7.4Unit 1: Cells and organisms
Cells tissues and organs — Cambridge Checkpoint Biology 0893 Revision Notes & Topical Questions
5 min read 9 parts Lesson 4 of 4 1 quiz
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Lesson summary
7.4 Cells tissues and organs — CHECKPOINT BIOLOGY 0893 notes: Describe the levels of organisation from cell to organism and compare the structures of plant and animal cells.The cell is the basic unit of life.The order is cell → tissue → organ → organ system → organism.Each level …
- Cell membrane
- Mitochondria
- Magnification
- Chloroplast
- Each level is built from the level before it
- Tissue = a group of similar cells that work together to carry out a function, such as muscle tissue
Section 1 of 9Levels of organisation
Levels of organisation
The cell is the basic unit of life.
The order is cell → tissue → organ → organ system → organism.
Each level is built from the level before it.
Section 2 of 9Tissue, organ and organ system
Tissue, organ and organ system
Tissue
Tissue a group of similar cells that work together to carry out a function, such as muscle tissue.
Organ
Organ a structure made of different tissues working together, such as the heart or a leaf.
Organ system
Organ system a group of organs working together, such as the digestive system.
Organism
Organism a whole living thing made of organ systems working together.
Section 3 of 9Examples
| Level | Human example | Plant example |
|---|---|---|
| Cell | Muscle cell | Palisade cell |
| Tissue | Muscle tissue | Palisade layer |
| Organ | Heart | Leaf |
| Organ system | Circulatory system | Shoot system |
| Organism | A person | A whole plant |
Examples
A leaf has several tissues: upper epidermis, palisade layer, spongy layer and lower epidermis.
The heart is made of muscle, nerve and other tissues.
Section 4 of 9Structures common to plant and animal cells
Structures common to plant and animal cells
Nucleus
- Nucleus contains genetic material and controls the cell.
Cytoplasm
- Cytoplasm where chemical reactions happen.
Cell membrane
- Cell membrane controls what enters and leaves.
Mitochondria
- Mitochondria the site of aerobic respiration, which releases energy.
Section 5 of 9Structures only in plant cells
Structures only in plant cells
Cell wall made of cellulose supports the cell and keeps its shape.
Chloroplasts contain chlorophyll and are the site of photosynthesis.
A large permanent vacuole containing cell sap keeps the cell firm.
Section 6 of 9Specialised cells in organs
1
Specialised cells have structures adapted to their job.
2
Red blood cells carry oxygen, with no nucleus and a biconcave disc shape.
3
Nerve cells are long and thin, with branched endings that carry electrical impulses.
4
Sperm cells have a tail and many mitochondria, and egg cells are large with a food store.
5
Root hair cells have a long extension and no chloroplasts, palisade cells have many chloroplasts, and ciliated cells have cilia that sweep mucus.
Section 7 of 9Magnification
Cells are observed with a light microscope.
Magnification
Magnification image size ÷ actual size, with both in the same unit.
Section 8 of 9Key terms
| Term | Meaning |
|---|---|
| Tissue | A group of similar cells working together to carry out a function. |
| Organ | A structure made of different tissues working together. |
| Organ system | A group of organs that work together. |
| Organism | A whole living thing. |
| Magnification | Image size divided by actual size. |
| Chloroplast | The structure where photosynthesis takes place. |
Section 9 of 9Exam technique
1
Saying an organ is a group of cells — it is a group of different tissues.
2
Saying the nucleus is the brain of the cell — it contains genetic material and controls the cell's activities.
3
Saying mitochondria make energy — they release energy by respiration.
4
Saying the cell wall controls what enters — the cell membrane does.
5
Saying animal cells have chloroplasts — only some plant cells have chloroplasts.
Marked practiceQuizzes for this lesson
Last updated:
Cambridge 9700 AS Biology
Core Formula
Magnification Triangle & Unit Conversion
Formula: M = I / A ⇔ A = I / M ⇔ I = M × A
Units: 1 mm = 1,000 μm = 1,000,000 nm.
Rule: Convert Image size (ruler mm) to μm by ×1,000 before dividing by Actual size.