Curriculum
Biology & Geology (STEM)
Chapter 1 - Support and Movement in Living Organisms
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1.1Why is support needed?1.2Support in plants1.3Support in animals1.4The human skeletal system1.5First: the skeleton1.62.1.1 The vertebral column1.72.1.2 The skull (cranium)1.82.1.3 The thoracic cage1.92.1.4 The pectoral girdle and the upper limb1.102.1.5 The pelvic girdle and the lower limb1.11Second: cartilages1.12Third: joints1.13Fourth: ligaments1.14Fifth: tendons
2.1Movement in living organisms2.2Movement in plants2.3Systems that cooperate in movement2.4The muscular system2.5Structure of a skeletal muscle2.6How the nerve impulse reaches the muscle2.7The sliding-filament theory of muscle contraction (Huxley)2.8Muscle fatigue and cramp2.9Summary of coordination in movement2.10Comparison: voluntary and involuntary muscles2.11Key terms2.12Practical tips for answering exam questions
Chapter 2 - Hormonal Coordination in Living Organisms
0/321.1Control of body functions1.2What is a hormone?1.3Discovery of animal hormones — Starling (1905)1.4Plant hormones — Jensen (1913)1.5How scientists found out what hormones do1.6Characteristics of hormones1.7Types of glands in man1.8Position and structure1.9Hormones of the adenohypophysis (anterior lobe)1.10Hormones of the neurohypophysis (posterior lobe)1.11The thyroid gland1.12Diseases of the thyroid (due to hypo- or hypersecretion of thyroxine)1.13The parathyroid glands
2.1The adrenal (suprarenal) glands2.2Hormones of the cortex (steroids; controlled by ACTH)2.3Hormones of the medulla (amino-acid derivatives; controlled by nerves)2.4The pancreas as a mixed gland2.5Insulin2.6Glucagon2.7Diabetes mellitus (hyposecretion of insulin)2.8The sex glands (gonads)2.9Male sex hormones — androgens2.10Female sex hormones2.11Gastrointestinal hormones2.12Comparison between nervous and hormonal co-ordination2.13Summary table of the endocrine glands2.14Key terms2.15Negative feedback — the idea behind every endocrine gland2.16Antagonistic pairs2.17Hormones that are linked to the hypothalamus2.18Additional worked examples2.19Typical exam checklists
Chapter 3 - Reproduction in Living Organisms
0/331.1Importance of reproduction1.2Reproductive capacity1.3Methods of reproduction1.4Asexual reproduction1.5Sexual reproduction1.6Comparison between asexual and sexual reproduction1.7Alternation of generations1.82.4.1 Life cycle of Plasmodium (malaria parasite)1.92.4.2 Life cycle of a fern (Polypodium, Adiantum)
4.1The breeding cycle and the menstrual cycle4.2Fertilisation4.3Pregnancy and embryonic development4.4Contraception (birth control)4.5Multiple births and twins4.6Test-tube babies (in vitro fertilisation, IVF)4.7Cloning and embryo culture4.8Gamete banks and sex control4.9Ethical note4.10Practical observations (as listed at the end of the chapter)4.11Summary comparisons4.12Key terms
Chapter 4 - Immunity in Living Organisms
0/341.1The constant threat1.2Definition1.3Two systems working together1.4Worked example 1 — classifying a defence1.5Worked example 2 — one infection, both systems1.6Immunity in plants1.7Structural immunity1.8Biochemical immunity1.9Why are phenols "biochemical" but cork "structural"?1.10Worked example 3 — what does a cut do to a tree?1.11Worked example 4 — compare two plants1.12Summary table — plant immunity
2.1Overview2.2Lymphoid organs2.3Worked example 5 — why swollen glands?2.4Summary table — lymphoid organs2.5White blood cells (leukocytes)2.6Antigens2.7Helper chemicals2.8Worked example 6 — why do interferons protect neighbours?2.9Antibodies2.10Structure of an antibody2.11How antibodies act2.12Worked example 7 — classify the mechanism
3.1How the human body protects itself3.2Natural (innate) immunity3.3Worked example 8 — a cut finger3.4Acquired (specific, adaptive) immunity3.5Worked example 9 — why a virus-infected cell cannot be cleared by antibodies3.6Stages of the acquired response — primary and secondary3.7Worked example 10 — reading the response graph in words3.8Comparison tables for revision3.9Key terms3.10Final recap
Chapter 5 - Molecular Biology - DNA Structure and Function
0/371.1The question1.2Evidence 1 — Bacterial transformation (Griffith, then Avery)1.3Evidence 2 — Bacteriophages (Hershey and Chase)1.4Is DNA the genetic material of every organism?1.5Evidence 3 — The quantity of DNA in cells1.6Worked example 1 — interpreting a Griffith-type result1.7Worked example 2 — predict the Hershey–Chase outcome
2.1The structure of DNA2.2The data a model had to fit2.3The Watson–Crick model2.4Why the model fits the data2.5Worked example 3 — complementary strand2.6Worked example 4 — base percentages2.7Worked example 5 — a test for the type of nucleic acid2.8Why replicate?2.9The steps and the enzymes2.10Where replication starts2.11Summary of the enzymes2.12Worked example 6 — template and product2.13Worked example 7 — how many fragments?2.14Worked example 8 — speed of copying2.15DNA damage and repair2.16Worked example 9 — why does RNA virus mutate more?2.17Prokaryotes2.18Eukaryotes – chromatin and condensation2.19Comparison2.20Worked example 10 — packing ratio2.21The genome2.22Repetitive DNA2.23Worked example 11 — reasons2.24Definition2.25Kinds2.26Gamete and somatic mutations2.27Origin of mutations2.28Worked example 12 — classify2.29Key terms2.30Final recap
Chapter 6 - Molecular Biology - RNA, Protein Synthesis and Genetic Engineering
0/381.1Two main groups1.2One building plan for thousands of proteins1.3Worked example 1 — counting bonds1.4RNA: structure and difference from DNA1.5Worked example 2 — identify the nucleic acid1.6Messenger RNA (mRNA) and transcription1.7Ribosomal RNA (rRNA)1.8Transfer RNA (tRNA)1.9Comparison1.10Worked example 3 — transcription1.11Why a triplet code?1.12Properties of the code1.13The codon table (mRNA, read 5′→3′; for reference)1.14Counting rules1.15Worked example 4 — translate1.16Worked example 5 — from DNA to protein1.17Worked example 6 — a gene of 150 base pairs1.18Worked example 7 — the effect of a mutation1.19Initiation1.20Elongation1.21Termination1.22Polyribosomes1.23The whole pathway1.24Worked example 8 — number of peptide bonds1.25Worked example 9 — why polysomes?
2.1Modern techniques of molecular technology2.2Nucleic acid hybridisation2.3Restriction endonucleases2.4Cloning a gene in a plasmid2.5Reverse transcriptase and cDNA2.6Polymerase chain reaction (PCR)2.7Recombinant DNA and its applications2.8Worked example 10 — design a cloning experiment2.9Worked example 11 — hybridisation question2.10The Human Genome Project2.11Worked example 12 — why compare genomes?2.12Key terms2.13Final recap
Chapter 7 - Geology, Earth Sciences and Ecology
0/202.11 Minerals: importance and definition2.22 Formation and chemical groups of minerals2.33 Crystallography: crystal structure and crystal systems2.44 Optical properties of minerals2.55 Cohesive properties of minerals2.66 Rocks and their three types2.77 Igneous rocks2.88 Sedimentary rocks2.99 Metamorphic rocks2.1010 Weathering2.1111 The rock cycle
Text lesson
Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans
Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans
Overview
Overview
🌳 Concept tree
Lesson 2→Movement in Plants and Muscle Contraction Mechanics in Humans
├── Movement in living organisms
├── Movement in plants
├── Systems that cooperate in movement
├── The muscular system
├── Structure of a skeletal muscle
├── How the nerve impulse reaches the muscle
- ├── The sliding-filament theory of muscle contraction (Huxley)
├── Muscle fatigue and cramp
├── Summary of coordination in movement
├── Comparison→voluntary and involuntary muscles
├── Key terms
└── Practical tips for answering exam questions
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Movement in living organisms
Movement in living organisms
- Movement is a phenomenon that distinguishes living organisms. It has several forms:
| Comparison aspect | Main idea | Example | Keywords |
|---|---|---|---|
| Movement inside the cell |
|
| continuousvitalactivitiescytoplasmic |
| Positional movement of parts | one part of the body moves while the organism stays in place — |
| bodymoveswhileorganism |
| Locomotion (total movement) |
| — | wholeorganismmovesplace |
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Movement in plants
Movement in plants
- Plants usually do not change place, but their parts do move in response to stimuli.
- (a) Touch movement (nastic movement).
- The leaves of Mimosa pudica (the "sensitive plant") collapse and fold their leaflets when touched.
- The movement is a response to a stimulus whose direction does not determine the direction of the movement; it is caused by rapid loss of turgor in the cells of the swollen leaf base (pulvinus).
- (b) Sleeping movement.
- The leaves of Mimosa and of some legumes partly close in darkness and return to their open position in the light.
- This alternation of light and dark produces the daily rhythm of the leaves, similar to sleeping and waking in animals; so it is called the sleeping movement.
- (c) Tropisms.
- A tropism is a growth response of part of a plant to a directional stimulus — light (phototropism), water/humidity (hydrotropism), gravity (geotropism), touch/contact (haptotropism/thigmotropism).
- The response is positive if towards the stimulus and negative if away from it.
- Hormonal control by auxins is explained in Chapter 2.
- (d) Haptotropism (pulling/twining movement). A special kind of movement seen in the tendrils of the pea plant, and in the contractile (pulling) roots of corms and bulbs.
- Tendrils. A tendril rises into the air and, as it grows, makes contact with a solid object.
- It then twines round the object in a few spiral turns.
- Its length decreases, so the stem is drawn near the support and can grow upright.
- The tendril thickens and lays down a good deal of mechanical (supporting) tissue, becoming stronger.
- If a tendril finds no support it withers and dies.
- Cause of twining growth is slower on the side that touches the support and faster on the side away from the support.
- The longer outer side makes the tendril curl around the support.
- Pulling roots of corms and bulbs. Corms and bulbs have special roots below them.
- When these roots contract (shorten), they pull the corm or bulb down to a suitable depth in the soil.
- The underground stem stays at a suitable distance from the surface, which supports it and protects the aerial parts from wind.
| Point | Pulling of tendrils | Pulling of roots of corms and bulbs |
|---|---|---|
| Stimulus | Contact with a solid support | Need to reach the correct soil depth |
| Mechanism | Unequal growth of the two sides | Contraction (shortening) of the contractile roots |
| Result | Plant climbs and is supported | Underground stem is pulled down and anchored |
| Organ | Tendril (aerial) | Roots (underground) |
- (e) Cytoplasmic streaming.
- Living cytoplasm is in continuous rotational movement inside the cell.
- It is easily seen in the leaf cells of Elodea (aquatic plant) under the high-power microscope: the cytoplasm forms a thin layer lining the inner side of the cell wall and flows in one direction.
- The movement is revealed by the chloroplasts carried along in the cytoplasm.
- It distributes materials inside the cell.
✍️ Worked examples
- Worked example 5.
- A student places a cucumber tendril against a pencil.
- After two hours the tendril has curled around it.
- Which cells grew faster?
- Those on the side away from the pencil, because the contact side grows more slowly; the faster growth of the outer side causes bending towards the support.
- Worked example 6.
- Why do Mimosa leaves open again some minutes after being touched?
- The cells in the pulvinus regain water, and turgor is restored.
Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans · 3 / 14
Systems that cooperate in movement
Systems that cooperate in movement
- In man (as an example of mammals) movement depends on three systems working together:
The skeletal systemprovides the levers and a firm place for the muscles to attach; the joints allow the movement.
The muscular systemcontracts and relaxes and so moves the bones.
The nervous systemsends the commands (nerve impulses) that make the muscles contract or relax.
If any system is damaged, movement is disturbed→broken bone, torn muscle, or damaged nerve each prevent normal movement.
Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans · 4 / 14
The muscular system
The muscular system
- The unit of structure of the muscular system is the muscle, made of muscular tissue.
- There are about 620 or more muscles in man (flesh).
- Muscles allow mechanical movement and locomotion.
- General characteristic of muscle cells they are elongated (thread-like) and able to contract and relax.
- Functions of muscles:
- Locomotion (moving from one place to another) and all body movements.
- Pushing blood in the circulation and maintaining blood pressure by the contraction of the involuntary (smooth) muscles in the walls of blood vessels (and the cardiac muscle of the heart).
- Movement of food in the alimentary canal (peristalsis), breathing movements (diaphragm and intercostal muscles), maintaining posture, producing body heat, protecting internal organs.
- Types of muscle:
| Type | Control | Appearance | Location |
|---|---|---|---|
| Skeletal | Voluntary | Striated | Attached to bones |
| Smooth | Involuntary | Unstriated |
|
| Cardiac | Involuntary | Striated (branched) | Heart wall |
- Most body muscles are under the control of the will and are called voluntary (skeletal, striated) muscles; the others are involuntary.
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Structure of a skeletal muscle
Structure of a skeletal muscle
- A skeletal muscle is made up of many thin cells called muscle fibres. Going from large to small:
- Muscle → muscle bundles (fascicles) → muscle fibres (cells) → myofibrils → myofilaments (actin and myosin).
- The muscle fibres are grouped in bundles, each surrounded by a membrane called the perimysium.
- Each muscle fibre is a long multinucleated cell (many nuclei). It contains:
- cytoplasm called sarcoplasm;
- a surrounding cell membrane, the sarcolemma;
- myofibrils, 1000 to 2000 per fibre, running parallel to the long axis of the fibre.
- Each myofibril shows alternating light and dark bands (cross-striations) — which is why skeletal and cardiac muscle is called striated; smooth muscle does not have this pattern and is called unstriated.
- Light band (I-band): formed of thin protein filaments, actin. It is bisected by a dark line, the Z-line.
- Dark band (A-band): formed of thick protein filaments, myosin (the thin filaments overlap the ends of the thick ones). It is bisected by a lighter region, the H-zone, where only myosin is present.
- Sarcomere: the distance between two successive Z-lines. It is the structural and functional unit of contraction of the muscle.
| Comparison aspect | Main idea | Keywords |
|---|---|---|
| Diagram in words | Z — [half I-band] — A-band (with H-zone in the middle) — [half I-band] — Z | halfbandzonemiddle |
| Worked example 7 (sarcomere arithmetic). |
| relaxedlongmusclefibre |
Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans · 6 / 14
How the nerve impulse reaches the muscle
How the nerve impulse reaches the muscle
| Comparison aspect | Main idea | Keywords |
|---|---|---|
| Resting state. |
| outersurfacemusclefibre |
| Stimulus. | The stimulus for contraction is the motor impulse coming from the brain or spinal cord along a motor nerve that is connected to the muscle fibre by a synapse (neuromuscular junction) | contractionmotorimpulsecoming |
| Transmitter release. |
| nerveendingcontainssynaptic |
| Depolarisation. |
| Acetylcholinechangespermeabilitymuscle |
| Repolarisation. |
| Afterfractionsecondenzyme |
- Why is cholinesterase important? If acetylcholine were not destroyed, the membrane would stay depolarised, the muscle would be stimulated continuously, and could not relax or respond again to a new impulse (spasm).
- Some poisons (organophosphate insecticides, nerve gases) inhibit cholinesterase and cause convulsions for this reason.
Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans · 7 / 14
The sliding-filament theory of muscle contraction (Huxley)
The sliding-filament theory of muscle contraction (Huxley)
- The most acceptable explanation is that of Huxley.
- Using the electron microscope to compare a contracted fibre with a relaxed fibre, he concluded that the protein filaments slide over each other; neither filament itself shortens.
| Comparison aspect | Main idea | Keywords |
|---|---|---|
| Cross-bridges |
| projectionsheadsmyosinfilaments |
| Contraction |
| crossbridgesattachactin |
| Relaxation |
| stimulusstopscrossbridges |
- So ATP is needed twice once to give the energy for the pulling stroke when the bridges attach and bend, and once for detaching the bridges from the actin.
- If ATP is missing, the bridges stay attached, the muscle stays contracted and cannot relax (as in rigor mortis after death, when ATP production stops and the muscles stiffen).
| Part | Relaxed | Contracted |
|---|---|---|
| Sarcomere length | Long | Short |
| Z-lines | Far apart | Near each other |
| I-band | Wide | Narrow |
| A-band | Unchanged | Unchanged |
| H-zone | Present | Narrow/disappears |
| Cross-bridges | Detached | Attached to actin |
✍️ Worked examples
- Worked example 8 (identifying a band).
- In a micrograph, a band that stays the same length when the muscle contracts is the A-band (myosin length is constant).
- The band that disappears when the muscle is maximally contracted is the H-zone, because actin filaments from both sides meet in the middle.
- Worked example 9 (ATP shortage).
- A person dies; after a few hours the body stiffens.
- Why?
- ATP is no longer produced, so the cross-bridges cannot detach from actin; muscles remain in a fixed contracted state.
- After tissues break down, the stiffness disappears.
Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans · 8 / 14
Muscle fatigue and cramp
Muscle fatigue and cramp
| Comparison aspect | Main idea | Keywords |
|---|---|---|
| Fatigue. |
| Repeatedrapidcontractionsmuscle |
| • |
| keepcontractingmusclebreaks |
| Muscle spasm (cramp). |
| Shortagepreventscrossbridges |
| Recovery. |
| restmusclereceivesenough |
✍️ Worked examples
- Worked example 10.
- A sprinter finishes a 100 m race and breathes heavily for several minutes.
- Explain during the race the muscles worked partly anaerobically, building up lactic acid; the extra oxygen intake afterwards repays the oxygen debt, oxidising the lactic acid and restoring ATP and glycogen.
Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans · 9 / 14
Summary of coordination in movement
Summary of coordination in movement
- Brain/spinal cord → motor nerve → neuromuscular junction (acetylcholine) → depolarisation of the muscle membrane → release of calcium → attachment of myosin heads to actin using ATP → sliding of filaments → contraction of the sarcomere and the muscle → the tendon pulls the bone at the joint → movement.
- Relaxation cholinesterase destroys acetylcholine → repolarisation → calcium removed → cross-bridges detach (ATP) → sarcomere lengthens.
Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans · 10 / 14
Comparison: voluntary and involuntary muscles
Comparison: voluntary and involuntary muscles
| Point | Voluntary (skeletal) | Involuntary (smooth) |
|---|---|---|
| Control | Under will | Not under will |
| Fibre shape | Long cylinder, multinucleated | Spindle, one nucleus |
| Striations | Present | Absent |
| Nerve supply | Cerebrospinal (somatic) | Autonomic |
| Contraction | Rapid, tires quickly | Slow, rhythmic, tires slowly |
| Position | Attached to the skeleton | Walls of internal organs |
Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans · 11 / 14
Key terms
Key terms
- Support; turgor; cutin; suberin; collenchyma; sclerenchyma; endoskeleton; axial and appendicular skeleton; vertebra; centrum; neural canal; foramen magnum; floating ribs; glenoid cavity; acetabulum; synovial joint; ligament; tendon; Achilles tendon; haptotropism; cytoplasmic streaming; muscle fibre; sarcolemma; sarcoplasm; myofibril; actin; myosin; Z-line; I-band; A-band; H-zone; sarcomere; acetylcholine; cholinesterase; cross-bridge; fatigue; lactic acid; spasm.
Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans · 12 / 14
Practical tips for answering exam questions
Practical tips for answering exam questions
| Comparison aspect | Main idea | Keywords |
|---|---|---|
| When asked to label a vertebra, always include |
| centrumneuralarchcanal |
| When asked why muscles get tired, give the sequence | rapid contraction → insufficient oxygen → anaerobic breakdown of glycogen → lactic acid → fatigue | rapidcontractioninsufficientoxygen |
| When asked about cholinesterase, say | breaks acetylcholine into choline and acetic acid → repolarisation → muscle relaxes and is ready for the next impulse | breaksacetylcholineaceticacid |
| • |
| askedslidingfilamentsmention |
| • |
| margin18pxbordersolid |
Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans · 13 / 14
Part 14
Part 14
- 📖
🔍 In-Depth Explanations, Deductions & Multi-Book Insights:
- DABOUR HUB ACADEMY • EGYPTIAN HIGH SCHOOL (THANAWEYA AMMA)
- EXPLANATION Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans
- Course Biology (Senior 3) | Chapter 1 – Support and Movement in Living Organisms | Official Ministerial Syllabus 2026/2027
- ―――――――――――――――――――――――――――――――――――――――――――――――――――――――
1. Academic Lesson Overview & Pedagogical Objectives
- Movement is a fundamental sign of life.
- This lesson covers touch, sleep, tropism, and haptotropism in plants, alongside neuromuscular transmission, Huxley's sliding filament theory, and muscle fatigue in humans.
2. Hierarchy Classification Tree (Cognitive Concept Map)
- Below is the hierarchical structural tree organizing the conceptual core of this lesson:
Mechanisms of Biological Movement
├── 1. Movement in Plants
- │ ├── Touch & Sleep Movement (Mimosa leaves via turgor shifts in pulvini)
- │ ├── Tropism (Phototropism, Geotropism, Hydrotropism via auxin distribution)
- │ ├── Haptotropism (Tendril twining around supports in climbers: pea, grape)
- │ └── Cytoplasmic Streaming (Continuous cyclosis inside living cells)
└── 2. Muscular Movement in Humans
├── Structural HierarchyMuscle → Fascicles → Muscle Fibers → Myofibrils → Sarcomeres
├── Sarcomere AnatomyZ-lines, I-band (Actin), A-band (Actin+Myosin), H-zone (Myosin only)
└── Huxley Sliding Filament TheoryCa2+ uncovers binding sites, ATP bridges pull actin inward
3. The Master Teacher's Blackboard & Exam Rules
| Comparison aspect | Main idea | Keywords |
|---|---|---|
| • |
| Extractedhighyieldrules |
| • RULE 1 |
| Duringmusclecontractionlines |
| • RULE 2 |
| ionsessentialreleasingAcetylcholine |
| • RULE 3 | ATP is required during both contraction (pulling actin) and relaxation (detaching transverse bridges) | requiredduringbothcontraction |
| • TRAP |
| Musclefatigueresultsanaerobic |
Lesson 2: Movement in Plants and Muscle Contraction Mechanics in Humans · 14 / 14
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