KIUTA DAY SECONDARY SCHOOL
BIOLOGY
LECTURE NOTES
FORMS I, II, III, IV
CLAIRE THOMAS
FORM I FIRST SEMESTER LECTURE NOTES
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1.0 Introduction to Biology
1.1 Basic concepts and terminologies of Biology
1. Biology is the study of living things or organisms.
2. Living things share life process (or seven characteristics).
a. Locomotion: All living things move.
b. Nutrition: All living things feed by taking in nutrients in order to obtain energy.
c. Irritability: All living things are sensitive to their surroundings.
d. Reproduction: All living things make more of their own kind.
e. Growth: All living things get bigger and repair damage.
f. Excretion: All living things get rid of toxic substances.
g. Respiration: All living things take in oxygen and release carbon dioxide.
3. A Cell is a unit of living matter. All things are made up of cells.
4. There are two main branches of biology
a. Botany is the study of plants
b. Zoology is the study of animals
5. Why do we study biology?
a. Biology helps us understand life
b. Biology helps us understand ourselves
c. Biology helps us understand the differences between plants and animals.
d. Biology helps us understand our enviroment and how to protect it.
e. The study of biology gives skills and knowledge that can be used in other areas.
Biology relates to the study of medicine, environment, engineering, farming, ect.
1.2 Scientific processes in biology
1. A Biologist is someone who studies living things.
a. The scientific method is the process by which scienctics answer scientific
questions through a series of investigations.
i. The 6 steps of the scientific method
1. Identifying the Problem
2. Hypthesis
3. Experimentation
4. Data Collection
5. Data Analysis and interpretation
6. Conclusion
b. Scientific questioning is the questions that may come up when you are observing
that will need to be answered. Hypothesis is an explanation or answer to these
questions. A hypothesis is an educated guess and may not always be right.
c. Experimentation is the process of doing a series of investigations in order to test a
hypothesis.
d. Observation is when we use sight, smell, touch, taste, or hearing to describe what
we are studying.
e. Measurement is when we use a set unit to describe a factor of the thing that we are
studying.
i. 6 Things that we measure are:
1. Mass is how heavy something is. It is measured in grams (g) or
kilograms (kg)
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2. Length is the how long or wide something is. It is measured in
centimeters (cm), meters (m) and kilometers (km)
3. Time is measured in seconds, minutes, and hours.
4. Temperature is how hot or cold something is. Temperature is
measured in degrees.
5. Rate is how quickly something changes. It is usually measured in
kilometers per hour.
6. Volume is the amount of space something takes up. It is usually
measured in liters.
f. A laboratory notebook helps to keep us to take notes, think about our experiment,
record our findings, and learn from the results.
1.3 The Biology Laboratory
1. The Common Features in a Biology Laboratory
a. Sink and a water supply
b. Gas supply and Bunsen burners
c. Fridge for storing specimens
d. Oven for drying specimens or for experiments to culture bacteria
e. Light Microscope
f. Test Tubes
g. Beakers
h. Scalpel
i. Forceps
j. Various items of equipment and apparatus for carrying out biological experiments
2. A light microscope is an apparatus used for viewing microscopic specimens.
a. A light microscope has 10 parts
i. Eye piece is the part of the microscope that we look through.
ii. Tube holds the eye piece and rotating nosepiece together.
iii. Rotating nosepiece allows us to chance objective lenses.
iv. Objective lens focuses and magnifies the image.
v. Stage is where the slide of the specimen is placed.
vi. Stage Clip holds the slide in place.
vii. Diaphragm controls the amount of light passing through the slide.
viii. Mirror reflects light through the specimen.
ix. Coarse objective knob focuses the image during low power magnification
x. Fine adjustment knob focuses the image during high power magnification.
3. Safety in the laboratory
a. Sometimes doing biology experiments can be dangerous. Hazard symbols are
signs which tell us what things in the lab are dangerous.
i. Toxic substances can cause death if eaten, breathed, or spilled on the skin.
Examples of toxic substances are acids and alkalis.
ii. Highly Flammable substances can catch on fire easily. Examples of highly
flammable substances are alcohol or gasoline.
iii. Corrosive substances attack and can kill living tissue and other materials.
Examples of toxic substances are acids and alkalis.
iv. Radioactive substances release harmful radiation which can hurt living
tissue.
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v. Biohazards are substances that have microbes or other factors which could
cause disease.
b. Because we want to be safe in the laboratory we have to follow a list of rules.
i. Move carefully around the laboratory. Do not run.
ii. Concentrate on your own experiment.
iii. Follow the instructions.
iv. Use clean equipment and clean up after working in the laboratory.
v. Do not eat or drink in the laboratory.
vi. Wash your hands before and after working in the laboratory.
vii. If you get injured or damage any equipment tell your teacher immediately.
1.
2. Safety in Our Environment
2.1 First Aid
1. Importance of First Aid
a. First aid is an immediate, temporary treatment carried out in cases of
emergency or sudden illness before professional treatment.
b. When First Aid is important because
i. First Aid can save lives.
ii. First Aid can reduce pain
iii. First Aid can prevent the illness or injury from becoming worse.
iv. First Aid can remove the fear of death, and help the patient recover
from shock.
2. First Aid Kit
a. A First Aid Kit is a small box which holds medical supplies for emergencies.
The medical kit should be placed in a safe and easy to see area.
b. A medical kit will have the following things:
i. Gauze is used to cover wounds to prevent dirt and microorganisms
from entering.
ii. Bandages are used for securing fractures and dislocated bones.
iii. Scissors are used for cutting dressing materials such as gauze,
bandages, or plaster.
iv. Razor blades is used for opening a wound to cut away loose tissue to
prevent further injuries and pain.
v. Antibiotic Ointment is used for preventing infection.
vi. Mentholated Spirit to clean wounds and reduce bleeding.
vii. Painkillers are used to reduce pain. Aspirin is an example of a painkiller.
viii. Soap is used for washing hands, wounds, and medical equipment.
ix. Forceps for removing things from wounds, like splinters or dirt.
x. Gloves are used to prevent the spread of pathogens.
3. First Aid Procedure
a. Risks or dangers of giving First Aid
i. When you are giving first aid be sure to keep yourself safe. Pathogens
are disease-causing organisms that can spread through the air or
through the blood. Air-borne pathogens can be pass on if a patient
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b.
c.
d.
e.
breathes, coughs, or sneezes. If a patient has a blood-born pathogen it
can be given to someone else if their blood mixes.
Minor Cuts and bleeding
i. If someone is cut, this is the way we can treat them
1. Clean the wound.
2. Dry the skin and wound around it.
3. Apply a bandage.
Major Bleeding
i. If a person gets a large cut, they can loss a lot of blood, which can
cause them to lose consciousness or even die.
1. Remove clothing around the cut and cover the cut using a piece
of gauze pad or clean cloth.
2. If possible, have the patient to apply direct pressure to the
wound for 5 to 15 minutes.
3. Elevate or raise the cut above the heart if possible.
Burns
i. Burns are caused by fire or other hot objects.
1. Put the burn in cold water as soon as possible.
2. Cover burn with a cloth to prevent infection.
3. Apply antibiotic ointment, burn cream, or aloe vera.
Fainting
i. If a person suddenly falls to the ground and is unconscious they may
have fainted.
1. Have the victim lay down and lift legs slightly.
2. Loosen tight clothing.
3. Offer them water once they are able to sit up.
f. Treatment of snake bites
i. Snake bites can be common in Africa, although not all snake bites are
poisonous. If possible, try to identify the snake to see if it is poisonous.
Do these steps to treat someone who has been bitten by a snake.
1. Support and keep the bitten area from moving because the more
that part of the body moves, the faster the poison will spread to
the rest of the body.
2. Tie a wide elastic bandage or clean cloth around the part of the
body to stop the blood flow and prevent poison from spreading.
3. Wash the bite with soap and water to remove the poison.
4. Take the person to the hospital right away.
g. Nosebleed
i. To treat a nosebleed, which is when a person’s nose starts to bleed, do
the following steps.
1. Ask the patient to sit with their head tipped forward.
2. Get them to pinch their nose for 10 minutes and breathe through
their mouth,
3. The patient should not talk, swallow, or sniff if possible.
h. Poisoning
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i. A poison can be defined as any substance which is capable of
destroying life or of seriously endangering a person’s health when
applied to the body internally or externally.
ii. If the poison is eaten or drank, it must be removed by having the victim
vomit. The victim can vomit by placing two fingers in the back of the
throat.
iii. Kerosene is a common poison in Tanzania because it is clear and
people thinking it is water. If a person swallows kerosene they should
not vomit, but instead drink water or milk.
iv. Call a doctor as soon as possible.
i. Choking
i. If someone is conscious but cannot breath, cough, or speak, they may
be choking, which means something is blocking their airway.
ii. To perform remove the object from the throat
1. Get behind a patient and wrap your arms around their chest.
2. Make one hand into a fist and wrap the other hand around it.
3. Push up and back on the victim’s chest. You are trying to push
air out of the lungs so the object will be loosened.
4. Once object is removed, give victim water and have them rest
until breathing is normal and they are calm.
2.2 Safety at home and school
1. Common Accidents
a. An Accident is an unexpected event that can cause injury and sometimes death.
b. Accidents are very common at home and school.
c. Examples of accidents are:
i. Fractures and dislocations caused by falls
ii. If a fire starts
iii. Burns caused by hot liquids or corrosive chemicals
iv. Choking caused by food or drink or swallowing something
v. Snake or insect bits
vi. Drowning
vii. Cuts and scratches caused by sharp objects
viii. Eye injuries from sand or dust
ix. Poisoning from drinking chemicals or taking too much medicine
2. Ways to Prevent Common Accidents
a. Be aware of the danger around you at the house and at home.
b. Follow these rules to prevent accidents at home.
i. Keep sharp objects away from children.
ii. Throw away sharp objects safely.
iii. Electricity should be turned off when you are not using it.
iv. Young children should not be given small objects to play with because
they can choke on them.
v. Turn off gas stoves when you are not using them.
vi. Mop up any liquids that have spilled on the floor right away.
vii. Follow lab safety rules.
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viii.
ix.
x.
xi.
Keep all dangerous chemicals and medicine away from children.
Keep medicine and chemicals clearly labeled.
Have a fire extinguisher in the lab at all times.
Cut grass and other plants around the house and classroom to keep
away snakes and bees.
xii. Keep medical kit full.
xiii. Check that water, electric, and gas systems are working.
2.3 Waste Disposal
1. What is waste?
a. Waste is an unwanted material.
b. Examples of waste are food scrapes, plastic bads, urine, and feces.
c. Waste can be solid, liquid, or gas.
d. Waste disposal is the way we get rid of or remove waste.
2. Types of Waste
a. Waste is classified by where it comes from, whether it is hazardous and how to
dispose of waste that is safe for people and the natural environment over
hundreds or thousands of years.
b. Household waste
i. Household waste that produced at your home.
ii. Examples of household waste are food scraps, paper, glass, paint,
broken watches or other electronics, batteries, feces and urine.
c. Commercial Waste
i. Commercial waste is from businesses.
ii. Examples of commercial waste are food and packing material, and
chemicals
d. Industrial Waste
i. Industrial Waste comes from industrial processes, such as factories,
construction, and mining.
ii. Examples of industrial waste are metal scraps, chemicals, coolants or
lubricants for machines, and packaging material
e. Hazardous and toxic
i. Hazardous waste or toxic waste is any material which may be fatal to
humans or animals, even in small does.
ii. Examples of toxic waste include used needles, bandages with blood,
chemicals like mercury from thermometers or cyanide, battery acid, or
radioactive material like the waste from some power plants.
3. Principles of Waste Disposal
a. Landfill
i. A landfill is putting waste into holes in the ground and then covered
with dirt.
b. Incinerator or burning trash
i. An incinerator burns waste at a very high temperature.
c. Recycling
i. Recycling is the process of reusing material.
d. Composting
i. Composting is using food and yard scraps to create fertilizer.
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4. The Effects of Poor Waste Disposal
a. The effects of poor waste disposal can lead to pollution. Pollution is the
presence or introduction into the environment of a substance or thing that
has harmful or poisonous effects.
b. Poor waste disposal can lead to the following effects:
i. Water Contamination
1. Waste can pollute lakes, rivers, and ground water supplies and
then humans, plants, or animals can become sick.
ii. Soil Contamination
1. Waste can change the composition of soil and kill crops.
iii. Habitat Destruction
1. Waste can enter lakes, rivers, and oceans and kill whole
ecosystems. Animals can eat waste, thinking it is food and be
killed. Also chemical waste can enter an environment and cause
many organisms to die.
iv. Damage to Human Health
1. Waste can cause injury, infections, disease or death to humans.
5. Ways of disposing of waste in community
a. The best way to dispose of waste is to reduce, reuse, and recycle.
b. Good waste management requires the effective storage, collection, transfer,
recycling, and final disposal of waste.
c. Landfill sites should be properly contained.
i. The base of the site should be lined with clay or synthetic membrane to
prevent leakage. Pipes are laid to collect and dispose of leakage.
ii. Methane (biogas) should be collected and tapped off to be recycled as
an energy source(fuel) for domestic and industrial use.
3.0 Health and Immunity
3.1 The concept of health and immunity
a. Definitions
a. Health is a person’s physical, emotional, and mental state of well being.
b. Healthy is the condition of being without disease.
c. Immunity is the body’s ability to fight disease.
d. Immune is the condition of being able to resist disease.
e. The immune system is the system of the body that protects the body against
disease.
f. Pathogens (agents of disease) are disease-causing orgnaisms.
g. White blood cells are cells in the blood stream that protect our body against
disease.
i. There are two types of White Blood Cells; Phagocytes and Lymphocytes.
1. Phagocytes destroy pathogens by engulfing them.
2. Lymphocytes produce antibodies to destroy pathogens.
b. Types of Immunity
a. Natural (Active) Immunity
i. Natural Immunity is immunity that develops because the body produces
antibodies.
ii. Natural Immunity is a result of recovering from an infection.
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b. Passive Immunity
i. Passive Immunity is when the body receives antibodies through injections
or immunizations to help fight off a disease.
c. Factors that affect body immunity
a. The body has a first line of defense to try and prevent infection from entering the
body.
i. The skin prevents pathogens from entering the body.
ii. The eyes produce tears to kill pathogens trying to enter the body.
iii. The respiratory system produces mucus in order to trap pathogens and
remove them from the body.
iv. The digestive system produces hydrochloric acid and enzymes which kill
pathogens trying to enter the body through the stomach.
v. If any of these system are not working properly pathogens can enter the
body and the immune system will begin to fight.
3.2 Personal hygiene and good manners
1. Personal Hygiene
a. Personal hygiene is how you attend to your personal appearance.
i. This means keeping the whole body clean, keeping good health, and having
a good appearance.
ii. Personal hygiene is important to protect our body from disease.
iii. By maintaining personal hygiene we lower the risk of getting disease.
iv. Principles of good hygiene are:
1. Washing your body daily
2. Washing your hands with soup
3. Brushing your teeth twice a day
4. Sitting and standing up straight for good posture
5. Exercising daily for good fitness and appearance
6. Getting plenty of sleep, at least 8 hours a day.
7. Eating a balanced diet.
8. Changing and cleaning clothes regularly
9. Avoid cigarettes, alcohol, and other drugs.
b. Good Manners
i. Good manners are behaving in a way that is accepted by the majority of
society.
ii. Good manners are important because:
1. People will like you if you use good manners
2. People will learn from you
3. You will be accepted by society
iii. Example of good manners are:
1. Keep your mouth closed when you chew
2. Do not use bad language
3. Greet others with respect.
4. Do not interrupt someone while they are speaking.
5. Introduce visitors to one another.
6. Cover your mouth when sneezing or yawning.
3.3 Infections and diseases
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1. Meaning of Diseases and Infections
a. A disease is a condition, other than injury, that interferes with the normal
functioning of the body.
b. An infection is a disease that is caused by microorganisms.
i. Examples of microorganisms that attack our cells are viruses, bacteria,
protozoa, fungi, insects, and worms.
1. These organisms enter your body and feed and reproduce inside of
it. They damage your cells and release toxic or poisons into the
body.
ii. There are two types of diseases; communicable and non-communicable.
1. Communicable diseases are diseases that can be passed from person
to person. They are also known as infectious diseases.
2. Non-communicable diseases are diseases that can not be passed
from person to person.
c. How diseases are spread
i. Direct transmission is the spread of disease through physical contact.
Examples of direct transmission are through blood, sexual fluids, or saliva.
ii. Indirect transmission is the spread of the disease through an intermediate
agent, like air, water, or other organisms.
1. By the air
a. Coughing, sneezing, breathing and even talking releases
microorganisms into the air. These microorganisms may
enter another person’s mouth when they breathe.
2. By infected food and water
a. When we eat food that is not fully cooked or dirty from
sewage, we can get sick.
3. By objects
a. Books, clothes, and door handles can all carry
microorganisms.
4. By insects or other animals
a. Organisms like mosquitoes or tsetse flies can spread disease.
Organisms that spread disease from one individual to
another are called vectors.
d. How we can prevent disease
i. We can prevent getting disease or infection by:
1. Maintaining good personal hygiene
2. Eating a good balanced diet
3. Taking regular exercise
4. Getting enough rest
5. Not smoking or drinking alcohol in excess
6. Using the preventative medical services
3.4 HIV/AIDS, STIs, and STDs
1. Sexually Transmitted Diseases STDs, (also know as Sexually Transmitted InfectionsSTI) all infectious diseases which are transferred from person to person during
sexual intercourse.
a. STDs
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i. Causes
1. STDs are caused by bacteria or viruses. Bacteria infections, like
Gonorrhea, Syphilis, and Chlamydia, are spread through sexual
intercourse, but can be cured with medication and time. Viral
diseases, like Hepatits and gential herpes can not be cured.
ii. Symptoms
1. A symptom is a physical or mental sign that can indicate the
presences of a disease.
2. Most STDs have similar symptoms because they affect the
genitals.
3. Common symptoms in women are:
a. Sores, bumps, or blisters near the genitals, anus, or
mouth
b. Burning or pain when urinating
c. Itching, bad smell, or unusual discharge from the vagina
or anus
d. Pain in the lower abdomen
e. Bleeding from the vagina between menstral periods
f. Many times there are no symptoms present
4. Common symptoms in men are:
a. Sores, bumps, or blisters near the genitals, anus, or
mouth
b. Burning or pain when urinating
c. Drip or discharge from the penis
d. Itching, pain, or discharge from the anus
e. Many times there are no symptoms present
iii. Modes of Transmission
1. STDs are transmitted when infected semen or vaginal juices
come into contact with the mouth, genitals, or anus. Some STDs
can be spread by sharing personal items like underwear or
towels.
iv. Effects
1. Each type of STI has different effects, but the most common are
loss of fertility, increased chance of complications during
pregnancy, social and mental problems, and in some cases,
death.
v. Prevention and Control
1. Prevention
a. The best way to prevent STDs is to be abstinent. This
means to not have sexual intercourse.
b. You can also have a faithful relationship with only one
partner
c. You should always use condoms during sexual
intercourse.
2. Testing and Treatment
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a. There are two types of STI; bacterial and viral
b. Bacterial Infections can be cured with antibiotics.
i. Examples of bacterial STIs are Chlamydia,
Syphilis, and gonorrhea.
c. Viral infections can not be cured.
i. Examples of viral infections are Hepatitis B and
Genital Herpes.
2. HIV/AIDS
a. AIDS (Acquired Immunodeficiency Syndrome) is caused by HIV (Human
Immunodeficiency Virus). People who are infected can look and feel
healthy and may not know for years that they are infected. However, they
can infect people even if they appear healthy. HIV is in a person’s blood,
semen, vaginal fluid, and brest milk. The only way to tell if someone is
infected with HIV is with a blood test.
b. If you are infected with HIV your body’s immune system gets very weak
and can not fight other infections.
c. To understand HIV, we must understand the immune system.
i. Our blood has hundreds of cells. Some of these cells are called white
blood cells. White blood cells help fight infections. Some of these
white blood cells are called “T-helper” cells.
ii. HIV attacks “T-helper” cells. HIV enters the T Helper cells and makes
copies of itself. As HIV attacks T Helper cells, the body is not about to
fight off infection and the person with HIV becomes sick from other
illnesses.
iii. When a persons T Helper cells reach a specific low level where their
body can no longer fight serious infections, they are diagnosed with
AIDS.
iv. Although many people die of AIDS, it is actually another infection such
as pnemonia or cancer that their body was not able to fight because of
AIDS.
d. There is no vaccine to prevent HIV infections and there is no cure for AIDS.
1. Symptoms
a. The symptoms of AIDS is common to other diseases.
i. Long term fatigue
ii. swollen lymph glands
iii. rapid and excessive weight loss
iv. persistent fever and night sweats
v. persistent shortness of breath
vi. persistent dry cough
vii. diarrhea
viii. pink or purple patches on the skin
ix. lethargy and depression
2. Modes of Transmission
a. A person can only contract HIV from another person through direct
contact with blood, breast milk, or seminal fluids (sperm and vaginal fluid)
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b. The most common modes of transmission are contact with blood, using
unclean needles for injections, sexual intercourse, and mother to child
through breast feeding.
3. Effects
e. HIV will eventually become AIDS. Although there is no specific amount of
time, it will happen.
f. AIDS will eventually cause death.
g. While a person has HIV/AIDS they may experience both physical and
emotional effects of the disease. The physical effects include weakness,
diarrhea, weight loss, skin rashes, and coughing. The emotional effects
include seperation from family and friends, guilt associated with
contracting the disease, depression, and being treated differently by family
and friends.
3.5 Management of STIs and HIV/AIDS
1. Ways of Reducing STDs and HIV
a. Abstinence from sexual intercourse
b. Being faithful to one partner
c. Being tested for STDs and HIV
d. Using a condom
e. Not sharing needles or medical instruments without cleaning them
2. Using a Condom
a. Check that the condom is not expired.
b. Make sure there are no tears or holes in condom packet.
c. Open the packet without ripping condom.
d. Take out the condom and place on penis, make sure the ring is on the outside.
e. Pinch the top of the condom to remove any air.
f. Roll condom down shaft of penis.
g. After sex, hold condom when coming out of the vagina so it does not come off.
3. Testing and treatment
a. The only way to find out is someone is HIV positive is through a blood test.
b. It may take up to three months after a person has been infected for a HIV test
to show positive. This is what we call a window period and it is essential that
a person get tested again after the three months window period to be sure
they are HIV negative.
c. If someone is HIV positive they can begin taken drugs called ARVs (Anti
retrovirals) which slow down the spread of the virus. ARVs can not cure HIV,
but they can provide a longer and healthier life for the infected person.
d. If a person has HIV they must try to have a healthy life style to keep their body
strong. They should eat lots of protein and vitamins, exercise, and get lots of
sleep.
3.6 Care and support of people living with HIV/AIDS (PLWHA)
1. People living with HIV/AIDS often experience stigma from family and friends.
2. The best way to care for and support a person living with HIV/AIDS is to spend time
with them and show them that you care about them.
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a. Because PLWHA have lowered immune systems, it is also important to
remember these rules when caring for someone with HIV/AIDS
i. They should have clean bedding
ii. They should clean their body and face regularly
iii. The should eat a balanced diet
iv. They should drink a lot of water and other fluids
v. They should keep cuts and sores covered.
4. Cell Structure and Organization
4.1 The concept of a cell
1. The cell is the basic unit of life.
2. All living things are made up of cells. Cells are very small.
a. If an organism is made of only one cell, it is called unicellular.
b. If an organism is made of many cells, it is called multicellular.
4.2 The cell theory
1. To understand cells, scientists developed a theory about cells and their function.
a. All living things are made up of cells
b. All life processes occur in the cell
c. Cells are the basic unit of structure of living organisms
d. All cells are produced from other cells
4.3 Cell structure
1. There are two types of cells; prokaryotic cells and eukaryotic cells
a. Prokaryotic cells are bacteria cells.
b. Eukaryotic cells are plant and animal cells.
2. Parts of a cell
a. Plant cells and Animal cells are different.
b. Cell membrane is the thin layer of living tissue which surrounds the cell. It
controls the movement of substances in and out of the cell. It is said to be
selectively permeable because it will only let some substances in.
c. Cytoplasm is the liquid substance that fills the cell, which holds the organelles
and allows chemical reactions to take place. The cytoplasm is made mostly of
water.
d. Nucleus is where genetic information is found. This information is the
instructions to make proteins. This information is kept on chromosomes,
which are passed down from the parents.
e. Mitochondria are organelles which perform cell respiration. The release
energy from food.
f. Vacuoles (in animal cell) are organelles filled with fluid which are used by
cells for secretion, storage, and excretion.
g. Sap Vacuoles (in plant cells) are filled with sap fluid, which keeps the plant
rigid and maintains cell shape
h. Cell Wall (in plant cell) is a strong covering around the cell made up of
cellulose, which supports and gives shape to the plant cells.
i. Chloroplasts (in plant cells) are organelles which perform photosynthesis by
making chlorophyll
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Plant Cells
Cell wall of Cellulose
Large permanent vacuoles
Have the ability to make chlorophyll using
chloroplasts
Animal Cells
No cell wall
Small temporary vacuoles or no vacuoles
Have no chloroplasts and therefore can not
make chlorophyll
4.4 Cell differentiation
1. There are two types of organisms
a. Unicellular organisms which are only composed of one cell. Examples are
bacteria, amoeba, paramecium, and euglena.
b. Multicellular organisms which are composed of more than one cell. Examples
are fungi, plants, and animals.
2. Differentiation is the processes by which a cell becomes specialized for a specific
function. It is important because it divides work and creates efficiency.
a. Examples of specialized cells
i. Red Blood Cells transport oxygen in animals
ii. White blood cells destroy pathogens in animals.
iii. Sperm cells fertilize the female egg in animals.
iv. Xylem cells allow transport of water and minerals up through the
plants.
v. Phloem cells allow transport of food products down through the plant.
3. Organization of the body
a. Cell is the basic unit of life. Example of cells are blood cells, nerve cells, and
epithelial cells.
b. Tissue is a group of cells that work together to perform a particular function.
Examples of tissue is blood, nervous tissue, and the top layer of skin.
c. Organ is a group of tissues that work together to perform a particular
function. Examples of organs are the heart, the brain, and the skin.
d. Organ system is a group of organs that work together to perform a particular
function. Example of organ systems are the circulatory system and the
nervous system.
e. Order of organization – Atoms, molecules, organelles, cells, tissues, organs,
organ systems, organism
5. Classification of Living Things I
5.1 The concept of classification
1. Classification is the grouping of organisms based on their similarities and
differences.
a. Classification has three main features:
i. The system is hierarchical, which means big groups can be divided into
smaller groups.
ii. Important biological differences and similarities are used to classify
organisms.
iii. Every organism is given a name, which tells which group it belongs to.
This is called nomenclature.
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2. Classification is important because:
a. It means any scientist in the world will know an organism based on the
classification.
b. Allows us to make assumptions about other organisms.
c. Provides evidence for evolution.
5.2 Classification systems
1. There are two types of classification; artificial and natural
a. Artificial classification is the classification system based on few observable
features, mainly comparing analogous structures of organisms.
i. Analogous structures are structures which perform the same function
but have different origin.
1. For examples the wings of a bird, the wings of a bat, and then
wings of a fly.
b. Natural classification is the classification system based on biological
similarities, mainly comparing homologous structures of organisms.
ii. Homologous structures are structures which perform different
functions but have the same origin.
1. For example, the arm of a human, the leg of a cow, and the wing
of a bat.
3. Differences between artificial and natural classification
Artificial Classification
Natural Classification
1. Based on few observable
features
2. Less Accurate
1. Based on scientific similarities
3. Looks at analogous structures
3. Look at homologous structures
4. Fast and inexpensive
4. Slow and expensive
5. Not a univeral system
5. Universal system
6. Requires simple skills
6. Requires advanced skills
2. More accurate
5.3 Major groups of living things
1. The largest group of classification is a kingdom. Then phylum, class, order, family,
genus, and species.
i. Species is a group of organisms which can interbred and produce fertile
offspring.
2. Kingdoms are 5 groups which all living organisms can be classified into.
i. The five kingdoms are:
1. Kingdom Monera
2. Kingdom Protoctista
3. Kingdom Fungi
4. Kingdom Plantae
5. Kingdom Animalia
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3. Scientists use nomeclaure to name organisms. Every organism is given two names.
The first name is the genus. The second name is the species. Both names are written
in Latin, so that everyone can understand them, regardless of their language.
5.3.1 Viruses
1. Viruses are very small infecting agent that can not be classified. This is
because viruses are not considered living organisms. They are not living
because they are not made up of cells, do not perform normal functions, and
cannot reproduce without a host cell.
2. Viruses are very small and only have two parts: a protein coat and a strand of
genetic material.
3. Characteristics of viruses
a. Viruses are made up of genetic material inside a protein coat
b. Viruses have no nucleus or organelles
c. Viruses cannot reproduce on their own
d. Viruses do not perform normal life processes like respiration, growth,
excretion, or nutrition.
e. Viruses are in a dormant state outside of cells.
4. How viruses cause disease
a. When a virus enters a cell in your its takes control of the cell. The cell
stops performing its normal functions and begins to make more
viruses. Eventually the cell will burst, releasing the new viruses. Each
of these new viruses will enter a new cell and reproduce itself.
5. Disadvantages of viruses
a. They attack living cells and destroy them
b. They multiple quickly inside living cells.
c. They cause disease.
d. They can spread easily, through the air or by contact.
e. They are difficult to kill.
5.3.2 Kingdom Monera
1. Kingdom Monera is all bacteria and blue-green algae. These are considered
the oldest organism on earth.
2. All organisms in Kingdom Monera are unicellular and are prokaryotic cells.
a. Prokaryotic cells are cells without a definite nucleus or membranebound organelles.
3. Bacteria can be found everywhere on earth
4. There are two phyla of Kingdom Monera
a. Phylum Bacteria
b. Phylum Cyanobacteria
i. Cynobacteria is blue-green algae. Cynobacteria can practice
photosynthesis.
5. Characteristics of bacteria
a. Bacteria are prokaryotic, single-celled organisms
b. Bacteria perform all like processes like respiration, growth, and
excretion.
c. Bacteria reproduce on their own through asexual reproduction.
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d. Bacteria cells have no nucleus
e. The genetic material is in the cytoplasm
f. Bacteria cells have a cell wall
6. Advantages of Bacteria
a. The following are ways bacteria are helpful:
i. the recycling of nutrients, like nitrogen
ii. the treatment of waste
iii. the production of vitamin K in our body
iv. the digestion of cellouse
v. the production of cheese, vinager, and youghurt
vi. the production of medicine
7. Disadvantages of Bacteria
a. The following are ways bacteria is harmful:
i. Some bacteria cause disease
ii. Some bacteria eat our food sources and cause them to become
harmful to eat and bad tasting
8. Differences between viruses and bacteria
Viruses
Not considered a living organism
Does not perform all life processes
Needs a host cell to reproduce
Bacteria
Considered a living organism
Performs all life processes
Reproduces on their own asexually
5.3.3 Kingdom Protoctista
1. The organisms in Protoctista are all very different.
2. All orgnasism in Kingdom Protoctista are made of eukaryotic cells.
a. Eukaryotic cells are cells that contain a nucleus and membrane-bound
organelles.
b. Many organisms in Kingdom Protoctista are unicellular but some are
multi-cellular.
3. Characteristics of protista
a. All are eukaryotic organisms
b. Most are unicellular
c. Most live in water
d. Many use flagella or cilia for movement
4. Examples of organisms in Kingdom Protoctista are algae and slime molds.
a. Organisms in the kingdom are collectively called Protozoa.
5. The three most common phylum of Kingdom
a. Rhizopoda
i. Amoeba
1. Characteristics of Amoeba
a. Amoeba are found in water
b. They use pseudopodia for locomotion
c. They are heterotropic and use pseudopodia for
feeding
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d. They reproduce asexually though binary fission
e. Some can be parasites
b. Ciliophora
i. Paramecium
1. Characteristics of Paramecium
a. Paramecium are found in water
b. They use cilia for locomotion
c. They are heterotrophic and use an oral groove for
feeding
d. They reproduce sexually or asexually
e. Some can be parasites
c. Euglenophyta
i. Euglena
1. Charactistics of Euglena
a. Euglena are found in water
b. They use a flagellum for locomotion
c. They have both plant-like and animal-like
characteristics; they are both autotropic and
hetertropic. They use chloroplasts for
photosynthesis.
d. They reproduce asexually
e. Euglena blooms can kill many fish in one area
6. Advantages of Kingdom Protoctista
a. Some protozoa are helpful to humans and other organisms
i. About ½ of the oxygen in the air from photosythesis is from
algae.
ii. Some algae is used for food.
iii. Some algae is used for fertilizer.
7. Disadvantages of Kingdom Protoctista
a. Some protozoa are harmful to humans and other organisms.
i. Diseases like malaria, sleeping sickness, and dysentery are all
caused by protozoa.
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FORM II FIRST SEMESTER LECTURE NOTES
1. Classification of Living Things II
1.1 Kingdom Fungi
1. The Kingdom Fungi
a. The kingdom fungi has 80,000 different species. There are 6 divisions (phylum) of
the kingdom fungi. The three important divisions are Basidiomycota, Zygomycota,
and Ascomycota.
2. General and Distinctive features of the Kingdom Fungi
a. They have no roots, stems, or leaves
b. They lack chlorophyll, are non-photosynthetic and have to get their own food by
feeding on dead plants or animals. (Notice the lack of green, because lack of
chlorophyll)
c. Most fungi have cell walls made of chitin, which is a substance made up of
proteins and sugar
d. Their body is made of a network of small, tube-like filaments called hyphae
e. Fungi store carbohydrates as glycogen
f. Fungi reproduce asexually by small structures called spores.
3. The Three Main Divisions (Phyla) of the Fungi Kingdom
a. Basidiomycota
i. Basidiomycota is the most common division of the Fungi Kingdom.
Mushrooms and toadstools are in this division.
ii. The part of the mushroom that grows above the ground is the reproductive
body and is divided into a stem, cap, and gills.
iii. Spores are released from the gills and are dispersed by the wind.
b. Zygomycota
i. Zygomycota grows on rotting material and looks like small white string.
An example of Zygomycota is bread mold.
c. Ascomycota
i. Ascomycota are single-celled organisms called yeasts that grow on the
surface of rotting fruit and reproduce by budding. We use yeast to bake
bread.
4. Advantages and Disadvantages of Kingdom Fungi
a. Advantages
i. Yeast is used to bake bread.
ii. Yeast is used to produce alcohol from sugar, a process called fermentation.
iii. Molds are used to make antibiotics, like penicillin.
iv. Molds are used to make cheese.
v. Mushrooms are used as food.
vi. Some fungi can be used to produce proteins.
vii. Fungi can be used in research in genetic engineering.
b. Disadvantages
i. Fungi can spoil food.
ii. Fungi can destroy crops.
iii. Fungi can destroy wood and harm our houses and furniture.
iv. Fungi can cause disease, like Athlete’s foot, head ringworm, and thrush.
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1.2 Kingdom Plantae
1. The Kingdom Plantae
a. The kingdom plantae is very large and contains many plants.
b. Although organisms in this group look very different, they all get their
nutrition from a process called photosynthesis.
c. Photosynthesis is a way to manufacture food from simple materials with the
help of the sun.
2. General and Distinctive features of the Kingdom Plantae
a. In all plants, the cell walls are made up of cellulose.
b. They are able to practice photosynthesis.
c. They have chlorophyll
d. They are multicellular and the plant body is separated into tissues, organs, and
systems.
3. Kingdom Plantae can be divided into 4 Divisions
a. Bryophyta- mosses and liverworts
b. Pteridophyta- ferns
c. Coniferophyta- pines and conifers
d. Angiospermophyta- flowering plants
1.2.1 Division of Bryophyta
1. Bryophyta
a. Bryophyta are mosses and liverworts. They live on the land, but can only
grow in wet places because they have no way to carry water. They also
need water to reproduce.
b. General and distinctive features of the Division Bryophyta.
i. They have no true roots, stems, or leaves.
ii. No vascular tissue (xylem or phloem)
iii. They reproduce by using spores
1.2.2 Division Filicinophyta (Pteridophyta)
1. Division Filicinophyta
a. These are ferns. They need water for fertilization.
b. They have true roots, stems, and leaves.
c. They reproduce by using spores.
d. General and distinctive features of the Division Filicinophyta
i. They have true roots, stems, and leaves.
ii. They have vascular tissue (xylem and phloem)
iii. The leaves produce sori which later produces spores so the fern can
reproduce.
iv. The leaves are called fronds.
v. They live in damp and shady places.
2. Nutrition
2.1 Nutrition and Food nutrients
1. Nutrition is the way in which organisms obtain materials they need to live.
2. There are two types of nutrition, autotrophic nutrition and heterotrophic nutrition.
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a. Autotrophic nutrition is how plants get their food by taking raw materials
and changing them into food. This process is called photosynthesis.
b. Heterotrophic nutrition is how animals get food and it must already be
made, like plants or other animals.
3. Food is anything that provides the body with a source of energy, material for
growth and repair, or factors for good health.
4. Nutrients are food substances which are needed for healthy growth. Food eaten by
humans contains nutrients which include carbohydrates, fats, proteins, vitamins,
and mineral elements.
5. Water is not considered a nutrient but must be part of our diet because it helps
digest and absorb nutrients.
6. Nutrition is important because it allows us to move, grow, keep our bodies warm,
repair damaged tissue and fight diseases.
2.2 Human nutrition
1. Types and Functions of food substances
a. Carbohydrates
i. Carbohydrates contain starches and sugars.
ii. The main sources of carbohydrates are cereals, cassava, potatoes,
bananas, yams, fruit, honey, and sugar cane.
iii. Carbohydrates provide the body with energy through the burning of
glucose (sugar).
a. Carbohydrates contain carbon, hydrogen, and oxygen.
b. Carbohydrates are classified as simple sugars, compound
sugars, and complex sugars.
i. Monosaccharides are simple sugars which are composed
of single molecules.
1. Monosaccharides are soluble in water.
2. Fructose is an example of monosaccharides.
Fructose can be found in ripe fruits like bananas
and pineapples.
3. Glucose is another example of a monosaccharide.
It can be found in grapes, carrots, and apples.
ii. Disaccharides are compound sugars made from two
molecules.
1. Disacchrides are soluble in water.
2. Disaccharides are found in sugar cane (sucrose),
malt (maltose), and milk (lactose.)
iii. Polysaccharides are complex sugars formed by lots of
monosaccharids coming together.
1. Polysaccharides are insoluble in water.
2. Examples of polysaccharides are starch (a plant
storage compound) and cellulose (structural
material in plant cell walls.)
a. Common foods containing starch are
potatoes, cassava, maize, and wheat.
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b.
c.
d.
e.
c. Carbohydrates can be indentified by using iodine solution which
turns black-blue in the presence of starch.
Lipids (Fats and Oils)
i. Lipids are fats (solid) and oils (liquid).
i. Oils are lipids which are in the liquid form at 20 degrees
Celsius.
a. Fats are lipids which are in the solid form at 20 degrees
Celsius
ii. Lipids are used as a source of energy, for food storage, and for
insulation (to keep our bodies warm).
iii. Lipids are not soluble in water or hydrophobic.
iv. The main source of lipids are milk and animal fats, nuts, coconuts,
avocado, and sweets.
v. Lipids are food substances made of carbon, hydrogen, and oxygen, like
carbohydrates. However, lipids have much less oxygen.
vi. Lipids dissolve in solvents like ether, chloroform, acetone, and hot
alcohol.
vii. Lipids can be identified by using Sudan III which turns reds or Osmic
Acid which turns black in the presence of lipids
Proteins
i. Proteins are food substances made of carbon, hydrogen, oxygen, and
nitrogen.
ii. Proteins are used for the growth and repair of the human body.
Proteins can also provide energy if there is no carbohydrates or lipids in
the body.
iii. Protiens are amino acids which are linked together to form
polypeptides, which then link together to form protiens.
1. Proteins are insoluble in water.
2. They easily coagulate or stick together when heated.
3. Proteins are found in beans, peanuts, peas, egg whites, and meat
4. Proteins react with Millon’s reagent to form a purple or reddish
color.
Vitamins
i. Vitamins help to keep the body healthy but are only required in very
small amounts.
2. Vitamins help control the chemistry of the body.
3. Function of Vitamins
a. Vitamin A gives our eyes color, helps with cell growth, and is
an antioxidant
b. Vitamin B helps with enzyme activity during respiration.
c. Vitamin C helps with enzyme activity and is an antioxidant.
d. Vitamin D helps balance calcium in the body.
e. Vitamin K helps the blood clot.
Mineral elements
1. Minerals are needed for growth, repair of tissues, and protection against
diseases.
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2. Minerals also help control the chemistry of the body.
3. Minerals are found in green vegetables, eggs, milk, and table salt.
Mineral Elements
Calcium
Chlorine
Iodine
Iron
Magnesium
Nitrogen
Phosphorus
Potassium
Sodium
Sulfur
Function
Strong bones and teeth, muscle contractions, nerve impulse transmission, and
blood clotting
Maintence of tissue fluids, blood, and lymph
Synthesis of thyroid hormones (regulation of growth)
Formation of blood
Healthy bones and teeth, muscles movement
Synthesis of proteins
Healthy bones and teeth, synthesis of protiens, production of ATP
Muscular movement and nerve transmission
Maintenance of tissue fluids, muscular movement, and nerve transmission
Synthesis of protiens
f. Water
i. Our bodies are 70% water!
ii. We need water because:
1. The cytoplasm of our cells is made mostly of water.
2. Our blood is made mostly of water and helps move nutrients
and waste products.
3. Water is needed in the digestion of food.
4. Water maintains the shape of cells and organs.
5. Water helps us cool down through the evaporation of sweat.
6. Water acts as a lubricant to reduce friction, like between the
eyelid and the eyeball.
2. Balanced Diet
a. A balanced diet contains the right amount of carbohydrates, lipids, proteins,
vitamins, minerals, and salts that we need to grow, repair, and keep the body
healthy.
3. Nutritional Requirements for Different People
a. Different amounts of nutrients are required for different people based on their
age, sex, activity and health of the body.
b. Pregnant Women should eat more protein, about 80 g a day.
c. Young Children need more energy and should eat at least 30 g of protein a day.
d. Elderly people need plenty of vitamins and minerals to help maintain good
health.
e. People with HIV/AIDs in a high protein diet to help repair damaged tissue.
They also need food with lots of vitamins and minerals to help the immune
system fight the disease.
4. Nutritional deficiencies and disorders
a. Malnutrition
i. Malnutrition is when a person cannot have a balanced diet.
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b. Marasmus a disease caused by a lack of food, especially in protein rich food
needed to build up the body. Marasmus is common in children and infants.
Symptoms of marasmus are stunted growth and loss in weight due to tissue
breakdown.
c. Kwashiorkor is a disease in children when they are missing protein in their
diet. If the mother’s milk does not have enough protein, the child can develop
kwashiorkor. Children with kwashiorkor do not live past 5 years old unless the
diet improves. Symptoms of Kwashiorkor are swollen belly, stunted growth,
and weakness and sleepiness. Children with kwashiorkor should eat foods rich
in protein like meat and beans.
d. Rickets is a disease caused by the lack of vitamin D which is needed for the
formation of bones. The bones do not harden properly and the legs bend
outwards under the weight of the body. Bow-leggedness is a symptom of
Rickets. Children with Rickets should eat food high in calcium like milk.
e. Obesity is when a person eats more food than their body can use. Symptoms
of obesity are people that are very fat. People suffering from obesity should
exercise and eat less food.
f. Anorexia is a condition where the person sees themselves as being fat, even
though they are very skinny. They eat very little. Female teenagers often
suffering from this disease.
5. The best way to prevent nutritional deficiencies and disorders is to have a balanced
diet.
2.4 Digestive system in humans
1. What is digestion?
a. Digestion is the process by which food is changed into a simple, soluble,
diffusible, and usable form.
b. Digestion involves two process: mechanical and chemical.
i. Mechanical breakdown of food takes place in the mouth. Chewing
breaks the food into smaller pieces so chemical breakdown can occur.
ii. Chemical breakdown changes large complex food molecules into small,
simpler molecules that can be absorbed by the body.
2.5 Digestive system disorders and diseases
1. Parts of the Reproductive system
a. The mouth is where food enters the body and stays for an average of 30
seconds.
b. The tongue mixes food with saliva and helps break it up.
c. Teeth are used to break the food up into smaller pieces.
d. The salivary gland makes saliva which passes into the mouth.
e. The alimentary canal is a muscular tube which is about 8 meters long, starting
at the mouth and ending at the anus.
f. Epiglottis prevents food from entering the trachea.
g. Esophagus makes a wave of muscle contractions which ensure that the food
reaches the stomach.
h. Stomach makes gastric juices which break down the food further. Food stays
here for 5 hours.
i. Liver produces bile and processes digested food.
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j. Gall bladder stores bile before it goes into the duodenum.
k. Pancreas makes pancreatic juice which passes into the duodenum.
l. Small intestine makes intestinal juices and food stays here about 5 hours. The
first part of the small intestines is called the duodenum. The second part is
called the ileum.
m. The large intestine or colon, removes water from the waste.
n. The appendix has no function.
o. The rectum holds waste before it exits the body.
p. The anus is a double sphincter muscle which keeps waste in until it is ready to
be released.
2. The Digestion Process
a. Digestion is the process of changing food materials from a solid or semi solid
state into a simple, diffusible, and usable form.
b. Our digestive system breaks down large food particles into pieces that are
small enough to pass through the gut wall and dissolve into the blood.
c. Digestion is carried out in two ways; Mechanically and Chemically.
i. Food is mechanically broken down by your teeth, tongue, and muscles
in the alimentary canal.
ii. Food is then chemically broken down by the enzymes and other
chemicals made by the salivary gland, liver, and pancreas.
iii. Both of these processes go on at the same time. The mechanical
breakdown of food helps the enzymes to do their work by mixing the
food with the enzymes and increasing the surface area of the food for
the enzymes to do their work.
d. Food moves along the alimentary canal through a series of coordinated muscle
contractions of circular and longitudinal muscle contractions.
e. Food enters the mouth and teeth chew the food to break it down into small
pieces and mixes with saliva.
f. Saliva contains two main substances.
i. An enzyme called Amylase which starts to digest starches.
ii. Mucus which wets the food and makes it easier to swallow.
g. The food is then swallowed and travels down the esophagus to the stomach.
The stomach is a muscular sac where food is temporarily stored and can
expand and shrink depending on the amount of food ingested.
h. Once the food is in the stomach is it sealed by two strong muscles at each end
called the sphincter muscles.
i. For the next few hours peristaltic waves pass along the walls of the stomach.
They mechanically break down the food and mix it with gastric juice made and
secreted by cells in the stomach wall.
i. Gastric juices contain the enzyme pepsin which starts the breakdown of
proteins. It also contains hydrochloric acid which kills any germs in the
food.
j. The processes in the stomach turn the food into a creamy semi-liquid called
chyme. The lower sphincter muscle relaxes and the chyme is released into the
small intestine.
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k. The small intestine is 6 meters long. The first 25 cm are called the duodenum
and the rest is the ileum. Muscles in the wall of the small intestine
mechanically breakdown food and three new digestive juices (Bile, Pancreatic
Juice, Intestinal juice) are released to chemically break down the food further.
i. Bile is produced in the liver and stored in the gall bladder before it
enters the duodenum through the bile duct. Bile neutralizes the acid in
the chyme and breaks up any fats or oils (lipids) into smaller pieces.
ii. Pancreatic juice is produced by the pancreas and is secreted into the
duodenum. Pancreatic juice contains the enzymes trypsin, amylase,
and lipase.
1. Trypsin breaks down proteins.
2. Amylase breaks down starch.
3. Lipase breaks down lipids.
iii. Intestinal juice are produced by special cells in the intestine wall.
Intestinal juices contain protease enzymes to complete the digestion of
proteins and carbohydrase enzymes to finish the digestion of
carbohydrates.
iv. The small intestine also finger-like projection called villa along its
walls. The villa increase surface area and allow absorption of nutrients.
The cell wall of the villi is very thin, allowing diffusion to easily occur.
Each villi is well supplied with blood for nutrients to enter and also
contains a lymph vessel into which fatty acids and glycerol (waste from
breakdown of starch) can pass. Nutrients absorbed into the blood are
then taken to the liver where it will be stored or processed so it can be
used by different parts of the body.
l. The food then travels to the large intestine. By this time most of the useful
nutrients have been removed and mostly water and minerals remain. The water
and minerals are absorbed into the blood.
m. The remaining solid material then moves to the rectum and is then called fecal
matter.
n. The fecal matter is then formed into feces and exits the body through the anus.
Complex food molecule
carbohydrates
fats and oils
proteins
Products of Digestion
Simple, soluble, breakdown products
Simple sugars e.g. glucose, galactose, fructose
Fatty acids and glycerol
amino acids
27
Summary of digestion in the human alimentary canal
Enzyme
Food digested
Products
Part of
alimentary
canal
Mouth
Source of
enzyme
Salivary glands Amylase
starch
maltose
Stomach
stomach wall
secretes gastic
juices
pancreas
secretes
pancreatic
juice
Pepsin
Trypsin
soluble milk
protein
protein
protein
Lipase
fats
Amylase
Sucrase
starch
sucrose
Maltase
Peptidase
Lipase
maltose
peptides
fats
insoluble milk
protein
polypeptides
peptides and
amino acids
fatty acids and
glycerol
maltose
glucose and
fructose
glucose
amino acids
fatty acids and
glycerol
Small
Intestine
intestinal juice
Rennin
Notes
food chewed to
break it up, saliva
also lubricates the
food for swallowing
hudrochloric acid
also secreted by
bile is added from
the liver via the
gallbladder and the
bile duct; bile salts
neutralize the acid
chyme; contents of
small intestines are
alkaline; bile salts
emulsify the fats
containing
3. Digestion in Other Mammals
a. Ruminants are mammals that have a rumen-an extended portion of the
esophagus where food is temporarily stored. The food is regurgitated (vomit)
inside the mouth for further chewing and digestion. Ruminants digestion
systems are different from humans because they also have extensions called the
reticulum and the omasum which act as false stomachs. They do not have
gastric juices but contain bacteria which breaks up the cellulose. The food is
then regurgitated and re-chewed and then re-swallowed and enters the
abomasums (true stomach) where digestion is continued.
4. Disorders and Diseases of the human digestion system
a. Dental caries
i. Dental caries, also known as tooth decay, occur when bacteria feed on
sugars in your mouth and release an acid which causes the
decomposition of tooth enamel. The loss of tooth enamel leads to the
exposure of dentine, which leads to cavities in the tooth. Cavities are
painful.
1. The bacteria live in a sticky white substance called plaque. By
brushing your teeth twice a day, using floss, and eating less
sugar, you lower your risk of getting dental caries.
b. Heartburn
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i. Heartburn is when the material in your stomach comes back up through
the esophagus a short distance. The acid in these contents causes a
burning sensation in the chest.
c. Indigestion
i. Indigestion is the pain or discomfort linked with the feeling of eating
too much.
ii. Indigestion can be avoided by eating moderate amounts of food and not
eating too much oily, spicy, or fatty foods. Drinking alcohol with these
foods can also cause indigestion.
d. Ulcers
i. Ulcers are small sores produced in the stomach which are very painful.
The are caused by hydrochloric acid and enzymes digesting the
stomach wall.
ii. Eating in moderation, not consuming large amounts of alcohol, and
keeping a healthy diet will help reduce the risk of ulcers.
e. Constipation
i. Constipation is when more water than normal is reabsorbed from
undigested food and the feces will be harder, drier, and more difficult to
pass through the anus.
ii. By having a diet willed with fiber and roughage, you can reduce the
risk of experiencing constipation.
f. Diarrhea
i. Diarrhea is when the faeces have too much water in them, usually
because of an infection.
ii. The faeces are liquid and sometimes painful to pass.
g. Flatulence
i. Flatulence is when the body produces large quantities of gas and it is
released either through the mouth or anus.
2.6 Nutrition in plants
2.6.1Mineral requirements in plants
1. Just like humans, plants need mineral to grow. These minerals are found in the
soil or dissolved in water. They are absorbed through the root hairs.
2. Required minerals for plant growth are nitrogen, phosphorus, potassium,
magnesium, calcium, sulphur, and iron.
Essential Plant Element
Nitrogen (N)
Role of Element in Plant Growth
Makes proteins, manufactures
chlorophyll, and promotes normal
plant growth
Phosphorus (P)
Root and Branch growth, makes
proteins, releases energy during
respiration
Potassium is used during
photosynthesis and for protein
metabolism in young leaves
Potassium (K)
Deficiency Symptoms
Leaves become pale green or
yellow, the plant has small
leaves, thin, weak stem,
stunned growth
Short or small roots, leaves,
and branches; leaves become a
reddish purple
Yellow leaves with dead spots
especially at the margins and
tips
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Magnesium (Mg)
Sulphur (S)
Creates chlorophyll and helps in
enzyme activity
Promotes normal plant growth and
the creation of cell walls
Synthesizes or creates proteins
Iron (I)
Creation of Chlorophyll
Calcium (Ca)
Leave become yellow
Poor root growth and dead
growing regions
Small growth and yellow
patches on leaves
Thin and weak stems; leaves
become white or pale
2.6.2 Photosynthesis
1. Photosynthesis
a. To make food, green plants need a supply of raw materials and energy. The
raw materials are carbon dioxide and water and the energy comes from
sunlight.
b. Photosynthesis is the process by which green plants use light energy trapped by
chlorophyll to form sugar from water and carbon dioxide.
i. ‘Photo’ means light and ‘synthesis’ means to make.
ii. Carbon dioxide and water will not combine unless energy is added.
Plants use chlorophyll to trap energy from the sun and then use that
energy to combine the water and carbon dioxide.
1. Chlorophyll is the pigment which makes a plant look green. It
is kept inside the chloroplasts of plant cell. When sunlight falls
on the chlorophyll molecule, energy is absorbed. The
chlorophyll molecule then releases the energy. The energy
makes the carbon dioxide combine with water, with the help of
enzymes inside the chloroplasts.
iii. Carbon Dioxide + water –---sunlight/chlorophyll----> glucose + oxygen
2. The Structure of a Leaf
a. Photosynthesis happens inside chloroplasts. Most chloroplasts are in the cells
of the leaves.
b. Leaves are specially adapted to allow photosynthesis to take place as quickly
and efficiently as possible.
c. A leaf consists of a broad, flat part called the lamina which is joined to the rest
of the plant by a leaf stock or petiole. Running through the petiole are vascular
bundles which then form the veins in the leaf. These contain tubes which carry
substances to and from the leaf. Each vein contains large, thick walled xylem
vessels for carrying water and smaller, thin walled phloem tubes for carrying
away food which the leaf has made.
d. The epidermis is the outer covering of the leaf and it is only one cell thick.
This allows light to reach the chloroplast quickly. The leaf is also usually
covered with a waxy substances called a cuticle which keeps water inside the
leaf.
3. The Process of Photosynthesis
a. Once a plant creates glucose from photosynthesis it converts it to starch.
Therefore, biologists often use the presence of starch to show that
photosynthesis has taken place.
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4. Importance of photosynthesis
a. Food production
i. Photosynthesis allows plants to grow, which are then consumed by
animals.
b. Balance of atmospheric gases
i. Oxygen is the by-product of photosynthesis and photosynthesis uses
carbon dioxide. Therefore, photosynthesis helps keep the gases in our
atmosphere balanced.
ii. Photosynthesis helps reduce the effects of greenhouses
c. Energy conversion
i. All energy used in our life starts from the sun. Photosynthesis makes it
possible for us to use that energy by converting it to chemical energy
which will be stored in food molecules that we will later eat.
2.8 Food processing preservation and storage
6. Processed Food is any food that has been treated in some way to make it taste better or
to preserve it.
7. Food preservation is the process of adding preservatives to food to prevent
deterioration by removing oxygen, water, or temperature to prevent the growth of
microrgansims.
8. Processing and preserving food is importance because it allows the food to be edible
for a longer period of time.
a. If food is not preserved, bacteria and fungi (microorganisms) grow on the food and
make it bad tasting and dangerous to eat.
9. Chemicals that stop the growth of microorganisms are called preservatives, such as
salts, acids, and sulphur dioxide.
10. The methods of preserving food can be classified as traditional and modern.
b. Traditional methods of food preservation
i. Smoking is when the food is dried using smoke. Because there is no
moisture in the food, microorganisms can’t grow. The food will usually
keep for a few weeks. Foods that are usually smoked include fish, cassava,
and meat.
ii. Drying is the process of removing water using the solar energy. Because
there is no water in the food, microorganisms can not grow. Foods that are
dried using the sun include beans, peas, rice, maize, vegetables, fruits, meat
and fish.
iii. Salting is the method of adding salt to remove water from the food. Salting
is used to preserve fish and meat.
c. Modern methods of food preservation
i. Modern methods are considered better because the food stays edible for a
longer amount of time and does not alter the taste of the food or its texture.
1. Pasteurizing is the process of heating food above 550 Celsius for
several minutes to destroy enzymes and microorganisms that can
lead to the decay of food. Pasteurizing is usually used for milk.
2. Refrigeration is the method of keeping foods at low temperatures
like 4o Celsius to slow down the growth of microorganisms.
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3.
4.
5.
6.
Refrigeration is temporary and used for food like milk, cheese,
vegetables, and meat.
Freezing is the method of preservation where food is keep in
temperatures below -10o C. This stops the growth of
microorganisms and food can be kept for months.
Canning and bottling is the method of preserving food by first
heating it to kill microorganisms and then placing it in a airtight can
or bottle. This method is used for fruit, baked beans, fish, tomatoes,
and meat.
Pickling is the process of putting food in vinegar. The acids will
stop the growth of microorganisms. Pickling is used for vegetables,
eggs, and fish.
Additives are chemicals like sodium chloride or sodium benzoate
which are added to foods to slow down the growth of
microorganisms.
3. Balance of Nature
3.1 The natural environment
1. The natural environment of an organism is all that surrounds that organism. This includes
both the living and non-living things that surround it.
a. The living things such as other plants and animals are called the biotic part of the
environment.
b. The non- living things such as rocks, soil, water, sunlight, air, climate and weather
are called the abiotic parts.
2. A biological community is group of living organisms in an environment that depend on
each other for life. A community includes organisms from all five kingdoms, Plantae,
Animalia, Fungi, Protoctista, and Monera.
a. Producers are organisms that are able to make their own food.
b. Consumers are organisms that rely on other organisms for food.
c. Decomposers are top consumers that eat dead plants and animals for food.
3. A Biosphere is a general term for the regions on earth (including the air and sea)
which may be inhabited by living organisms.
4. A habitat is where an organism lives. For example, the habitat of the weaver bird is the
palm tree, but its environment includes the palm tree, the wind, rain, insects and bacteria.
5. An ecosystem is the community of living organisms in a habitat plus the non-living part of
the environment. An ecosystem is self-supporting. A forest is an ecosystem where the
plants absorb light and water to make food through photosynthesis; the animals feed on
the plant food and on each other. The dead plants and animals are decomposed by fungi
and bacteria which return nutrients to the soil for the plants to grow.
6. A community is the total collection of living organisms (both plant and animal) living
within a defined area or habitat.
7. A population is a group of individuals of the same species within a community.
8. Why is the protecting the environment important?
a. Since 1800 humans have destroyed half of the rainforest, created holes in the
atmosphere, created acid rain, and caused many plants and animals to become
extinct.
b. We should protect the environment around us because:
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i. Economic Value
1. Some plants and animals are used for food or medicine.
ii. Education
1. Scientists are studying many plants and animals to see how they
live and work.
iii. For beauty
1. We want our children to see the beautiful plants and animals that
we saw as children.
iv. For the planet’s future
1. Global warming and holes in the ozone layer could lead to the
destruction of earth.
3.2 Interaction of organisms in the environment
1. Ecology is the branch of science that studies living organisms in relation to their
environment.
a. The purpose of ecology is to try to explain how an organism survives and why it is
successful in living in a particular environment.
2. The Balance of Nature
a. Materials and molecules are reused and recycled over and over again.
i. For example, when a plant or animal dies, its body materials are
decomposed by bacteria and fungi. The water, minerals and molecules such
as carbon and nitrogen are left behind in the soil and absorbed by plants to
grow their plant bodies (respiration, photosynthesis and transpiration). The
plants are eaten by animals (respiration) to make things such as muscle and
skin tissue in their bodies. Excretion of gaseous wastes returns oxygen and
carbon dioxide, and nitrogen gas to the air for reuse. Also, water, carbon
and nitrogen are excreted in solid and liquid waste and returned to the soil
for reuse.
b. WATER CYCLE
i. The water cycle is the constant circulation of water between the
atmosphere, land, and oceans.
ii. Water molecules are cycled through the environment in the following
ways:
1. Evaporation of gaseous water from soil, lakes, rivers, and oceans
into the atmosphere.
2. Condensation of liquid water in the upper atmosphere in the form of
clouds.
3. Precipitation of water from the atmosphere to the soil, lakes, rivers,
and oceans in the form of rain and snow.
4. Transpiration of liquid water from the soil through xylem vascular
cells in plant roots, stems and leaves. Water is pulled into the
atmosphere from the leaves through stomata.
5. Drinking water by animals and excreting water through sweat,
urine, and respiration (breathing out waste water).
c. CARBON CYCLE
i. Carbon is in the air as carbon dioxide gas.
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ii. The carbon cycle is the constant circulation of carbon between the
atmosphere, plants, animals, and the soil.
1. Plants and other producers take in carbon dioxide from the air
during photosynthesis.
2. Through photosynthesis, producers convert carbon dioxide into
carbohydrates in the form of roots, leaves and stems.
3. In producers, carbohydrates can be changed into proteins and fats
high in carbon (beans and nuts).
4. The carbon element in these food substances is passed on to other
organisms through “feeding levels” or Trophic Levels of
consumers.
5. When organisms die they are eaten by decomposers. This results in
carbon dioxide released into the air from the respiration of
decomposers.
6. All consumers respire and release carbon dioxide into the air during
their life.
7. Burning wood, charcoal, and oil releases carbon dioxide into the air.
Charcoal and oil come from ancient forests that have changed into
underground fuel over millions of years.
8. Photosynthesis uses the carbon dioxide in the air and the cycle
continues.
d. NITROGEN CYCLE
i. Nitrogen is the raw material for making proteins.
ii. Proteins are the raw material for growth and repair of all organism’s body.
These are enzymes that control this. Enzymes are proteins. Without
proteins there would be no growth, no life!
1. Nitrogen gas in the air must be changed into a nitrogen compound
(nitrates) before producers can absorb them through their roots.
There are two ways in nature to do this and one way by industry:
a. Lightning storms cause nitrogen to combine with oxygen to
form nitric acid which falls to the ground. Then nitric acid
combines with other minerals to make nitrates in the soil.
b. “Nitrogen fixing” bacteria in the soil can absorb nitrogen
gas and produce nitrates for plants. Some nitrogen fixing
bacteria live in root nodules of bean plants.
c. Nitrogen gas is taken from the air changed into nitrogen
compounds for industrial uses.
2. Producers (plants) absorb the nitrates through their roots and make
protein foods such as beans and nuts.
3. Consumers eat the plant foods high in protein and nitrogen
compounds. These are used for enzymes to grow and to make body
tissues like muscles.
4. Producers and consumers die and decomposers breakdown the
proteins in their bodies into nitrogen compounds (nitrates).
5. Some of these nitrates are compost for new plants and the nitrogen
cycle continues.
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6. Some of the nitrates are changed back into nitrogen gas by different
bacteria and Nitrogen gas is released back into the air.
3.3 Food chains and food webs
1. A trophic level is a feeding level that groups organisms with similar feeding habits
together
2. Food Chain
a. A food chain that shows the flow of energy and nutrients due to the interaction of
different organisms through a feeding relationship.
i. Producers are organisms that can make their own food by photosynthesis.
These are plants and some protoctista and bacteria.
ii. Primary Consumers are organisms that feed on plants only. These are
animals that are called herbivores. For example, zebra, gazelles,
wildebeest, cows and goats.
iii. Secondary Consumers are organisms that feed primarily on other herbivore
animals. For example, carnivores that eat primarily insects (insectivores)
such as birds, frogs, and lizards.
iv. Tertiary Consumers are organisms that feed primarily on secondary
consumers carnivores. For example carnivores such as lions, hyenas,
humans, birds of prey such as eagles and owls.
v. Decomposers are bacteria and fungi that absorb nutrients from all dead
organisms and can feed at all levels.
b. Energy and nutrients flow from producers to consumers, to decomposers.
3. Food Web
a. Food webs are a network of interrelated food chains. A food web shows a network
of feeding relationships in an ecosystem.
4. Transport of Materials in Living Things
4.1 The concept of transport of materials in living things
1. Living things need transport systems to supply all their cells with food, oxygen, and
other materials in order to carry out life processes such as growth, respiration, and
reproduction.
a. Lungs take in oxygen for the combustion of food and they eliminate the carbon
dioxide produced. The urinary system disposes of dissolved waste molecules
(urea), the intestinal tract removes solid wastes, and the skin and lungs rid the
body of heat energy. The circulatory system moves all these substances to and
from cells where they are needed or produced, responding to changing
demands.
b. The methods of transport are diffusion, osmosis and mass flow.
4.2 Diffusion, osmosis and mass flow
1. Diffusion
a. Atoms, molecules, and ions are always moving. In liquid particles can move
freely. They will continue moving until the concentration of particles is even
through the liquid. This process is called Diffusion. Diffusion can be defined
as the movement of particles from an area of high concentration to an area of
low concentration.
35
b. The rate of diffusion depends on the difference of concentrations between the
two areas: if the difference is large, then the particles will diffuse quickly. If
the difference is small, then the particles will diffuse slowly.
c. Diffusion is importance because many organisms obtain their requirements by
diffusion. Most organisms get rid of waste through diffusion. Diffusion is also
important for gas exchange in plants and animals. Some of the products of
digestion are absorbed from the intestines by diffusion.
2. Osmosis
a. Osmosis is the diffusion of water molecules through a selectively permeable
membrane from a weak(low concentration) to a strong (highly concentrated)
solution.
b. Water and soluble particles act differently when membranes are involved.
Membranes are like a net, some particles can go through and some can’t.
Membranes can be permeable (having holes) or impermeable (not having
holes). Impermeable membranes do not let any material through.
c. Some membranes are selectively permeable. That means the membrane only
lets certain particles pass through.
d. Due to this property living systems absorb and transport water in the body by
osmosis.
e. Due to the limited space in the cells, entry of water creates an outwardly
directed pressure called turgor pressure. At the same time, the plasma
membrane and the cell wall exert an equal but inwardly directed pressure
against the cytoplasm called wall pressure.
f. The cell is said to be turgid when the turgor pressure is equal to the wall
pressure.
i. When plant cells are surrounded by water, they absorb water by
osmosis until they become fully turgid.
g. When a plant cell is surrounded with a concentrated solution, water from the
cells moves into the concentrated solution by osmosis. When a cell loses water,
it is plasmolysed. That means its cytoplasm shrinks away from the cell wall. A
plasmolysed cell feels soft rather that rigid.
3. Mass Flow
a. Mass flow is the movement of fluids within a cell or along a vessel or tube
without passing through a membrane.
b. Mass flow is used in larger organisms to get materials they need in large
quantities to travel great distances.
i. Examples in animals are the circulatory system and the lymphatic
system.
ii. Examples in plants are the xylem vessels which carry water and mineral
salts. Phloem vessels also use mass flow to move sugars through a
plant.
4.3 Transport of materials in mammals
4.3.1 The blood
1. Blood is the fluid found in animals bodies that transports oxygen, food materials,
and waste products from cells.
2. The three functions of Blood
36
a. Transport
b. Defense against disease
c. Regulation of body temperature
3. The 2 Components of Blood
a. Plasma is the first component of blood. Plasma is the liquid part of blood
which consists mainly of water (90%). Proteins, mineral salts, hormones,
antibodies, and waste products are also found in the plasma. Plasma
transports materials and delivers heat to different parts of the body.
b. Blood cells are the second component.
i. There are three types of blood cells; red blood cells, white blood
cells, and platelets.
1. Red Blood Cells or Erythocytes
a. Red Blood cells are disc shaped red cells with no
nucleus. They are made in the red bone marrow
inside our bones. They live for only four months
and are then killed by our liver.
b. Red blood cells are the only cell in our body that
does not contain a nucleus.
c. There main function is to transport oxygen.
d. Red Blood Cells give blood it red color because
these cells contain a red pignenet called
haemoglobin. Haemoglobin combines with oxygen
in the lungs and is then carried to the rest of the
body by the red blood cells.
2. White Blood Cells or Leucocytes
a. White blood cells have a large nucleus and no color.
b. The function of white blood cells is to fight against
disease.
c. There are two types of white blood cells;
Lymphocytes and phagocytes
i. Lymphocytes are white blood cells that
produce antibodies to fight infections.
ii. Phagocytes are white blood cells that
surround and kill harmful pathogens
3. Platelets or Thrombocytes
a. Platelets are small fragments in the blood that help
the blood to clot.
4.3.2 Blood groups and blood transfusion
1. Blood Groups
a. There are four types of blood groups: A, B, AB, and O
b. Classification of blood groups depends on whether or not antigen A or B is
present in the red blood cells.
i. Antigens are chemicals that mark red blood cells.
1. Type A are marked with antigen A
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2. Type B are marked with antigen B
3. Type AB are marked with antigens A and B
4. Type O is marked with no antigens.
2. Blood transfusion
a. A blood transfusion is the transfer of blood directly into a person’s vein.
i. Blood transfusions are usually given to people who have lost a lot
of blood because of an injury or illness.
ii. Blood transfusions are only possible between compatible blood
groups.
1. If the blood groups are not compatible, the red blood cells
clump together. This clumping process is called agglutinate
and it can lead to death.
iii. A donor is someone who gives blood.
iv. A recipient is someone who receives blood.
v. A Universal Donor is a person who can give blood to any other
blood group. These people have Type O blood. Because Type O
contains no antigens, it can not be attacked by the recipent’s
antigens.
vi. A Universal Recipient is a person who can receive blood from
anyone. This is because their blood does not contain antigen A or B
and therefore can not be attacked by antibodies of the recipient’s
blood.
3. Rhesus Antigen
a. The Rhesus factor (antigen D) is an antigen present in red blood cells in
addition to the ABO blood group.
i. People with rhesus antigen are called positive and people without
the rhesus antigen are called negative.
ii. A person with the rhesus antigen (Rh+) can receive blood from
someone who is Rh -. However, a Rh- person can not receive
blood from a Rh+ person or the blood will clump together and may
cause death.
1. This can be a problem during pregnancy. If the mother is
Rh- and gives birth to a Rh+ child there will be no problems.
However, the mother’s body will build up antigens during
the second pregnancy to fight against the Rh+ blood of the
second child, which will lead to the death of the child
during birth.
Blood Group
Can give blood to
A
B
AB
A and AB
B and AB
AB
Can receive blood
from
A and O
B and O
A, B, AB, and O
38
Donor
Group
A
Recipent Group
B
AB
A


O
B


AB
O

O


Blood
A, B, AB, and O
Group
A
B
AB

O
Antigens
O
present
A
B
A and B
none
Antibodies
Present
anti-B
anti-A
none
anti-A and
anti-B
4.3.3 The structure of the mammalian heart and blood vessels
1. Your heart is the most important organ in the circulatory system. It pumps
blood through the blood vessels and around your body.
a. The heart is located on the left side of your chest and is protected by
your ribcage. It is the size of your hand and has two halves.
i. Each half has an upper chamber called an atrium and a lower
chamber called a ventricle. The atrium and ventricle are
connected by a cuspid valve. There are also valves leaving the
ventricles called semi-lunar valves. These valves control the
flow of blood so that it only moves in one direction.
ii. The walls of the heart are made of cardiac muscle. These
muscles contract and pull the blood in and push the blood out
of the heart. These muscles receive oxygen and food from
coronary vessels in the cardiac muscle.
b. Blood flow through the heart
i. The left atrium receives blood from the lungs through the
pulmonary vien. The right atrium receives blood from the rest
of the body through the vena cava.
ii. Blood from the upper parts of the body enters the right atrium
through the anterior vena cava which is also called the
superiour vena cava. Blood from the lower parts of the body
enters through the posterior neva cava which is also called
inferior vena cava.
iii. As the atria fills up, the pressure within the atria rises and the
tricuspid and bicuspid valves are forced open.
iv. The ventricles, which are relaxed, start to fill up with blood
from the atria.
v. Muscles in the walls of the ventricles then contract, increasing
the pressure on the blood with the left ventricle generating the
greater pressure.
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vi. The pressure closes the bi- and tricuspid valvces between the
base of the pulmonary artery and the aorta opens and blood is
squeezed out of the heart.
vii. The pulmonary artery directs blood into the pulmonary circuit
and the aorta directs blood inot the systematic circuit.
c. Pulse
i. A pulse is when an artery presses against something solid like a
bone. In humans this happens every heartbeat. The easiest
place to feel your pulse is on your neck or wrist.
d. Blood Pressure
i. Blood pressure is the pressure of the blood inside your arteries.
Blood pressure is measured using two readings, systolic, which
is taken during the contraction of the ventricle, and diastolic,
which is taken during the relaxation of the ventricle. Normal
blood pressure is 120 / 80.
2. Blood Vessels
a. There are three main kinds of blood vessels: arteries, capillaries, and
veins. These form a network of tubes around your body through
which your blood flows.
i. Arteries
1. Take blood with oxygen away from the heart and
towards tissue.
2. Arteries have thick muscular walls because they have to
withstand high pressure from the heart. Nearer to the
tissue, arteries divide into smaller vessels called
arterioles.
ii. Capillaries
1. Capillaries are found at the ends of arterioles.
2. Capillaries are extremely thin used to carry blood
through tissues.
3. Capillary walls are only one cell thick. This allows
diffusion of food and oxygen to easily happen from the
blood to the tissues. Waste products and carbon
dioxide diffuse from the tissue into the blood through
the capillary wall as well.
iii. Veins
1. Capillaries then join together to form slightly larger
vessels called venules. These then join up to form
veins. Veins take deoxygenated blood to the heart.
Deoxygenated blood is blood that has little oxygen in it
and is carrying carbon dioxide and waste products.
2. Veins have much thinner walls than arteries. Veins
contain valves to make sure the blood flows in one
direction.
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4.3.4 Blood circulation
1. Blood flows from the heart through a system of arteries, capillaries, and veins
back to the heart.
2. Humans have a double circulation system. That means the blood passes through
the heart twice to make a complete circuit. First it travels through the right
ventricle from the lungs, then the left ventricle from the body.
3. The Flow of blood
a. Oxygenated blood leaves the heart through the aorta. The aorta splits;
one branch goes to the head and arms and the other travels to the lower
body. The Hepatic artery branches off from the aorta to take oxygenated
blood to the liver. The Mesenteric artery branches off to supply
oxygenated blood to the stomach and intestines. The aorta continues
down the body to the kidneys, genitals, and legs. Dexygenated (without
oxygen) blood then returns to the heart from the lower portion of the
body through the inferior vena cava. Deoxgenated blood from the arms
and head returns to the heart through the superior vena cava. The
inferior vena cava and superior vena cava meet and inter the right side of
the heart. The blood then travels away from the heart to the lungs
through the Pulmonary artery. The lungs supply oxygen to the
deoxygenated blood from the pulmonary artery. The new oxygen rich
blood then leaves the lungs through the pulmonary vein traveling towards
the heart. Once in the heart, its is pushed out to the rest of the body to
supply oxygen to the cells and the cycle is repeated again.
4. Diseases and disorders of the Circulatory system
a. High blood pressure
i. Blood pressure is the amount of pressure on the blood inside your
arteries. Normal blood pressure is 80/120.
ii. High blood pressure is when the measurement is above normal.
High blood pressure can be caused by cholesterol which are fat
deposits that can stick to the walls of the blood vessels and make
them smaller. This makes it more difficult for the blood to pass
through and therefore the pressure of the blood increases.
iii. High blood pressure can also be caused by stress. If someone is
stressed, their heart rate will increase, increasing their blood
pressure.
iv. High blood pressure can lead to an aneurism, stroke, or heart
failure.
v. The best way to prevent high blood pressure is to exercise, eat a
balanced diet, and try to remove stress.
b. Heart Disease
i. Heart Disease is when the arteries in the heart become blocked
and blood can not pass through. Because blood can not reach the
heart, the heart does not receive oxygen and can stop beating.
This is called a heart attack and usually results in death.
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ii. The arteries become blocked with cholesterol, which comes from
food that has a lot of fat, like oil and butter.
iii. Heart disease can be caused by smoking, having high blood
pressure, having high cholesteral levels, or having a family history
of heart disease.
c. Leukaemia
d. Sickle-cell anaemia
e. Diabetes
4.3.5 The lymphatic system
1. All tissue contains lymph vessels. These are part of the lymphatic system which is
connected to the circulatory system near the heart. The lymph will rejoin the
blood, but before it does it is filtered many times to remove waste and foreign
substances. These filters are called lymph nodes or lymph glands. Lymph glands
provide your blood with lymphocytes.
2. The main lymph glands in your body are found in the neck, armpits, abdomen,
and groin.
3. Sometimes our lymph glands can be blocked. This causes lymph to stay in the
tissue and cause swelling. This is called Elephantisis and is usually caused by
worms.
4.4 Transport of materials in plants
4.4.1 The vascular system
1. Like animals, plants transport materials throughout their body. The vascular
system is like a circulatory system in plants, it carries water and food to the plant
cells and removes waste. The vascular system is made of two tissues; xylem and
phloem. Xylem carries water in a plant and phloem carries food. The vascular
tissue is arranged differently in stems and roots.
a. In stems, the xylem tissue is on the inside and the phloem is on the
outside.
b. In roots, the xylem and phloem tissue are separate. The tissues are
arranged in the shape of a star in monocot roots and in the shape of a ring
in diocot roots.
2. Functions of Xylem and Phloem
a. Xylem vessels transport water from the roots to the stem to the leaves.
The walls of the xylem vessels are thick and make them strong. The
function of the xylem is to carry water and mineral salts and give the plant
support. Transport within the xylem is called conduction and always
moves upwards.
b. Phloem vessels transport food made in the leaves to all of the parts of the
plants. Transport within the phloem is called translocation and can be in
any direction.
4.4.2 Absorption and movement of water and mineral salt in plants
1. Root hairs
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a. Root hairs are elongated epidermal cells. Root hairs look like fur or hair
on a root of a plant. Root hairs are adapted to absorb water and mineral
salts from the soil for the plant to use.
b. Water moves from the soil into the root hair cell by osmosis.
c. Once the water reaches the xylem tissue it is pushed up the stem by
pressure generated in the root system. This pressure is called root
pressure. However, root pressure is not enough for large plants like trees.
2. Transpiration
a. Water is taken in at the roots, however only a small amount is used in
photosynthesis. The remaining water is lost into the atmosphere through
the leaves. This process of losing water by evaporation is called
transpiration.
b. Because the leaves loose water, the concentration of the sap increases,
pulling water from the neighboring cells into the xylem and up to the veins
of the leaf.
c. Factors that affect rates of transpiration
i. Because transpiration is evaporation, anything that effects
evaporation will effect transportation.
1. Temperature and wind are factors of evaporation
2. Humidity also affects transportation. If there is high
humidity in the air, or a lot of water vapor, then water from
the leaves will not be evaporated.
5. Gaseous Exchange and Respiration
5.1 The concept of gaseous exchange
1. Living organisms need energy to perform life functions. Producing oxygen, a process
called oxidation, results in the formation of carbon dioxide, water, and energy.
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5.2 Gaseous exchange in mammals
5.3 Gaseous exchange in plants
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5.4 Respiration
5.4.1 Aerobic respiration
5.4.2 Anaerobic respiration
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5.4.3 Infections and diseases of the respiratory system
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FORM III FIRST SEMESTER LECTURE NOTES
1. Classification of Living Things
1.1 Kingdom Plantae
1.1.1 Division Coniferophyta (conifers)
a. Coniferophyta are a phylum of the Kingdom Plantae.
b. Coniferophyta are cone bearing plants with needle-shaped leaves.
c. The male cones are smaller and produce a yellow powder called pollen.
d. The female cones are larger and have small seed-like structures called
ovules.
2. General and distinctive features of the division Coniferophyta
a. They are mostly shrubs and trees with needle shaped leaves
b. Their reproductive structures are cones.
c. The ovule are not enclosed inside an ovary wall.
d. The majority are Evergreens, which means they keep their leaves all
year round.
3. Advantages and disadvantages of the division Coniferophyta
a. Advantages
i. They are fast growing.
ii. They are used in the construction of buildings, in paper making,
and electric line poles.
b. Disadvantages
i. Conifers are soft woods and therefore need preservatives to
keep termites out.
1.1.2 Division Angiospermophyta (flowering plants)
1. The general and distinctive features of the division Angiospermophyta
a. Their reproductive structures are flowers.
b. Ovules are enclosed in an ovary and seeds are enclosed in a fruit.
c. They all have the same structure in their flowers
i. Sepals which protect the flower when it is in bud.
ii. Petals which are brightly colored to attract insects to help with
pollination.
iii. The Stamen which produces male gametes.
iv. The carpel which produces female gametes.
2. Angiopermophyta are divided into two classes: Monocotyledonous and
Dicotyledonous
a. Monocotyledonous seeds have only one cotyledon.
i. Monocots have a fibrous root system, leaves with parallel
venation, three part floral system, and vascular bundles which
are scattered.
b. Dicotyledonous seeds have two cotyledon.
i. Dicots have a tap root system, leaves with net-like veins, floral
parts in fours or fives, and vascular bundles which form a ring
in the stem.
3. Advantages and disadvantages of Angiosperms
a. Advantages
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i. The wood of some angiosperm is used for building and furniture
making because it is a hard wood.
ii. Many angiosperms are used for medicine.
iii. Cotton is grown to make clothes.
iv. Baskets and mats are made from some angiosperms.
v. Many angiosperm are eaten as food.
b. Disadvantages
i. Some Angiosperms can be poisonous.
2. Movement
2.1 Concept of movement and locomotion
1. Movement and Locomotion
a. Movement is the change in position of an organism or part of an organism.
b. Two types of movement:
i. Animals, protoctista, and some bacteria use locomotion to move their
whole body from place to place.
ii. Plants use growth curvature to respond to stimuli such as light, gravity and
important chemicals needed for growth and survival.
c. LOCOMOTION
i. Animals, protoctista, and some bacteria move to serve different needs
including:
1. Finding habitat
2. Finding food and water
3. Finding shelter and moving away from predators
4. Finding a mate for reproduction
ii. Vertebrate organisms use their skeletal system together with muscular and
nervous system for body movement.
iii. Invertebrate organisms use their hydrostatic system for their movement that
depends on the incompressible nature of water and other fluids.
iv. Types of Locomotion
1. Ciliary
a. Protozoans such as Paramecium and larvae of aquatic
animals use small hair-like cilia that move in effective and
recovery strokes to move the organism forwards, backwards,
and to turn.
2. Flagellar
a. Protoctista such as Euglena, Chlamydomonas, Trypanosoma
and some bacteria use whip-like flagella that causes the
water to swirl and the organism’s body to rotate at the same
time move forward.
3. Muscular
a. Vertebrates such as humans use muscle tissue which can
contract and transfer the contraction movement to rigid
tissues such as cartilage, bone or both which act as levers.
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Most animals have cartilage and bone organized into a
skeleton that provides anchoring points for muscles.
Muscles are attached to bones across joints of the skeleton
creating different kinds of movement.
2.2 Movement of the human body
2.2.1 The human skeletal system
1. Describe the human skeleton
a. Your skeleton is the basic framework inside your body-without it, you
would collapse.
b. The skeleton has a number of functions:
i. It brings about movement or locomotion by working with muscles.
ii. It supports your body and gives it shape.
iii. It provides protection for some organs, like the brain is protected by
the skull.
iv. Some bones produce blood cells or store calcium.
c. Structure of the Human skeleton
i. The human skeleton is made from structures called bones. There
are 206 bones in your body.
ii. The skeleton can be divided into two parts: the axial skeleton and
the appendicular skeleton.
1. The axial skeleton is the skull, ribcage, and backbone. All
of these provide protection for vital organs.
a. The skull protects the brain, eyes, and ears.
b. The backbone protects the spinal cord and is also
very important for support and movement.
c. The ribcage protects the heart and lungs and is
involved in breathing.
2. The appendicular skeleton consists of the pectoral and
pelvic girdles, the arms and legs.
2. Components of the Human Skeleton
a. The skeletal system is made up of bones, ligaments, and joints.
i. Bones are the rigid organs made up of living cells embedded in
calcium salts that make up the skeletal system.
ii. Ligaments are the tough flexible fibers that connect bones together
at joints.
iii. Joints are the parts of the skeletal system where two bones meet.
b. Types of joints
i. Pivot joint
1. Pivot joint is a joint that allows a twisting movement. An
example is the neck joint.
ii. Ball-and-socket joint
1. A ball and socket joint is a joint that allows movement in
several directions. Examples of ball and socket joints are
the shoulder and the hip.
iii. Hinge joint
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1. A hinge joint are joints that allow movement in one
direction. An example of a hinge joint is the elbow.
c. Adaptations of joints to movement
i. All moveable joints are covered by a layer of cartilage which
reduces friction.
ii. Some bones, such as the vertebrate in the spinal cord, are separated
by a cushion called discs of cartilage.
iii. Synovial fluid is a liquid inside the joints that lubricates the joints.
iv. Ligaments hold joints together to prevent dislocation.
2.2.2 Muscles and movement
1. Muscles are organs made up of muscle fibers that can contract and cause
movement in the body.
2. There are three types of muscles; smooth, cardiac, and skeletal
a. Smooth muscles are the involuntary muscles found in the walls of organs
such as the bladder and stomach. You do not think about using these
muscles, they do so on their own.
b. Cardiac muscles are the involuntary muscles that cause the heart to beat.
Cardiac muscles are only found in the heart.
c. Skeletal Muscles are the voluntary muscles attached to bone that relax and
contract to facilitate movement. Skeletal muscles are called skeletal
muscles because they are attached to the skeleton. Their job is to pull the
bones to produce movement and to keep the body in the right position.
Skeletal muscles move when they are told to do so by the brain.
3. Muscles create movement through contraction and relaxation.
a. Contraction is the shortening of the muscle. ATP is the fuel of muscle
contractions.
b. Relaxation is the lengthening of a muscle.
c. The biceps and the triceps are two examples of skeletal muscles in the arm.
The biceps and the triceps work antagonistically (work in pairs opposite
one another) to facilitate movement in the arm.
i. To flex the arm, the biceps relax while the triceps contract.
ii. To extend the arm, the biceps relax while the triceps contracts.
d. Muscles are attached to bones by tendons.
i. Tendons are the tough flexible fibers that attach muscles to bones at
joints.
4. Adaptations of muscles are:
a. Muscles are made up of muscle fibers which can contract and relax to
allow movement.
b. Muscles can store oxygen which can be used for vigorous exercise.
c. Muscles contain abundant mitochondria which produce ATP for muscle
contractions.
5. Muscle cramps
a. Muscle cramps are sudden, involuntary contractions of a muscle or group
of muscles which can be painful.
b. Muscles cramps are caused by lack of oxygen or calcium in the muscles.
c. Muscle cramps can be treated by stretching and applying heat.
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2.3 Movement in plants
1. Plants do not perform locomotion, they move by growth curvature
a. Growth curvature is how plants use leave, stems, and roots to show growth
response away from or towards a stimulus.
b. Two types of movement in plants are tropic movement and nastic movement.
i. Tropic movement is the directional movement of a plant in response to an
external stimulus.
1. Tropic movements are called tropisms.
2. Examples of tropic movement are phototropism. Geotropism, and
hydrotropism.
a. Phototropism is the growth of shoots towards light.
i. The word photo- in Latin means light.
b. Geotropism is the downward growth of root in response to
gravity.
c. Hydrotropism is the growth of roots towards water.
i. The word hydro in Latin means water.
ii. Nastic movement is the non-direction movement of a plant in response to a
stimulus.
1. Examples of nastic responses in plants are the opening and closing
of flowers and the folding of leaves on the mimosa plant.
c. Movement is important in plants because:
i. Plants use phototropism to obtain the light they need for photosynthesis.
ii. Plants use geotropism to germinate properly.
iii. Flowers use nastic responses to function properly.
3. Coordination
3.1 Concept of coordination
1. Coordination is the process of different organs working together to perform a particular
function.
2. All living organisms use coordination to respond to changes in their environment.
3. There are two types of coordination in mammals; hormonal coordination and nervous
coordination.
a. Hormonal coordination is the coordination of the body by the secretion of
hormones from the endocrine glands.
i. Examples of hormonal coordination are panic response, sleepiness, and
sexual arousal.
b. Nervous coordination is the coordination of the body by the activity of the nervous
system.
i. The five components of nervous response are stimulus, receptor,
coordinator, effectors, and response.
1. A stimulus is a change in the internal or external environment of an
organism.
2. A receptor is a part of the body which detects change in the
environment. Examples of receptors are sense organs, like eyes,
ears, and tongue.
3. A coordinator is an organ which receives sensory nerve impulses
from receptors, coordinates the message, and sends motor nerve
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impulses to the effectors. Examples of coordinators are the brain
and the spinal cord.
4. An effector is an organ in the body which receives motor nerve
impulses from the coordinator and performs the appropriate
response. Examples of effectors are muscles and glands.
5. A response is the reaction to a particular stimulus.
3.2 Nervous coordination in humans
3.2.1 Neurons
1. Nervous coordination in humans is carried out by the nervous system.
a. The nervous system is the system in the body that receives stimuli and
coordinates appropriate responses.
b. The Nervous System is made up of specialized cells called neurons or
nerve cells.
i. Neurons have two important properties. They can quickly respond
to a stimulus (excitability) and they can quickly send messages or
nerve impulses (conductivity).
ii. Neurons contain the same basic parts of an animal cell; nucleus,
cytoplasm, and cell membrane. But their structure is specially
adapted to be able to carry messages very quickly.
1. The main characteristic of nerve cells are the many
projections coming from the cell body. These projections
are called axons and dendrites and they help send nerve
impulses to and from the cell body.
2. Some neurons have myelinated axons in order to transmit
rapid impulses. Myelinated axons are surrounded by a
myelin sheath made up of Schwann cells. The space
between each Schwann cell is called a node of Ranvier.
3. Non-myelinated axons have no Schwann cells and transmit
slower impulses.
c. Three types of neurons are sensory neurons, relay neurons, and motor
neurons.
i. Sensory neurons transmit impulses from sense organs to the brain
or spinal cord.
ii. Relay neurons are neurons which transmit impulses from sensory
neurons to motor neurons.
iii. Motor neurons are neurons which transmit impulses from the brain
or spinal cord to effectors organs.
3.2.2 Central nervous system (CNS)
1. The Nervous System is made up of two parts; the central nervous system and the
peripheral nervous system.
2. The central nervous system is the part of the nervous system which analyses nerve
impulses and coordinates a response.
a. The central nervous system is made up of two parts; the brain and the
spinal cord.
i. The brain is the part of the central nervous system found inside the
skull which is the control center for the body.
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1. The brain is divided into three regions; forebrain, midbrain,
and hindbrain.
a. The forebrain is the anterior region of the brain that
is responsible for speech, reasoning, memory, and
coordinating voluntary activities (activities which are
knowingly done.) The forebrain also contains the
cerebrum, which is responsible for higher level
thinking, and the olfactory lobes, which receive
impulses of smell from the nose.
b. The midbrain is the small region of the brain that
relays information between the forebrain and
hindbrain. The midbrain relays information from the
eyes as well.
c. The hindbrain is the posterior region of the brain. It
is made up of the cerebellum, which coordinates
balance and equilibrium and the medulla oblongata,
which controls all unconscious activities.
i. The medulla oblongata is responsible for
breathing, digestion, temperature regulation,
blood vessel dilation, and gland secretion.
2. The spinal cord is the part of the central nervous system
found in the vertebral column which conducts nerve
impulses and coordinates involuntary action.
a. Involuntary actions are those actions which are fast
and automatic, they can not be controlled and do not
need to be learned.
i. Involuntary reactions are called reflex
actions. Examples of reflex actions are
sneezing, coughing, or blinking.
3.2.3 Peripheral nervous system
1. The peripheral nervous system is the part of the nervous system which is made up
of the sensory nerves and the motor nerves.
a. The function of the peripheral nervous system is to relay information
between the central nervous system and the rest of the body.
b. A nerve is a bundle of neurons or nerve cells.
2. Conduction of nerve impulses
a. Nerve impulses are the electro-chemical signals sent through neurons to
coordinate the body.
b. A nerve pulse begins as a change in the arrangement of chemicals at one
end of a nerve fiber.
i. Between two neurons there is a small gap called a synapse. Nerve
impulses travel from one neuron to another through the use of
synaptic transmitters. When the axon terminal of a neuron is
stimulated by a nerve impulse, it secretes synaptic transmitters.
These synaptic transmitters travel across the synapse and stimulate
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the dendrites of the second neuron. If the threshold level is reached,
the second neuron then reproduces the nerve impulse.
1. The threshold level is the amount of stimulation required to
produce a nerve impulse.
2. The refractory period is the small period of time during
which the neuron recovers for a nerve impulse. It is
impossible to simulate a neuron during the refractory period.
3. The ‘all or none’ principle is the concept that all nerve
impulses are the same size no matter the size of the
stimulus.
3.2.4 Reflex action
1. A reflex action is a rapid automatic response to a stimulus that is not voluntarily
controlled by the brain.
a. Your body performs reflex actions without thinking, like when you touch
something very hot, you move your hand quickly without thinking.
b. During a reflex action the nerve impulse travels in a path from the receptor
organs to the effector organ. This path is known as the reflex arc.
c. Simple reflex actions are those that are un-conditioned or natural, such as
blinking, knee-jerk, and yawning.
d. Conditioned reflexes must be learned. Walking, for example, may be
difficult at first, but then you do it without even thinking about it and it
becomes a reflex.
3.3 Drugs and drug abuse
1. A drug is a chemical substance that can alter the way your mind or body works.
a. Drugs act directly on your nervous system. Drugs are usually prescribed by a
doctor to ease pain when a patients is sick. However, some drugs can be
harmful or be used improperly.
2. Drug abuse is when drugs are taken on a regular basis, purely for enjoyment.
a. Drug addiction or drug dependence is when a person uses a drug so much that
life seems unbearable without it.
b. There are many drugs that can be abused such as:
i. Caffeine is found in coffee, tea, and cola.
ii. Nicotine is found in tobacco, like cigarettes and cigars. This drug also
makes the nervous system accelerate the heart rate and increase the
amount of sugar in the blood.
1. Smoking cigarettes can cause caner of the lungs, mouth, throat,
and other body organs. It can also cause disease of the lungs
and lead to heart attacks.
iii. Cocaine is a found in the leaves and nuts of coca plants. It increases
heart rate, reduces appetite, and is highly addictive.
iv. Marijuana is produced from a weed called hemp. Marijuana produces a
relaxed feeling and loss of judgment.
v. Alcohol is found in alcoholic beverages like beer and pombe. It
interferes with the transmission of nerve impulses and causes
insensitive, loss of coordination, and difficulty speaking.
3. The effects of drug abuse:
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a. Health Problems, like cancer, loss of memory, and heart disease.
b. Rejection from friends and family
c. Loss of work and money to feed the addition
d. Many users turn to crime to pay for their habit.
4. Prevention and Control of Drug Use
a. Just say No
3.2.5 Sense organs
1. Animals detect changes with special sensory cells called receptors.
a. Sense organs are a group of specialized receptor cells which detect changes
in the external environment.
b. The five sensory organs found in humans are the:
i. Nose
ii. Tongue
iii. Skin
iv. Ears
v. Eyes
c. Any change that produces a respond is a stimulus.
i. A stimulus is a change in the internal or external environment of an
organism.
ii. Examples of changes or stimuli in our environment are light, sound,
heat, cold, touch, pressure, and chemicals.
d. A sensation is an effect created by the brain in response to a stimulus.
i. Examples of sensations are smell, taste, touch, burning, hearing,
sight.
2. Skin
a. The skin is the sense organ covering the entire body which is sensitive to
pressure, pain, and temperature changes.
b. The function of the skin is to protect the body against pathogens, produce
some vitamins, and be sensitive to touch, pain, and temperature changes.
c. Your skin is the largest of your sense organs.
d. Human skin has a variety of receptors which are sensitive to certain types
of stimuli.
i. Touch receptors, which help us feel pressure and shape.
ii. Pressure receptors, which control the force we use to hold things.
iii. Pain receptors, which are nerve endings that are sensitive to pain.
iv. Heat receptors, which are sensitive to heat.
v. Cold receptors, which are sensitive to cold.
e. Adaptive features of the skin are that the epidermis layer prevents
pathogens from entering the body and the nerve endings allow the skin to
detect touch, pain, and temperature change.
3. Tongue and Nose
a. The tongue and nose are both stimulated by chemicals. They are
permanently covered by a layer of moisture in which chemicals must first
dissolve before they can be sensed. The nose and tongue also work together
to give the flavor of a food.
b. Tongue
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i. The tongue is a sense organ located in the mouth which is sensitive
to flavor chemicals.
ii. The function of the tongue is to detect tastes in the external
environment and allow talking and swallowing.
iii. There are sensory receptors on your tongue called taste buds. The
tongue has four types of taste buds; bitter, sour, sweet, and salty.
iv. The adaptive features of the tongue are that taste buds allow the
tongue to detect chemicals in the mouth and the presence of saliva
in the mouth allows flavor chemicals to dissolve.
c. Nose
i. The nose is the sense organ which is sensitive to odor chemicals.
ii. The function of the nose is to breathe and to detect odors in the
external environment.
iii. The sensation of smell is created when chemical receptors in the
nasal cavity are stimulated.
iv. Adaptive features of the nose include the olfactory nerves which
carry impulses to the olfactory bulb in the brain for processing, the
mucus secreting cells which keep the nasal passage moist and allow
odor chemicals to dissolve and be detected, and the sensitive hairs
in the nose which trap bugs and dust before they can enter the nasal
passage.
4. Ears
a. The ears are the sense organs which are sensitive to sound and acceleration.
b. The function of the ear is to detect sound and to maintain function.
c. The three parts of the ear are the outer ear, the middle ear, and the inner
ear.
i. The outer ear consists of the pinna, the ear canal, and the ear drum.
The function of the outer ear is to collect sound waves and send
them to the middle ear.
ii. The middle ear consists of the Eustachian tube, the ear ossicles, the
round window, and the oval window. The function of the middle
ear is to send sound vibrations to the inner ear and maintain
pressure in the ear.
iii. The inner ear consists of the cochlea, the semi-circular canals, the
utriculus, and the sacculus. The function of the inner ear is to detect
sound and send it to the brain as well as sense acceleration and
equilibrium.
d. How we hear
i. The pinna collects sound waves from the environment and sends the
sound waves through the ear canal to the ear drum. The sound
waves hit the ear drum and cause it to vibrate. These vibrations
cause the ear ossicles to vibrate. The vibrations are sent through the
oval window into the cochlea.
ii. In the cochlea, the sound vibrations stimulate sensory hair cells.
The sensory hair cells stimulate the sensory neurons and produce
nerve impulses. These nerve impulses are sent to the brain through
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the Auditory Nerve. When the nerve impulses reach the brain, they
create the sensation of hearing.
5. Eyes
a. The eyes are the sense organ which are sensitive to light.
b. The function of the eyes is to detect light.
c. The eye has importance parts which help it function such as the cornea, the
pupil, the lens, the retina, and the optic nerve.
i. The cornea is the part of the eye which protects the eye ball.
ii. The pupil is the part of the eye which allows light to pass through.
iii. The lens is the part of the eye which focuses the light.
iv. The retina is the part of the eye which detects light using rods and
cones.
v. The optic nerve is the part of the eye which sends nerve impulses
from the eye to the brain.
d. How we see
i. As light passes through the lens it is bent, or refracted. This
refraction allows the eye to focus images of the retina in order to
see clearly.
3.4 Hormonal coordination in humans
1. The Endocrine System
a. The endocrine system produces chemical messengers called hormones.
b. Hormones are chemical messengers produced by special structures called glands.
c. Hormones diffuse from these glands into the blood and circulate the body until
they reach their place of action. The hormones then diffuse out of the blood into
the organ and deliver their message. These hormones usually control certain body
functions.
d. Hormonal coordination is the regulation of bodily functions through the release of
hormones.
e. There are about 30 hormones produced by 8 glands.
2. Glands
a. The Pituitary
i. The Pituitary gland is a small projection below the brain.
ii. The pituitary gland is very important because it produces hormones which:
1. Control other glands
2. Influence growth during childhood
3. Initiate milk production by the mammary glands
4. Induce labor during childbirth
5. Influence the amount of water in the blood
b. Thyroid
i. The thyroid gland is located in the neck in front of the trachea.
ii. The thyroid produces thyroxin, a hormone which influences cellular
metabolism.
c. Pancreas
i. The pancreas is located in the abdomen.
ii. The pancreas produces a hormone called insulin which influences the
amount of glucose or sugar in the blood.
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d. Adrenal
i. The adrenal glands are found above the kidneys.
ii. The adrenal glands produce hormone adrenalin, which prepares the body
for action.
iii. The adrenal glands also produce hormones which influence the amount of
sodium in the blood and help the body to manage stress.
e. Testes
i. Testes are located in the male reproductive system.
ii. Testes produce testosterone, the male sex hormone which influences male
sexuality and maturity.
f. Ovaries
i. Ovaries are located in the female reproductive system.
ii. Ovaries produce the female sex hormones estrogen and progesterone which
control the menstrual cycle and influence female sexuality.
3. Disorders associated with hormonal coordination
a. Cretinism is when the thyroid gland does not secrete enough of the hormone
thyroxin in the developmental stages of a child and causes stunted growth and
mental retardation.
b. Myxoedema is a similar condition but under secretion occurs when the person is an
adult and leads to mental retardation, sensitive to cold, memory loss, and appears
much older than he actually is.
3.5 Coordination in plants
3.5.1 Concept of tropic and nastic responses
1. Plant hormones have several effects on plants. They control when a plant flowers,
cell division, and cell elongations.
2. Phototropism is a plant’s response to light.
3. Geotropism is a plant’s response to gravity. Roots are positively geotropic while
shoots are negatively geotropic.
4. Hydrotropic is a plant’s response to water. Roots will grow towards water and
against gravity, meaning water has a great effect on plant growth than gravity.
4. Excretion
4.1 Concept of excretion
1. Excretion is the getting rid of waste products of metabolism. Metabolism includes all the
chemical reactions going on inside a living organism’s systems.
a. For example respiration is a metabolic process. Carbon dioxide is one of the
products of that is not needed and can be toxic to the organism. The process of
removing toxic waste products which have been made by cells is called excretion.
1. Excretory products are the substances that are produced by the chemical reactions of
metabolic processes in an organism which are not needed and often poisonous.
2. Excretory organs are the organs that get rid of excretory products
4.2 Excretion in humans
1. Humans have three main excretory substances:
a. Carbon dioxide:
i. This is made by all cells, in respiration. It is transported in blood plasma to
the alveoli of the lungs, where it is excreted in the air you breathe out.
b. Bile pigments:
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i. These are made in the liver, from the hemoglobin in old red blood cells.
They are carried in the bile into the duodenum, and excreted in the feces.
c. Urea:
i. This is made in the liver, from excess proteins. It is carried in the blood
plasma to the kidneys, where it is excreted in urine. It contains nitrogen, so
it is a nitrogenous excretory product.
2. Humans have three excretory organs
a. Lungs – these remove carbon dioxide, and some water and heat.
b. Kidneys – these organs remove water, urea dissolved in them as urine.
c. Skin – the skin is a big excretory organ in human beings. It removes water, salts
and urea in the form of a liquid called sweat.
3. Urine Formation
a. Proteins that you eat are broken down into amino acids. The liver allows some
amino acids to enter the blood to go to other parts of the body. However, if you
have eaten more than you need, then some amino acids must be removed.
b. Amino Acids contain energy, so enzymes in the liver split up each amino acid so
some can be stored for later. Part of the energy is kept and turned into
carbohydrates or fat. The rest, is turned into urea. The urea then dissolves into the
blood plasma and travels to the kidneys.
c. The kidneys are made up of thousands of tiny tubes or nephrons. The job of the
kidneys is to take unwanted substances from the blood and to pass them on to the
bladder to be excreted. Blood is brought to the bowman’s capsule in a branch of
the renal artery. Small molecules, like water, glucose, and salts, are filtered out of
the blood into the bowman’s capsule. Any useful substances are then taken back
into the blood again. The liquid remaining liquid left in the bowman’s tubule is
called urine, and goes into the ureter and is taken to the bladder.
d. The bladder store the urine until you go to the bathroom. Urine then travels down
a tube called the urethra and out of your body.
4.3 Complications and disorders of the excretory system
Disorders
Kidney (renal)
failure: Chronic
Causes
Bacterial infection, inflammation of
glomerulus, blockage of ureters, sugar
diabetes, high blood pressure, heart failures
Kidney (renal)
failure: Acute
Shock, decreased blood supply, trauma,
drug toxicity, blockage of ureters, bladder,
or urethra e.g. by kidney stones
Inflammation of the glomeruli due to
bacterial infections such as throat
infections, small pox, typhoid.
Failure of the pituitary gland to release
ADH
Nephritis
Diabetes Insipidus
Symptoms
Progressive destruction of nephrons:
reduced quantity of urine, dilute
urine, coma, convulsions, salt
imbalance, severe high blood
pressure
Pain, little or no urine produced,
nitrogenous waste build up in the
blood, salt imbalance.
Fever, headache, vomiting, highly
colored urine, general weakness,
edema(swelling)
Large quantities of water produced
together with urine.
4.4 Excretion in plants
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1. Like animal cells, plant cells are constantly respiring, and so produce carbon dioxide
as a waste product. BUT, during the day, they photosynthesize faster than they respire,
and so they use up the carbon dioxide faster than they produce it. At night, they are not
photosynthesizing so the carbon dioxide is excreted through the stomata. In the day,
oxygen is a waste product of photosynthesizing and is excreted through the stomata.
a. Plants do not produce excretory from proteins, like urea, because they do not
eat proteins! They make their own proteins.
b. Other waste substances which plants make accumulate in their leaves. When
the leaves grow old and are dropped, these substances are lost. These
substances include:
Plant Excretory Product
Tannins and other organic
acids
Usefulness of plant excretory product
The bitter acids have a protective role in deterring leaf-eating
animals from feeding on the plant.
Gums, resins and latexes
Used to make turpentine, paints, varnishes, soaps, cosmetics,
foods, surgical items, golf balls, bubble gum, and rubber.
5.0 Reproduction
5.1 Concept of reproduction
1. Reproduction is the ability of an organism to form new ones of their own kind.
2. The result of reproduction is the increase in the number of organisms and the
perpetuation of life on Earth.
3. Organsims can reproduce sexually or asexually.
a. Sexual reproduction uses special cells called sex cells or gametes. There are
two types of gametes, male and female.
b. Fertilization is the fusion of a male and female gamete that produces a new
organism.
i. Usually male organisms produce male gametes and female organisms
produce female gamete.
1. Some animals are hermaprodites, which means they have both
male and female sex organs and can make both gametes.
4. Asexual Reproduction
a. In asexual reproduction there are no sex cells involved. The following are
different methods for asexual reproduction:
i. Binary fission
1. Binary fission is the process of an organism spliting themselves
down the middle into two even parts. Each part then grows to
attain the orginal size of the parent cell and becomes a separate
and independent organism. Organisms that use binary fission
are Amoeba, Paramecium, Euglena, and Trypanosome.
ii. Fragmentation
1. Fragmentation is when an organism is broken into two or more
parts, and then each part grows to become a complete
organism. Examples of fragmentation can be seen in flatworms.
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iii. Multiple fission
1. Also called sporulation, this is the asexual process of creating
reproductive cells called spores to reproduce. These spores
then grow into new organisms. Examples of organisms that
practice multiple fission are fungi, mosses, ferns, and Amoeba.
iv. Budding
1. Budding is the process of new organisms coming from the
outgrowth or bud of an older organism. The bud then
sepereates and grows. Yeast and Hydra practice budding.
v. Gemmae-cup formation
1.
vi. Leaf tips
vii. Tubers
viii. Leaf buds
ix. Suckers
x. Bulbils
5. Sexual Reproduction
6. Advantages and disadvantages of sexual and asexual reproduction
Asexual Reproduction
Sexual Reproduction
Advantages
Disadvantages
Advantages
Disadvantages
6.2 Meiosis and reproduction
6.3 Reproduction in flowering plants
6.3.1 The structure of the flower
6.3.2 Pollination
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6.3.3 Fertilisation
6.4 Reproduction in Mammals
i. Female Reproductive System
1. Anatomy
a. Ovaries
i. Situated near the kidney
ii. Produce ova (eggs)
iii. Produce the sex hormones oestrogen which creates lining of
the uterus and progesterone which prevents the production
of another ovum during pregnancy and contracts the
uternine muscles.
b. Fallopian Tubes
i. Also known as the egg tube or oviduct
ii. Tube that has a funnel shaped opening very near to each
ovary
iii. Ova are released into this tube
iv. Fertilization usually takes place here.
c. Uterus
i. The fallopian tubes unite and form an expanded tubular
organ called the uterus or womb.
ii. Thick walls made of muscle tissue
iii. Zygotes or the fertilized ovum implant into the uterine wall
and develop into an embryo
iv. It is about the size of a fist but expands during pregnancy
v. At the base is a small muscule ring called the cervix which
leads to the vagina.
d. Vagina
i. This tubular opening connects the uterus to the outside of
the body.
ii. It is where sperm is deposited.
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ii. Male Reproductive System
1. Anatomy
a. Testes
i. A pouch of skin called the scrotum protects the testes.
ii. The scrotum hangs away from the body and maintains the
testes at a slightly lower body temperature (34 C) required
in normal sperm development in humans.
iii. Testes produce sperm
iv. also endocrine glands which secrete the sex hormone
testosterone
v. Epididiymis temporarily stores sperm.
vi. From the epididimyis the sperm travels through the sperm
duct or vas deferens which then transports sperm to the
penis.
b. Seminal vesicles and prostrate gland
i. The two seminal vesicles in conjunction with the prostrate
gland create a liquid which mixes with sperm as it passes
through the vas deferens. The fluid provides nourishment
and protection to sperm.
ii. The combined sperm and liquid is called semen.
c. Penis
i. The penis is a copulatory organ. Copulation is the act of the
male sex organ entering the female sex organ.
ii. Used to introduce sperm into the vagina, called ejaculation.
iii. The urethra carries both urine and semen at the same time.
b. 6.4.1 Gamete Formation and Fertilization
i. Gametes
1. Sex cells produced by meiosis.
a. Haploid cells (single set of chromosomes)
2. Eggs (ova)
a. Cell containing a nucleus
b. Made from the cells of the epithelium of the ovary
3. Sperm
a. Has a head containing a nucleus
b. Middle piece with mitochondria
c. Tail for propultions
ii. Puberty
1. Sexual Maturity, when secondary sexual characteristic appear and
gametes begin to be produced
2. Changes are stimulated by hormones
a. Progesterone and oestrogen in females and testosterone in males
3. Males
a. Usually occurs at 14-16
b. Testes start to produce sperm and testosterone
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c. hair on chin, chest, and pubic region, shoulders widen, voice
becomes deeper, body odor increases, experience erection of the
penis, increased interest in females
4. Females
a. Usually occurs at 12-14
b. Menstruation begins.
c. Hair develops underarms and pubic region, enlargement of
mammary glands and hips, body odor increases, disposition of fat
that creates hourglass figure, and experience wetness in vagina
when stimulated by sexual feelings, increased interest in males
iii. Menstrual Cycle (Oestrus cycle)
1. By the time a female is born, her ova have already been formed, but are
only partially developed. At puberty, one ovum develops or matures every
28 days. The mature ovum is surrounded by a group of cells called the
follicle. The follicle moves to the edge of the ovary and eventually bursts,
releasing the ovum into the fallopian tube.
2. Ovulation
a. The releasing of an egg from the ovary
3. Ovulation alternating between the two ovaries. The 28 days cycle is called
the menstrual cycle in humans and the oestrus cycle in non-humans.
4. After ovulation occurs, the ovary begins to secrete progesterone. If the egg
is fertilized and the woman becomes pregnant, the ovaries will continue to
produce progesterone for three months. But if the woman is not pregnant,
the secretion of progesterone ends after 14 days. As long as the woman is
not pregnant, the menstrual cycle should continue to occur every 28 days.
5. The menstrual cycles (oestrous in non-humans) is controlled by
hormones. Before ovulation begins the ovaries produce the hormone
oestrogen, which stimulates growth in the lining of the uterus. The lining
develops blood vessels and glands to secrete nutrients in order to prepare
the uterus for pregnancy.
6. After ovulation the follicle cells develop into the corpus Iuteum, which
continues to secrete oestrogen and progesterone. These hormones keep
the uterine wall thick and supplied with blood. If the ovum is not
fertilized, the corpus Iuteum disintegrates and the hormone secretion
stops, triggering the blood vessels in the thickened lining to constrict and
cut off blood flow. The lining detaches and menstruation begins to occur.
7. Menstruation
a. is the discharge of the uterine lining (mucus, epithelial cells and
blood) through the vagina. It usually lasts 3-5 days.
iv. Copulation
1. When a male is stimulated blood flows to the penis and becomes erect.
The penis enters the vagina and ejaculation occurs. Ejaculation is the
release of semen. 100 million sperm are released in one ejaculation.
2. Once in the vagina, the sperm swim towards the oviducts. Organism in
female constricts the vagina and adds the sperm in movement towards the
fallopian tubes.
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v. Fertilization
1. The fusion of the male gamete with the female gamete to produce a zygote
(diploid cell).
2. If an ovum is in the fallopian tubes when ejaculation occurs, it is likely
fertilization will happen. Sperm can remain alive in the uterus and oviduct
for up to 48 hours. An ovum can remain alive for up to 36 hours from time
of ovulation. The fertile period is when the woman is most likely to get
pregnant and occurs two days before ovulation until one day after.
Therefore the fertile period is from the 11th to the 17th day after
menstruation.
3. Only one sperm can enter the ovum. Once a sperm inters the ovum a
tough membrane forms around the ovum blocking other sperm from
entering. The sperm enters and the nuclear matter from the sperm and
ovum combine, fertilization. The result is a diploid cell called a zygote.
The zygote then begins to divide through mitosis into a ball of cells and
travels to the uterus, which usually takes 3-5 days. The zygote, now called
an embryo attaches itself to the uterine wall in an act called implantation.
In 4-5 days the embryo becomes firmly attached to the uterus. The
embryo then forms two enveloping membranes. The outer is called the
chorion and the inner is called the amnion. The amnion is filled with a
liquid called amniotic fluid which the embryo is suspended in and protects
the developing baby.
4. The chorion is a thin membrane that develops finger-like projections
called villi which become deeply embedded in the uterus. The placenta is
formed where the villi connect the chorion and uterus.
5. A placenta develops around the embryo which deliveries nutrients and
oxygen to the embryo from the maternal blood. The placenta also filters
out waste from the embryo. The placenta secretes the sex hormone
progesterone during the late period of pregnancy. Progesterone prevents
the production of ova and stops the contractions of the uterine wall, so
that the menstrual cycle does not occur during pregnancy.
6. The umbilical cord connects the embryo and the placenta. The umbilical
cord carries two arties and a vein from the embryo to the placenta, where
nutrients and waste diffuse between the mother’s circulatory system and
the embryo. However, no mixing of blood occurs in the placenta.
7. 8 weeks after fertilization the embryo will have formed body
characteristics of a human and is referred to as a foetus from this point
onward. The foetus remains in the uterus for a totally of 9 months and is
released during birth. From implantation up to the time of birth the
female is pregnant. The amount of time the female is pregnant is known
as the gestation or incubation period.
vi. Birth
1. Begins with a sudden decrease in oestrogen and progesterone.
Contractions begin and cause pain caused labour pains. The body secrete
other hormones which trigger additional contractions which are
infrequent at first but become more regular and painful thorough birth.
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The contractions force the foetus to the lower part of the uterus and cause
the cervix to dilate. The amniotic sac breaks and the amniotic fluid comes
out of the vagina, water breaks.
2. The foetus is forced through the cervix and then vagina via contractions.
The umbilical cord is then cut and tied.
3. Further contractions separate the placenta from the uterine wall and force
through the vagina.
4. The concentration of CO2 and change in environment temperature
stimulate the breathing centre in the medulla oblongata and the baby
starts breathing.
vii. Factors which may hinder pregnancy
1. 1-in-10 couples do not conceive a child after a year or more of trying.
2. Female dependant
a. Ova are not released in the normal monthly cycle
b. The Fallopian tubes may be blocked or twisted
c. The uterus may not allow an embryo to implant due to an
imbalance of hormones
d. The womb lining may only grow in patches, making implantation
difficult
e. The woman may make antibodies that destroy the sperm
3. Male dependant
a. Very few sperm are produced in one ejaculation
b. A high proportion of the sperm produced are abnormal
c. The vas deferens may be blocked
4. Alternative ways to conceive a child
a. In-vitro fertilization
i. When the oviduct or Fallopian tubes are blocked, in-vitro
fertilization may be used. Several ova are removed from a
woman’s ovaries and placed in a petri dish with her
partner’s sperm and kept warm for a few hours. Thus
fertilization occurs in the dish rather than the oviduct. One
or more embryos are then placed into the woman’s uterus
where hopefully one will implant and develop into a baby.
There are ethical issues pertaining to the spare embryos
that are not used.
b. Fertility drugs
i. Some women are sterile because their ovaries fail to develop
ova because the hormone that is responsible for ova
production is not present. A procedure can occur where a
woman receives an injection of fertility drug in her ovaries
to stimulate ova production. This may lead to over
production of ovum and thus multiple pregnancies can
occur.
c. Artificial insemination
i. Semen can be rapidly frozen using liquid nitrogen and retain
its fertile quality. Woman can use sperm from a sperm bank
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if their male partner is infertile of for woman who choose to
become pregnant independent from a man. However this
option has moral and ethical issues surrounding it because
the mother can select what qualities she wants her child to
have.
c. 6.4.2 Multiple Pregnancies
i. Occasionally more than one ovum is released into the oviduct and thus it is
possible for more than one ovum to be fertilized. If the multiple embryos then
implant into the uterine wall and develop, the result is described as a multiple
pregnancy. May occur naturally or from fertility drugs or in-vitro fertilization.
ii. Fraternal and identical twins
1. Fraternal twins are when two different sperm fertilize two different ova.
2. Identical twins are when the zygote, fertilized by a single sperm, splits in
two. Thus the twin will be identical genetically and physically.
iii. The most children a woman has ever had are 69. Between 1725 and 1782 had 16
pairs of twins, 7 sets of tripletes, and 4 sets of quadruplets.
2. 6.5 Disorders of the reproductive system
a. Cancer
i. Cancer cell can manifest in reproductive organs, uterine, cervical, ovarian,
prostate and testicular.
ii. Reasons for reproductive cancers are unknown, although high levels of hormones
contribute to their risk.
iii. If caught early, can be treated with surgery, chemotherapy, or radiation.
b. Ovarian Cyst
i. Non-cancerous (benign) tumor in the ovary. In young woman a follicle can
develop into a cyst
ii. Usually caused by imbalance of hormones.
iii. Can be removed surgically.
c. Fibroids
i. Benign tumor consist of fibrous and muscle tissue that develop in the uterus.
ii. Caused when an area of muscle fails to shrink with the rest of the womb at ht
onset of menstruation.
iii. Causes heavy bleeding but can be removed by surgery.
d. Prostate Problems
i. Prostate gland may become enlarged due to cancer or infection.
ii. Difficulty urinating.
iii. Can be treated with antibiotics.
e. Impotence
i. Failure to maintain an erect penis.
ii. Often psychological. Also connected to diabetes and alcoholism.
iii. Depends on the cause.
3. 6.6 Complications of the Reproductive System
a. Breech birth
i. When a baby fails to be birthed head first
ii. More difficult to deliver and may require the use of forceps to assist
b. Disorders requiring a caesarean section (C- section)
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i. If baby is too large or mother’s hips too small
ii. Caesarean section occurs where baby is removed from the uterus by surgical
means.
c. Miscarriage
i. The loss of a developing embryo before the 28th week of pregnancy. Bleeding is
the first sign of a miscarriage, followed by early contractions. If the foetus dies in
the womb it is called a stillborn.
ii. The main reasons for miscarriage are development of deformed embryo, failure
of embryo to implant properly on the womb, and failure of the placenta to
develop to a sufficient size.
d. Abortion
i. Deliberate termination of a pregnancy
ii. Doctor may recommend if foetus shows a genetic abnormality or if pregnancy
will endanger life of mother.
e. Ectopic Pregnancy
i. Occasionally, zygote will remain in fallopian tubes after fertilization and continue
development there.
ii. May be caused by an infection in the fallopian tube.
iii. Ectopic pregnancies rarely last more than 2 months. Occasionally, the foetus
survives and can be delivered via Caesarean section.
4. 6.7 Sexuality and sexual behavior
a. Sexuality
i. Main role is to reproduce
ii. Sexuality is about “maleness” and “femaleness”
1. Our attraction to the opposite sex (heterosexual)
b. Social and Cultural Factors
i. Gender
1. Men are expected to provide, woman to be care givers or submissive
a. This is a social expectation
2. Woman are raised to be subservient and often miss finishing school
because they are at home completing domestic activities
c. Responsible and Irresponsible sexual behavior
i. Irresponsible behavior can lead to the spread of STIs, including AIDS, and
unwanted pregnancies
1. Irresponsible sexual behavior includes
a. Having premarital sex
b. Having several sexual partners
c. Having unsafe sex
d. Not using contraceptive devices
2. You have the right to say no to irresponsible sexual behavior from peers
and relationship partners
5. 6.8 Family Planning and contraception
a. Reasons for birth control and child spacing
i. Human babies require more attention than other mammals, the recommended
time being 2 years. If a mother becomes pregnant during this period it may lead
to neglect or reduced breast-feeding and reduce the health of the baby.
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ii. The process of birth is very demanding on the health of the mother.
iii. Expensive
iv. More time for women to work to improve their life (education) and the
community.
b. Methods of Birth Control
i. Abstinence
1. Best method
ii. Sterilization
1. Most reliable
2. Vasectomy in males, tubal ligation (tubes tied) in females
iii. Oral contraceptives
1. A pill that uses synthetic hormones to mimic oestrogen and progesterone.
2. Prohibit follicle from forming, and thus ovulation does not occur
3. Menstruation still occurs
4. Disadvanges: nausea, tender breast, weight gain.
5. 99% Effective
iv. Intra-uterine devices
1. IUD plastic coil placed in the vagina by physician which prohibits embryo
from implanting.
2. Disadvantanges: Could be expelled, uterus can be irritated or punctured
3. 96% effective
v. Diaphragm
1. Rubber cap inserted into the vagina to cover opening of cervix and blocks
sperm from entering uterus
2. Disadvantages: It can burst, especially if undersized
3. 85% effective
vi. Condom
1. Rubber sheath that is worn over penis to trap semen
2. Disadvantages: may burst or lead
3. 88% effective
vii. Coitus Interruptus
1. Withdraw of the penis just before ejaculation
2. Disadvantages: Precum, requires extreme self-control
3. 70% Effective
viii. The rhythm method
1. Abstaining during ovulation period (11th – 17th)
2. Disadvantages: menstral cycles are irregular and time of ovulation can
vary
3. 75% effective
6.0 Regulation
1. The Concept of Regulation (Homeostasis)
a. Regulation is the maintenance of a constant internal environment.
i. The environment of a living organism is always changing. The temperature
in the air around you changes. The amount of water in the air around you
changes. The cells inside your body, however, do not change with the
external environment; your body keeps the environment inside your body
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almost the same, all the time. Keeping this internal environment constant,
in a “steady state” is called homeostasis.
1. Homeostasis comes from two Latin words, homoios meaning same
and stasis meaning standing.
2. Importance of homeostasis
a. The internal environment of an organism’s body is never constant. Conditions such
as salt, body pH and temperature are always changing in response to changes in the
external environment. But, the changes are steady and well maintained to enable
chemical processes of metabolism to continue as usual. It is important to keep the
following steady for survival:
i. Keeping your body a constant temperature of around 37 C helps enzymes
to work efficiently. This types of regulation is called Thermoregulation.
ii. Keeping a constant amount of water means your cells are not damaged by
loosing or absorbing too much water by osmosis. This types of regulation is
called osmoregulation.
iii. Keeping a constant amount of glucose means there is always enough fuel
for respiration. This type of regulation is called blood sugar regulation.
3. Temperature Regulation in Animals (thermoregulation)
a. Animals are in two groups according to their response and adaptation to
temperature changes in the environment:
i. ECTOTHERMs (also known as “cold-blooded”)
1. “Ecto” comes from latin meaning outside or external. These means
these organisms body temperature changes with the environment.
a. EXAMPLES: toads, frogs, and other amphibians; snakes,
chameleons, turtles and other reptiles; fish; and houseflies,
grasshoppers, worms and other invertebrates.
b. These organisms’ body temperature changes with that of the
environment. They DO NOT control their body temperature.
Their body temperature is the same as the temperature of the
air or water surrounding them. When the temperature is
cold, their body is cold. Cold temperatures slow down
chemical reactions, which slow down the activity of the
organism.
ii. Homeotherms (also called endotherms or “warm-blooded”)
1. Homeotherm is a Greek word for “same heat”, meaning organisms
whose body temperatures remain constant regardless of changes in
the environmental temperatures.
a. EXAMPLES: mammals and birds
b. Mammals and birds are able to keep their body temperature
constant, no matter what the temperature of the environment
is. When the weather is very cold, their body remains warm.
b. Importance of temperature regulation
i. It is important to both homeotherms and ectotherms to control body
temperature for their metabolic processes because:
1. Muscles and nerves work best at 35C – 40C
2. Enzymes are proteins.
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a. The rise of temperature above optimum would lead to the
denature of the enzyme structure and negatively affect the
body’s functions.
b. If the temperature drops below optimum required for
enzyme reactions, enzymes would become inactive.
c. HOW HUMANS CONTROL THEIR BODY TEMPERATURE
i. The hypothalamus is located almost in the middle of your head at the base
of your brain. The hypothalamus keeps a constant check on the temperature
of the blood flowing through it. The hypothalamus controls the body
temperature.
ii. If the temperature is too low, the hypothalamus sends messages along
nerves to various parts of your body to increase heat production, and reduce
heat loss from your skin. If the temperature is too high, then messages are
sent to reduce heat production, and increase heat loss. This system works
well as your body temperature rarely varies by more than 0.5C.
d. THE SKIN
i. The skin is the largest organ in the mammal body.
ii. It has many functions.
1. For temperature regulation, its function is to vary the rate at which
heat is lost from your body to the air.
iii. The structure of human skin
1. Human skin has two layers: Top layer is the epidermis and the
lower layer is the dermis.
2. Epidermis
a. Protects the deeper layers
b. The top layer is hard and waterproof so it can protect the
softer, living cells underneath. It is always being worn away,
and replaced by cells from beneath.
c. Some cells in the epidermis contain a dark pigment called
melanin. Melanin absorbs the harmful ultra-violet rays in
sunlight, which would damage the deeper layers of the skin.
d. Hair grows from folds in the skin called hair follicles. Hair
is made of keratin. Each hair follicle has a sebaceous gland
opening from the side of it. These glands make an oily
liquid called sebum. Sebum keeps the hair and skin soft and
supple.
3. Dermis
a. Most of the dermis is made of connective tissue. This tissue
contains elastic fibres. When person gets older, the fibres
lose their elasticity, so the skin becomes loose and wrinkled.
b. The dermis contains sweat glands. These secrete a liquid
called sweat. Sweat is mostly water, with a small amount of
water and urea dissolved in it. Sweat travels up the sweat
ducts, and out onto the surface of the skin through sweat
pores. Sweat helps regulate body temperature.
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c. The dermis contains blood vessels and nerve endings. The
nerve endings are sensitive to temperature, touch, pain,
pressure and touch. So, they help to keep you aware of the
changes in your environment.
d. Underneath the dermis is a layer of fat. This is made up of
cells which contain large drops of oil. This layer helps to
insulate your body from temperature loss, and also acts as a
food reserve.
iv. How the skin reacts when you are too cold
1. When your body temperature drops below 37C, messages from
your hypothalamus cause your skin to cut down the rate of heat
loss.
2. First: the messages make the erector muscles attached to the hair
follicles contract, making your hairs stand on end. If you were a
very furry animal such as squirrel, this would provide you with a
thick layer of hair, trapping air – which is an excellent insulatornext to your skin! As it is, you just get goose pimples, which do not
help at all.
3. Second: the messages make the muscles around the arterioles (small
arteries), which supply blood to the capillaries near the surface of
your skin, contract (called vasoconstriction). This closes off the
arterioles, and stops the blood flowing along the pathway. Instead, it
has to go through the capillaries which lie below the fat layer. This
reduces the amount of heat which is lost by radiation from your
blood to the air. Your skin looks blue or white, and feels cold – but
your blood will stay warm.
4. Other responses which do not involve your skin when your blood is
too cold:
a. Shivering – A very fast, random contraction and relaxation
of muscles, which generates heat to warm your blood.
b. Metabolic reactions in your liver may speed up, again
generating extra heat.
c. Behaviors you may do in response to feeling cold:
i. Jumping up and down, this also increases the amount
of heat generated.
ii. Moving to a warmer place to conserve heat.
iii. Putting on more clothes to insulate from heat loss.
v. How the skin reacts when you are too warm.
1. When your body temperature raises much above 37C, messages
from your hypothalamus cause your skin to increase the rate of heat
loss.
2. First: the messages make the erector muscles relax, so that the hairs
lie flat against the skin, no longer trapping as much air and so
allowing more heat to be lost by radiation.
3. Second: the messages make the muscles around the arterioles,
which supply blood to the capillaries near the surface of your skin,
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relax (called vasodilation). This opens the arterioles, so the blood is
free to flow through the surface capillaries. This brings the blood
close to the surface of the skin, so that is can lose more heat by
radiation from your blood to the air.
4. Third: The sweat glands begin to secrete sweat. This is a fluid made
from blood plasma, containing mostly water and some salt and a
little urea. It flows from the glands, through the sweat ducts and
onto the surface of the skin. Here it evaporates, which cools the
skin. This is a very important process, because it is the only way we
have of making our body temperature lower than the temperature
around us.
5. Other responses which do not involve your skin when your blood is
too cold:
a. Lie still, so you generate less heat within your body
b. Take off layers of clothes, or wear light, loose fitting
clothes.
c. You can swim or shower; when you get out of the water, the
water evaporates from your skin and cools you down.
d. You can move into the shade or a cool room with a breeze to
evaporate the sweat more rapidly.
e. Mammals such as dogs and birds use panting as a way to
cool the body by evaporation through the tongue and
respiratory system.
6. Heat Stroke is a condition where the body cannot cool fast enough
through evaporation of sweat in humid weather and your body
temperature may rise to over 41C resulting in a coma or
convulsions. If the body is not cooled this condition can result in
death.
e. How Ectothermic animals regulate temperature.
i. In cold countries, the most difficult time for any animal to survive is in the
winter, when temperatures fall, and food is in short supply. In cold
countries, Poikilothermic (ectothermic) animals are so cold during the
winter months that their metabolic rate is far too low for them to be active.
Reptiles, amphibians, and most invertebrates spend the winter in an
inactive or what is called a dormancy state.
ii. When the environmental temperature becomes too hot and dry, to avoid
being overheated, poikilothermic animals become inactive (low metabolic
rate) going into a deep sleep called aestivation in burrows or nests.
iii. Basking is when poikilothermic animals expose their body to the sun of
shade to absorb more or less heat from the environment.
f. Behavioral Adaptations to Extreme cold and hot Environments
i. Hibernation: Some mammals eat the sort of food that is not available in the
winter in cold countries. Because they cannot find enough food during the
winter to keep their body temperature high enough to be active, they
hibernate. Towards the end of summer, when food is plentiful, they eat as
much as they can, and build up large fat stores in their bodies. In autumn,
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they find a sheltered, well insulated place and make a nest. They curl into a
small ball, to keep as much body heat as possible, and go to sleep. It is not
an ordinary sleep. Their metabolism rate slows down; their body
temperature drops well below normal. They do not usually wake until
spring.
ii. Migration: This is movement of animals from place to place in search of
favorable environments, foods, or shelter. Animals can migrate long
distances, from one continent to another. Certain birds migrate from
Europe to Africa responding to changes in climate factors.
iii. Aestivation: Homeotherms and poikilotherms subjected to hot dry
conditions lasting for long periods they go into a state of rest. They hide in
nests or burrows during this time. Their body metabolism slows down and
they become inactive.
4. The Control of Glucose Content
a. Importance of Glucose:
i. All cells in your body respire all the time. They must do this to provide
themselves with a supply of energy. If they stop respiring, they die.
ii. For many of your cells, the fuel they use in respiration is glucose. It is
therefore very important that the concentration of glucose in your blood
and tissue fluid is kept fairly constant, so your respiring cells do not run
out. THIS IS ESPECIALLY IMPORTANT FOR BRAIN CELLS! Brain
cells die quickly if they become short of glucose.
iii. Glucose concentration in the blood is normally around 100 mg of glucose
in every 100 cm3 of blood.
b. The Pancreas and Liver control the concentration of glucose in your blood.
i. The Pancreas secretes insulin and glucagon
ii. The pancreas is an unusual organ because it has two very different
functions. Most of the pancreas is made of cells that secrete pancreatic
juice, which flows along the pancreatic duct into the duodenum where it
helps digestion.
iii. Dotted around in the pancreas are groups of cells called islets of
Langerhans. These cells secrete the hormones insulin and glucagon.
iv. The cells in the islets of Langerhans constantly monitor the amount of
glucose in the blood.
1. If the blood glucose level rises too high, then they secrete insulin.
2. If the blood glucose level falls too low, they secrete glucagon.
v. The Liver changes the amount of glucose in the blood.
1. Insulin and glucagon are carried around the body, in solution in
blood plasma. Both of them affect the behavior of liver cells.
2. Insulin makes the liver remove glucose from the blood, thereby
lowering the blood glucose level. The liver uses some of the
glucose in respiration. Stimulated by insulin, the liver can also
change some into the polysaccharide glycogen, which it stores
inside its cells.
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3. Glucagon makes the liver release glucose into the blood, thereby
increasing the blood glucose level. The glucose that the liver
releases is made by breaking apart the glycogen stored in its cells.
c. Lack of insulin causes Diabetes mellitus or sugar diabetes.
i. Causes, symptoms and effects of high and low levels in the blood
1. Diabetes mellitus: A disease of people whose pancreas does not
produce enough insulin. When this happens, there is nothing to
control the amount of glucose in the blood. In a diabetic person,
after a meal, all the glucose goes into the blood and goes around the
body. This creates too high glucose levels in the blood. High levels
of glucose can damage brain cells, cause comas and possible death.
2. Also, if there is no insulin in the body, then the liver and muscles
will not build up stores of glycogen. So later, when the blood
glucose levels have dropped again, there will be no reserves to draw
on. The blood glucose may drop too low causing coma or death.
3. Diabetes cannot be cured but it can be controlled. Most can remain
healthy through carefully controlling carbohydrates in the diet.
Some need daily injections of insulin.
4. Symptoms:
a. Extra glucose in the blood is excreted by the kidneys. A
person with diabetes will have sugar in their urine. A
healthy person will have NO sugar in their urine.
b. Severe thirst
c. Loss of weight
d. Lack of energy
e. Frequent urination
f. Cuts slow to heal
5. Effects:
a. Without medical treatment cannot get energy from food
b. Eyes and kidneys are affected if untreated
c. Coma and cardiac failure if not treated
5. Osmoregulation: The Control of Water content of the body
a. The Kidneys help with osmoregulation.
i. The kidneys, acting together with the hypothalamus and pituitary gland, are
responsible for osmoregulation in humans.
b. Importance of Osmoregulation:
i. Changes in the amount of water in the blood and tissue fluid can have great
effects on the body cells. If there is more water than there is needed – that
is if the blood is too dilute- then water nay move into cells by osmosis,
causing the cells to swell and perhaps even burst. If the blood is too
concentrated, water will move out of the cells, causing them to shrink. In
both of these cases, the reactions which go on inside the cells will be
disrupted.
ii. The hormone ADH regulates water loss in urine.
1. The hypothalamus continuously monitors the concentration of the
blood. If there is too little water, it causes the hormone ADH
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(antidiuretic hormone) to be secreted from the pituitary gland. The
ADH dissolves in the blood plasma, and is carried all over the body.
2. When it reaches the kidneys, it affects the walls of the collecting
ducts in the nephrons. It makes them very permeable to water. As
the urine flows down the collecting ducts, much of the water in it
passes through the walls of the collecting ducts, and into the blood.
So the maximum amount of water is kept in the blood, and the
minimum amount is lost in the urine. The urine will be more
concentrated than usual.
3. The hypothalamus also sends messages to the conscious areas of
your brain, and makes you thirsty. You respond to this by drinking,
which helps to increase the amount of water in your blood.
If the hypothalamus senses that there is too much water in your blood, then it
stops secreting ADH, and stops you feeling thirsty. Now the collecting ducts in
the kidneys become impermeable to water. As the urine flows down through
them, the water can no longer go through their walls and into the blood. The
water stays in the urine. More urine is made than usual, and it will be very
dilute.
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FORM IV FIRST SEMESTER LECTURE NOTES
1. Classification of living Things
1.1 Kingdom Animalia
1. General and distinctive features of the Kingdom Animalia
a. Animals are multicellular.
b. Animals are differentiated into tissues.
c. Animals are heterotrophic feeders.
d. Animals are capable of locomotion.
e. Animals have a nervous system (with the exception of sponges.)
2. Kingdom Animalia is divided into many phyla.
a. Chordata are animals that have a notochord, which in many animals
develops into a backbone.
b. Porifera, Cnidaria, Ctenophora, Mollusca, Echinodermata, Platyhelinthes,
Nematoda, Annelida, and Arthopoda do not have a notochord and are
collectively called non-chordates.
1.1.1 Phylum Platyhelinthes
1. Platyhelinthes are also known as flatworms.
2. Their defining characteristic is that their bodies are dorso-ventrally
flattened and most are parasitic and feed off other organisms.
3. This phylum is divided into three classes: Trematoda (Flukes), Cestoda
(tapeworms), and Turbellaria.
a. Trematoda or flukes are parasitic. They are flat and use suckers to
feed.
b. Cestoda or tapeworms are flat, tape-like and have segmented or
divided bodies. They are parasitic and use suckers and hooks to
feed. Tapeworms live in the human intestine and hurt humans by
absorbing partly digested food. They can cause disease as well as
malnutrition.
c. Turbellaria are flat and have cilia which help them move.
1.1.2 Phylum Nematoda (Aschelminthes)
1. General and Distinctive features of the phylum Nematoda
a. They have unsegmented, cylindrical bodies with pointed ends
b. Cuticle of protein
c. Unbranched gut from mouth to anus
2. Examples of Roundworms
a. It is likely that 90% of the people in this room have parasitic
roundworms.
b. Ascariasis is a roundworm that lives in the small intestine.
Ascariasis rarely causes symptoms and is not usually treated.
c. Threadworms are very small worms that infest the large intestine
and cause itching in the skin.
d. Filariasis, including elephantiasis, infects the lymphatic and skin
tissue and causes extreme swelling.
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e. Hookworm enters through the skin, travels to the lungs, and then to
the intestine. Hookworms cause diarrhea, stomach pain, and
anemia.
f. Washing hands regularly can prevent most roundworm infections
and making sure food is cleaned and cooked.
1.1.3 Phylum Annelida
1. General and Distinctive features of the phylum Annelida
a. They are segmented. They have separate internal organs and body
walls.
b. They have a thin, moist, non-chitnous cuticle
c. There is a presences of bristles.
2. Examples of Annelida are earthworms and leeches.
a. Earthworms have a mouth at their anterior end and anus at the
posterior with a clitellum that holds eggs. The earthworm uses
bristles to burrow through the dirt.
3. Advantages of Earthworms
a. Earthworms are a benefit to farmers because they breakup the soil,
allowing oxygen and water to enter the soil easily.
1.1.4 Phylum Arthropoda
1. General and Distinctive Features of the Phylum Arthropoda
a. Jointed appendages
b. An exoskeleton made of chitin
2. Classes of Arthropoda
a. Insects
i. Insects have a head, thorax, and abdomen.
ii. They have one pair of antennae.
iii. They have three pairs of jointed legs.
iv. Most adult insects have wings.
v. Examples of insects include grasshoppers, flies, ants, and
beetles.
vi. Insects are helpful:
1. They help pollinate plants.
2. Insect that live in the soil help speed up the process
of decay.
vii. Insects can be harmful:
1. Some carry disease, like mosquitoes.
2. Some feed on plants and kill crops.
b. Arachnida
i. Arachnids have four pairs of jointed legs.
ii. Arachnids have a cephalothorax (head and thorax) and
abdomen
iii. Examples of arachnids are spiders, scorpions, ticks, and
mites.
iv. Spiders are helpful in that they eat insects.
v. However, some scorpions and spiders are poisonous.
c. Crustacea
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i. Crustacea have two pairs of antennae
ii. Crustacea have Bi-forked appendages
iii. Examples of Crustacea are crabs, prawns, lobsters, and
barnacles.
iv. Crustacea are helpful because they feed humans and other
marine organisms.
d. Diplopoda and Chilopoda
i. Diplopoda and Chilopoda are very similar classes of
Arthropoda in that they both have long bodies consisting of
many segments.
ii. An example of a diplopoda is a millipede.
iii. An example of a Chilopoda is a centipede.
1.1.5 Phylum Chordata
1. The distinguishing characteristics of phylum Chordata
a. They have a notochord in the embryonic stage. In most chordates
this will be replaced with a vertebral column.
b. They have a nerve chord.
c. They have gill slits during the embryonic stage.
d. They have a tail which is behind the anus.
2. Classes
a. Chondrichthyes
i. Chondrichthyes are also known as cartilagous fish.
ii. Chondrichthyes include sharks, skates, and rays.
iii. Defining characteristics of Chondrichthyes are:
1. The skeleton is made of cartilage. (Like our
earlobes or tip of the nose)
2. The body is covered with placoid scales. (like
sandpaper.)
3. The tail fin is asymmetrical.
4. The gill slits are visible.
5. The mouth and two nostrils are centrally placed.
6. They are cold blooded or ectothermic. This means
their body temperature changes with the
environment.
b. Osteichthyes
i. Osteichthyes are also known as bony fish.
ii. Defining characteristics of Osteichthyes are:
1. The skeleton is made of bone.
2. The body is covered with scales.
3. The gills are covered.
4. The tail fin is symmetrical.
5. Most have an air sac or swim bladder.
6. They are cold blooded or ectothermic. This means
their body changes temperature with the
environment.
c. Amphibia
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i. Examples of Amphibians are toads, frogs, and salamanders.
ii. Distinguishing characteristic of Amphibians are:
1. They have to spend part of their life in water.
2. Their skin is always moist and without scales.
3. Their life cycle involves a form called a tadpole.
4. They are cold-blooded or ectothermic.
d. Reptilia
i. Examples of reptiles are snakes, lizards, crocodiles, and
turtles.
ii. Distinguishing characteristics of reptiles are:
1. They have dry skin with horny scales.
2. They are cold blooded or ectothermic.
3. They lay their eggs on land and the eggs have a soft
shell.
e. Aves
i. Are also known as Birds.
ii. Distinguishing characteristics of birds are:
1. Their body is covered with feathers.
2. They have wings.
3. They have a bill or beak.
4. They lay hard-shelled eggs.
5. They are warm blooded or homothermic, which
means they maintain a constant body temperature.
f. Mammalia
i. Distinguishing characteristics of mammals are:
1. They have a developed brain.
2. They have hair or fur on their body.
3. They have mammary glands which in females,
produce milk.
4. They have teeth.
5. They have a diaphragm.
6. They are viviparous, which means the fetus
develops inside the mother’s body.
7. They have sweat glands.
8. They are warm blooded or homoeothermic.
2. Growth.
2.1 Concept of growth
1. Growth is the permanent increasing in size.
2. Growth happens through cell division or cells getting larger.
3. Growth is irreversible. We cannot go back to our size, shape, and weight as a
child.
4. Growth can be positive or negative
a. Positive growth is when the rate of cell increase is greater than the rate
of cell loss.
b. Negative growth is when the rate of cell increase is less than the rate of
cell loss.
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5. Factors that affect growth
a. Light
b. Genetics
c. Space
d. Nutrients
e. Water
f. Hormones
g. Disease
h. Parasites
i. Temperature
2.2 Mitosis and growth
1. The concept of Mitosis
a. The way that cells divide to produce new cells for growth is called mitosis.
b. Mitosis is a method of cell division which makes two new cells with
exactly the same number and kind of chromosomes as the original cell.
2. The Stages of Mitosis
a. The nucleus of a cell contains 4 chromosomes. A chromosome is made of
two chromatids held together by a centromere.
b. Prophase
i. This is the first stage of mitosis.
ii. When a cell is not dividing the chromosomes are very long and
thin in the nucleus.
iii. During prophase the chromosomes get short and fat.
iv. A network of fibers called a spindle begins to develop.
c. Metaphase
i. This is the second stage of mitosis.
ii. During this stage the nuclear membrane disappears.
iii. The chromosome line up in the center of the spindle, with each
centromere attached to a spindle fiber.
d. Anaphase
i. This is the third stage of mitosis.
ii. The centromere of each chromosome splits, so the two chromatids
separate. The chromatids move away from each other along the
spindle fibers.
e. Telophase
i. This is the last stage of mitosis.
ii. The chromatids arrive at opposite ends of the cell and form into
two separate groups.
iii. A nuclear membrane forms around each group and the spindle
fibers fade away.
iv. The cytoplasm then divides (cytokinesis) and two new daughter
cells are formed.
3. The Significance of Mitosis
a. Mitosis results in the formation of two identical daughter cells that are
identical to the parent cell.
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b. Mitosis allows an organisms to increase in size but maintain the same
number of chromosomes in its cells.
c. Mitosis is also important for repairing damaged cells.
2.3 Growth and development stages in humans
1. The concept of growth and development in humans
a. As humans grow, the number of cells within us increases.
b. As the cells divide they specialize to do certain things. This is called
cell differentiation.
2. The stages of postnatal growth and development
a. A development stage is a period of time during which the body
performs a particular type of growth.
b. There are three development stages in humans; childhood,
adolescences and adulthood.
i. Childhood is the period of time between birth and adolescence
during which time the body grows taller due to growth
hormones.
1. Changes that occur during childhood are:
a. The body grows taller.
b. The body produces growth hormones.
c. The brain develops.
ii. Adolescence is the period of time between childhood and
adulthood during which time the body develops the secondary
sexual characteristics.
1. Examples of secondary sexual characteristics are:
a. Public hair
b. Deeper voices in men
c. Ability to ejaculate in men
d. Brest in women
e. Menstruation in women
2. Changes that occur during adolescence are:
a. The body grows stronger.
b. The body produces sex hormones.
c. The secondary sexual characteristics develop.
3. Girls usually being puberty at 12 and boys usually
begin at 14.
iii. Adulthood is the final development stage in humans during
which growth slows down until senescence.
1. Changes that occur during adulthood are:
a. The body grows thicker.
b. The body produces less growth hormone and
sex hormones.
c. The body undergoes senescence.
i. Senescence is the gradual decrease of the
body’s ability to function properly.
Senescence is also called aging.
2. Features of aging or senescence include
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a. Gray hair or loss of hair
b. Wrinkly skin
c. Weak immune systems
d. Weak muscles and bones
c. Why do organisms die?
i. The aging process of an organisms is due to the irreversible
processes of cells. Organisms age and eventually die because
the cells that make up the organisms die. Cells have a fixed
life span.
ii. Scientists are not sure what causes cells to have a fixed life
expectancy, but there are three hypotheses that try to explain
cell life span.
1. One hypothesis says that cell death is caused by genetic
mutation.
2. Another hypothesis says that cell death is due to the
accumulation of metabolic waste.
3. A third hypothesis says that cell death is a normal
cellular event written in the cell’s genetic material.
3. Factors affecting growth and development in humans
a. Many factors that affect growth and development in humans are due to
life style and environment. Examples are:
i. Quality and quantity of food consumed
ii. General health of the individual and quality of life.
iii. Level of sanitation and hygiene at home and in the community
iv. Occupation
v. Level of fitness
vi. Mental state
vii. Level of hormones
2.4 Growth in flowering plants
1. The Concept of Seed Germination
a. In most flowering plants, growth starts when the seed begins to germinate.
b. Germination is the development of a seed into a seedling.
c. A seedling is a young plant.
2. Changes that occur during seed germination
a. The seed absorbs water and swells.
b. The seed coat bursts and the radicle emerges.
c. The radicle grows downward and produces many side roots.
d. The seed coat is discarded and the two cotyledons (seed leaves) open out
and begin to photosynthesize. The plumule grows from in between the
cotyledons and produces the first true leaves.
3. Conditions necessary for seed germination
a. Germination requires energy or the proper temperature.
b. Germination requires oxygen.
c. Germination requires water.
4. Epigeal and Hypogeal germination
a. During epigeal germination the cotyledons grow above the soil.
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b. In hypogeal germination the cotyledons grow beneath the soil.
5. The growing regions of a flowering plant
a. Meristems are the regions where cell division and growth occurs in plants.
i. Three types of meristems are apical, lateral, and auxiliary
1. Apical meristems are the regions of growth in plants that
cause the shoots and roots to grow longer.
2. Lateral meristems are regions of growth in plants that cause
the shoots and roots to grow thicker.
3. Auxiliary meristems are regions of growth that cause the
shoot to grow new branches.
3. Genetics
3.1 Concept of genetics
1. Genetics is the study of how parents pass on traits to their children.
2. Vocabulary
a. Chromosomes are found in the nucleus of all cells. Each chromosome
carries thousands of genes.
b. Genes are a set of instructions which the body can uses to produce a trait
or characteristic.
c. A trait or characteristic is a feature that can be passed on from a parent to
child. Examples of traits in humans are hair color, body type, and skin
color.
d. Inheritance is the passing of traits from parents to their offspring.
e. Offspring are the immediate descendents of an individual. In humans,
offspring are the children of the parents.
f. Genotype is the genetic makeup of an organism.
g. Phenotype is the outward appearance of the organism.
3.2 Genetic materials
1. A nucleus is composed of protein and a nucleic acid called deoxyribonucleic acid
or DNA.
2. DNA carries the instructions for the proteins that the cell will make.
3. DNA is made of two strands with are twisted together to make a spiral or helix.
4. The two strands are linked together by bases
a. There are four kinds of bases in DNA. They are Adenine (A), Thymine
(T), cytosine (C), and guanine (G). These bases are different sizes are
shapes, so only A will fit next to T and C next to G.
5. DNA is found in the nucleus, but proteins are made in the cytoplasm. A
messenger molecule called ribonucleic acid or (mRNA) copies the instructions
from DNA and then carries them to the ribosomes in the cytoplasm.
3.3 Principles of inheritance
3.3.1 Concept of inheritance
1. Each chromosome has bases arranged along its length in a certain
sequence. This is called the genetic code and determines cell chemistry.
2. A gene is a short section of the genetic code which will determine one
trait.
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3. When a cell divides the DNA is copied and passed on to the next
generation of cells. It is in this why that genetic characteristics are
inherited.
3.3.2 Mendelian inheritance
1. In 1856 a scientist named Gregor Mendel began studying inheritance in
garden pea plants. Mendel studied these plants because he saw that
several traits from the parent plants were showing the offspring and he
wanted to know why.
2. To study the inheritance of garden pea plants, Medel used pure line plants
to perform cross breeding experiments. It the cross breeding experiments
Mendel cross pollinated two pure line plants that express one trait
differently.
a. For example, Mendel crossed one pure line plant with yellow seeds
with another pure line plant having green seeds.
3. Mendel found that all the seeds of the offspring had yellow seeds.
a. It seemed that the green seed trait disappeared but it did not. When
the offspring were cross-pollinated with a pure line green plant,
one in every four offspring had green seeds.
4. To explain these results, Mendel created the first law of inheritance
a. Mendel’s First Law of Inheritance says that during gamete
formation the two factors responsible for the expression of a
particular trait segregate, so that only one factor from each parent
is represented in each gamete.
5. The factors that Mendel wrote about are called genes.
6. Alternative forms of the same gene are called alleles.
a. Sometimes the two alleles present in an organism are identical.
Identical alleles are called homozygous.
b. Sometimes the two alleles are different. When the two alleles are
different they are called heterozygous.
7. The Punnett Square
a. Punnett squares are used to calculated the probabilities of crosses.
i. A cross the is mating between two organisms.
ii. Probability is the fraction of number of chances for an
event over the number of possible events.
b. If an individual expresses a recessive trait it most be homozygous.
c. If an individual expresses a dominant trait is might be
heterozygous or homozygous.
8. Simple Mendelian Traits
a. Although Mendel studied garden pea plants, there are some traits
that follow Mendelian Inheritance. These traits are called Simple
Mendelian Traits.
i. Examples of simple Mendelian traits are:
1. Tongue rolling
a. Non-tongue rollers are homozygous
recessive.
2. Albinism
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a. Homozygous Recessive
3. Sickle-cell anemia
a. Homozygous recessive
4. Color-blindness
a. Homozygous recessive
5. Hemophilia
a. Homozygous recessive
3.3.3 Non-Mendelian inheritance
1. Non-Mendelian inheritance is inheritance which does not follow Mendel’s
law of inheritance.
a. There are two types of non-Mendelian inheritance
i. Sometimes a gene can show incomplete dominance or codominance.
1. Incomplete dominance is the types of nonMendelian inheritance when the heterozygous
genotype produces a unique phenotype.
a. An example of this is when a red flower and
a white flower are crossed, and a pink
flower is produced.
2. Co-Dominance is the type of non-Mendelian
inheritance in which the heterozygous genotype
expresses both phenotypes. Both alleles are
expressed.
a. An example of co-dominance is the roan
coat color in cattle. When a red coat cow is
crossed with a white coat cow, the offspring
have a roan coat, some hairs are white and
some hairs are red.
3.4 Sex determination and inheritance
1. In sexually reproducing organisms there are two sexes or genders; female and
male. The sex of an organism is determined by the sex chromosome.
2. Sex determination is the process by which the sex of an organism is determined.
a. In humans the two sex chromosomes are the X chromosome and the Y
chromosome.
i. The Y chromosome is called the male chromosome and the X
chromosome is called the female chromosome.
ii. Humans have two sex chromosomes. Males have XY and Females
have XX.
1. The female parent only gives the X chromosome, which the
male parent can give an X or Y chromosome.
b. Sex differentiation is the process by which organisms develop into their
respective sex.
i. Sex differentiation is determined by sex hormones. The major sex
hormone in males is testosterone, while in females the major sex
hormone is estrogen.
3. Sex Linkage
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a. Sex linkage is the idea that some genes which are found on the sex
chromosome do not control sex determination.
b. Sex linked genes are genes which are found on the sex chromosome but
do not control sex determination.
c. Sex-linked traits are traits controlled by sex-linked genes.
i. Some sex-linked traits only appear on one of the sex
chromosomes.
d. Examples of sex-linked traits are color-blindness and Hemophilia.
i. Color-blindness and hemophilia are both recessive traits found on
the X chromosome, but not the Y.
4. Sex Influenced Traits
a. Sex influenced Traits are characteristics that are influenced by the sex of
the individual.
i. They are usually used to attract the opposite sex and are common
in males.
1. Examples of sex influenced traits are:
a. Feathers of male peacocks, the red comb on a cock,
a lion’s mane, and the horns of cattle.
3.5 Variation among organisms
1. Variation is the differences that exist between living organisms.
2. No two people on this planet, with the exception of identical twins, are exactly
alike. From 23 chromosomes, meiosis can produce 8,000,000 different gametes!
a. Variation within a species can be caused by two things:
i. It can come from the genes of the organism. These variations are
said to be inherited.
ii. It can come from the environment that it lives in. Variations from
the environment are said to be acquired.
3. Variation within a population falls into two categories:
a. Discontinuous variation is when there are two extreme and no
intermediates. The variation is entire due to the genes present and the
environment has no influence.
i. Examples of discontinuous variation are sex and blood groups.
ii. When grafted, discontinuous variation will not show a clear range
or curve.
b. Continuous variation has intermediates, usually because of environmental
influences.
i. Examples of continuous variation are height, skin color, and
intelligence.
ii. When grafted, continuous variation will show a smooth bell curve.
3.6 Genetic disorders
1. Genetic disorders are caused by mutations.
a. A mutation is a spontaneous change in the genetic material of an
organism.
b. There are two different types of genetic mutations, gene mutations and
chromosome mutations.
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i. Gene mutations occur when DNA is copying itself and the wrong
base is used.
1. This can happen because of a duplication, a deletion, a
substitution, or an inversion.
2. Examples of gene mutations are cancer, hemophilia, and
sickle-cell anemia.
ii. Chromosome mutations occur when there is an addition or loss of
a chromosome, because of unbalanced meiosis. Instead of having
23 chromosomes, the gamete may have 22 or 24. Therefore the
zygote will have 45 or 47.
1. People with Down’s Syndrome have 47 chromosomes.
2. Other chromosome mutations can occur because the sex
chromosomes fail to separate during meiosis.
a. Turner’s syndrome is where a female has a sex
chromosome make up of XO, thus missing an X
chromosome.
b. Klinefelter’s syndrome is caused in males who have
a sex chromosome makeup of XXY. These men are
sterile.
c. Many things can cause mutations. Anything that can cause mutation is
called a mutagen.
i. Examples of mutagens are:
1. Over-exposure to x-rays or certain types of chemicals such
as chlorine gas, mustard gas, mercury, DDT, and other
pesticides.
2. Some organic compounds can also cause mutations such as
food additives, drugs, and the ingredients in tobacco
smoke.
3.7 Application of genetics
1. Breeding
2. Genetically modified food
3. Genetic engineering
4. Cloning
4. Evolution
4.1 Concept of organic evolution
1. Organic evolution is the theory that present day life forms are different from
those which first appeared on Earth. These differences are due to changes
over generations, however it means we have all decended from a common
ancestor.
2. Evolution is the sequence of gradual changes over millions of years in which
new species may be produced.
4.2 Theories of the origin of life
1. When the earth was created by the Big Bang, there was no life on earth. The
theories for the origin of life, or how life began, are as follows:
a. Steady state theory, which says there was always life on earth.
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b. Creation theory, which suggests that earth and all its organisms were
created by God.
c. Cosmozian (Panspermian) Theory, which says that life from
somewhere else in the universe arrived here and continued.
d. Spontaneous generation theory, which says that living things arose
from non-living material.
e. Organic evolution theory, which states that life came from the
evolution of simple organic molecules into more complex molecules
which then evolved into cells.
i. The organic evolution theory is the most widely accepted
theory for the origin of life.
4.3 Theories of organic evolution
4.3.1 Lamarckism
1. In 1801 French scientist Jean Baptiste Lamark proposed a theory
for evolution through the inheritence of acquired characteristics.
a. This theory had two main points.
i. The first was the belief that if a trait was useful to
an organism it would be passed on and not useful
traits would be lost.
ii. The second point was that traits that were modified
or changed during an organisms life time could be
passed on to the offspring. For example, if a giraffe
stretches there neck to reach leaves, then the
offspring will be born with longer necks, and after
many generations the giraffe will have long necks.
b. However, we know from the study of genetics that this can
not be true. Offspring inherit the genes of their parents, not
traits they acquire during their lifetime.
2. Problems with Lamark’s Theory of Inheritence of Acquired
Characteristics
a. Features aquired by the individual during its lifetime
cannot be inherited by its offspring
b. The theory only explains about enviroemtnal changes, not
genetic changes
c. The theory can not be applied to vestigial organs (organs
that have no use, like the appendix)
4.3.2 Darwinism
1. Charles Darwin was an English biologist who wanted to find the
origin of life. He sailed around the world for five years collecting
specimens and observing different organisms. He then wrote a
book called the Origin of Species, which explains his theory of
natural selection.
2. During his observations, Darwin developed his theory of natural
selection, which suggests that the best adapted orgnaisms are
selected to pass on the characterists to the next generation.
a. Adapt- to live successfully in an environment
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3. The Theory of Natural Selection
a. Variation
i. Darwin noticed that organisms show a number of
variations, or differences. These variations are
caused by mutations, which are a mistake during the
copying of DNA, and cause individuals to be
different. Some variations may be better adapt
some organisms to their environment than other
organisms.
b. Over production
i. Most organisms make more offspring than will
actually survive to adulthood.
c. Struggle for Exsistence
i. Because populations are not always increasing,
there must be competition for survival between
organisms.
d. Survival of the fittest
i. Only the orgnaisms which are the most adapt to
their enviroment will survive.
e. Advantagous characteristics are passed on to offspring
i. Only these well adapted organisms will be able to
reproduce successfully, and will pass on their
helpful characteristics to their offspring.
f. Gradual Change
i. Over a long period of time the population will lose
all the poorly adapted organisms and the population
will become more adapted to its enviroment.
4. Although Darwin never saw evolution occur, scientists have
observed many example of natural selection.
a. One of the most famous examples was the observation of
the peppered moth in England.
i. The pepperd moth, Biston betularia, lives in England
and spends most of its time resting on the trunks of
trees. They have speckled or spotted wings which
help it camoflage on lichen covered tree trunks. Up
until 1849, there were mostly light colored
peppered moths, because the darker variation could
eaily be seen on the lichen covered tree trunks. But
by 1900, 98% of the moths were black.
ii. This is because in the late 1800’s in England the
Industrial Revolution began. Factories increase and
began producing soot, which made the trees darker.
Therefore, the dark colored moths were more adapt
to their enviroment and able to camoflague with the
darkened trees better than the white moths.
5. The Problems with Darwin’s Theory
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a. The theory of Natural Selection does not explain the origin
of new characteristics
b. The theory does not explain the presence of vestigial
organs (organs that have no use).
4.4 Evidence of organic evolution
1. Evolution has occurred over millions of years, and therefore is
difficult to prove through short term experiments. Therefore
scientists use fossil records, comparative anatomy, comparative
embryology, and comparative physiology to prove the theory of
organic evolution.
2. Fossils are the preserved remains of organisms that lived long ago
and are usually found in rock layers. By studying fossils and the
time period during which the animal lived, scientists can see
changes that have occurred and present day organisms that are
related.
3. Comparative anatomy is the
5. HIV, AIDs, and STIs
5.1 Relationships between HIV, AIDs, and STIs
1. HIV stands for Human Immunodeficiency virus
2. AIDS stands for Acquired Immunodeficiency Syndrome.
a. AIDS is caused by the virus HIV.
b. If you are infected with HIV your body’s immune system gets very
weak and can not fight other infections.
c. To understand HIV, we must understand the immune system.
d. Our blood has hundreds of cells. Some of these cells are called white
blood cells. White blood cells help fight infections. Some of these
white blood cells are called “T-helper” cells.
e. HIV attacks “T-helper” cells. HIV enters the T Helper cells and makes
copies of itself. As HIV attacks T Helper cells, the body is not about to
fight off infection and the person with HIV becomes sick from other
illnesses.
f. When a persons T Helper cells reach a specific low level where their
body can no longer fight serious infections, they are diagnosed with
AIDS.
5.2 Management and control of HIV/AIDs and STIs
1. Modes of Transmission
a. A person can only contract HIV from another person through
direct contact with blood, brest milk, or seminal fluids (sperm
and vaginal fluid)
b. The most common modes of transmission are contact with
blood, using unclean needles for injections, sexual intercourse,
and mother to child through breast feeding.
2. Ways of Reducing STDs
e. Abstinence from sexual intercourse
f. Being faithful to one partner
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g. Being tested for STD and HIV
h. Using a condom
i. Not sharing needles or medical instruments without cleaning them
3. Using a Condom
j. Check that the condom is not expired.
k. Make sure there are no tears or holes in condom packet.
l. Open the packet without ripping condom.
m. Take out the condom and place on penis, make sure the ring is on the
outside.
n. Pinch the top of the condom to remove any air.
o. Roll condom down shaft of penis.
p. After sex, hold condom when coming out of the vagina so it does not
come off.
4. Testing and treatment
a. The only way to find out is someone is HIV positive is through a blood
test.
b. It may take up to three months after a person has been infected for a
HIV test to show positive. This is what we call a window period and is
essential that a person get tested again after the three months
window period to be sure they are HIV negative.
c. If someone is HIV positive they can began taken drugs called ARVs
which slow down the spread of the virus. ARVs can not cure HIV, but
they can provide a longer and healthier life for the infected person.
d. If a person has HIV they must try to have a healthy life style to keep
their body strong. They should eat lots of protein and vitamins,
exercise, and get lots of sleep.
5.3 Voluntary counseling and testing (VCT)
1. Voluntary counseling and testing (VCT) is a program which educates the
public about HIV/AIDS and provides free testing. If someone tests positive
for HIV they are given counseling.
2. Testing is always voluntary. This means it is your decision to be tested for
HIV. You can not be forced or required to be tested.
3. To test for HIV, the blood is tested for HIV antibodies. If antibodies are
present in the blood, then HIV has entered the body and that person is said to
be HIV positive. Because of the window period, a person should be tested
twice in three months to confirm they are HIV negative.
4. After testing, counseling is provided on how to treat yourself physically and
emotionally if you have HIV. All results and counseling sessions are kept
confidential or secret.
5. VCT is important because it helps prevent the spread of HIV, reduce stigma
about the disease, support those living with HIV, and education the
population about the need to be tested and practice safe sex.
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