The Cell Biology SS 1 First Term Lesson Notes Week 4

Biology Lesson Notes: The Cell

Subject: Biology
Class: SS1
Term: First Term
Week: 4
Age: 15-16 years

Topic: The Cell
Sub-topic: Structure and Function of the Cell
Duration: 2 weeks

Behavioural Objectives

By the end of the lesson, students should be able to:

Define what a cell is and explain its significance as the basic unit of life.
Describe the different forms in which living things exist.
Identify the structure and functions of various cell components.
Compare and contrast plant and animal cells.
Relate the functions of organelles to the overall life processes of the organism.

Keywords

Cell
Organism
Prokaryotic
Eukaryotic
Cell theory
Organelles
Membrane
Cytoplasm

Set Induction

Begin the lesson by asking students to imagine the smallest living thing they can think of. Prompt a discussion about how all living things, no matter how large or small, are made up of cells.

Entry Behaviour

Students should have a basic understanding of living organisms and their characteristics, including the knowledge that all living things grow and reproduce.

Learning Resources and Materials

Textbooks: Lagos State Scheme of Work, Classic Practical Biology
Diagrams of plant and animal cells
Microscopes for hands-on observation
Projector and slides for presentations
Interactive cell models

Building Background / Connection to Prior Knowledge

Remind students of previous lessons on the characteristics of living things and their basic organization. Discuss how cells relate to larger structures, such as tissues and organs.

Embedded Core Skills

Critical thinking
Teamwork
Observation skills
Communication skills

Learning Materials

Cell diagrams (both plant and animal)
Interactive cell models (3D representations)
PowerPoint presentation on cell structure and function

Reference Books

Classic Practical Biology for Senior Secondary Schools
New Comprehensive Practical Biology

Instructional Materials

Whiteboard
Markers
Projector for visual aids

Content

Cell as a Living Unit:
- A cell is the smallest unit of life that can replicate independently and perform all necessary functions of life. For example, in multicellular organisms like humans, cells work together to form tissues, organs, and systems that support life.
Forms in which Living Things Exist:
- Independent Organisms: These are single-celled organisms that can live on their own. Examples include:
  - Amoeba: A shapeshifting organism that uses pseudopodia to move and capture food.
  - Paramecium: A ciliated organism that uses hair-like structures for movement and feeding.
  - Euglena: A unique organism that can photosynthesize due to its chloroplasts but can also feed heterotrophically in the absence of light.
- As a Colony: Some organisms exist in colonies where they live together but maintain individual functions. An example is:
  - Volvox: A spherical colony of thousands of cells that can coordinate movement and reproduction.
- As Filament: Other organisms, such as:
  - Spirogyra: A filamentous green algae that grows in water, demonstrating how cells can exist in chains.
Cell Structure:
- The Cell Theory: This fundamental theory states:
  - All living things are made up of one or more cells.
  - The cell is the basic unit of life.
  - All cells arise from pre-existing cells.
- Structure and Function of Cell Components:
  - Nucleus: The control center of the cell that houses genetic material (DNA) and regulates cell activities.
  - Mitochondria: Known as the powerhouses of the cell, they convert nutrients into energy through respiration.
  - Ribosomes: Tiny structures that synthesize proteins by translating mRNA.
  - Endoplasmic Reticulum (ER): A network of membranes involved in protein and lipid synthesis. The rough ER is studded with ribosomes, while the smooth ER is involved in lipid synthesis and detoxification.
  - Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.
  - Cell Membrane: A semi-permeable membrane that controls the movement of substances in and out of the cell, maintaining homeostasis.
  - Cytoplasm: The gel-like substance where organelles are suspended and various metabolic processes occur.
- Differences and Similarities Between Plant and Animal Cells:
  - Plant Cells: Have a rigid cell wall, chloroplasts for photosynthesis, and large central vacuoles for storage and maintaining turgor pressure.
  - Animal Cells: Lack cell walls and chloroplasts but have smaller, more numerous vacuoles. They contain centrioles that aid in cell division.

Evaluation

15 Fill-in-the-Blank Questions

The smallest unit of life is called a __________. (a) tissue (b) cell (c) organ (d) system
Amoeba and Paramecium are examples of __________ organisms. (a) colonial (b) multicellular (c) independent (d) filamentous
__________ is the term used to describe the fundamental unit of life. (a) organism (b) cell (c) tissue (d) system
The theory that states all living things are composed of cells is called __________. (a) atom theory (b) cell theory (c) organism theory (d) life theory
Chloroplasts are found in __________ cells. (a) animal (b) fungal (c) plant (d) prokaryotic
__________ cells do not have a definite nucleus. (a) Eukaryotic (b) Prokaryotic (c) Multicellular (d) Unicellular
The jelly-like substance within the cell is called __________. (a) cytoplasm (b) cell wall (c) nucleus (d) membrane
__________ are responsible for energy production in the cell. (a) Ribosomes (b) Mitochondria (c) Nucleus (d) Lysosomes
The __________ is the control center of the cell. (a) mitochondria (b) nucleus (c) ribosome (d) Golgi apparatus
__________ is a characteristic of living things that cells exhibit. (a) Non-living (b) Growth (c) Decay (d) Destruction
A cell wall is present in __________ cells. (a) animal (b) plant (c) bacterial (d) both (b) and (c)
Cells that can exist independently are called __________ cells. (a) dependent (b) colonial (c) multicellular (d) unicellular
The __________ is a protective layer surrounding the cell membrane in plant cells. (a) cell wall (b) cytoplasm (c) nucleus (d) vacuole
Organisms like spirogyra exist in __________ form. (a) filamentous (b) colonial (c) independent (d) multicellular
The basic unit of structure and function in living organisms is the __________. (a) tissue (b) cell (c) organ (d) system

Class Activity Discussion

15 FAQs

What is a cell?
A cell is the smallest unit of life that can function independently, carrying out all necessary processes for survival.
What are the different types of cells?
There are two main types of cells: prokaryotic cells (like bacteria) which lack a nucleus, and eukaryotic cells (like plant and animal cells) which have a nucleus.
Why are cells important?
Cells are crucial because they perform essential functions necessary for life, such as metabolism, growth, and reproduction.
What does the cell theory state?
The cell theory states that all living organisms are made up of cells, and cells are the basic unit of life that arise from pre-existing cells.
What is the difference between plant and animal cells?
Plant cells have a cell wall, chloroplasts for photosynthesis, and large central vacuoles, while animal cells do not have these structures.
What are organelles?
Organelles are specialized structures within a cell that perform specific functions, like energy production, protein synthesis, and waste processing.
Can a cell live independently?
Yes, single-celled organisms like amoeba can live independently, while multicellular organisms rely on cooperation between cells.
What is the function of the nucleus?
The nucleus contains the cell’s genetic material (DNA) and regulates activities such as growth, metabolism, and reproduction.
How do cells reproduce?
Cells reproduce through cell division, primarily via mitosis (for growth and repair) and meiosis (for producing gametes).
What is cytoplasm?
Cytoplasm is the gel-like substance within the cell that holds organelles in place and facilitates metabolic processes.
What are ribosomes responsible for?
Ribosomes are responsible for synthesizing proteins by translating messenger RNA (mRNA) into amino acid sequences.
How do plant cells obtain energy?
Plant cells obtain energy through photosynthesis, a process where they convert light energy, usually from the sun, into chemical energy stored in glucose.
What role do mitochondria play in the cell?
Mitochondria generate energy in the form of adenosine triphosphate (ATP) through the process of cellular respiration.
How does diffusion occur in cells?
Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration, allowing substances to move across cell membranes.
What is osmosis?
Osmosis is the specific movement of water across a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration, essential for maintaining cell turgor.

Presentation

Step 1: Teacher revises the previous topic on the characteristics of living things to contextualize the importance of cells.
Step 2: Teacher introduces the new topic, “The Cell,” using diagrams and models.
Step 3: Students are encouraged to share prior knowledge, and the teacher clarifies any misconceptions.

Activities

Teacher’s Activities:

Present a PowerPoint on cell structure and functions.
Facilitate interactive discussions on the importance of different organelles.
Demonstrate the use of microscopes to observe different types of cells, encouraging students to note differences.

Learner’s Activities:

Engage in group discussions and collaborate to answer fill-in-the-blank questions.
Observe and identify cells under the microscope, documenting their observations.
Create a chart comparing the structures of plant and animal cells.

Assessment

Evaluation Questions

Define a cell and explain its significance in living organisms.
List the two main types of cells and provide examples of each.
Describe the structure and function of the nucleus.
What are chloroplasts, and what role do they play in plant cells?
Explain the difference between prokaryotic and eukaryotic cells with examples.
What is the role of mitochondria in cellular energy production?
Compare and contrast the structures of plant and animal cells.
What is the significance of the cell membrane in maintaining homeostasis?
Describe the process of diffusion and its importance in cells.
Explain how cells reproduce and the significance of cell division.

Conclusion

The teacher will circulate around the classroom to mark the fill-in-the-blank exercises and provide feedback, ensuring students grasp the fundamental concepts of cell structure and function, as well as their relevance to the larger organism.