Lesson Notes By Weeks and Term - Senior Secondary 1

TERM – 1^ST TERM

WEEK FOUR

Class: Senior Secondary School 1

Age: 15 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Biology

Topic: The cell

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

1. Define a cell
2. Identify the forms in which a cell exist.

iii. Identify the functions of a cell

1. Identify the similarities and differences between plants and animals cellv.

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION	TEACHER’S ACTIVITY	STUDENT’S ACTIVITY
STEP 1 INTRODUCTION	The teacher define the cell and explain the forms which a cell exist.	Students pay attention
STEP 2 EXPLANATION	Teacher discusses the functions of the cell.	Students pay attention and participate
STEP 3 DEMONSTRATIO N	Teacher explain the similarities between plants and animals cell (Using the diagram of both plant and animal cell)	Students pay attention and participate
STEP 4 NOTE TAKING	The teacher writes a summarized note on the board	The students copy the note in their books

 

NOTE

THE CELL

A cell is the basic structural and functional unit of all living organisms. It is the smallest unit of life that can carry out the fundamental processes necessary for an organism's existence. Cells can vary widely in structure, function, and size, but they share common features such as a cell membrane, genetic material (DNA or RNA), and the ability to undergo reproduction and metabolism. The diversity of cells contributes to the complexity and variety of living organisms.

Forms in which cells exist

Cells of living organisms exist in different forms, they include

1. Unicellular/single or free-living: Unicellular organisms consist of a single cell as their entire body. These organisms carry out all the necessary life processes within a single, microscopic cell. Examples of unicellular organisms include: Bacteria, Archaea, Protists, Yeasts
2. As colony: A colony of cells refers to a group of individual cells that live together but may not be structurally connected. Each cell in the colony is capable of functioning independently and carries out its own life processes. This is common in certain microorganisms. Examples include, Bacteria, Algae, Protozoa
3. As filament: Cells organized in filaments typically form a chain or thread-like structure, and this arrangement is commonly observed in certain types of organisms. Examples include: Cyanobacteria, Spirogyra (Green Algae), Streptomyces (Bacteria)
4. As part of a living organism: Cells are the fundamental units of life and are organized into tissues, organs, and systems within living organisms. The following is an overview of how cells function as part of a multicellular organism:

       -  Tissues: Cells of similar types group together to form tissues. Examples include muscle tissue, nerve tissue, and connective tissue. Each type of tissue has specialized functions         contributing to the overall function of the organ.

       - Organs:  Organs are structures composed of different types of tissues working together to perform specific functions. For instance, the heart is an organ made up of muscle               tissue, connective tissue, and nerve tissue, all working together to pump blood.

       - Organ Systems: Organs collaborate to form organ systems, such as the cardiovascular system, digestive system, or nervous system. These systems coordinate activities to               maintain the overall health and function of the organism.

       -  Whole Organism: Collectively, all the organ systems contribute to the functioning of the entire organism. Cells communicate and cooperate to sustain life processes, respond to         stimuli, reproduce, and maintain homeostasis.

Structure of plants and animals cell

Plant and animal cells share similarities in basic structure but have key differences. Both contain a cell membrane, nucleus, and cytoplasm. Plant cells have a rigid cell wall and chloroplasts for photosynthesis, while animal cells lack these features. Animal cells may have centrioles, absent in most plant cells, aiding in cell division.

 

Function of the cell components

Cells have various components, each with specific functions:

1. Cell Membrane: Regulates what enters and exits the cell, providing a protective barrier.
2. Nucleus: Contains genetic material (DNA) and controls cellular activities.
3. Cytoplasm: Gel-like substance where organelles are suspended and where many cellular processes occur.
4. Endoplasmic Reticulum (ER): Rough ER synthesizes proteins, while smooth ER is involved in lipid synthesis and detoxification.
5. Golgi Apparatus: Modifies, packages, and transports proteins and lipids.
6. Mitochondria: Generates energy through cellular respiration.
7. Vacuole (in plant cells): Stores nutrients and waste products.
8. Ribosomes: Synthesize proteins using information from the DNA.
9. Lysosomes: Contain enzymes for digestion and waste removal.
10. Cytoskeleton: Provides structural support and helps in cell movement.
11. Centrioles (in animal cells): Aids in cell division.

Similarities between plant and animal cells

Plants and animal cells share similarities in basic structures such as

1. The presence of a cell membrane, nucleus, and organelles like mitochondria and endoplasmic reticulum.
2. Both cell types also have a similar genetic material, DNA, housed in the nucleus. However, plant cells have unique features like a cell wall, chloroplasts for photosynthesis, and a large central vacuole, which are not present in animal cells.

Differences between plants and animals cell

The following are some major difference between plant and animal cells.

Feature	Plant Cell	Animal Cell
Cell wall	Present (composed of cellulose)	Absent
Chloroplasts	Present (for photosynthesis)	Absent
Vacuoles	Large central vacuole	Smaller and fewer vacuoles
Shape	Fixed, often rectangular	Variable in shape
Lysosomes	Less common, may have similar structures	Common, present as true lysosomes
Centrioles	Usually absent	Present, involved in cell division
Morality structure	Typically absent	Cilia, flagella, or other motility structures
Nucleus position	Usually centrally located	Can be centrally or peripherally located

 

EVALUATION: 1. identify 2 similarities between plant and animal cell

2. Identify four difference between plant and animal cells
3. Mention at least five functions of a cell
4. Identify the forms in which a cell can exist

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively