PMR My Learning Home 我的学习部落 : 2012

CHAPTER 3: EXCRETION

Process of removing waste material from our body

HUMAN

LUNG

1. carbon dioxide and water vaour

SKIN

1. largest organ in human body

2. water, urea and mineral salt

3. excrete waste product in form of sweating

KIDNEY

1. water, urea, mineral salt

2. eliminate as urine

3. bean shape

4. regulate amount of water and mineral

salt, blood concentration

KIDNEY- filter and remove waste product

URETER- channel urine from kidney to urinary bladder

URINARY BLADDER- store urine

URETHRA- channel urine from urethra out of body

THE IMPORTANCE OF KIDNEYS

1. Removing excretory materials in the form of urine. Urine contains nitrogenous substances such as urea, ammonia and uric acid.

2. Urea is formed from carbon dioxide and ammonia while ammonia is the breakdown of protein in the liver. Therefore, the removal of urea can maintain the pH balance in the blood.

3. Reabsorbing materials such as mineral salts, glucose and amino acid required by the body from the blood and so control the blood concentration equilibrium.

4. Eliminating chemical compounds from blood for example, toxin, alcohol and drugs. The accumulation of toxic materials in the blood can result in death.

LIVING WITH KIDNEY FAILURE

1. Kidney failure happens when they do not work properly. This could be due to infections caused by microorganisms.

2. A blockage in ureter and urethra can cause damage to the kidneys because urine cannot flow out of the body.

3. A person who has only one kidney still can live normally.

4. If both kidneys fail, the person will have to rely on an artificial kidney machine called the dialysis machine to remove wastes from the blood.

DIALYSIS

1. The process of filtering and cleansing the blood using a dialysis machine.

2. Dialysis removes excess water and wastes through a semi-permeable membrane.

3. A semi-permeable membranes has pores which allow urea and salts to go through. Larger particles such as blood cells, bacteria, viruses or protein cannot pass through this membrane.

4. The common dialysis method is hemodialysis where waste products and excess water are separated artificially from the patient’s blood by diffusion and ultrafiltration

SKIN	WATER, MINERAL SALT, UREA	SWEATING
KIDNEY	WATER, MINERAL SALT, UREA	URINATING
LUNG	CARBON DIOXIDE, WATER	EXHALING/ BREATHING

PLANT

1. no specify respiratory system

2. oxygen, carbon dioxide, water, mineral salt, nitrogenous waste

LATEX- RUBBER TREE- TYRE

RESIN- CASUARINA STEM- VARNISH AND GUM

GUM- ACACIA STEM- COUGH MEDICINE

TANNIC ACID- TEA, COFFE, MANGROVE BARK- INK

QUINNE- CINCHONA BARK- MALARIA MEDICINE

OIL- FLOWER OR LEAF- PERFUME AND INSECT BITE OINTMENT

1.1 Science is Part of Everyday Life

1. Science is the knowledge of things that happen in nature and the systematic study of nature and how it affects the environment and us.

2. Things that happen in nature are also known as natural phenomena.

3. Science helps us to understand natural phenomena, to understand ourselves, to make discoveries and to gain knowledge.

4. Science improves our standard of living and the quality of our environment.

5. Physics, chemistry and biology are the three main branches of science.

6. The study of science requires a positive attitude.

7. Example of natural phenomenon is: lighting strikes, growth of human from babyhood to adulthood, flowers blossoming, water evaporation, ball falling to the ground, ice melting, the growth of animals and plants, foundation of rainbow and many more.

The importance of science in everyday life

- Science is very important in our daily life. We use the knowledge of science to make machines and develop new technologies.

- These machines help us to do our work more efficiently. The machines also make our life more comfortable.

- Technology is the application of science knowledge for our needs and helps us to improve our standard of living.

- Contributions of science and technology to the lives of human beings: Health, Comforts of life, Commerce, Transportation, Security, Medicine, Communication, Space exploration, Agriculture and Entertainment.

Careers related to science

- Science has three main branches of studies, namely chemistry, biology and physics.

- Each branch of science has careers closely related to it. Therefore, you must be very good at science if you are interested in careers related to science.

Science also has various fields of scientific study, such as:

-Political science > national science and a branch of social science that is associated with government, organizations and nations in a practical way

-Applied science > used in various type of work

-Sport science > combines various fields of knowledge to used in sport

-Computer science > the study of the basic principles and uses of computers

- Example of careers related to science: science teacher, doctor, biochemists, computer programmers, engineers, astronomers, pharmacists, dentists, sport physiologist, sport psychologist and others.

- The following information on various careers and their subject requirements can help you to plan your career.

Careers	Major subject requirements
Astronomer	Physics
Dentist	Biology
Engineer	Physics and Chemistry
Pharmacist	Biology and Chemistry
Science teacher	Physics, Biology and Chemistry

1.2 Your Science Laboratory

Scientists usually work in a laboratory. We will also work in a laboratory when we carry out scientific investigations during our science lessons.

Laboratory safety rules

The laboratory is a place equipped with apparatus for conducting experiments, investigation and tests. So, we need to work safely in the laboratory. Accidents can happen if we are careless. Here are some laboratory safety rules that we must follow while working in a laboratory.

Enter the laboratory with your teacher’s permission.
If the class arrives before the teacher, line up outside the laboratory and wait quietly.
After entering the laboratory, go to your places without jostling or grabbing of stools.
No food or drinks should be taken into the laboratory.
Open all doors and windows while in the laboratory.
Pupils must not perform experiments without permission.
Read and understand the instructions given before you attempt to do the experiment. When in doubt always ask your teacher for help and advice.
Always keep laboratory clean.
Label all containers clearly and the label should draw attention to any particular hazard.
Always read the label on the bottle before using the chemicals in contains.
Do not play, run or walk around unnecessarily in the laboratory.
Handle all apparatus correctly and carefully.
Breakages and faulty equipments must be reported to the teacher at once.
Do not waste any chemicals. Use only the required amount.
Do not pour unused chemicals back into their containers.
Water, gas and electricity must not be waste.
Do not damage any fitting or the electrical mains in the laboratory.
Do not obstruct passage or access to emergency exits or fire extinguishers.
Do not light a Bunsen burner with a piece of paper. Turn off the gas after used.
Do not handle chemicals with your fingers. Always use a spatula.
Do not taste any chemical or inhale any gas unless asked to do so by the teacher.
When heating any solution in a boiling tube, always make sure that the mouth of the tube is not pointed to anybody.
Solid wastes must be put in the bins provided. Do not throw solid waste into the sinks.
Any mishaps, cuts, burns scalds or substances which get into your mouth must be reported to the teacher at once.
After the experiments, wash all used apparatus and return them to their respective places.
Do not remove any apparatus or chemical from the laboratory.
Wash your hands thoroughly.
The benches must be left clean and tidy.
All taps and switches must de turned off.

Hazardous substances found in the laboratory

There are many substances in the science laboratory. Some of these substances are hazardous. We use hazard warning symbols to show the danger of the substance. Below are some common hazard warning symbols.

Laboratory Apparatus

We use apparatus when doing scientific investigations. You will learn how to use the laboratory apparatus by doing scientific investigations in the laboratory. You should also learn how to draw the apparatus you use in a scientific investigation. Here are some common apparatus that you can find in the laboratory.

1.3 Steps in a Scientific Investigation

Scientists obtain the knowledge of science by doing scientific investigation. The scientific method of investigation is a method carried out based on scientific rules and principles that are accurate, disciplined and systematic.

Identify the problem: Determining the problem to be examined.
Forming a hypothesis: Making a smart guess to explain the problem.
Planning an investigation: How to rest the hypothesis, what apparatus to use, how to put the apparatus together, what materials are needed and what procedure to follow.
Controlling the variables: Changing one or more of the conditions of the experiment.(a)Constant variable (b)Manipulated variable (c)Responding variable
Carrying out experiment:

(a) Collecting data: Recording of data

(b) Analysing data: Analysis of data in the form of a table or graph

(c) Evaluating data: Interpretation of data to show the relationship between the length of a string and the swinging time of a pendulum

(d) Making conclusion: Making a statement regarding the outcome of experiment based on the hypothesis.

6. If the hypothesis is right, science theory is build. If the hypothesis is wrong, back to the step 2 (Forming a hypothesis).

7. Writing a report: Writing a report of the finding of the experiment.

1.4 Physical Quantities and Their Units

- Physical quantities are quantities that can be measured.

- The five base quantities are length, time, mass, temperature and electric current. Pre fixes are used when the quantities that we measured have very small values or very big values.

- Physical quantities are measured in SI units. The symbol S.I. is an abbreviation for the French term Le Système International d’ Unités. It means International System of Units.

Physical quantity SI unit Unit symbol

Length Meter m

Mass Kilogram kg

Time Second s

Temperature Kelvin K

Electric current Ampere A

Prefix Symbol Value Standard Form

Giga G 1000000000 10⁹

Mega M 1000000 10⁶

Kilo k 1000 10³

Hecto h 100 10²

Deca da 10 10¹

Desi d 0.1 10^-1

Centi c 0.01 10^-2

Milli m 0.001 10^-3

Micro μ 0.000001 10^-6

Nano n 0.000000001 10^-9

Pico p 0.00000000000001 10^-12

1.5 Is Mass the Same as Weight?

1.1 Learning how to Use Measuring Tools

Measuring length

- Length is the distance between two points.

- The S.I. unit for length is kilometre (km), metre (m), centimeter (cm), and millimeter (mm)

- Different tools are used to measure different type of lengths.

The relationship between the units:

1cm=10mm

1m=100cm

1km=1000m

Measurement of the length

-The length of a straight line can de measured with metre ruler, half-metre ruler, ruler or measuring tape.

- thread and a ruler are used to measure the length of a curved line.

- An opisometer can be used to measure the length of a curved line.

- When we are taking reading from the scale ruler, the correct eye position is very important in order to obtain an accurate reading.

- A number of readings should be taken to get an average value that is more accurate.

The accuracy of a measurement can be improved if the person doing the measurement can
avoid making errors. The error caused by an incorrect eye position when taking measurement
is known as parallax error.

Measurement of the diameter

-Internal diameter of a container

The internal diameter of a container like a beaker

or boiling tube can be measured using a pair of

internal calipers and a ruler.

The distance between

the two arms of the calipers marks the inside

diameter of a container.

-External diameter of a container

The external diameter of a container like a beaker

or boiling tube can be measured using a pair of

external calipers and a ruler.

Measure the distance

between two points of the calipers with a ruler.

-Diameter of a spherical object

The diameter of a spherical object can be measured

with two wooden block and a ruler or two set

squares and a ruler.

-Vernier calipers

Vernier calipers are used to measure small distances

accurately. The internal jaws are used to measure the

internal diameter of a container. The external jaws are

used to measure the external diameter of a container.

This instrument gives readings with an accurately of

up to 0.01cm (2 decimal places). The Vernier calipers

have two scales. The main scale is graduated in centimeter

units. The Vernier scale, a scale of 9mm, has 10 divisions.

One division is 0.9mm.

Measurement of the Area

Area is the total surface occupied by an object. Area is measured in units of square metres (m²), square centrimetres (cm²) and square millimeters (mm²). Different tools are used to measured different types of lengths.

Measurement of a regular shape

Regular shape area can be calculated by using Mathematical formulae:

Measurement of an irregular shape

-The area of irregular shape like leaves and petals

can be estimated by using a graph paper.

- A graph paper has small squares boxes.

-The irregular shape object is estimate by counting the number of square

^1cm

covered by the tracing.

- A check mark is made on the graph paper for each

full square and half full squares,or more than half full squares.

5×1cm×1cm=5cm²

-Then, the number of check marks are counted.

-The area of the object is estimate by multiplying the number of check marks

with the area of one square on the graph paper.

- More accurate approximate of area can be obtained by using a graph paper with squares that are smaller in size.

Measurement of Volume of Liquids

- Volume is the total area occupied by an object.

- Volume is measured in litres (l), milliliters (ml), cubic metres (m³) and cubic centrimetres (cm³).

Measuring cylinder-The measuring cylinder is a vessel that ha its outside surface marked (graduated) with units of volume in cubic centrimetres. To obtain an accurate reading of the volume of a liquid, the reading has to be taken above or below the curve of the meniscus.

Pipette-The pipette is a glass tube with a bulb at its centre and a spout at one end. The other and has a mark indicating the fixed volume of liquid that the pipette can measure. Pipettes in the laboratories are usually used to measure volumes of5, 15, 20 and 25ml accurately.

Burette-The burette is used to deliver volumes of liquids more accurately than a measuring cylinder.

Measurement of Volume of Solids

The volume of regular and irregular shape solids can be determined by using the water displacement method.

1.1 The Importance of Standard Units in Everyday Life

- The standard units used are the S.I. units.

- The use of standard units makes it easier for people from different countries to communicate with each other.

- People need to communicate when they are involved in interactions such as buying and selling, international business, industries, and transportation.

- Furthermore, the use of a standard unit means a measurement in that unit has the same value anywhere in the world. For example, if you were to buy 1kg of sugar in Malaysia and 1kg of sugar in Thailand, you would get the same amount of sugar from each country. - If standard units absence, accurate and precise measurement would be a problem, people from different countries will face difficulties to communicate with each other especially in interactions such as business and transportation and scientists around the world would have difficulty in comparing studies that have been carried out.

Length-British Imperial System-inches, feet, yard, chain, mile -metric system-metre, kilometre

Area-British Imperial System-inches², feet², yard², mile², acre-metric system-metre², kilometre²

Volume- British Imperial System-inches³, feet³, yard³, gallon-metric system-metre³

Mass or weight- British Imperial System-pound, ounce, kati, tahil, ton, pikul

-metric system-gram, kilogram

Length-12inches=1foot, 3feet=1yard, 22yard=1chain, 10chain=1furlong, 8furlong=1mile, 5280feet=1mile, 1760yards=1mile, 1inch=25.4mm, 1foot=0.305, 1mile=1.6km, 1foot=0.093m, 1m=3.3feet, 1km=0.6mile

Area-144 square inches=1 square foot, 9 square foot=1 square yard, 4840 square yard=1 acre, 640 acre=1 square mile, 1 acre=4046.9m², 1m²=10.8feet²

Volume-1728 cubic inches=1 cubic foot, 27 cubic feet=1 cubic yard, 1 foot³=0.028m³, 1 gallon=4.5 litre, 1ml=0.0000g inches³, 1m³=35.3 feet³, 1 litre=0.22 gallon

Mass-437.5 grains=1 ounce, 16 ounces=1 pound, 14 pounds=1 stone, 12 ounces=1 pound, 1 pound=0.45kg, 1ton=1016kg, 1kati=0.6kg, lg=0.035ounce, 1g=0.026tahil, 1kg=1.65katis

PMR My Learning Home 我的学习部落

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