1
Princeton College
9/33 Olatunde Onimole Street, Surulere, Lagos, Nigeria
admin@princeton-schools.com/ www. Princeton-schools.info
01-8137135, 01-4336486, 01-7741487, 08034079557
BIOLOGY
SCHEME OF WORK
&
LECTURE NOTES
FOR
GRADE 11
2ND TERM
(2023 – 2024 session)
INSTRUCTOR: Mr. Gabriel Isichei
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
2
WEEK
1
TOPIC
EXCRETORY SYSTEM IN LIVING
THINGS
•
•
•
•
2
Definition of excretion in living things
Types of excretory systems in organisms
Types of excretory system in organisms
Excretory mechanisms in some organisms
like; insects, flatworms, pices, mammals
and flowering plants
TISSUES AND SUPPORTING SYSTEM
IN ANIMALS (The Vertebrate Skeletal
System)
• Definition of the skeletal system and the
vertebrate skeletal system
• Biological significance of the vertebrate
skeletal system
• Types of skeletal systems in organisms
e.g. exoskeleton & endoskeleton
• Forms of skeleton in living things e.g.
bones, cartilages, chitin and hydrostatics
3
CATEGORIES OF THE MAMMALIAN
SKELETON
•
•
4
The axial skeleton and its components
The appendicular skeleton and its
components
JOINTS
•
•
•
•
Definition and types of joints
Functions of joint
Mechanism of joint movement
Practical on bones and joints
LEARNING OBJECTIVES
At the end of the lesson, the students should be
able to:
• Define excretion and state its importance in living
organisms
• Mention some common organisms with their
excretory systems
• Describe the mechanism of excretion in insects,
flatworms and flowering plants
At the end of the lesson, the students should be
able to:
•
•
•
Define and explain the functions of skeleton
to mammals
Distinguish between bones and cartilages in
a table
Describe the forms and types of skeletons
with suitable examples
At the end of the lesson, the students should be
able to:
•
•
Distinguish between the axial and the
appendicular skeleton
Mention the bones of the axial and
appendicular skeleton
At the end of the lesson, the students should be
able to:
•
•
•
•
•
Define a joint.
Mention different joints found on the human
skeleton and name their respective bones.
Group all joints into immovable and movable
joints.
State the major functions of the joints.
Mention some common diseases of the joint.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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5
SUPPORTIVE TISSUES IN PLANTS
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•
•
•
6
Types of plant supportive tissues
Features of plant supportive tissues
Functions of plant supportive tissues
Practical on sectioning
DIGESTIVE SYSTEM
• Describe the digestive system and define
digestion of food
• Alimentary tract of invertebrates and
vertebrates
At the end of the lesson, the students should be
able to:
•
•
•
At the end of the lesson, the students should be
able to:
•
•
• Practical on dissection
•
7
FEEDING HABITS
• Categories and mechanisms e.g., filter
feeding, fluid feeders, piercing and
sucking.
• Modification in organisms to reflect their
feeding habits e.g., feeding in amoeba,
hydra and man
• Adaptation of dentition to mode of
nutrition in herbivores, carnivores and
omnivores.
8
TRANSPORT SYSTEM
• Need for transportation and materials for
•
transportation e.g. food, oxygen and
wastes products
Media of transportation e.g. cytoplasm
lymph and blood
• Blood and lymph composition and
Name and describe plant supportive tissues
State the functions of a named plant
supportive tissue
State the characteristics of parenchyma,
collenchyma and sclerenchyma
Describe the digestive system of earthworm,
cockroach, grasshopper, tapeworm, birds
and mammals (rat)
State the similarities and differences
between the digestive systems of
grasshopper and birds
Draw and label correctly the alimentary
canal of bird and man
At the end of the lesson, the students should be
able to:
• Enumerate the various feeding habits in
•
•
•
organisms
Describe the mechanism and modification of
feeding in mosquito larva, tapeworm,
butterfly, mucor, man, amoeba and hydra
Describe the types, structures of tooth
herbivores, carnivores and omnivores
Explain how the teeth of rabbit and dogs are
adapted to suit their mode of feeding
At the end of the lesson, the students should be
able to:
• Highlight the need for transportation I
•
•
organisms
List the materials and media of
transportation in organisms
Explain the composition, structure and
function of the mammalian blood
function
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
4
9
CIRCULATORY SYSTEM IN
MAMMALS
•
•
•
10
Structure of the mammalian heart,
arteries, veins and capillaries
Types of circulation and mechanism of
circulation e.g. double circulation
Open and closed, single and double
circulation
MECHANISM OF TRANSPORT IN
HIGHER PLANTS
• Explanation of absorption and transport of
At the end of the lesson, the students should be
able to:
• Draw and label the structure of a mammalian
heart, arteries, veins and capillaries
• Explain the singe ad double blood circulation
• Distinguish between arteries and veins
At the end of the lesson, the students should be
able to:
• Explain the mechanism of transport in higher
plants
water and mineral salts
• Explanation of transpiration
• Explanation of translocation
11
REPRODUCTIVE SYSTEM IN
VERTEBRATES
• Structure and function of the male and
female reproductive system
• Differences between the male and female
reproductive system
At the end of the lesson, the students should be
able to:
• Compare reproduction in vertebrates on mode of
fertilization, zygote growth, feeding of embryo
and parental care
• Describe with examples, the reproductive
behaviours in animals
• Structure of the male and female
reproductive gametes e.g., sperm and egg
• The process of fertilization and the
development of embryo
• Reproductive behaviors in Pisces,
Amphibians, Birds, Reptiles and
Mammals
12
Revision / Examination
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
5
Week: 1
Topic:
EXCRETORY SYSTEM IN LIVING THINGS
Learning objectives:
At the end of the lesson, the students should be able to:
• Define excretion and state its importance in living organisms
• Mention some common organisms with their excretory systems
• Describe the mechanism of excretion in insects, flatworms and flowering plants
Reference materials:
•
Lam Peng Kwan, Eric Y.K. Lam and Julie O. Ofoefunna (2022)
NEW SYSTEM BIOLOGY FOR SENIOR SECONDARY SCHOOLS,
Published by: FIRST PUBLISHERS, Plot 5/7A, Odofin park estate,
Ijesha bus stop, oshodi Apapa expressway, Lagos, Nigeria.
ISBN: 978 978 08 4232 1
•
DG Mackean and Dave Hayward
CAMBRIDGE IGCSE ™ BIOLOGY (Fourth Edition) 2022
Published by: HODDER EDUCATION, 50 Victoria Embankment,
London EC4Y ODZ. www.hoddereducation.com
ISBN: 9781 3983 1045 2
New words:
Learn these words:
Excretion, metabolism, toxic, metabolites, kidney, lungs, gills, nitrogenous compounds, urea, uric acid,
ammonia, urine
Learn more:
•
•
•
Excretion in plants https://youtu.be/J0hjnC14uMM
Excretory system in earthworm https://youtu.be/Gsmef_HmTUU
The kidneys as excretory organs https://youtu.be/c05mJaeIQuY
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
6
Content:
Definition:
Excretion is defined as the removal of toxic
metabolic wastes from the body of an
organisms.
Excreted materials are referred to as
byproducts of metabolic reactions or
metabolism. Therefore, it is important to
remove these wastes, because the
accumulation of them can be toxic to the
cells of the body and hinder their functions.
Examples of metabolic wastes includes:
carbon dioxide (CO2), oxygen (O2) in plants
during photosynthesis, nitrogenous
compounds like urea (CH4N2O), ammonia,
(NH3), uric acid (C5H4N4O3).
Importance of Excretion in
organisms
Through excretion organisms:
• control osmotic pressure, which is
the balance between inorganic ions
and water.
• It helps to maintain acid-base
balance.
• The process of excretion helps to
promotes homeostasis, which is the
maintenance of the organism's
internal environment.
The following are some excretory systems
and their mechanisms in some common
organism.
The contractile vacuole system in
protozoa
The contractile vacuole is a membrane bounded
organelle found fresh water protists like
amoeba, paramecium, euglena etc. the
contractile vacuole helps to expel excess water
in fresh water protists to prevent bursting of
the cell also known as cytolysis. It is the water
regulator of the ell.
The cytoplasm of the cell has a higher solute
concentration than the water surrounding
them, so water molecules move into the cell via
osmosis. Excess water in the cytoplasm
gradually enters the contractile vacuole until
they are fully filled with water, and ions are
pumped back into the cytoplasm.
Subsequently, the vacuole contracts and water
are discharged through a pore n the cell
membrane into its exterior. The discharged
water is almost free of ions.
Excretory systems in different
organisms and their mechanisms
Different types of organisms possess
different organs for excretion due to their
environment and in relation to their pattern
of adaptation.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
7
The Flame cell system
in flatworm
The Malpighian tubule system in
insects
A flame cell is a hollow bulb shaped cell
lined by tufts of cilia and flagella move
liquid. In some invertebrates such as
flatworms, a hollow excretory cell that has a
tuft of projections cilia resembling hairs,
whose movement serves to force out waste
products from the organism.
The Malpighian tubule system is a type of
excretory and osmoregulatory system
found in some insects, myriapods,
arachnids and tardigrades.
Malpighian tubules are found at the
junction of midgut and hindgut in insects
and other arthropods. It plays a major role
in excretion and osmoregulation.
The Nephridia system in annelids
and arthropods
The Mammalian Urinary System
The nephridia are excretory tubules which
help to remove waste materials like the
kidneys. They are present in annelids and
arthropods. The nephridia help to excrete
nitrogenous wastes like urea. As the waste
materials move along the tube, some useful
substances like glucose and salts are
reabsorbed back into the blood circulation
through the tube wall.
The mammalian urinary system includes the
kidney, ureters, bladder and the urethra.
The kidneys ae the major organs for
excretion in mammals. They are
paired organ whose functions include
removing waste products from the blood
and regulating the amount of fluid in the
body. The basic units of the kidneys are
microscopically thin structures called
nephrons, which filter the blood and cause
wastes to be removed in the form of urine.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
8
Mechanism of excretion in some
organisms
Flatworms
In flatworms, excretion is accomplished by
the epithelial lining of the gut, by the body
wall, by exocytosis of vesicles, and by
protonephridia. Osmoregulation in
flatworms has not been demonstrated
conclusively, but is thought to take place in
the protonephridia.
Insects
The processes of excretion in insects
are carried out by the organs of the insect
gut. These include the midgut, the
Malpighian tubules, and the structures in
the hindgut, namely the ileum and rectum.
The midgut is a tubular epithelium.
In plants
Evaluation
1. Define excretion and state its importance in
living organisms
2. Mention some common organisms with their
excretory systems, organs and excretory
products.
3. Describe the mechanism of excretion in
insects, flatworms and flowering plants.
Assignment
Attempt any TWO (2) question
1. Explain the functions of the Nephron and
Bowman’s capsule
2. List and briefly explain the major processes
of urine formation in man.
3. Define and explain the concept
“Homeostasis” and mention any three (3)
homeostatic processes in man.
4. Explain the major functions of the nephrons
Excretion is carried out in the plants in the
following ways: The gaseous wastes,
oxygen, carbon dioxide, and water vapor
are removed through the stomata of leaves
and lenticels of stems. Some waste
products collect in the leaves and bark of
trees. When the leaves and bark are shed,
the wastes are eliminated. Plants also
excrete during photosynthesis, guttation and
transpiration.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
9
Week 2:
Topic:
TISSUES AND SUPPORTING SYSTEM IN ANIMALS
(The Vertebrate Skeletal System)
Learning objectives:
At the end of the lesson, the students should be able to:
• Define and explain the functions of skeleton to mammals
• Distinguish between bones and cartilages in a table
• Describe the forms and types of skeletons with suitable examples
Reference materials:
New words:
•
Lam Peng Kwan, Eric Y.K. Lam and Julie O. Ofoefunna (2022)
NEW SYSTEM BIOLOGY FOR SENIOR SECONDARY SCHOOLS,
Published by: FIRST PUBLISHERS, Plot 5/7A, Odofin park estate,
Ijesha bus stop, oshodi Apapa expressway, Lagos, Nigeria.
ISBN: 978 978 08 4232 1
•
DG Mackean and Dave Hayward
CAMBRIDGE IGCSE ™ BIOLOGY (Fourth Edition) 2022
Published by: HODDER EDUCATION, 50 Victoria Embankment,
London EC4Y ODZ. www.hoddereducation.com
ISBN: 9781 3983 1045 2
Learn these words:
Skeleton, cartilage, ligament, tendon, bone, chitin, exoskeleton, endoskeleton, hydrostatic skeleton and
ossification.
Learn more:
•
•
The human skeletal system https://youtu.be/38MsEkhdECM
Bone disorders https://youtu.be/UkPu5ta_M2E
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
10
Content:
Definition
The skeletal system is your body's central
framework. It consists of bones and connective
tissue, including cartilage, tendons, and
ligaments which forms a skeleton.
The skeleton of other invertebrates like insects,
worms etc., may not be made of bones, but
they are structures that provides support, gives
protection, or maintains shape in an
invertebrate animal, e.g., the shell of a snail or
the cuticle of a crab.
The skeleton is the rigid framework of
interconnected bones and cartilage that
protects and supports the internal organs and
provides attachment for muscles in humans and
other vertebrate animals
Biological significance of the
vertebrate skeletal system
In humans, the skeletal system is made up of
about 300 bones, but becomes lesser about 206
bones during ossification.
1) They act as body frame work, giving
shape to the body.
2) They protect the body’s vital organs like
brain, heart and lungs.
3) They act as site for new red blood
production e.g., bone marrow
4) They help to store minerals like calcium
Types of skeletal systems in
organisms
A skeletal system is necessary to support the
body, protect internal organs, and allow for the
movement of an organism. There are three
different skeleton designs that provide
organisms these functions. They are:
• Hydrostatic skeleton
• Exoskeleton
• Endoskeleton
Hydrostatic skeleton
It is also referred to as fluid skeleton. It is found
in soft bodied animals like cnidarians (jelly fish),
flatworm (planaria) annelids, (earthworm) and
nematodes (round worms), whose body cavity
is filled with fluid.
Their shape is maintained by the hydrostatic
pressure together with the muscular
contraction of the body, maintains the shape of
soft bodied organisms.
Annelids like earthworms have the additional
ability to move by peristalsis, which is a series
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
11
of rhythmic waves of muscle contractions that
progresses from one of the body to another end
of its body.
Skeletal materials in organisms
The following are materials that make up the
skeletal system in organisms:
Bone:
They are the major hard structures forming
the skeleton in vertebrate animals. They are
principally composed of collagen fiber and
calcium phosphate.
Exoskeleton
Exoskeleton is a hard covering on the
outside of organisms that provides support
and protection. As found in crustaceans,
insects, turtles, molluscs and armadillos.
The major component of exoskeleton is
chitin. The chitin is a tough semitransparent
substance that forms part of the protective
outer casing cuticle of some insects and other
arthropods, and the cell walls of some fungi.
Chitin is covered by a thin waxy layer called the
cuticle.
Endoskeleton
This is a skeleton made up of bones, cartilages
and ligaments. It is the skeleton found mostly in
vertebrates like fishes, frogs, lizards, birds,
mammals and man. Bones of different shapes
and sizes forms the endoskeleton.
Cartilage:
They are strong, tough connective elastic tissue
that protects our joints and bones. They can be
found in the nose, throat, ear and in other parts
of the body, which forms most of the skeleton
in infancy and changing to bone during growth.
In the skeletal system, they are also found inbetween bones of the vertebra column disc and
also at joints. They help to absorb shock and
prevent friction between bones.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
12
Ligament:
It is a tough elastic tissue or band of tough
fibrous tissue that connects bones or cartilage
at a joint. They help to attach bone to bone in a
joint. They also support organs, muscles and
other body parts during movement.
Chitin:
They are tough protective structures acting as
outer coverings which forms cuticle found in
arthropods, crustaceans and molluscs. They also
form the cell walls of some fungi. They consist
majorly of polysaccharides which is the major
constituents of exoskeleton in arthropods.
Bones of the human
body
Other names
Cranium
Maxilla
Mandible
Clavicle
Scapula
Sternum
Ribs
Humerus
Radius and ulna
Incus, malleus and staple
Carpals and Metacarpals
Phalanges
Vertebra column
Pelvic
Femur
Patella
Tibia and fibula
Tarsals and Metatarsals
Phalanges
Skull
Upper jaw bone
Lower jaw bone
Collar bone
Shoulder blade
Chest bone
Slender bones
Upper arm bone
Lower arm bones
Ear bones
Wrist bones
Finger bones of the hand
Back bone
Waist bone
Upper leg bone
Knee cap
Lower leg bone
Foot bones
Finger bones of the leg
Evaluation
1.
Explain the following words: skeleton, cartilage,
ligament, tendon, bone, chitin, exoskeleton,
endoskeleton, hydrostatic skeleton and
ossification.
2.
List different types of skeletal materials and state
how they contribute to strength and flexibility.
Assignment
Attempt any two (2) questions
Important bones of the human
skeletal
The human skeletal system is made up of bones
of different shapes and sizes. They are also
located at various parts of the body in relation
to their function. They include:
a.
List and explain the three (3) basic cartilages in
vertebrates and their location
b.
Describe cartilaginous fishes with suitable
common examples.
c. Describe the bone and mention the cells that
make up the bone.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
13
Week: 3
Topic:
CARTEGORIES OF THE MAMMALIAN SKELETON
Learning objectives:
At the end of the lesson, the students should be able to:
• Describe the axial skeleton and the appendicular skeleton.
• Mention the bones of the axial and appendicular skeleton.
• Distinguish between the axial and the appendicular skeleton.
• Name the different bones of the vertebra column and mention their number of bones.
Reference materials:
New words:
•
Lam Peng Kwan, Eric Y.K. Lam and Julie O. Ofoefunna (2022)
NEW SYSTEM BIOLOGY FOR SENIOR SECONDARY SCHOOLS,
Published by: FIRST PUBLISHERS, Plot 5/7A, Odofin park estate,
Ijesha bus stop, oshodi Apapa expressway, Lagos, Nigeria.
ISBN: 978 978 08 4232 1
•
DG Mackean and Dave Hayward
CAMBRIDGE IGCSE ™ BIOLOGY (Fourth Edition) 2022
Published by: HODDER EDUCATION, 50 Victoria Embankment,
London EC4Y ODZ. www.hoddereducation.com
ISBN: 9781 3983 1045 2
Learn these words: axial skeleton, appendicular skeleton, vertebrae column, cervical,
thoracic, lumbar, caudal and sacral vertebrae.
Learn more:
•
•
The human skeletal system https://youtu.be/38MsEkhdECM
Supportive tissues in plants https://youtu.be/aU--ACCi_BQ
https://youtu.be/xWUuDM1g4Rg
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
14
Content:
The Mammalian skeletal system and
its components
Description:
The mammalian skeleton is composed of
the skull, spine, rib cage, and appendicular
skeleton (limbs and their attachments to the
trunk). The skull is composed of the cranium
(braincase) and the mandible (jawbone). The
spine, or vertebral column, is made up of
the cervical (neck), thoracic (chest), lumbar
(lower back), sacrum (pelvis), and coccyx
(tailbone) regions.
The rib cage, also known as the thorax, is
composed of the ribs and the sternum
(breastbone). The appendicular skeleton is
made up of the bones of the limbs,
including the humerus (upper arm), radius
and ulna (forearm), carpals (wrist),
metacarpals (hand), phalanges (fingers),
femur (thigh), tibia and fibula (lower leg),
tarsals (ankle), metatarsals (foot), and
phalanges (toes).
phalanges, while the bones of the feet
include the tarsals, metatarsals, and
phalanges.
In addition to the bones, the mammalian
skeleton also includes cartilage, tendons,
and ligaments, which work together to
support the bones, allow for movement,
and provide stability and strength to the
skeletal system.
Finally, the skeletal system plays an
important role in the production and
storage of blood cells, which are produced
within the bone marrow and stored in the
bones. This makes the skeletal system an
important part of the body's overall health
and well-being.
In addition to the bones of the limbs, the
appendicular skeleton also includes the
scapula (shoulder blade) and the clavicle
(collarbone). These bones, along with the
bones of the arms and legs, make up the
skeletal framework for movement and
support for the body. The bones of the
appendicular skeleton are connected to the
bones of the axial skeleton through joints,
which allow for movement and flexibility.
The skeletal system also includes the bones of
the hands and feet, which are specialized for
grasping and balance. The bones of the
hands include the carpals, metacarpals, and
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Categories of the skeletal system in mammals
Description:
The mammalian skeleton can be divided into two main categories: the axial skeleton and the
appendicular skeleton.
The Axial skeleton
The axial skeleton is made up of the bones that form the central axis of the body, including the
skull, vertebral column (spine), and rib cage. These bones provide support and protection for
the brain, spinal cord, and vital organs.
The axial skeleton is the part of the mammalian skeleton that forms the central axis of the
body, providing support and protection for the brain, spinal cord, and vital organs. It includes
the following bones:
•
•
•
Cranium (braincase)
✓ Facial bones (including the mandible, or jawbone)
Vertebral Column (spine):
✓ Cervical vertebrae (neck)
✓ Thoracic vertebrae (chest)
✓ Lumbar vertebrae (lower back)
✓ Sacrum (pelvis)
✓ Coccyx (tailbone)
Rib Cage:
✓ Ribs
✓ Sternum (breastbone)
The axial skeleton also includes the hyoid bone, which is located in the neck and serves as a support
structure for the tongue and larynx.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Biological functions
a) The bones of the axial skeleton provide support and protection for the body's vital
organs e.g. the cranium, rib cage and vertebra column
b) They allowing the movement of the head and neck e.g., axis and atlas
c) It allows the movement and flexibility of the trunk.
The Appendicular skeleton
The appendicular skeleton is made up of the bones of the limbs and their attachments to the
trunk. This includes the bones of the arms and legs, such as the humerus, radius, ulna, femur,
tibia, and fibula, as well as the bones of the hands and feet. The appendicular skeleton also
includes the scapula and clavicle, which are responsible for movement and support of the
upper body.
The appendicular skeleton is the part of the mammalian skeleton that is made up of the bones
of the limbs and their attachments to the trunk. It includes the bones of the arms and legs, as
well as the bones of the hands and feet. It is made up of the following bones:
Upper Limb:
•
•
•
•
•
•
•
Scapula (shoulder blade)
Clavicle (collarbone)
Humerus (upper arm bone)
Radius and Ulna (forearm bones)
Carpals (wrist bones)
Metacarpals (hand bones)
Phalanges (finger bones)
Lower Limb:
▪ Pelvis (hip bone)
▪ Femur (thigh bone)
▪ Tibia and Fibula (lower leg bones)
▪ Tarsals (ankle bones)
▪ Metatarsals (foot bones)
▪ Phalanges (toe bones)
These bones are connected to the bones of the axial skeleton through joints, which allow for movement
and flexibility. The appendicular skeleton is responsible for movement, support and balance.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
17
Skeleton
Axial Skeleton
Functions
1. Support and protection for the brain and spinal cord.
2. Support and protection for the vital organs.
3. Movement of the head and neck.
4. Support and protection for the spinal cord.
5. Movement and flexibility of the trunk.
1. Movement and support of the upper and lower body.
2. Support and balance.
3. Protection of the joints.
4. Production and storage of blood cells in the bone marrow.
Appendicular Skeleton 5. Attachment point for muscles and tendons.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
18
The Vertebra column
The vertebral column, also known as the spine or backbone, is a series of bones that runs
vertically along the posterior aspect of the body. It is made up of 33 individual bones called
vertebrae, which are stacked on top of each other. It is divided in five sections: cervical,
thoracic, lumbar, sacral and coccyx.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
19
Biological functions
•
•
•
The vertebral column provides structural support for the body
it protects the spinal cord, which runs through a hollow channel in the center of the
column.
It also allows for movement, such as bending and twisting.
Section
Type of Vertebrae
Location
Cervical
Cervical vertebrae
Neck
Thoracic
Thoracic vertebrae
Lumbar
Function
Number of
Vertebrae
Support head and allow for head movement
7
Upper back
Connect the rib cage to the spine
12
Lumbar vertebrae
Lower back
Support the upper body and allow for trunk
movement
5
Sacral
Sacral vertebrae
Pelvis
Connect the spine to the pelvis and support the
weight of the upper body
1 (fused)
Coccyx
Coccygeal vertebrae
Tailbone
Anchor muscles and ligaments
4 (fused)
Evaluation:
• Describe the axial skeleton and the appendicular skeleton.
• Mention the bones of the axial and appendicular skeleton.
• Distinguish between the axial and the appendicular skeleton.
• Name the different bones of the vertebra column and mention their number of bones.
Assignment:
Attempt any ONE (1) question
1. Explain how these functions of skeleton in animals like protection, support, locomotion, and respiratory
movement are performed in relation to the adaptation of the animal.
2. Describe the different types of supportive tissues in plants, with their basic functions. Diagrams are
inclusive.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
20
Week: 4
JOINTS
Topic:
Learning objectives:
At the end of the lesson, the students should be able to:
• Define a joint.
• Mention different joints found on the human skeleton and name their respective bones.
• Group all joints into immovable and movable joints.
• State the major functions of the joints.
• Mention some common joint diseases and their major causes.
Reference materials:
New words:
•
Lam Peng Kwan, Eric Y.K. Lam and Julie O. Ofoefunna (2022)
NEW SYSTEM BIOLOGY FOR SENIOR SECONDARY SCHOOLS,
Published by: FIRST PUBLISHERS, Plot 5/7A, Odofin park estate,
Ijesha bus stop, oshodi Apapa expressway, Lagos, Nigeria.
ISBN: 978 978 08 4232 1
•
DG Mackean and Dave Hayward
CAMBRIDGE IGCSE ™ BIOLOGY (Fourth Edition) 2022
Published by: HODDER EDUCATION, 50 Victoria Embankment,
London EC4Y ODZ. www.hoddereducation.com
ISBN: 9781 3983 1045 2
Learn these words:
Suture joint, Hinge joint, Ball and socket joint, Gliding joint, Pivot joint, Pectoral girdles, Pelvic girdles,
forelimbs, hindlimbs
Learn more:
•
•
The joints https://youtu.be/0cYal_hitz4
Diseases of the joint https://youtu.be/Bz78_63OiR4
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
21
Content:
Definition
Joints are the places in the body where two or more bones meet to allow movement and provide support
for the body. Joints define the motion f the body.
There are several different types of joints, including immovable joints (such as the skull), slightly
movable joints (such as the spine), and freely movable joints (such as the knee and elbow). Joints can be
classified based on the type of tissue that holds the bones together, including fibrous, cartilaginous, and
synovial joints. Injuries or diseases of the joints, such as arthritis, can cause pain and limit movement.
Bone
Cartilage
Synovial membrane and synovial fluid
Joints play several important roles in the body, including:
1. Movement: Joints allow for movement of the body, including flexion, extension, rotation, and
more complex movements such as grasping and walking.
2. Support: Joints provide support for the body by holding bones together and allowing for weight
bearing.
3. Stability: Joints help to stabilize the body and maintain balance.
4. Shock absorption: Joints act as shock absorbers, helping to distribute and dissipate forces that
are placed on the body.
5. Protection: Joints protect the bones and surrounding structures by limiting the range of motion
and preventing excessive movement that could lead to injury.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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6. Lubrication: Some joints, like synovial joints, have a lubricating fluid that reduces friction
between the bones and allows for smooth movement.
7. Sensation: Joints have receptors that detect changes in position, movement and force, this
information is sent to the brain and is used to control muscle activity and balance.
Overall, joints play a vital role in allowing for movement and supporting the body, and any dysfunction
or injury to the joints can significantly impact a person's ability to move and perform daily activities.
Types of Joints
There are several different types of joints in the human body, including:
1. Suture joints: These joints are connected by fibrous tissue, such as tendons or ligaments. They
are typically immovable or only slightly movable, such as the sutures in the skull.
2. Ball-and-socket joints: These joints have a round surface of one bone that fits into a cuplike
depression of another bone. These joints allow for movement in many directions, such as the
shoulder and hip joint.
3. Hinge joints: These joints allow for movement in one direction, such as the elbow and knee
joints.
4. Pivot joints: These joints allow for rotational movement, such as the joint between the first and
second cervical vertebrae in the neck.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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5. Gliding and sliding joints: These joints allow bones to move over each other. They are
found at the wrist, ankle, carpals, metacarpals, tarsals and metatarsals bones.
Common Joint Diseases
Some common diseases of the joints include osteoarthritis, rheumatoid arthritis, gout, and lupus.
•
Osteoarthritis is a degenerative condition that occurs when the cartilage between joints wears
down, causing pain, stiffness, and limited movement. It is most commonly found in the hips,
knees, and hands and is more common in older adults.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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•
Rheumatoid arthritis is an autoimmune disorder that causes inflammation in the joints,
resulting in pain, stiffness, and difficulty moving. It can also affect other organs in the
body.
•
Gout is a type of arthritis caused by the buildup of uric acid crystals in the joints, leading
to sudden, severe attacks of pain and swelling.
•
Lupus is a chronic autoimmune disorder that can cause inflammation and damage to
various parts of the body, including the joints.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Causes of Joint disorders
The causes of these diseases can be different, but some include, genetics, age, injury, infection, and
lifestyle factors such as obesity and smoking.
Disease
Causes
Remedies
Osteoarthritis
Wear and tear on joint due to
age, injury, or obesity
Exercise, weight management, pain medication, physical
therapy
Rheumatoid
arthritis
Autoimmune disorder
Medications to reduce inflammation and slow disease
progression, physical therapy
Gout
Buildup of uric acid crystals in
joints
Medications to reduce uric acid levels, pain management,
lifestyle changes such as diet and exercise
Lupus
Autoimmune disorder
Medications to reduce inflammation and slow disease
progression, physical therapy
Evaluation:
•
•
•
•
•
Define a joint.
Mention different joints found on the human skeleton and name their respective bones.
Group all joints into immovable and movable joints.
State the major functions of the joints.
Mention some common joint diseases and their major causes.
Assignment:
Attempt any ONE question only.
1. Draw the skeletal system of man and label only the joints found.
2. Draw the skeletal system of a bird and label the joints found.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Week: 5
SUPPORTIVE TISSUES IN PLANTS
Topic:
Learning objectives:
At the end of the lesson, the students should be able to:
a) Name and describe plant supportive tissues
b) State the functions of a named plant supportive tissue
c) State the characteristics of parenchyma, collenchyma and sclerenchyma
Reference materials:
New words:
•
Lam Peng Kwan, Eric Y.K. Lam and Julie O. Ofoefunna (2022)
NEW SYSTEM BIOLOGY FOR SENIOR SECONDARY SCHOOLS,
Published by: FIRST PUBLISHERS, Plot 5/7A, Odofin park estate,
Ijesha bus stop, oshodi Apapa expressway, Lagos, Nigeria.
ISBN: 978 978 08 4232 1
•
DG Mackean and Dave Hayward
CAMBRIDGE IGCSE ™ BIOLOGY (Fourth Edition) 2022
Published by: HODDER EDUCATION, 50 Victoria Embankment,
London EC4Y ODZ. www.hoddereducation.com
ISBN: 9781 3983 1045 2
Learn these words:
Parenchyma, collenchyma, sclerenchyma, vascular tissues, xylem, phloem, sieve tubes, companion cells
Learn more:
Transport in plants https://youtu.be/DhyYtT1K844
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Content:
Definition
Plant supportive tissues are group of tissues that give the plant support, resilience , rigidity,
transportation of water, assimilation of nutrients, food production and storage.
Unlike animals, plants do not need to move about to look for food or escape from predators.
However, plants require turgidity and support to prevent themselves from collapsing in strong
winds or heavy rain. They also need their stem to remain upright to get enough sunlight, so as
to be able to make their food through photosynthesis.
Types of Plant Supportive Tissues
Parenchyma is a type of plant supportive tissue that provides support and helps in storage of
food and water.
• It is made up of thin-walled cells and is found in various parts of the plant, including
stems, leaves, and fruits.
• Parenchyma cells can also participate in the process of photosynthesis and the exchange
of gases.
The main functions of parenchyma tissue in plants are:
1. Support: Parenchyma provides support to the plant and helps it maintain its shape.
2. Storage: Parenchyma cells can store food and water in the form of starch, sugars, and
oils.
3. Photosynthesis: Parenchyma cells can participate in photosynthesis, the process by which
plants convert sunlight into energy.
4. Gas exchange: Parenchyma cells help in the exchange of gases such as oxygen and
carbon dioxide.
5. Tissue repair: Parenchyma cells can divide and differentiate into specialized cells,
allowing the plant to repair damaged tissues.
6. The parenchyma tissue plays a crucial role in maintaining the overall health and functioning
of the plant.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Collenchyma is a type of supportive tissue found in plants that provides structural support and
helps maintain the shape of the plant.
• It is composed of elongated cells with thicker walls that are reinforced with cellulose,
pectin, and lignin. Unlike xylem, which is responsible for water transport, collenchyma
does not have specialized vessels for transport. Instead, it is primarily responsible for
providing mechanical support to the plant, especially in growing shoots and leaves.
• Additionally, collenchyma helps to prevent wilting in leaves by maintaining turgor
pressure and enabling the plant to bend and flex without breaking.
• Collenchyma cells are living cells and can also participate in growth and metabolic
processes.
The main functions of collenchyma tissue in plants are:
1. Structural support: Collenchyma cells provide mechanical support to the plant, helping to
maintain its shape and prevent wilting.
2. Turgor maintenance: The thicker cell walls of collenchyma cells help to maintain turgor
pressure, which enables the plant to resist wilting and remain upright.
3. Growth and elongation: Collenchyma cells are capable of growth and elongation, which
allows the plant to continue to grow and develop even as it matures.
4. Metabolic processes: Collenchyma cells are living cells and participate in metabolic
processes such as photosynthesis, respiration, and cell division.
5. Temporary support: Collenchyma provides temporary support to the plant, allowing it to
grow and develop until more permanent supportive tissues such as xylem and phloem
are formed.
6. Flexibility: The flexible nature of collenchyma cells allows the plant to bend and flex
without breaking, which is important for avoiding damage from wind, rain, and other
environmental factors.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Sclerenchyma is a type of plant tissue composed of tough, supportive cells with thick cell walls.
•
•
•
It provides mechanical support to the plant and helps to maintain the shape of stems
and leaves.
Sclerenchyma is often found in regions of the plant where there is a need for additional
support, such as in the stems of woody plants.
Unlike other plant tissues, sclerenchyma cells are not capable of division and growth,
which makes them well-suited for their supportive role.
The main functions of sclerenchyma tissue in plants are:
▪
▪
▪
▪
To provide mechanical support to the plant and maintain its structure.
It helps the plant withstand external pressures such as wind, rain, and gravity.
Additionally, sclerenchyma cells play a role in preventing water loss in the plant by
sealing off the openings between cells, known as stomata.
The thick walls of sclerenchyma cells also make them an important source of lignin, a
complex organic polymer that provides additional strength and rigidity to the plant
tissue. This makes sclerenchyma essential for the growth and development of woody
plants and provides structural support to the plant throughout its life cycle.
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Sclerenchyma Tissues
Sclerenchyma tissues are a type of plant tissue that is composed of cells with thick, lignified cell
walls. These cells provide structural support and protection to the plant. There are two main
types of sclerenchyma cells, fibers and sclereids.
Fibers are long and slender cells with thick walls that are arranged in bundles. They provide
tensile strength and support to the plant, helping it resist bending and breaking. Fibers can also
serve as water and nutrient transport channels, and they may play a role in storing nutrients
and metabolites.
Sclereids, on the other hand, are short, irregularly shaped cells that can have a variety of
functions. They can be found in the shells of nuts, in the hard outer coatings of seeds, in the
fruit walls of some plants, and in the leaves and stems of many species. Sclereids provide
protection to the plant by forming a tough barrier against physical damage, herbivory, and
pathogens.
Overall, sclerenchyma tissues are an important component of plant anatomy, and their unique
properties allow plants to survive and thrive in a wide range of environments.
Types of Plant fibers and sclereids
Plant fibers are important materials used for a variety of purposes, including textiles, paper, and
construction materials. There are several types of fibers found in plants, including:
Plant fibers
1. Bast fibers: These are long, strong, and flexible fibers that are found in the phloem of
plant stems. Examples of plants with bast fibers include flax, hemp, and jute.
2. Leaf fibers: These fibers come from the leaves of plants and are commonly used to make
textiles. Examples include sisal, agave, and pineapple.
3. Seed fibers: These fibers come from the seeds of plants and are used to make textiles,
paper, and other products. Examples include cotton, kapok, and milkweed.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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4. Fruit fibers: These fibers are found in the fruit of certain plants and are used for a variety
of purposes, including textiles and construction materials. Examples include coir (from
coconut), kapok (from kapok tree), and raffia (from a type of palm tree).
5. Wood fibers: These fibers come from the xylem tissue of trees and are commonly used to
make paper and other products. Examples include softwood fibers (from trees like pine
and spruce) and hardwood fibers (from trees like oak and maple).
These are just a few examples of the many types of fibers found in plants, each with their own
unique properties and uses.
Plant Sclereids
Sclereids are a type of sclerenchyma cell that provide structural support and protection in
plants. There are several types of sclereids based on their shape and location in the plant. Here
are some examples:
1. Brachysclereids: These are short, isodiametric (similar in all dimensions) sclereids that are
found in the mesophyll of leaves and in the cortex of stems.
2. Macrosclereids: These are elongated sclereids that are found in the pericarp of fruits,
such as the hard shell of a nut.
3. Osteosclereids: These are bone-like sclereids that are found in the seed coat of legumes,
such as beans and peas.
4. Astro-sclereids: These are star-shaped sclereids that are found in the fruit of the starfruit
(Averrhoa carambola).
5. Trichosclereids: These are hair-like sclereids that are found in the outer layers of the seed
coat in some plants, such as the coconut.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Fibers and sclereids are types of plant cells that are responsible for providing mechanical
support and strength to various parts of the plant, such as the stem, leaves, and fruits.
Here are some common uses of fibers and sclereids in a table:
Type of Cell
Common Uses
Fibers
•
•
•
•
Used to make textiles such as cotton, linen, and jute fibers
Used in the paper industry to provide strength to paper products
Used as reinforcement in composite materials such as fiberglass and carbon fiber
Found in fruits and vegetables to provide structural support
Sclereids
•
•
•
•
Found in nutshells and seed coats to provide protection to the seed
Found in the shells of fruits such as coconuts and in the pits of fruits such as peaches and plums
Provide structural support to the leaves and stems of some plants
Used in traditional medicine for their potential health benefits.
Vascular Bundles
Vascular bundles are specialized structures in plants that help in the transport of water,
nutrients, and sugars.
▪ They are composed of xylem tissue, which transports water and minerals from the roots
to the rest of the plant, and phloem tissue, which transports sugars and other organic
compounds from the leaves to other parts of the plant.
▪ The arrangement of vascular bundles varies among plant species, and can be found in
stems, leaves, and roots.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Here is a table outlining the two types of vascular bundles and their functions:
Vascular Bundle
Function
Xylem
Transport of water and minerals from the roots to the rest of the plant
Phloem
Transport of sugars and other organic compounds from the leaves to other parts of the
plant
Evaluation:
a) Name and describe plant supportive tissues
b) State the functions of a named plant supportive tissue
c) State the characteristics of parenchyma, collenchyma and sclerenchyma
Assignment
Attempt any ONE question
i.
In a table, distinguish between monocot stem and dicot stem.
ii.
Describe other types of cells that make up the sclerenchyma tissues in plants.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
34
Week: 6
THE DIGESTIVE SYSTEM
Topic:
Learning objectives:
At the end of the lesson, the students should be able to:
• Describe the digestive system of Man and other vertebrates like fishes, frogs, birds, lizards and rat
• Describe the digestive system of invertebrates like earthworm, cockroach, grasshopper, tapeworm,
• State the similarities and differences between the digestive systems of a named invertebrates and
vertebrates e.g. bird and cockroach.
• Draw and label correctly the alimentary canal of a Man
• Carryout a simple experiment on food test
Reference materials:
New words:
•
Lam Peng Kwan, Eric Y.K. Lam and Julie O. Ofoefunna (2022)
NEW SYSTEM BIOLOGY FOR SENIOR SECONDARY SCHOOLS,
Published by: FIRST PUBLISHERS, Plot 5/7A, Odofin park estate,
Ijesha bus stop, oshodi Apapa expressway, Lagos, Nigeria.
ISBN: 978 978 08 4232 1
•
DG Mackean and Dave Hayward
CAMBRIDGE IGCSE ™ BIOLOGY (Fourth Edition) 2022
Published by: HODDER EDUCATION, 50 Victoria Embankment,
London EC4Y ODZ. www.hoddereducation.com
ISBN: 9781 3983 1045 2
Learn these words: Alimentary canal, Ingestion, Digestion, Assimilation, Absorption,
Egestion, Foregut, Hindgut, Midgut.
Learn more:
✓ Alimentary canal of man and process of food digestion
https://youtu.be/X3TAROotFfM
✓ Digestive system in insects https://youtu.be/5IdSruWQG5k
✓ Food test https://youtu.be/ZAeqG-woHKc
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Content:
Definition:
The human digestive system is a complex series of organs and structures that work together to
break down food, absorb nutrients, and eliminate waste. It includes the mouth, esophagus,
stomach, small and large intestines, pancreas, liver, and gallbladder. Food is broken down
mechanically and chemically through the use of enzymes and digestive juices, and nutrients are
absorbed into the bloodstream through the walls of the small intestine. Waste products are
eliminated through the rectum and anus.
The Alimentary Canal
The alimentary canal, also known as the gastrointestinal (GI) tract, is the long tube-like
structure that runs through the body from the mouth to the anus and is responsible for
digestion and absorption of food. It includes the mouth, esophagus, stomach, small and large
intestines, and anus.
The alimentary canal works in coordination with accessory organs like the liver, pancreas, and
gallbladder to break down food into smaller molecules, absorb nutrients, and eliminate waste.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Parts of the Alimentary canal and their functions
Part of Digestive System
Function
Mouth
Chews and grinds food, mixes with saliva, starts carbohydrate digestion
Esophagus
Moves food from mouth to stomach via peristalsis
Stomach
Mixes and grinds food with stomach acid and enzymes to begin protein digestion
Small Intestine
Completes digestion of carbohydrates, proteins, and fats, absorbs nutrients into
bloodstream
Large Intestine
Absorbs water and electrolytes, forms and eliminates feces
Rectum
Stores feces before elimination
Anus
Opening for elimination of feces
Liver
Produces bile, which aids in fat digestion and absorption
Gallbladder
Stores and releases bile into small intestine
Pancreas
Produces enzymes to digest carbohydrates, proteins, and fats, produces bicarbonate to
neutralize stomach acid
It's worth noting that the human digestive system is a complex and interconnected system, and the
functions of these different parts often overlap and work together to break down food and extract
nutrients.
Digestion, Absorption and Assimilation
Digestion, absorption, and assimilation are the three main processes involved in the conversion
of food into energy and nutrients that the body can use. Here's a brief explanation of each
process:
1. Digestion: This is the process by which food is broken down into smaller molecules that
the body can absorb. It begins in the mouth, where food is mechanically broken down
by chewing and mixed with saliva, which contains enzymes that start to break down
carbohydrates. The food then travels to the stomach, where it is mixed with stomach
acid and enzymes that break down proteins. From there, the partially digested food
moves to the small intestine, where enzymes from the pancreas and the small intestine
itself break down carbohydrates, proteins, and fats.
2. Absorption: Once the food has been broken down into its component molecules, it can
be absorbed into the bloodstream and transported to cells throughout the body. This
occurs primarily in the small intestine, where the walls of the intestine are lined with
tiny finger-like projections called villi that increase the surface area available for
absorption. Nutrients such as glucose, amino acids, and fatty acids are transported
across the intestinal wall and into the bloodstream.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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3. Assimilation: Once the nutrients have been absorbed into the bloodstream, they can be
used by the body's cells for energy and other functions. For example, glucose can be
used for energy or stored in the liver and muscles as glycogen. Amino acids can be used
to build proteins, while fatty acids can be used for energy or stored in fat cells for later
use.
Overall, digestion, absorption, and assimilation work together to ensure that the body receives
the energy and nutrients it needs to function properly.
Food Classes and Their End Products
Here is a table outlining the main food classes and their end products:
Food Class
Examples
End Products
Carbohydrates
Bread, pasta, rice, fruits, vegetables
Glucose
Proteins
Meat, eggs, dairy, beans, nuts
Amino acids
Fats
Butter, oil, avocado, nuts, seeds
Fatty acids and glycerol
Vitamins
Fruits, vegetables, grains, dairy, meat
Essential micronutrients
Minerals
Leafy green vegetables, dairy, meat, nuts
Essential micronutrients
Water
Tap water, mineral water, juices, soups
Hydration, helps with nutrient transport and digestion
It's important to note that some foods may contain a combination of these classes, and that
different types of food may have different ratios of each nutrient. Additionally, some foods may
contain other beneficial substances such as fiber and antioxidants that can contribute to overall
health.
The Process of Food Digestion
Food digestion is a complex process that involves the breakdown of food into smaller
components that can be absorbed and used by the body. Here's a brief overview of the process
of food digestion:
1. Mouth: The process of digestion begins in the mouth, where teeth break down food into
smaller pieces and saliva mixes with the food to start breaking down carbohydrates.
2. Esophagus: Once the food is chewed and swallowed, it travels down the esophagus via a
series of contractions called peristalsis.
3. Stomach: In the stomach, the food is mixed with stomach acid and enzymes that break
down proteins. The stomach also contracts to further break down the food and mix it
with the digestive juices.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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4. Small intestine: The partially digested food then moves into the small intestine, where it
is mixed with enzymes from the pancreas and bile from the liver. The enzymes break
down carbohydrates, proteins, and fats, while the bile helps to emulsify fats so that they
can be more easily broken down.
5. Absorption: Once the food is broken down into its component molecules, it can be
absorbed into the bloodstream and transported to cells throughout the body. This
occurs primarily in the small intestine, where the walls are lined with tiny finger-like
projections called villi that increase the surface area available for absorption.
6. Large intestine: Any remaining food that is not absorbed moves into the large intestine,
where water is absorbed and waste products are formed into feces .
7. Rectum and anus: The feces are stored in the rectum until they are eliminated through
the anus during a bowel movement.
Overall, the process of food digestion involves mechanical and chemical breakdown of food,
absorption of nutrients, and elimination of waste products. The digestive system works in
coordination with other organs and systems in the body to ensure that the body receives the
energy and nutrients it needs to function properly.
Digestive System of Insects
The digestive system of insects is a specialized system that is responsible for breaking down
food into nutrients that can be used by the insect's body. The digestive system of insects
consists of several different parts, including the foregut, midgut, and hindgut.
The foregut is responsible for storing food and breaking it down into smaller particles using
mechanical digestion. It also secretes enzymes that help break down the food chemically.
The midgut is where most of the digestive process takes place. This is where the enzymes
secreted by the foregut are mixed with the food and nutrients are absorbed into the insect's
body.
The hindgut is responsible for removing waste material from the insect's body. This includes
undigested food, as well as other waste products.
Insects also have a specialized organ called the Malpighian tubules, which help to regulate the
insect's water balance by removing waste products and excess water from the insect's body.
Overall, the digestive system of insects is highly specialized and adapted to their specific
feeding habits and lifestyles.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
39
Food Test Practical
There are many different food tests that can be performed in a laboratory setting to determine
the presence of specific nutrients or other components in a food sample. Here are a few
examples of common food tests and how they are performed:
1. Benedict's test for reducing sugars: This test is used to detect the presence of reducing
sugars such as glucose and fructose. To perform the test, a small amount of the food
sample is mixed with Benedict's reagent (a blue solution containing copper ions) and
heated. If reducing sugars are present, they will react with the copper ions to form a
reddish-brown precipitate.
2. Biuret test for proteins: This test is used to detect the presence of proteins. To perform
the test, a small amount of the food sample is mixed with sodium hydroxide and copper
sulfate. If proteins are present, they will react with the copper ions to form a violet
color.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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3. Sudan III test for lipids: This test is used to detect the presence of lipids (fats and oils). To
perform the test, a small amount of the food sample is mixed with Sudan III solution,
which is a red dye that is insoluble in water but soluble in lipids. If lipids are present, the
Sudan III will bind to them and cause the sample to turn a bright red color.
4. Iodine test for starch: This test is used to detect the presence of starch. To perform the
test, a small amount of the food sample is mixed with a solution of iodine. If starch is
present, it will react with the iodine to form a blue-black color.
It's important to note that these tests are just a few examples of the many different food tests that exist,
and that each test has its own limitations and caveats. Additionally, it's generally not recommended to
perform food tests at home without proper training and equipment, as some tests can be hazardous or
produce inaccurate results if not done properly.
Evaluation:
• Describe the digestive system of Man and other vertebrates like fishes, frogs, birds, lizards and rat
• Describe the digestive system of invertebrates like earthworm, cockroach, grasshopper, tapeworm,
• State the similarities and differences between the digestive systems of a named invertebrates and
vertebrates e.g. bird and cockroach.
• Draw and label correctly the alimentary canal of a Man
• Carryout a simple experiment on food test
Assignment
Attempt any ONE question
i.
Draw and label the digestive system of a bird
ii.
Draw and label the digestive system of a cow
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Week: 7
FEEDING HABITS IN LIVING ORGANISMS
Topic:
Learning objectives:
At the end of the lesson, the students should be able to:
•
•
•
•
Enumerate the various feeding habits in organisms.
Describe the mechanism and modification of feeding in mosquito larva, tapeworm, butterfly,
mucor, man, amoeba and hydra.
Describe the types, structures of tooth herbivores, carnivores and omnivores.
Explain how the teeth of rabbit and dogs are adapted to suit their mode of feeding.
Reference materials:
•
•
New words:
Lam Peng Kwan, Eric Y.K. Lam and Julie O. Ofoefunna (2022)
NEW SYSTEM BIOLOGY FOR SENIOR SECONDARY SCHOOLS,
Published by: FIRST PUBLISHERS, Plot 5/7A, Odofin park estate,
Ijesha bus stop, oshodi Apapa expressway, Lagos, Nigeria.
ISBN: 978 978 08 4232 1
DG Mackean and Dave Hayward
CAMBRIDGE IGCSE ™ BIOLOGY (Fourth Edition) 2022
Published by: HODDER EDUCATION, 50 Victoria Embankment,
London EC4Y ODZ. www.hoddereducation.com
ISBN: 9781 3983 1045 2
Learn these words:
Prehension, Mastication, Salivation, Deglutition, Digestion, Elimination, Dentition,
Diastema, Carnivore, Omnivore, Herbivore, Canine, Incisors, Premolar, Molar,
Parasitism, Symbiosis
Learn more:
✓ Alimentary canal of man and process of food digestion
https://youtu.be/X3TAROotFfM
✓ Digestive system in insects https://youtu.be/5IdSruWQG5k
✓ Food test https://youtu.be/ZAeqG-woHKc
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
42
Content:
Definition
Feeding mechanism in organisms refers to the process by which organisms obtain and
consume food to provide themselves with the energy and nutrients necessary for survival and
growth.
Different organisms have evolved various feeding mechanisms that are adapted to their specific
habitats and lifestyles.
For example, herbivores are organisms that feed on plants, while carnivores feed on other
animals. Omnivores, on the other hand, consume both plants and animals. Filter feeders are
organisms that obtain their food by filtering it out of water or air, such as some species of
whales and plankton. Some organisms, such as fungi and bacteria, obtain their food through
absorption of nutrients from their surroundings.
The feeding mechanism of an organism can also involve specialized structures, such as teeth or
beaks, that are adapted to the type of food they consume. The process of digestion is also a
part of the feeding mechanism, as it involves breaking down food into smaller molecules that
can be absorbed and used by the organism's cells.
Types of feeding mechanisms in organisms
There are several types of feeding mechanisms in living organisms, including:
• Herbivory: Herbivores are animals that feed primarily on plants, algae or other
•
•
•
•
•
•
autotrophs. They have specialized digestive systems that are able to break down the
tough cellulose found in plant cell walls.
Carnivory: Carnivores are animals that feed primarily on other animals. They have
specialized teeth and digestive systems that allow them to efficiently break down animal
tissue.
Omnivory: Omnivores are animals that feed on both plants and animals. They have a
flexible digestive system that can handle both plant and animal material.
Detritivory: Detritivores are organisms that feed on dead plant or animal material, such
as fallen leaves, dead animals or feces. They play an important role in breaking down
and recycling organic matter.
Filter feeding: Filter feeders are aquatic organisms that filter small particles, such as
plankton, from the water using specialized structures, such as gills or tentacles.
Parasitism: Parasites are organisms that live on or inside other organisms, known as
hosts, and obtain nutrients from them. Parasites can have a range of feeding strategies,
including absorbing nutrients directly from the host's tissues or consuming its blood.
Symbiosis: Some organisms form symbiotic relationships with others, in which both
partners benefit from the relationship. For example, some plants have evolved to
provide food to ants in exchange for protection from herbivores.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Modification in organisms to reflect their feeding habits
Organisms can undergo various modifications to reflect their feeding habits, depending on the type of
food they consume and their ecological niche. Here are some examples:
Feeding modification in Amoeba
Amoebas are unicellular organisms that belong to the kingdom Protista. They are known for
their ability to change shape and move using pseudopodia, which are temporary extensions of
their cytoplasm. Amoebas are heterotrophic, meaning they obtain their nutrients by consuming
other organisms.
Amoebas feed by engulfing their prey with their pseudopodia. When a potential food particle is
detected, the amoeba surrounds it with its pseudopodia and forms a food vacuole. The food
vacuole then fuses with lysosomes, which are specialized organelles that contain digestive
enzymes. The enzymes break down the food particles into smaller molecules that can be
absorbed by the amoeba's cytoplasm.
Amoebas are known to feed on a variety of organisms, including bacteria, algae, and small
protozoa. They are also capable of phagocytizing small particles such as debris or other organic
matter. Amoebas are opportunistic feeders, meaning they will consume whatever food is
available to them.
Overall, amoebas have a unique feeding mechanism that involves engulfing prey with their
pseudopodia and breaking down the food particles with digestive enzymes. Their opportunistic
feeding habits allow them to survive in a wide range of environments and obtain nutrients from
a variety of sources.
Feeding modification in Hydra
Hydra are freshwater cnidarians, which are carnivorous and feed primarily on small aquatic
invertebrates such as water fleas, small crustaceans, and larvae of insects. They capture their
prey using their stinging cells, called nematocysts, which are present on their tentacles.
When a suitable prey comes into contact with the tentacles, the nematocysts discharge and
inject a toxin that paralyzes the prey. The tentacles then bring the prey to the hydra's mouth,
where it is engulfed and digested. Hydra have a simple digestive system that consists of a saclike gut with a single opening that serves as both the mouth and anus.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
44
Hydra can also feed on small fish or even other hydra if they are small enough. They have been
observed to actively hunt for prey and can use their tentacles to capture and kill larger prey.
Overall, the feeding habits of hydra are typical of carnivorous cnidarians, using their tentacles
and nematocysts to capture and immobilize prey before digestion in their simple gut.
Feeding modification in Man
Humans are omnivores, meaning that they eat both plant and animal-based foods. Our feeding
habits can vary widely based on cultural, economic, and personal factors. However, in general,
humans consume a wide variety of foods that can be broadly categorized as follows:
•
Carbohydrates: Carbohydrates are a primary source of energy for humans, and they are
found in foods such as grains (wheat, rice, oats, etc.), fruits, vegetables, and sugars.
•
Proteins: Proteins are essential for building and repairing tissues in the body, and they
are found in foods such as meat, fish, eggs, beans, and nuts.
•
Fats: Fats are a rich source of energy and are important for the absorption of certain
vitamins. They are found in foods such as oils, butter, meat, and nuts.
•
Vitamins and minerals: Vitamins and minerals are essential for various bodily functions
and are found in a variety of foods, including fruits, vegetables, and whole grains.
In addition to these basic food groups, many humans also consume processed foods, fast foods,
and other convenience foods that are high in salt, sugar, and fat. However, it is important to
balance these foods with more nutritious options to maintain good health.
Overall, the feeding habits of humans are varied and complex, but a balanced diet that includes
a variety of nutrient-rich foods is essential for optimal health and wellbeing.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Feeding Process in Man
Humans are omnivores, which means that they consume both plant and animal-based foods.
The feeding mechanism in humans involves several stages:
I. Prehension: The first stage of feeding in humans is prehension, which involves bringing
food to the mouth. This can be done using the hands, utensils, or other tools.
II.
Mastication: Once the food is in the mouth, the teeth and jaw muscles are used to break
it down into smaller pieces. This process is known as mastication or chewing.
III.
Salivation: During mastication, the salivary glands secrete saliva, which moistens the
food and begins the process of digestion. Saliva also contains enzymes that help to
break down carbohydrates.
IV. Deglutition: After the food is sufficiently chewed, it is formed into a ball-like mass called
a bolus and pushed to the back of the mouth by the tongue. The bolus then enters the
pharynx and triggers the swallowing reflex, which moves it through the esophagus and
into the stomach. This process is known as deglutition or swallowing.
V. Digestion: Once the food reaches the stomach, it is further broken down by stomach acid
and digestive enzymes. The nutrients are then absorbed into the bloodstream and
transported to the cells of the body to be used for energy, growth, and repair.
VI. Elimination: Any waste products that are not absorbed by the body are eliminated
through the rectum and anus as feces.
Overall, the feeding mechanism in humans involves a series of complex processes that allow us
to obtain nutrients from a variety of foods. Proper nutrition and hydration are essential for
maintaining overall health and well-being.
Adaptation of Dentition to Mode of Nutrition
in Herbivores, Carnivores and Omnivores
Dentition, or the arrangement and type of teeth in an animal's mouth, has evolved to suit different
modes of nutrition in herbivores, carnivores, and omnivores. Here are some of the adaptations in
dentition that are specific to each of these dietary categories:
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
46
•
Herbivores: Herbivores are animals that primarily eat plant material. Their teeth are adapted to
grinding and crushing tough plant material, and their digestive systems are equipped to extract
nutrients from fibrous plant matter. Herbivores have broad, flat molars that are used to grind
and crush plant material. Their incisors are often small or absent, as they do not need to bite off
large pieces of food. Additionally, some herbivores have a specialized dental structure called a
diastema, which is a gap between their front teeth that allows them to better manipulate and
grind their food.
•
Carnivores: Carnivores are animals that primarily eat meat. Their teeth are adapted to tearing
and cutting through tough animal tissue, and their digestive systems are equipped to break
down proteins and fats. Carnivores have sharp, pointed canines that are used to grip and tear
prey. They also have sharp, serrated premolars and molars that are used to shear through flesh
and bone.
•
Omnivores: Omnivores are animals that consume both plant and animal-based foods. Their
teeth are adapted to a range of tasks, from grinding and crushing plant material to tearing and
cutting through animal tissue. Omnivores have a mix of flat molars for grinding plant material
and sharp, pointed canines and premolars for tearing and cutting meat. Their incisors are often
broad and strong, allowing them to bite off and grasp food of different textures.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Overall, the adaptation of dentition to mode of nutrition in herbivores, carnivores, and
omnivores reflects their dietary requirements and the mechanical challenges they face
when consuming different types of food. These adaptations have allowed animals to
thrive and survive in a variety of ecological niches.
Evaluation:
• Enumerate the various feeding habits in organisms
• Describe the mechanism and modification of feeding in mosquito larva, tapeworm, butterfly, mucor,
man, amoeba and hydra
• Describe the types, structures of tooth herbivores, carnivores and omnivores
• Explain how the teeth of rabbit and dogs are adapted to suit their mode of feeding
Assignment
Attempt any ONE (1) question
iii.
iv.
Draw and label the Dentition of a Man and write out its dental formula.
Draw and label the Dentition of a named Ruminant and write out its dental formula.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
48
Week: 8
TRANSPORT SYSTEM IN LIVING ORGANISMS
Topic:
Learning objectives:
At the end of the lesson, the students should be able to:
•
•
•
Highlight the need for transportation in organisms
List the materials and media of transportation in organisms
Explain the composition, structure and function of the mammalian blood
Reference materials:
•
•
New words:
Lam Peng Kwan, Eric Y.K. Lam and Julie O. Ofoefunna (2022)
NEW SYSTEM BIOLOGY FOR SENIOR SECONDARY SCHOOLS,
Published by: FIRST PUBLISHERS, Plot 5/7A, Odofin park estate,
Ijesha bus stop, oshodi Apapa expressway, Lagos, Nigeria.
ISBN: 978 978 08 4232 1
DG Mackean and Dave Hayward
CAMBRIDGE IGCSE ™ BIOLOGY (Fourth Edition) 2022
Published by: HODDER EDUCATION, 50 Victoria Embankment,
London EC4Y ODZ. www.hoddereducation.com
ISBN: 9781 3983 1045 2
Learn these words:
Learn more:
✓ Transportation in man https://youtu.be/ML2WX84gsGE
✓ Cytoplasmic streaming in cells https://youtu.be/BB5rvjZzgFU
✓ Translocation and transpiration in plants https://youtu.be/9FTafxnbwHQ
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Content:
Definition
The transport system in organisms refers to the mechanisms by which substances, such as nutrients,
oxygen, and waste products, are transported throughout the body.
In multicellular organisms, such as humans, there are two main transport systems: the circulatory
system and the lymphatic system.
The circulatory system, which consists of the heart, blood vessels, and blood, is responsible for the
transportation of oxygen, nutrients, and hormones to cells throughout the body, as well as the removal
of carbon dioxide and other waste products. The heart pumps blood through the arteries, which branch
out into smaller arterioles, and eventually into even smaller capillaries. The capillaries are where the
exchange of gases, nutrients, and waste products occurs between the blood and the body's cells.
The blood then flows back to the heart through veins, which become larger as they merge together.
The lymphatic system is responsible for the transportation of lymph, a clear fluid that contains white
blood cells, throughout the body. The lymphatic vessels run parallel to the blood vessels and drain
excess fluid from tissues. The lymphatic system also plays a crucial role in the immune system by helping
to remove foreign substances and microorganisms from the body.
In unicellular organisms, such as bacteria, transport occurs through diffusion, which is the movement of
particles from an area of high concentration to an area of low concentration. This process occurs directly
through the cell membrane.
Need For Transportation in Organisms and Materials for Transportation
Transportation is a vital process for organisms as it enables the movement of essential materials,
such as nutrients, gases, and waste products, throughout their bodies. Without transportation, these
materials would not be able to reach the cells that need them, leading to malnourishment, toxicity, and
other health issues.
Organisms use different mechanisms for transportation, depending on their size, complexity, and
environment. For example, single-celled organisms use diffusion to exchange materials with their
surroundings, while multicellular organisms have specialized tissues and organs, such as circulatory
systems and respiratory systems, that facilitate transportation.
In addition to the need for transportation, organisms require materials for transportation. These
materials can vary depending on the mechanism used for transportation. For example, in animals with
circulatory systems, the materials used for transportation include blood, which contains red blood cells
that carry oxygen, white blood cells that fight infection, and plasma that transports nutrients, hormones,
and waste products.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Plants, on the other hand, use a system of vascular tissues, xylem and phloem, for transportation. Xylem
transports water and minerals from the roots to the rest of the plant, while phloem transports sugars
and other organic compounds from the leaves to other parts of the plant.
Overall, transportation is a fundamental process in organisms that enables the exchange of materials
necessary for their survival and growth.
Media for transportation in Organisms
1. Diffusion: This is the passive movement of particles from an area of higher concentration
to an area of lower concentration. Diffusion is used to transport small molecules such as
oxygen and carbon dioxide across cell membranes.
2. Circulatory system: In complex organisms such as mammals, materials are transported
throughout the body via the circulatory system. The circulatory system consists of the
heart, blood vessels, and blood, and is responsible for transporting oxygen, nutrients,
hormones, and waste products.
3. Lymphatic system: The lymphatic system is a network of vessels and organs that helps to
transport lymph, a fluid that contains white blood cells and other immune system
components. The lymphatic system helps to remove waste and excess fluids from the
body.
4. Active transport: Active transport is the movement of molecules across a cell membrane
from an area of lower concentration to an area of higher concentration. This process
requires energy, typically in the form of ATP, and is used to transport larger molecules
such as glucose and amino acids across cell membranes.
5. Endocytosis and exocytosis: Endocytosis is the process by which a cell takes in substances
from its external environment by engulfing them in a vesicle. Exocytosis is the opposite
process, by which a cell releases substances into its external environment by fusing a
vesicle with the cell membrane. These processes are used to transport large molecules
such as proteins and lipids.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Different Mechanisms for Transportation in Organisms
There are several ways that materials can be transported within organisms, including through
the cytoplasm of cells, lymphatic system, and circulatory system.
• Cytoplasmic streaming:
Cytoplasmic streaming is the movement of the cytoplasm within a cell. It is most
commonly found in plant cells, where it plays a role in distributing nutrients and
organelles throughout the cell. This process is driven by actin filaments and myosin
motor proteins.
Some of the functions of cytoplasmic streaming include;
1. Transport: Cytoplasmic streaming allows for the transport of nutrients, proteins, and
other molecules throughout the cell. This movement helps distribute resources to areas
of the cell that need them.
2. Organelle movement: Organelles such as mitochondria, chloroplasts, and peroxisomes
move along the cytoskeleton to different regions of the cell through cytoplasmic
streaming.
3. Wound healing: Cytoplasmic streaming plays a role in the repair of wounded plant cells
by transporting molecules and organelles to the site of the injury.
• Lymphatic system:
Lymph is a clear fluid that circulates throughout the lymphatic system, which is a network of
vessels and organs that help the body fight infections and diseases.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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The functions of lymph include:
1. Immune defense: Lymph contains white blood cells that help defend the body against
infections and diseases.
2. Transport: Lymph carries excess fluid, proteins, and waste products away from
tissues and back into the bloodstream.
3. Fat absorption: Lymphatic vessels in the small intestine help absorb dietary fats and
transport them to the bloodstream.
• Blood circulatory system:
Blood is a type of connective tissue that circulates throughout the body, carrying
oxygen, nutrients, and waste products to and from tissues.
The main functions of blood include:
1. Transport: Blood carries oxygen and nutrients to the cells and tissues of the body,
while also carrying waste products away from them.
2. Immune defense: Blood contains white blood cells that help defend the body
against infections and diseases.
3. Regulation: Blood helps regulate body temperature, pH levels, and fluid balance.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Within the blood, materials are transported in several ways:
a) Oxygen and carbon dioxide are carried by red blood cells, which contain the protein
hemoglobin.
b) Nutrients, hormones, and waste products are carried by plasma, the liquid component
of blood.
c) White blood cells are responsible for fighting infections and are transported throughout
the body via the blood.
Overall, the transport of materials within organisms is a complex process that involves a variety
of mechanisms and systems.
Types of circulatory systems in organisms and mechanisms of
circulation
Circulatory systems are crucial for the transport of nutrients, gases, and waste products within
an organism's body. There are several types of circulatory systems found in different organisms.
Here are the main types:
1. Open Circulatory System:
• Description: In an open circulatory system, blood or hemolymph is not confined
to vessels but instead bathes the organs directly. The fluid is pumped by a simple
heart into the body cavity, where it comes into direct contact with cells and
tissues.
• Examples: Insects, mollusks, and some arthropods.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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2. Closed Circulatory System:
• Description: In a closed circulatory system, blood is enclosed in vessels and is
distinct from the interstitial fluid. The blood is pumped by a muscular heart, and
it circulates through a network of vessels that reach all parts of the body.
• Examples: Vertebrates, including mammals, birds, reptiles, and fish, as well as
some invertebrates like annelids and cephalopods.
3. Single Circulatory System:
• Description: In a single circulatory system, blood flows through the heart once
during each complete circuit of the body. Oxygenated and deoxygenated blood
may mix to some extent.
• Examples: Fish have a single circulatory system.
4. Double Circulatory System:
• Description: In a double circulatory system, blood is pumped through the heart
twice during each complete circuit of the body. There are two separate circuits:
one for oxygenated blood and another for deoxygenated blood, preventing their
direct mixing.
• Examples: Mammals, birds, and reptiles have a double circulatory system.
Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.
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Princeton college, Surulere/Biology/Grade 11/Second term/2023-2024 Academic session/Mr. Gabriel Isichei C.