JAMB Biology Note- Support and Movement

Sub Topics:

a. Tropic, tactic, nastic and sleep movements in plants
b. supporting tissues in animals
c. Types and functions of the skeleton
i. Exoskeleton
ii. Endoskeleton
iii. Functions of the skeleton in animals

Table of Contents

• Sub Topics:
  • A. Tropic, Tactic, Nastic, and Sleep Movements in Plants
    • 1. Tropic Movements
    • 2. Tactic Movements
    • 3. Nastic Movements
    • 4. Sleep Movements
  • B. Supporting Tissues in Animals
    • 1. Chitin
    • 2. Cartilage
    • 3. Bone
  • C. Types and Functions of the Skeleton
    • 1. Exoskeleton
    • 2. Endoskeleton
  • D. Functions of the Skeleton in Animals
  • E. Joints and Their Types
    • Types of Joints:
  • Summary
  • Conclusion

A. Tropic, Tactic, Nastic, and Sleep Movements in Plants

1. Tropic Movements

• Tropisms are directional growth movements in response to environmental stimuli, where the direction of the response is dependent on the direction of the stimulus.
  • Phototropism: Movement towards or away from light (e.g., plant shoots grow towards light).
  • Gravitropism (Geotropism): Movement in response to gravity (e.g., roots grow downward, away from light).
  • Hydrotropism: Movement towards or away from water.
  • Thigmotropism: Movement in response to touch (e.g., tendrils of climbing plants wrapping around a support).

2. Tactic Movements

• Tactic movements are movements of the entire organism in response to a stimulus. They are usually more pronounced in animals.
  • Positive Taxis: Movement towards a stimulus (e.g., bacteria moving towards food).
  • Negative Taxis: Movement away from a stimulus (e.g., organisms moving away from light).

3. Nastic Movements

• Nastic movements are non-directional responses to stimuli, where the movement is independent of the direction of the stimulus.
  • Thigmonasty: Movement in response to touch (e.g., Venus flytrap closing its leaves).
  • Nyctinasty: Movement in response to light and dark (e.g., the opening and closing of flowers at night).
  • Photonasty: Movement in response to light intensity.

4. Sleep Movements

• These are movements that occur in response to the day-night cycle, such as the closing of leaves at night in some plants (e.g., Mimosa pudica).

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B. Supporting Tissues in Animals

1. Chitin

• Location: Found in the exoskeletons of arthropods (insects, crustaceans).
• Function: Chitin provides structural support and protection for the organism, acting as a hard outer skeleton.

2. Cartilage

• Location: Found in joints, ear, nose, and the trachea.
• Function: Cartilage provides flexible support, cushioning for joints, and reduces friction in joints.

3. Bone

• Location: Found in the skeleton of vertebrates.
• Function: Bone provides rigid support for the body, protects internal organs, stores minerals, and produces blood cells in the bone marrow.

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C. Types and Functions of the Skeleton

1. Exoskeleton

• Structure: A hard outer skeleton found outside the body of organisms.
• Example: Found in arthropods like insects, crustaceans.
• Function: Provides protection, support, and prevents desiccation; allows for movement through muscles attached to the exoskeleton.

2. Endoskeleton

• Structure: An internal skeleton found in vertebrates (e.g., humans, birds, mammals).
• Example: Bone and cartilage structure in humans.
• Function: Provides support, protection of internal organs, facilitates movement, and plays a role in mineral storage and blood cell production.

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D. Functions of the Skeleton in Animals

The skeleton has several important functions in animals:

1. Protective Function: The skeleton protects vital internal organs (e.g., the skull protects the brain, the rib cage protects the lungs and heart).
2. Support Function: The skeleton provides a framework that supports the body and maintains its shape.
3. Locomotive Function: The skeleton allows for movement by providing points of attachment for muscles and acting as a lever system.
4. Respiratory Function: The skeleton facilitates respiration, such as in the rib cage, which helps in the expansion and contraction of the lungs during breathing.

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E. Joints and Their Types

Joints are the places where two or more bones meet. They allow for movement and flexibility in the body.

Types of Joints:

1. Hinge Joint: Found in the elbow and knee, allowing for back-and-forth movement.
2. Ball-and-Socket Joint: Found in the shoulder and hip, allowing for rotational movement.
3. Pivot Joint: Found in the neck, allowing for rotation of the head.
4. Gliding Joint: Found in the wrists and ankles, allowing bones to slide past each other.
5. Saddle Joint: Found in the thumb, allowing for a wide range of movement.

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Summary

Support and movement are vital functions for organisms, allowing them to maintain structural integrity and move in response to environmental stimuli. In plants, various movements (tropic, tactic, nastic, and sleep movements) help them adapt to their environment. In animals, the skeleton (either exoskeleton or endoskeleton) provides structure, support, and protection. Different supporting tissues like cartilage, chitin, and bone help in various supportive functions, and joints facilitate movement.

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Conclusion

Understanding support and movement in organisms allows us to appreciate the complexity of life and the evolutionary adaptations that enable organisms to thrive in diverse environments. The skeleton, supporting tissues, and movement mechanisms are crucial for survival, growth, and reproduction.