IB MYP Integrated Science- Biology - Cells, tissues, organs, and systems-Study Notes - New Syllabus
IB MYP Integrated Science- Biology – Cells, tissues, organs, and systems -Study Notes – New syllabus
IB MYP Integrated Science- Biology – Cells, tissues, organs, and systems -Study Notes -As per latest Syllabus.
Key Concepts:
Update
IB MYP Integrated Science -Concise Summary Notes- All Topics
Cells
🌱 What is a Cell?
A cell is the smallest living structure capable of performing all life processes.
Every organism, from tiny bacteria to humans, is made of cells.
Why cells matter
- They carry genetic information (DNA).
- They perform all metabolic activities.
- They grow, divide, and keep the organism alive.
Cells are often called the building blocks of life.
🌿 Discovery of Cells
- Robert Hooke (1665): observed cork cells → coined the term “cell”.
- Leeuwenhoek: first to observe living cells (bacteria, protozoa).
- Advances in microscopes helped us understand more structure and functions.
🧠 Cell Theory – Core Rules
Modern cell theory states:
- All organisms are made of one or more cells.
- The cell is the basic unit of structure and function.
- All cells arise from pre-existing cells (through division).
- Cells contain DNA which is passed from one cell to the next.
- All life activities occur inside cells.
🧫 Types of Cells
A. Prokaryotic Cells
Small, simple, primitive.
- No true nucleus (DNA floats in nucleoid region).
- No membrane-bound organelles.
- Ribosomes are present but small.
- Cell wall usually present.
- Reproduce by binary fission.
- Examples: bacteria, archaea.
B. Eukaryotic Cells
Large, complex, advanced.
- True nucleus enclosed by a nuclear membrane.
- Many organelles like mitochondria, ER, Golgi, lysosomes.
- Cytoskeleton for support and shape.
- Can be unicellular or multicellular.
- Examples: plant cells, animal cells, fungi, protists.
🍃 5. Plant Cell vs Animal Cell
Plant Cells
- Have cell wall (cellulose).
- Contain chloroplasts.
- Large central vacuole.
- Usually fixed, rectangular shape.
Animal Cells
- No cell wall.
- No chloroplasts.
- Many small vacuoles.
- Usually rounded or irregular.
🏭 Structure of a Cell – Organelles & Functions
Below are a breakdown of major organelles and their roles.
- Cell Membrane
Thin, flexible boundary around the cell.
Controls what enters and exits.
Made of phospholipid bilayer + proteins.
Maintains homeostasis. - Cytoplasm
Jelly-like fluid where all reactions occur.
Contains organelles.
Mostly water, salts, and proteins. - Nucleus
Largest organelle in many cells.
Stores DNA as chromatin.
Has nucleolus (makes ribosomes).
Controls cell growth, protein synthesis, and division. - Mitochondria
Powerhouse of the cell.
Produces ATP through respiration.
Has its own DNA. - Ribosomes
Tiny particles made of rRNA + proteins.
Sites of protein synthesis.
Free in cytoplasm or attached to rough ER. - Endoplasmic Reticulum (ER)
Rough ER: has ribosomes, makes proteins.
Smooth ER: makes lipids, detoxifies chemicals. - Golgi Apparatus
Packages, modifies, and transports proteins.
Forms vesicles and lysosomes. - Lysosomes (Animal)
Contain digestive enzymes.
Break down waste and old organelles. - Vacuoles
Storage sacs.
Plants: one large central vacuole.
Animals: many small vacuoles. - Chloroplasts (Plants)
Site of photosynthesis.
Contain chlorophyll.
Have their own DNA. - Cell Wall (Plants)
Strong outer layer.
Made of cellulose.
Provides structure, shape, and protection. - Cytoskeleton
Network of protein fibers.
Gives shape, helps in movement, anchors organelles.
🔁 How Cells Reproduce
Cells divide to make new cells.
- Mitosis (growth, repair, asexual reproduction)
- Meiosis (gamete formation in sexually reproducing organisms)
🔋 Why Cells Stay Small
- Smaller cells exchange materials faster.
- Large surface area to volume ratio ensures efficient transport.
- Diffusion becomes slow if a cell grows too large.
🧩 Specialized Cells
Different cells perform different tasks.
- Neurons → transmit signals
- Muscle cells → contraction
- RBCs → carry oxygen
- Guard cells → control stomatal opening
- Root hair cells → absorb water
Specialization is called cell differentiation.
📌 Summary Table
| Part | Function |
|---|---|
| Cell membrane | Controls entry and exit |
| Nucleus | Stores DNA, controls activities |
| Mitochondria | Produces energy |
| Ribosomes | Make proteins |
| ER | Synthesizes proteins/lipids |
| Golgi | Packages & transports |
| Lysosomes | Digestion |
| Vacuole | Storage |
| Chloroplast | Photosynthesis |
| Cell wall | Support & protection |
⚡ Quick Recap
Cell = smallest unit of life
Two types: prokaryotic & eukaryotic
Plant vs animal cell differences
Organelles + their key functions
Cell theory basics
Specialized cells exist for specific tasks
Tissues
🌱 Introduction
A tissue is a group of similar cells that work together to perform a specific function.
Cells organize into tissues → tissues form organs → organs form systems.
Why tissues matter
- They allow division of labour inside the body.
- They make organisms more efficient.
- They give structure and support to organs.
Multicellular organisms survive because tissues share work and support each other.
🧬 Types of Tissues
Tissues differ in plants and animals, so they are studied separately.
Plant Tissues
Plant tissues are grouped into meristematic (actively dividing) and permanent (fully differentiated).
Meristematic Tissues
These are actively dividing tissues found in growing regions of plants.
Key Features
- Thin-walled cells
- Dense cytoplasm
- Large nucleus
- No or very small vacuole
- Cells tightly packed
Types
- Apical Meristem
Located at root and shoot tips
Responsible for primary growth (length) - Intercalary Meristem
Found at internodes or leaf bases
Helps in regrowth (e.g., grass) - Lateral Meristem
Found in sides of stems and roots
Responsible for secondary growth (thickness)
Includes cambium and cork cambium
Permanent Tissues
These come from meristematic tissues after they stop dividing and become specialized.
Two Types
1. Simple Permanent Tissues
- Parenchyma
Soft, loosely packed
Thin walls, large vacuole
Stores food
Forms bulk of plant body
Special type: Aerenchyma for floating plants - Collenchyma
Thickened corners
Provides support and flexibility
Present in leaf stalks and young stems - Sclerenchyma
Very thick, lignified walls
Dead at maturity
Provides hardness and rigidity
Found in shells of nuts and coconut fibers
2. Complex Permanent Tissues
- Xylem (water transport)
Components: tracheids, vessels, xylem parenchyma, xylem fibers
Conducts water and minerals upward
Provides mechanical support - Phloem (food transport)
Components: sieve tubes, companion cells, parenchyma, fibers
Transports sugar (food) from leaves to other parts
Animal Tissues
Epithelial Tissue
Covers body surfaces and lines organs.
Features
- Cells tightly packed
- Acts as a barrier
- Protects, absorbs, secretes
Types
- Squamous
- Cuboidal
- Columnar
- Ciliated
- Glandular
Muscular Tissue
Enables movement through contraction.
- Skeletal muscle
Voluntary, striated, multinucleated
Moves bones - Smooth muscle
Involuntary, non-striated
Found in stomach, intestines, blood vessels - Cardiac muscle
Involuntary, striated
Found only in heart
Has intercalated discs
Never fatigues
Nervous Tissue
Specialized for communication and control.
- Contains neurons and glial cells
- Neuron parts: dendrites, cell body, axon
- Receives, processes and sends signals
Connective Tissue
Supports, protects and connects structures.
- Areolar tissue
- Adipose tissue
- Bone
- Cartilage
- Tendons
- Ligaments
- Blood
📊 Summary Table
| Tissue Type | Major Function | Examples |
|---|---|---|
| Meristematic | Growth | Apical, intercalary, lateral |
| Simple permanent | Storage and support | Parenchyma, collenchyma |
| Complex permanent | Transport | Xylem, phloem |
| Epithelial | Protection and lining | Skin, gut lining |
| Muscular | Movement | Skeletal, smooth |
| Nervous | Coordination | Neurons |
| Connective | Support and transport | Bone, blood |
📦 Quick Recap
Tissue = group of similar cells working together
Plants → meristematic and permanent tissues
Animals → epithelial, connective, muscular, nervous
Each tissue type has a special structure to match its function
Organs and Systems
🌱 Introduction
An organ is a structure made of different tissues working together to perform a specific job.
Example: the heart pumps blood, the stomach helps in digestion.
🧬 What exactly is an Organ?
- Formed when two or more tissues combine.
- Tissues stay arranged in a special way so the organ can work smoothly.
- Each organ has its own shape, location, blood supply and function.
- Organs are the building blocks for organ systems.
🧱 Examples of Organs
- Heart
Pumps blood throughout the body.
Made of cardiac muscle, connective tissue, nervous tissue and blood vessels. - Lungs
Main site for gas exchange.
Contain alveoli lined with epithelial tissue. - Stomach
Breaks down food using acid and enzymes.
Has muscular walls for churning. - Kidneys
Filter blood and remove wastes (urea, salt, excess water). - Brain
Control center for thoughts, movements and sensations. - Skin
Largest organ.
Protects body and regulates temperature.
📌 Key Points to Remember
- Organs = multiple tissues working as a team.
- Each organ has one main function but may assist in others.
- Organs interact with each other to form systems.
🌐 Systems
A system is a group of organs working together to carry out a major life function.
Examples: digestion, breathing, movement, circulation.
🧬 What is a System?
- Highest level of body organisation.
- Formed by many organs linked physically or functionally.
- Helps the body function as one coordinated unit.
- If one system fails, others are affected because everything is interconnected.
🧩 Major Human Body Systems
- Digestive System
Breaks down food and absorbs nutrients.
Main organs: mouth, stomach, liver, small intestine. - Respiratory System
Takes in oxygen and removes carbon dioxide.
Main organs: lungs, trachea, diaphragm. - Circulatory System
Transports blood, gases, nutrients and wastes.
Main organs: heart, arteries, veins, capillaries. - Excretory System
Removes metabolic wastes.
Main organs: kidneys, ureters, bladder. - Nervous System
Controls and coordinates body activities.
Main organs: brain, spinal cord, nerves. - Endocrine System
Regulates long-term processes using hormones.
Main organs: thyroid, pituitary, pancreas. - Musculoskeletal System
Supports the body and helps movement.
Main organs: bones, muscles, joints. - Reproductive System
Produces gametes and supports reproduction.
Main organs: testes, ovaries, uterus. - Immune or Lymphatic System
Defends against infections, clears toxins.
Main organs: lymph nodes, spleen, lymph vessels. - Integumentary System
Protects body and regulates temperature.
Main organ: skin.
🔗 How Organ Systems Work Together
- Respiratory + Circulatory → oxygen from lungs carried by blood.
- Digestive + Circulatory → nutrients absorbed into bloodstream.
- Nervous + Muscular → nerves send signals for movement.
- Endocrine + Reproductive → hormones control reproductive processes.
📊 Summary Table
| Level | Meaning | Examples |
|---|---|---|
| Organ | Structure made of multiple tissues | Heart, lungs, kidney |
| System | Group of organs doing a major function | Digestive system, nervous system |
📦 Quick Recap
Organs are made of many tissues.
Each organ has a main job.
Systems are made of many organs.
10 major systems: digestive, respiratory, circulatory, excretory, nervous, endocrine, musculoskeletal, reproductive, immune, integumentary.
Systems always work together for survival.