Lesson Notes By Weeks and Term v5 - Grade 10

Lesson Video

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Performance objectives

• Define 'tissue' and name the four main types of animal tissues.
• Describe the structure and function of the main types of plant tissues.
• Relate the structure of specific tissues to their functions.
• Identify examples of tissues from diagrams.
• Explain how tissues work together to form organs.

Lesson summary

Life on Earth is incredibly diverse, ranging from microscopic bacteria to giant redwood trees and complex animals like ourselves. But what are all these living organisms actually made of? The answer lies in tissues – groups of similar cells performing specific functions. Understanding plant and animal tissues is crucial to understanding how organisms function, grow, and adapt to their environments. This knowledge is directly relevant to many aspects of South African life, from agriculture and food security to understanding human health and disease. For example, understanding how plant vascular tissue transports water is crucial for efficient irrigation in drought-prone areas.

Lesson notes

2. 1. What is a Tissue? A tissue is a group of similar cells that perform a specific function. In multicellular organisms like plants and animals, cells are organized into tissues, which then work together to form organs. Organs, in turn, work together to form organ systems. This hierarchical organization allows for greater efficiency and complexity in living organisms. 2.

2. Animal Tissues There are four main types of animal tissues: Epithelial Tissue: This tissue covers surfaces, lines cavities, and forms glands. Its primary functions include protection, secretion, absorption, and excretion.

Types: Squamous epithelium: Thin, flattened cells allowing for easy diffusion (e.g., lining of alveoli in lungs).

Cuboidal epithelium: Cube-shaped cells involved in secretion and absorption (e.g., kidney tubules).

Columnar epithelium: Column-shaped cells with microvilli for increased surface area, involved in absorption and secretion (e.g., lining of the small intestine). Some have goblet cells that secrete mucus.

Transitional epithelium: Capable of stretching and changing shape (e.g., lining of the urinary bladder).

Example: The lining of your small intestine is composed of columnar epithelium, adapted for absorbing nutrients from the food you eat.

Connective Tissue: This tissue supports, connects, and separates different tissues and organs. It is characterized by having cells embedded in an extracellular matrix.

Types: Loose connective tissue: Supports and cushions organs and tissues (e.g., under the skin). Contains fibroblasts, collagen and elastin fibres.

Dense connective tissue: Provides strength and support (e.g., tendons and ligaments). Mostly collagen fibres.

Cartilage: Provides flexible support (e.g., ears, nose, joints). Chondrocytes in a matrix of collagen and elastin.

Bone: Provides rigid support and protection (e.g., skeleton). Osteocytes in a mineralized matrix.

Blood: Transports oxygen, nutrients, and waste products (e.g., throughout the body). Consists of red blood cells, white blood cells, platelets and plasma.

Example: Tendons connecting muscles to bones are made of dense connective tissue, allowing you to move your limbs.

Muscle Tissue: This tissue is responsible for movement.

Types: Skeletal muscle: Voluntary movement (e.g., muscles attached to bones). Striated appearance.

Smooth muscle: Involuntary movement (e.g., muscles in the walls of the digestive tract). No striations.

Cardiac muscle: Found only in the heart; responsible for pumping blood. Striated and involuntary.

Example: The muscles in your arms are skeletal muscles, allowing you to consciously lift objects.

Nervous Tissue: This tissue transmits electrical signals for communication and coordination.

Components: Neurons: Nerve cells that transmit signals.

Neuroglia: Supporting cells that nourish and protect neurons.

Example: The brain and spinal cord are primarily composed of nervous tissue, allowing you to process information and respond to stimuli. 2.

3. Plant Tissues Plants have four main types of tissues: Meristematic Tissue: This tissue is responsible for plant growth. It consists of actively dividing cells.

Types: Apical meristems: Found at the tips of roots and shoots; responsible for primary growth (lengthening).

Lateral meristems: Found in the stems and roots; responsible for secondary growth (thickening). (e.g. vascular cambium and cork cambium)

Example: The apical meristem at the tip of a maize (mealie) plant's stem allows it to grow taller.

Epidermal Tissue: This tissue forms the outer protective layer of the plant.

Functions: Protects against water loss, pathogens, and mechanical damage. Often covered with a waxy cuticle to reduce water loss.

Adaptations: Some epidermal cells have root hairs to increase surface area for water absorption. Other epidermal cells form guard cells around stomata, which regulate gas exchange.

Example: The epidermis of a succulent plant like aloe has a thick cuticle to minimize water loss in dry environments.

Vascular Tissue: This tissue transports water, minerals, and nutrients throughout the plant.

Types: Xylem: Transports water and minerals from the roots to the rest of the plant. Consists of tracheids and vessel elements (dead cells).

Phloem: Transports sugars (produced during photosynthesis) from the leaves to other parts of the plant. Consists of sieve tube elements and companion cells (living cells).

Example: Xylem transports water from the roots of a sugarcane plant to its leaves for photosynthesis.

Ground Tissue: This tissue makes up the bulk of the plant and performs various functions, including photosynthesis, storage, and support.

Types: Parenchyma: Thin-walled cells involved in photosynthesis, storage, and secretion.

Collenchyma: Thick-walled cells that provide flexible support.

Sclerenchyma: Very thick-walled cells that provide rigid support.

Example: The flesh of an apple is primarily composed of parenchyma cells, which store sugars produced during photosynthesis. 2.4.