The document discusses antibody production and vaccination. It begins by defining antigens and antibodies, and how blood groups are determined by antigens on red blood cells. It then describes the specific immune response of producing antibodies after macrophages display antigens to T cells and B cells. The process results in plasma cells that produce antibodies and memory cells. Vaccines work by containing weakened pathogens that trigger an immune response without causing disease, allowing for a stronger secondary response if exposed to the actual pathogen. Gametogenesis and the production of eggs and sperm are also summarized, including the stages of meiosis involved in forming haploid cells from diploid germ cells.

1. 11.1 Antibody Production and Vaccination
Antigens in blood transfusion
● Antigen​: ​toxic or foreign​ substance which can trigger an immune response
● Antibody​: blood protein produced in response to a specific antigen
Antigens in blood transfusion
● Blood groups are based on the presence of certain types of antigens on the surface of
haemoglobins
● Agglutination ​(foreign response) and ​hemolysis​ (haemoglobins destroyed and
accumulate in the vessels) can occur if wrong blood type is given
Specific immune response
● Specific Immune response​: producing antibodies in response to pathogens
● Process (①~③ on the right)
1. Macrophage​ (type of WBC) engulfs pathogen, displays antigen
2. Helper T cells/lymphocyte​ (WBC) binds to the antigen using receptor
protein → T cell activates
3. T cells bind to ​B cells/lymphocyte​ (WBC) with same receptor protein
→ B cell activated
Plasma Cells
● Plasma cells​ are mature B cells which can produce specific antibodies during
an immune response
● Has large rough endoplasmic reticulums to transport proteins (antibodies)
Clonal selection and memory cell formation
● Process (④~⑥ on the right)
1. (After B cell activated) B cell divides to produce ​memory cells​ (cells
which can respond to the same pathogen when exposed)...
2. ...and also to produce antibody-secreting plasma cells (differentiated
B cells)
3. Plasma cells produce more clones and produces specific antibodies
Antibody functions
● Opsonisation: makes pathogens more recognisable for phagocytes
● Neutralisation of viruses and bacteria: prevents viruses from attaching to host
cells
● Neutralisation of toxins: binds to toxins to prevent them from affecting cells
● Activation of complement: causes pathogens to rupture by forming a pore in the membrane
● Agglutination: antibodies can stick together pathogens for easier phagocytosis
Immunity
● Immunity to a disease is due to the presence of antibodies which recognises the antigens causing the disease
● Immune system releases memory cells and antibodies in response to a challenge
Role of vaccines towards immunity
● Vaccines contain weakened pathogens or antigens that can trigger primary immune response but not cause the disease
● Secondary immune response occurs if the same pathogen enters by infection (stronger response)

2. Ethics behind Jenner’s vaccine experiments
● After hearing that milkmaids don’t get smallpox after being exposed to cowpox, Edward Jenner tested this by
infecting a young boy with cowpox and exposing him to smallpox later → boy had ability to resist smallpox
● Ethical problems
○ Jenner didn’t do preliminary investigation
○ Smallpox can be fatal
Eradication of smallpox
● Factors contributing to the eradication:
○ Only humans can get smallpox
○ Symptoms are obvious (fast vaccination)
○ Immunity to smallpox is long term (no reinfection)
Vaccines and epidemiology
● Epidemiology: study of disease distribution and causes within population (predicting outbreaks)
Zoonosis
● Zoonosis​: diseases that can cross a species barrier
Histamines
● White cells can produce ​histamines​ (widens small blood vessels to allow flow of immune components)
● Histamines cause allergic symptoms (e.g. itching, mucus secretion)
Production of monoclonal antibodies using hybridoma cells
1. Animal (often mouse) is injected with an antigen → produces
plasma cells
2. Plasma cell collected from spleen
3. Plasma cells are fused with myeloma (tumour) cells for division
(fused cells: ​hybridoma cells​)
4. Hybridoma cells are screened to select only the one which
produces the specific antibodies
5. Hybridoma cells produce ​monoclonal antibodies​ (highly specific
antibodies)
Pregnancy tests employ monoclonal antibodies
● Pregnancy test kits use monoclonal antibodies to detect hCG in urine, a type of hormone produced by the developing
embryo and the placenta.
● Point C is the test site and point D is the control site

3. 11.2 Movement
Function of bones and exoskeletons in muscle movement
● Bones and exoskeletons facilitate movement by acting as levers (changing size
and direction of forces)
● Components of the lever
○ Effort force (​➨​)
○ Fulcrum (pivot) [​▲​]
○ Resultant force (​■​)
● Position of the components on the lever determine its class
Skeletal muscles are antagonistic muscles
● Skeletal muscles are ​antagonistic​ (​when one contracts, the other relaxes​)
● Triceps and Biceps are antagonistic
Antagonistic muscles in insects
● Hindleg of grasshoppers are specialised for jumping
● Femur and tibia are close together when preparing to
jump (flexing) → extensor relaxed, flexor contracts
● Tibia extends, grasshopper jumps → extensor
contracts, flexor relaxes
Human elbows are synovial joints
● Cartilage​: covers bones, prevents friction, and absorbs shock (prevents
fracture)
● Synovial fluid​: lubricates the joint (fills up space between bones), prevents
frictions
● Joint capsule​: prevents dislocation of joints by sealing the joint and
holding it to the synovial fluid
Joint movement
● Knee joints → both hinge joints and pivotal joints (pivotal hinge joint)
○ Flexion (bending)
○ Extension (straightening)
● Hip joints → ball and socket joint
○ Flexion
○ Extension
○ Rotation
○ Adduction/abduction (in/out of midline)
Structure of muscle fibres
● Skeletal/striated muscles​ are muscles used to move
the body which are attached to bones
● Striated muscles are composed of bundles of
muscle cells called ​muscle fibres
● Myofibrils​: contractile units inside muscle fibres
● Sarcolemma​: plasma membrane which surrounds
each muscle fibre
● Sarcoplasmic reticulum​: wraps around myofibrils
to convey signals to contract
● Mitochondria for ATP production
Myofibrils
● Myofibrils​: long parallel structures making up the
muscle fibres
● Light and dark pattern caused by layout of thick
myosin filament and thin actin filament
● Actin filaments​ attached to Z-line/disk at one end
● Myosin filaments​ surrounded by 6 actin filaments
(forms cross-bridge) during muscle contraction

4. Drawing the sarcomere
● Length of actin and myosin
filaments should be indicated
(short of long) to indicate extent
of contraction
● Draw myosin with heads
Skeletal muscle contraction mechanism
● Thick myosin filaments pull thin actin filaments​ towards centre of sarcomere → ​muscle contraction
● Process of contraction
1. Myosin filaments have heads/projections that can bind to actin filaments (​cross-bridge​)
2. ATP is used to exert force for pulling actin
● Many cross bridges​ form because of multiple heads on myosin and binding sites on actin
Skeletal muscle contraction process
1. Tropomyosin​ blocks the binding sites on actin when
muscle are relaxed
2. Motor neuron sends signals to contract
3. Sarcoplasmic reticulum​ releases ​calcium ions
4. Calcium ions​ bind to ​troponin
5. Troponin ​moves ​tropomyosin​, exposing binding sites
6. Myosin heads bind to actin
7. (process repeated)
ATP in skeletal muscle contraction
● To repeat the above process, ATP is used.
● Process
1. ATP binds to myosin heads and detaches
it from actin binding site (​cross-bridge
broken​)
2. ATP is hydrolysed​ into ADP + P,
allowing ​myosin head to to change the
angle​ (ADP + P binds to head)
3. Heads attach to the ​next binding site​ away
from the centre of sarcomere (​P released​)
4. ADP released, heads pull the actin
filament​ towards centre of sarcomere
(​power stroke​)
Use of fluorescence to study contraction
● Visible or invisible light which can be detected by light microscopes as a result of exposure to radiation of different
wave length
11.3 The Kidney and Osmoregulation
Different responses to changes in osmolarity in the environment
● Osmolarity: solute concentration of a solution
● Animals are either osmoregulators or osmoconformers
○ Osmoregulators
■ Organisms which maintains a constant internal solute concentration
■ ⅓ of the concentration of seawater and 10 times that of fresh water
■ E.g. terrestrial animals
○ Osmoconformers
■ Organisms which maintains the same internal solute concentration as the concentration of solutes in
its surrounding
■ E.g. most marine animals
Malpighian tubule system in insects
● Malpighian tubule​: system which carries out osmoregulation and removal of nitrogenous wastes in ​insects
● Hemolymph are the circulating fluid in insects (​blood​)

5. ● Process
1. Cells lining the tubules ​actively transport ions and uric acid​ from the hemolymph
(blood) ​into the lumen​ of the tubules
2. Water enters the lumen from the hemolymph through ​osmosis
3. Tubules contents move into the hindgut​, where most of the water and salts are
reabsorbed
4. Nitrogenous waste remains, ​excreted​ with feces
Drawing the human kidney
● Cortex​: selective reabsorption of blood contents
● Medulla​: Reabsorbs water
● Pelvis​: where urine is discharged
● Ureter​: carries urine to bladder
● (Renal vein should be wider than renal arteries)
● (Cortex ⅕ thickness in relation to kidney)
Renal artery and renal vein
● Kidneys​ remove substances from the blood which are unnecessary
or are harmful
Renal artery Renal vein
-Unfiltered blood
-More ingested toxins
-More excretory waste
-More water
-More salt
-More oxygen and glucose, less
CO​2​ (metabolism by kidney)
-Filtered blood
-Less ingested toxins
-Less excretory waste
-Less water
-Less salt
-Less oxygen and glucose, more
CO​2​ (metabolism by kidney)
● Substances filtered (excess or undesired) are removed by the ureter into the bladder
Bowman’s capsule ultrastructure
● Ultrafiltration​ (separation of particles differing in size) occurs in the
glomerulus (inside Bowman’s capsule)
● Ultrafiltration
1. Blood enters from ​afferent arteriole
2. Fenestrations​: passes fluids but not blood cells
3. Basement membrane​: prevents plasma proteins from being
filtered out
4. Podocytes​: prevents small molecules from being filtered
5. Unfiltered particles enter ​efferent arteriole
6. Filtered particles (glomerular filtrate) are ​removed out from
proximal convoluted tubule
Role of proximal convoluted tubule
● Proximal convoluted tubule​ ​actively reabsorbs useful substances from the glomerular filtrate
● All glucose, amino acids, and 80% of the water, sodium, and other mineral ions are absorbed
● Adaptations
○ Microvilli​ for increasing surface area
○ Many mitochondria​ (ATP for active transport)
Nephron
● Nephron​: functional units in kidney made of glomerulus and various tubules
Ultrafiltration Capillaries Tubules
-​Afferent arteriol​e: brings unfiltered
blood
-​Glomerulus​: site of ultrafiltration
-​Bowman’s capsule​: collects fluid
filtered from blood
-​Efferent arteriole​: transports filtered
blood (narrow for high pressure)
-​Vasa recta​: carries blood into medulla
and back to cortex
-​Peritubular capillaries​: absorbs fluid
from convoluted tubules
-​Venule​: carries blood to renal vein
-​Proximal convoluted tubule​: actively
reabsorbs useful substances from
filtrate
-​Loop of Henle​: carries filtrate into
medulla and back to cortex
-​Distal convoluted tubule​: reabsorbs
useful substances (less capable)
-​Collecting duct​: carries filtrate to
renal pelvis (to urine)

6. Loop of Henle function
● Descending​ loop of Henle: ​permeable to water​ but not to sodium ions → increased solute concentration
● Ascending​ loop of Henle: ​permeable to sodium ions​ but not to water → allow osmosis of water from descending loop
● Filtrates more sodium than water (dilute)
● Generate ​high concentration of solutes in medulla​ compared to filtrate in nephron → ​aid reabsorption of water​ (by
medulla) ​in the collecting duct
Some animals have long loops of Henle
● Longer loop of Henle → ​more water reabsorption​ by the medulla
● Common in animals adapted to ​dry habitats
Function of ADH
● ADH​: hormone which balances the water concentration of the blood by changing the permeability of the collecting
duct
● If the individual is dehydrates, ADH makes the collecting duct more permeable to water (​allows individuals to excrete
less water​)
Animals vary in terms of the type of nitrogenous waste they produce
● Different organisms are adapted to excrete nitrogenous waste in different forms (ammonia, urea, or uric acid)
○ Ammonia is toxic
○ Conversion of ammonia into uric acid or urea requires extra energy
○ Uric acid doesn’t require water to excrete
○ Uric acid doesn’t dissolve in eggs when released by developing fetus (less toxic)
● Excretion of nitrogenous waste in different organisms
○ Most marine animals release waste directly as ammonia (can be diluted)
○ Terrestrial organisms (including marine mammals) use energy to convert ammonia into less toxic urea or
uric acid
○ Amphibians release ammonia in larval stage and release urea after metamorphosis (less energy)
○ Birds and insects convert ammonia into uric acid (no water = less weight to carry)
Dehydration and overhydration consequences
Dehydration Overhydration
-Metabolic waste cannot be removed (urine requires
water) → increased tissue exposure to metabolic waste
-Less water in blood → low blood pressure
-Unable to sweat → body temperature cannot be
controlled
-Dilution of blood solutes → body fluid becomes
hypotonic (low solute) → swelling of cells due to osmosis
Kidney failure treatment
Hemodialysis Kidney transplant
-Uses dialysis machine (​artificial kidney​)
-Common when kidney is unable to filter out products
properly
-Risk of ​infection
-Kidney from donor is ​transplanted​ to recipient
-Greater independence for recipient
-Recipient’s body ​may reject organ

7. Urinalysis
● Urinalysis: detects blood cells, glucose, proteins, and drugs in urine
● Indications
○ Blood cells: cancer, infections, diseases
○ Glucose: diabetes
○ Large number of proteins: kidney disease
○ Drugs: drug usage
11.4 Sexual Reproduction
Similarities between oogenesis and spermatogenesis
● Oogenesis​: production of egg cells in the ​ovaries
● Spermatogenesis​: production of sperm cells in the ​testes​ (inside ​seminiferous tubules​)
● Similarities
○ Ultimately produces haploid cells through meiosis
○ Undergoes mitosis to produce diploid cells
Stages of gametogenesis
● Oogenesis
1. (During ​fetal development​) ​germinal cells​ undergo ​mitosis​ to produce 2 diploid ​oogonia​ (2n) and grows
larger (​stops at prophase​)
2. (At ​puberty​) ​oogonium ​(2n) undergoes ​mitosis​ to produce 2 diploid ​primary oocytes​ (2n) [becomes
contained in primary follicles​]
3. Primary oocytes​ (2n) undergoes ​meiosis I​ to produce a ​secondary oocytes​ (n) and a ​polar body​ (n)
a. Polar body (n) ​degenerates​ (unequal division)
b. Secondary oocytes​ (n) continues into meiosis II (​stops at prophase II​)
4. Secondary oocyte​ (n) completes meiosis II in ​secondary follicle​, forms ovum (​egg​) and a polar body (n)
a. Polar body (n) degenerates
b. Ovum (​egg​) remains inside mature follicle
5. Ovum (​egg​) is ovulated and the follicle forms ​corpus
luteum​, which produces estrogen and progesterone
(develops uterus lining) and degenerates
● Spermatogenesis
1. Outer layer cells​ (​germinal epithelial cells​) undergo
mitosis​ to produce 2 diploid ​spermatogonia ​(2n)
2. Spermatogonium​ (2n) grows larger into ​primary
spermatocytes​ (2n)
3. Primary spermatocytes​ (2n) undergoes ​meiosis I​ to
produce 2 ​secondary spermatocytes​ (n)
4. Secondary spermatocytes​ (n) undergoes ​meiosis II​ to
produce 2 ​spermatids​ (n)
5. Spermatids​ (n) associates with ​sertoli cells​ to differentiate
into spermatozoa (​sperm​)
6. Spermatozoa (​sperm​) detaches from Sertoli cells
Diagrams of seminiferous tubule and the ovary

8. Diagrams of sperm and egg
Differences in the outcome of spermatogenesis and oogenesis
Oogenesis Spermatogenesis
-Each meiotic division results in ​1 functioning haploid cell -Each meiotic division results in ​4 functioning haploid
cells
-Volume of ​cytoplasm increases​ (takes in volume from
polar body)
-Volume of ​cytoplasm decreases
-Continues ​until menopause​ after puberty -Continues ​until death​ after puberty
-Only ​few hundred​ eggs produced -​Millions​ of sperms are present at a time
Preventing polyspermy during fertilisation
● Fertilisation process
1. Acrosome reaction​: sperm binds to jelly coat, ​releases enzymes​ from the acrosome → digests jelly coat
2. Penetration​ of membrane: protein on the tip of sperm binds to egg membrane, ​fuses together​ → ​releases
sperm nuclei
3. Cortical reaction​: egg is activated and ​releases cortical granules​ (exocytosis) containing ​enzymes​ which
digest binding proteins​ and ​harden​ the jelly coat
Internal and external fertilisation
Internal fertilisation External fertilisation
-Common in terrestrial animals
-Prevents gametes from drying out
-Assures fertilisation (closer together)
-Embryo can be protected inside female
-Common in aquatic animals
-Risks predation, susceptibility to environmental variation
(e.g. temperature, pH)
Implantation of the blastocyst
● Blastocyst​: hollow ball of dividing cells undergoing mitosis (​early form of embryo​)
● Implantation​ (blastocyst sinking into the endometrium) process
1. (7 days) Blastocyst ​reaches uterus​, ​gel coat breaks down
2. Blastocyst sinks into the endometrium (​implantation​)
3. Blastocyst grows ​finger-like projections to penetrate uterus lining​ to obtain nutrients for growth
4. (8 weeks) blastocyst ​grows bone tissues​ → becomes fetus
Role of hCG in early pregnancy
● Embryo produces hCG at early stage of pregnancy
● hCG stimulates corpus luteum ​(ovary) to secrete progesterone and estrogen
→ stimulate development of uterus
Materials exchange by the placenta
● Placental villus​ increase during pregnancy to allow greater exchange of
materials
● Blood flows in the intervillous space​ to allow for greater exchange of
materials (between villi and intervillous space)
● Placental barrier thin​ to allow for quicker diffusion of nutrients
● Placental barrier is selectively permeable​ to regulate diffusion of nutrients
● Umbilical arteries carry deoxygenated blood​ (along with waste products)
● Umbilical vein carry oxygenated blood​ (along with hormones and nutrients)

9. Release of hormones by the placenta
● Placenta takes over role of secreting ​estrogen and progesterone​ (​corpus luteum unneeded​) after 9 weeks → stimulate
development of uterus
● Can lead to miscarriage if switchover fails
Role of hormones in parturition (birth)
● Progesterone produced by the placenta inhibits production of oxytocin​ (which stimulates contraction of muscle fibres
in the myometrium) and ​prevents contraction of ​myometrium
● Hormones produced at the end of pregnancy ​stops secretion of progesterone​ → oxytocin is produced
● Oxytocin contracts the myometrium, causing it to ​produce more oxytocin​ → gradual increase in contraction → birth
Gestation times, mass and growth, and development strategies
● Gestation time: length of time in which the fetus develops inside the womb
● Longer gestation period allows the newborn to be more independent (mobile, has hair, open eyes) → ​precocial
● Shorter gestation period leads to less developed newborn → ​altricial
Hormone functions in females summary
Hormone Produced by Function
FSH​ (follicle
stimulating hormone)
-Pituitary gland -Stimulates production of mature follicle around egg
hCG​ (human chorionic
gonadotropin)
-Embryo -Stimulates corpus luteum (ovary) to secrete progesterone and
estrogen
Progesterone -Corpus luteum
-Placenta
-Stimulates development of uterus wall
-Prevents contraction of uterus wall (myometrium)
Estrogen -Corpus luteum
-Placenta
-Development of secondary female sexual characteristics
Oxytocin -Pituitary gland -Stimulates contraction of uterus wall (myometrium)