal.
IGCSE Biology places considerable emphasis on understanding and use of scientific ideas and
principles in a variety of situations, including those which are well-known to the learner and those
which are new to them. It is anticipated that programmes of study based on this syllabus will
feature a variety of learning experiences designed to enhance the development of skill and
comprehension. This approach will focus teachers and learners on development of transferable
life-long skills relevant to the increasingly technological environment in which people find
themselves. It will also prepare candidates for an assessment that will, within familiar and
unfamiliar contexts, test expertise, understanding and insight.
0610 BIOLOGY IGCSE 2010
3
ASSESSMENT OBJECTIVES
The three assessment objectives in Biology are:
A Knowledge with understanding
B Handling information and solving problems
C Experimental skills and investigations
A description of each Assessment Objective follows.
A KNOWLEDGE WITH UNDERSTANDING
Students should be able to demonstrate knowledge and understanding in relation to:
1. scientific phenomena, facts, laws, definitions, concepts, theories;
2. scientific vocabulary, terminology, conventions (including symbols, quantities and units);
3. scientific instruments and apparatus, including techniques of operation and aspects of
safety;
4. scientific quantities and their determination;
5. scientific and technological applications with their social, economic and environmental
implications.
The subject content defines the factual material that candidates may need to recall and explain.
Questions testing these objectives will often begin with one of the following words: define, state,
describe, explain (using your knowledge and understanding) or outline. (See the glossary of
terms at the back of this syllabus.)
B HANDLING INFORMATION AND SOLVING PROBLEMS
Students should be able, using oral, written, symbolic, graphical and numerical forms of
presentation, to:
1. locate, select, organise and present information from a variety of sources;
2. translate information from one form to another;
3. manipulate numerical and other data;
4. use information to identify patterns, report trends and draw inferences;
5. present reasoned explanations of phenomena, patterns and relationships;
6. make predictions and propose hypotheses;
7. solve problems, including some of a quantitative nature.
These assessment objectives cannot be precisely specified in the subject content because
questions testing such skills may be based on information that is unfamiliar to the candidate. In
answering such questions, candidates are required to use principles and concepts that are
within the syllabus and apply them in a logical, reasoned or deductive manner to a novel
situation. Questions testing these objectives will often begin with one of the following words:
discuss, predict, suggest, calculate, explain (give reasoned explanations and explain the
processes of using information and solving problems) or determine. (See the glossary of terms
at the back of this syllabus.)
C EXPERIMENTAL SKILLS AND INVESTIGATIONS
Students should be able to:
1. use techniques, apparatus, and materials (including the following of a sequence of
instructions, where appropriate);
2. make and record observations and measurements;
3. interpret and evaluate experimental observations and data;
4. plan and carry out investigations, evaluate methods and suggest possible improvements
(including the selection of techniques, apparatus and materials).
0610 BIOLOGY IGCSE 2010
4
SPECIFICATION GRID
The approximate weightings allocated to each of the assessment objectives in the assessment
model are summarised in the table below.
Assessment Objective Weighting
A Knowledge with understanding 50% (not more than 25% recall)
B Handling information and solving problems 30%
C Experimental skills and investigations 20%
Teachers should take note that there is an equal weighting of 50% for skills (including handling
information, solving problems, practical, experimental and investigative skills) and for knowledge
and understanding. Teachers’ schemes of work, and the sequence of learning activities should
reflect this balance, so that the aims of the syllabus may be met, and the candidates prepared for
the assessment.
WEIGHTING OF ASSESSMENT OBJECTIVES
The relationship between the assessment objectives and the scheme of assessment is set out in
the table below.
Paper 1
(marks)
Paper 2 or 3
(marks)
Paper 4, 5 or 6
(marks)
Whole
assessment
(%)
AO1: Knowledge with
understanding
25-30 48-52 0 47-54
AO2: Handling, applying
and evaluating
information
10-15 27-32 0 26-33
AO3: Experimental and
investigative skills
0 0 40 20

LAB REPORT TEMPLATE

Lab Report Template

Title:

* a brief, concise, yet descriptive title

Statement of the Problem:

* What question(s) are you trying to answer?
* Include any preliminary observations or background information about the subject

Hypothesis:

* Write a possible solution for the problem.
* Make sure this possible solution is a complete sentence.
* Make sure the statement is testable.

Materials:

* Make a list of ALL items used in the lab.

Procedure:

* Write a paragraph (complete sentences) which explains what you did in the lab.
* Your procedure should be written so that anyone else could repeat the experiment.

Results (Data):

* This section should include any data tables, observations, or additional notes you make during the lab.
* You may attach a separate sheet(s) if necessary.
* All tables, graphs and charts should be labeled appropriately

Conclusions:

* Accept or reject your hypothesis.
* EXPLAIN why you accepted or rejected your hypothesis using data from the lab.
* Include a summary of the data - averages, highest, lowest..etc to help the reader understand your results
* List one thing you learned and describe how it applies to a real-life situation.
*Discuss possible errors that could have occurred in the collection of the data (experimental errors)

Introduction to Science

A- Define carefully.

Cell


Organism


Metabolism


Homeostasis


Respiration


Stimulus


Response


Secretion


Excretion


Reproduction


Classify


Prokaryote


Eukaryote


Nucleus


Binomial nomenclature

Taxonomy


Domain


Species



B- Compare each pair of terms listed below.

Unicellular



Multicellular
Autotrophic



Heterotrophic
Ingest



Digest
Asexual reproduction Sexual reproduction



Internal stimuli External stimuli



Voluntary response


Involuntary response
Movement


Location
Warm blooded animal Cold blooded animal




C. Life Functions
1. Name the life activity described:

a. birth to death
b. obtaining food for growth, energy and cell repair
c. collection and elimination of waste
d. ability to react to situations
e. motion either within an organism or a change in position or location
f. taking in O2 and combining it with food to release energy
g. the need for the essential fluid that composes about 65-70% of the organism
h. change in size, shape, form
i. production of chemicals such as hormones, enzymes, etc.
j. to produce an organism of the same species

2a. Do both animals and plants need to ingest food?



2b. Do both animals and plants need to digest food? Explain



3. Write the word formulas for photosynthesis and respiration. How are these reactions related?



4. How do plants and animals take in 02?



5. Which life processes compose an organism’s metabolism?



6. Write 4 reasons why H20 is essential to all organisms.



7. Why must all organisms have sufficient living space?



8. How do warm-blooded and cold-blooded animals maintain homeostasis?



9.What is the main source of energy for all living things? Explain.




10. What makes a living thing different from a non-living thing?




D. Classification

1.Why do scientists classify organisms?




2.What did Aristotle contribute to the development of scientific classification?




3.What two contributions did Linnaeus make to taxonomy?




4.What two important factors are considered in today’s modern classification system?




5. What are the levels of classification? (in order, of course!)



6. Which two levels are used for scientific naming?



7.Which level of classification include organisms that are the most similar? ……the least similar?



8.Name the three domains. Write three facts about each domain.






9a. Name the four kingdoms in the Eukarya domain.


9b.Name the kingdoms for each of the following descriptions

a. examples include heterotrophs and autotrophs
b. examples are all autotrophs
c. examples are all hetertrophs
d. multicellular (most or all)
e. unicellular (most)
f. most complex kingdom
g. examples often have both animal like and plant like characteristics.
h. hetertrophic and cannot move about
i. hetertrophic and can move about
j. autotrophic and can move about
k. examples include corn, cabbage, and carrots
l. examples include mold, yeast, and mildew
m. examples include Amoeba, saiamecieem, Euglena
n. examples include mussels, rabbits and man.


E. Scientific naming

1.What is the system of scientific naming called?


2. Who devised this system?


3.Which language is used in most of the scientific naming?


4.Who names a newly discovered organism?


5.Which two levels of classification are used to name organisms?


6.What is the rule that is applied to scientific names when written in script? When written in print? (books, magazines, journals, etc.)


7. Why is it important for scientist to agree on one naming system?


8. Using your notes, write the scientific name for: Remember to underline each name.

a. lion
b. man
c. rose

8b. Rewrite the scientific name for rose and indicate which is the genus and species name.


F. The Microscope


1.What is the proper way to carry a microscope?


2.Where are the lenses on the microscope?


3.What parts of the microscope are used for focusing?


4.How are the objectives changed?


5.How does the diaphragm work?


6.What 2 parts “support” the microscope?


7.What are the function of the:

a. body tube-
b. stage-
c. stage clips
d. mirror-

8. How is total magnification determined and give an example?

** Be able to Identify All Parts of The Microscope **

Introduction to science

Introduction to science

1. Science
2. Classify
3. Life Science
4. Earth Science
5. Physical Science
6. Theory
7. Inferring
8. Predicting
9. Scientific Method
10. Scientific Law
11. Hypothesis
12. Control Group
13. Experimental Group
14. Meter
15. Liter
16. Gram
17. Farenheit Scale
18. Celsius Scale
19. Kelvin Scale
20. Direct Observation
21. Indirect Observation
22. Data
23. Qualitative Data
24. Quantitative Data
25. Technology
26. Kilogram
27. Zoology
28. Botany
29. Ecology
30. Experiment



Part B- General Information.

1. Write 4 characteristics exhibited by many scientists.
2. Write 4 places a scientist works.
3. What is the main difference between a scientific theory and a scientific law?
4. List the steps of the scientific method.
5. Name the four parts of the experiment.
6. What is a variable?
7. Why is a control group necessary?
8. Compare qualitative and quantitative data, Include Examples.

Part C- The Metric System

1. What are the three basic units in the metric system? Give their meaning and their abbreviations.
2. Which prefixes make the base units larger? ----smaller? Include their meanings and their abbreviations.
3. Complete the chart:

Name Abbreviation Meaning
a. hectoliter
b. decagram
c. kilometer
d. deciliter





4. Measure these lines in: (cm and mm)

A) _________________________


B) ___________


C) _______________________________________________________________________


5. What is another name for the Metric System?


Part D- Temperature.

Name the three temperature scales and give the freezing and boiling points of each.




Part E- Word-Part Meaning: Define these words.




Part F- Essay

1. Explain how technology can have a positive and a negative effect on society as well as include 2 specific examples.