Lesson Notes By Weeks and Term v4 - JHS 1
LIVING CELLS
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LIVING CELLS
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Subject: Science
Class: JHS 1
Term: 1st Term
Week: 6
Grade code: B7.1.2.1.2
Strand code: 1
Sub-strand code: 2
Content standard code: B7.1.2.1
Indicator code: B7.1.2.1.2
Theme: DIVERSITY OF MATTER
Subtheme: LIVING CELLS
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All living things in Ghana—humans, goats, maize plants, mushrooms, even the tiny organisms in “koko” fermentation—are made of cells. Cells are the basic unit of life. Understanding the parts of a plant cell and what each part does helps learners explain real-life issues such as: why plants need water, why leaves are green, how crops grow, and why plants wilt when conditions are poor. Indicator focus (B7.1.2.1.2): *State the functions of each (organelle/part of the plant cell).*
2.1 What is a cell? A cell is the smallest unit that can carry out all life processes (nutrition, respiration, growth, excretion, reproduction, response). Unicellular organisms have one cell (e.g., some bacteria). Multicellular organisms have many cells (e.g., humans, cassava plant). 2.2 Plant cell (focus) and why it is special A plant cell is a type of eukaryotic cell (it has a true nucleus). Plant cells have some parts that animal cells do not have, such as: Cell wall Chloroplasts Large central vacuole 2.3 Plant cell organelles and their functions (core of the indicator)
Below are the main parts learners should know at JHS1 level, with clear functions and Ghanaian examples. 1) Cell wall Description: Tough, non-living outer layer made mainly of cellulose. Function: Gives the cell shape and support (helps plants stand upright). Protects the cell. Prevents the cell from bursting when too much water enters. Example: When kontomire (cocoyam leaves) is fresh and firm, strong cell walls help maintain structure. 2) Cell membrane (plasma membrane) Description: Thin living layer just inside the cell wall. Function: Controls what enters and leaves the cell (selectively permeable). Helps maintain a stable internal environment. Example: Like a security gate at a school—some things are allowed in, others are not. 3) Cytoplasm Description: Jelly-like fluid where organelles are found. Function: Site for many chemical reactions. Holds organelles in place and allows materials to move around the cell. Example: Like soup in which pieces of fish and vegetables (organelles) are found. 4) Nucleus Description: Control centre containing genetic material (DNA). Function: Controls cell activities (growth, repair, reproduction). Contains instructions for making proteins. Example: Like the headteacher’s office directing school activities. 5) Chloroplast Description: Green organelle containing chlorophyll. Function: Site of photosynthesis—makes food (glucose) using sunlight, water, and carbon dioxide. Gives leaves their green colour. Example: Explains why maize leaves are green and why plants grow better in sunlight.
Photosynthesis word equation (for understanding): Carbon dioxide + Water —(sunlight, chlorophyll)→ Glucose + Oxygen 6) Large central vacuole Description: Large fluid-filled sac containing cell sap. Function: Stores water, salts, sugars, and wastes. Maintains turgor pressure (keeps plant firm and upright). Example: When a garden egg plant is not watered, vacuoles lose water, cells become flaccid, and the plant wilts. 7) Mitochondrion (mitochondria) Description: Small organelle where respiration occurs. Function: Releases energy from food during cellular respiration. Provides energy for growth, transport, and repair. Example: Even at night when there is no sunlight, plants still need energy—mitochondria help provide it. 8) Ribosomes Description: Tiny structures found in cytoplasm (and on rough ER in higher detail). Function: Site of protein synthesis (making proteins needed for growth and repair). Example: Proteins help form enzymes that support processes like ripening of fruits (e.g., mango). 9) Endoplasmic reticulum (ER) *(basic mention for JHS1)* Description: Network of membranes inside the cell. Function: Helps transport materials within the cell. Rough ER (with ribosomes) helps in protein processing. Example: Like corridors in a school that help move people/materials from one room to another. 10) Golgi apparatus *(basic mention)* Description: Stack-like organelle. Function: Packages and transports proteins and other materials to where they are needed. Example: Like a packaging centre that prepares goods for delivery.
> Teacher note (scope control): For JHS1, ensure learners master the functions of: cell wall, cell membrane, cytoplasm, nucleus, chloroplast, vacuole, mitochondria, ribosomes. ER and Golgi can be enrichment or brief mention. 2.4 How the parts work together (simple reasoning) Chloroplast makes food (glucose) in sunlight. Mitochondria use glucose to release energy. Nucleus controls the whole process and cell division. Vacuole stores water and keeps the plant firm. Cell membrane controls entry/exit of materials needed for photosynthesis and respiration. Cell wall supports and protects.