JAMB CBT PRACTICE TEST

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BIOLOGY LESSON NOTE ON HUMAN KIDNEY

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Lesson Note on the Human Kidney Topic: The Human Kidney Duration: 40 minutes Specific Objectives: By the end of the lesson, students should be able to: Define the kidney and state its location in the human body. Identify and describe the structure and functions of the kidney. Explain the processes involved in urine formation (filtration, reabsorption, and secretion). Describe how the kidney contributes to homeostasis. Identify common kidney-related diseases and how to prevent them. Evaluate the importance of maintaining kidney health. Lesson Content: 1. Introduction to the Human Kidney The kidneys are vital organs in the human body responsible for filtering waste from the blood and regulating water and electrolyte balance. They are part of the excretory system and play a crucial role in homeostasis. Location: The kidneys are located in the abdominal cavity, on either side of the spine, just below the rib cage. Each kidney is bean-shaped and about the size of a fi...
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BASIC SCIENCE LESSON NOTE ON TYPES AND FUNCTIONS OF SKELETONS (JSS2 THIRD TERM LESSON NOTE)

Class

JSS2

Term

Third Term

Week

Week 3

Topic

Types and Functions of Skeletons

Duration

40 Minutes

Instructional Materials

  • Charts showing different types of skeletons
  • Pictures of man, fish, grasshopper, snail, crab, and earthworm
  • Human skeleton model
  • Shell of snail
  • Insect specimens
  • Video clips on animal skeletons

Reference Books

  1. NERDC Basic Science Curriculum for JSS
  2. STAN Basic Science for Junior Secondary Schools
  3. Evans Basic Science for Junior Secondary Schools
  4. Comprehensive Basic Science by A.O. Ogunniyi

Specific Objectives

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

  1. Define skeleton.
  2. State the different types of skeletons.
  3. Explain the characteristics of each type of skeleton.
  4. Identify animals with different types of skeletons.
  5. State the functions of skeletons.
  6. Differentiate between endoskeleton, exoskeleton, and hydrostatic skeleton.

Introduction

Animals need support to maintain their shape and protect their internal organs. This support is provided by the skeleton.

Different animals possess different types of skeletons depending on their body structure and habitat. The three major types of skeletons are endoskeleton, exoskeleton, and hydrostatic skeleton.

Meaning of Skeleton

A skeleton is the supporting framework of an organism that gives shape, support, and protection to the body.

Types of Skeletons

There are three major types of skeleton:

  1. Endoskeleton
  2. Exoskeleton
  3. Hydrostatic Skeleton

1. Endoskeleton

An endoskeleton is a skeleton found inside the body.

It is made up of bones and cartilages.

Characteristics of Endoskeleton

  1. Located inside the body.
  2. Made of bones and cartilages.
  3. Grows along with the organism.
  4. Provides support and protection.
  5. Allows flexibility and movement.

Animals with Endoskeleton

Examples include:

  • Human beings
  • Birds
  • Fish
  • Frogs
  • Lizards
  • Snakes
  • Dogs
  • Cats

Advantages of Endoskeleton

  1. Supports large body size.
  2. Grows with the organism.
  3. Provides protection for internal organs.
  4. Allows easy movement.

Disadvantages of Endoskeleton

  1. Internal organs may still be injured by external force.
  2. Bones can break or fracture.

2. Exoskeleton

An exoskeleton is a hard covering found on the outside of the body.

It is made mainly of chitin, calcium carbonate, or other hard substances.

Characteristics of Exoskeleton

  1. Located outside the body.
  2. Hard and rigid.
  3. Protects soft internal organs.
  4. Does not grow continuously with the organism.
  5. Must be shed and replaced during growth (moulting).

Animals with Exoskeleton

Examples include:

  • Grasshopper
  • Cockroach
  • Crab
  • Prawn
  • Snail
  • Beetle
  • Spider

Advantages of Exoskeleton

  1. Protects the body from injury.
  2. Prevents water loss.
  3. Gives shape to the body.
  4. Protects against predators.

Disadvantages of Exoskeleton

  1. Restricts body growth.
  2. Organisms must moult to grow.
  3. Heavy exoskeleton may reduce flexibility.

Moulting

Moulting is the process by which animals shed their old exoskeleton and replace it with a new one.

Animals that Moult:

  • Grasshopper
  • Cockroach
  • Crab
  • Snake (sheds skin)

3. Hydrostatic Skeleton

A hydrostatic skeleton is a skeleton formed by fluid-filled spaces within the body.

The fluid exerts pressure that supports the body.

Characteristics of Hydrostatic Skeleton

  1. Contains fluid under pressure.
  2. Flexible and soft.
  3. Allows movement through muscle contraction.
  4. Found mainly in soft-bodied animals.

Animals with Hydrostatic Skeleton

Examples include:

  • Earthworm
  • Jellyfish
  • Sea anemone
  • Hydra

Advantages of Hydrostatic Skeleton

  1. Allows flexibility.
  2. Enables easy movement.
  3. Lightweight.
  4. No hard structures required.

Disadvantages of Hydrostatic Skeleton

  1. Provides little protection.
  2. Cannot support large body sizes.
  3. Easily damaged.

Comparison of Types of Skeleton

Feature Endoskeleton Exoskeleton Hydrostatic Skeleton
Position Inside body Outside body Fluid-filled body cavity
Composition Bones and cartilage Chitin or hard shell Fluid and muscles
Growth Grows with body Requires moulting Grows with body
Protection Moderate High Low
Examples Human, fish Grasshopper, snail Earthworm, jellyfish

Functions of Skeletons

Skeletons perform the following functions:

1. Support

They provide support and maintain body shape.

2. Protection

They protect delicate internal organs.

Examples:

  • Skull protects the brain.
  • Rib cage protects the heart and lungs.
  • Shell protects the snail.

3. Movement

Skeletons work with muscles to enable movement.

4. Shape

They give organisms their characteristic body shape.

5. Blood Cell Production

In vertebrates, bones produce blood cells in the bone marrow.

6. Storage of Minerals

Bones store minerals such as:

  • Calcium
  • Phosphorus

Practical Activities

Activity 1: Observe Different Animals

Observe pictures or specimens of man, grasshopper, snail, and earthworm.

Observation: Each animal possesses a different type of skeleton.

Conclusion: Animals have different skeletons according to their body structure.

Activity 2: Examine Snail Shell

Observe a snail shell.

Observation: The shell is hard and external.

Conclusion: Snail possesses an exoskeleton.

Activity 3: Observe Human Skeleton Model

Observe a skeleton model.

Observation: Bones are located inside the body.

Conclusion: Humans possess an endoskeleton.

Conclusion

Skeletons provide support, protection, and movement in animals. The three major types are endoskeleton, exoskeleton, and hydrostatic skeleton. Different animals possess different skeletons depending on their body structure and way of life.

Evaluation

Answer the following questions:

  1. Define skeleton.
  2. State the three types of skeletons.
  3. Explain endoskeleton with examples.
  4. Explain exoskeleton with examples.
  5. What is hydrostatic skeleton?
  6. Define moulting.
  7. Mention four animals with exoskeleton.
  8. State four functions of skeletons.
  9. Differentiate between endoskeleton and exoskeleton.
  10. State two advantages of hydrostatic skeleton.

Objective Questions

Choose the correct answer from A–D.

  1. The supporting framework of an organism is called ______.
    A. tissue
    B. muscle
    C. skeleton
    D. cartilage

Answer: C

  1. The skeleton found inside the body is called ______.
    A. exoskeleton
    B. hydrostatic skeleton
    C. endoskeleton
    D. cartilage

Answer: C

  1. Which of the following animals has an exoskeleton?
    A. Human being
    B. Fish
    C. Grasshopper
    D. Frog

Answer: C

  1. The skeleton of an earthworm is ______.
    A. endoskeleton
    B. exoskeleton
    C. hydrostatic skeleton
    D. cartilage

Answer: C

  1. The hard covering of insects is made mainly of ______.
    A. protein
    B. fat
    C. chitin
    D. starch

Answer: C

  1. Shedding of exoskeleton is called ______.
    A. germination
    B. moulting
    C. fertilization
    D. budding

Answer: B

  1. Which of the following animals possesses an endoskeleton?
    A. Snail
    B. Crab
    C. Human being
    D. Cockroach

Answer: C

  1. The shell of a snail is an example of ______.
    A. hydrostatic skeleton
    B. exoskeleton
    C. endoskeleton
    D. cartilage

Answer: B

  1. Bones store ______.
    A. minerals
    B. carbohydrates
    C. proteins
    D. vitamins

Answer: A

  1. The skull protects the ______.
    A. lungs
    B. kidney
    C. brain
    D. liver

Answer: C

Essay Questions

  1. Define skeleton and explain its functions.
  2. Differentiate between endoskeleton, exoskeleton, and hydrostatic skeleton.
  3. Explain moulting and state its importance.
  4. State the advantages and disadvantages of exoskeleton.
  5. Draw a table comparing the three types of skeletons.

Assignment

  1. List five animals with endoskeleton and five with exoskeleton.
  2. Explain the process of moulting in insects.
  3. State six functions of the skeleton.

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