Biological Systems & Classifications: A Comprehensive Reference

Sexual Reproduction

• Viviparous: blue whale, camel, human, zebra, manatee, rabbit
• Oviparous: peacock, sea turtle, hummingbird, crocodile, quail, duck
• Ovoviviparous: kangaroo, frog, tropical fish (guppy, xiphophorus), weasel, lizard

Asexual Reproduction

• Vegetative Propagation: strawberry, rose, pineapple, sweet potato, garlic, moss
• Budding: anemone, coral, bryozoan, sponge, yeast (e.g., Penicillium), medusa
• Sporulation: fungi, lycopodium, green algae, amoeba, wheat rust
• Fragmentation: planaria, brown algae, coral, pink fungus, lichen, worm

Leaf Morphology and Classification

Leaf Venation Types

• Uninervate: Single prominent vein
• Parallelinervate: Veins run parallel
• Curvinervate: Veins curve
• Pinnately Nerved: Veins branch off a central midrib like a feather
• Palminervate: Veins radiate from a central point like fingers on a palm

Leaf Attachment Types

• Petiolate: Has a petiole (leaf stalk)
• Sessile: Lacks a petiole, attached directly to the stem
• Peltate: Petiole attached to the center of the leaf blade
• Sheathing: Base of the leaf wraps around the stem

Leaf Apex Shapes

• Awned: Tipped with a bristle-like appendage
• Caudate: Tail-like tip
• Acuminate: Tapering to a long, sharp point
• Acute: Ending in a sharp point, but less tapered than acuminate
• Rounded: Smoothly curved tip
• Retuse: Slightly notched at the tip
• Cordate: Heart-shaped tip
• Truncated: Squared-off tip

Leaf Base Shapes

• Rounded: Smoothly curved base
• Truncate: Squared-off base
• Cuneate: Wedge-shaped base
• Obtuse: Blunt or rounded base
• Horned: Horn-like projections
• Oblique: Unequal sides at the base
• Cordate: Heart-shaped base
• Peltate: Petiole attached to the center of the leaf blade

Leaf Margin (Edge) Types

• Entire: Smooth, unbroken margin
• Sinuate: Wavy margin
• Serrate: Saw-toothed margin with teeth pointing forward
• Dentate: Toothed margin with teeth pointing outwards
• Doubly Dentate: Teeth that are themselves toothed
• Lobed: Indented margin, but not divided to the midrib
• Parted: Divided deeply, almost to the midrib
• Palmately Parted: Deeply divided in a palmate fashion

Leaf Blade (Lamina) Types

• Simple Leaf: Single, undivided blade
• Compound Leaf: Blade divided into leaflets
  • Paripinnate: Pinnately compound with an even number of leaflets
  • Imparipinnate: Pinnately compound with an odd number of leaflets (terminal leaflet)
  • Trifoliate: Compound with three leaflets
  • Palmate: Leaflets radiating from a single point
  • Bipinnate: Leaflets further divided into sub-leaflets

Leaf Shapes (Form)

• Lanceolate: Lance-shaped, broader in the middle, tapering to ends
• Acicular: Needle-like
• Ensiform: Sword-shaped
• Oblong: Longer than wide with parallel sides
• Spatulate: Spatula-shaped, broad at apex, tapering to base
• Horned: Horn-like shape
• Rhomboid: Diamond-shaped
• Oval: Broadly elliptical
• Cordate: Heart-shaped
• Orbicular: Circular
• Reniform: Kidney-shaped
• Circular: Round
• Elliptical: Oval, tapering equally to both ends
• Squamous: Scale-like
• Striplike: Narrow and elongated
• Deltoid: Triangular
• Fan-shaped: Resembling a fan
• Falcate: Sickle-shaped

The Digestive System

The process of digestion involves:

1. Ingestion: Taking food into the body.
2. Digestion: Breaking down food into smaller molecules.
3. Absorption: Taking nutrients into the bloodstream.

Key Organs of the Digestive System

• Teeth
• Mouth
• Tongue
• Epiglottis
• Esophagus
• Stomach
• Liver
• Pancreas
• Duodenum
• Small Intestine
• Large Intestine
• Rectum
• Anus

The Respiratory System

Breathing is essential for life, facilitating the exchange of gases.

Cellular Respiration: Food (Glucose) + Oxygen → Energy + Carbon Dioxide (CO₂) + Water (H₂O)

Photosynthesis: Carbon Dioxide (CO₂) + Water (H₂O) + Light Energy → Food (Glucose) + Oxygen

Gas exchange between cells and their environment is called cellular respiration or internal respiration, while ventilation refers to the mechanical movement of air into and out of the lungs.

The general chemical reaction that occurs during the transport of CO₂ from tissues to the lungs is illustrated below:

The Circulatory System

Components of Blood

• Red Blood Cells (Erythrocytes): Carry oxygen, lack a nucleus, contain hemoglobin.
• White Blood Cells (Leukocytes): Involved in immune response. Types include neutrophils, eosinophils, basophils, lymphocytes, and monocytes.
• Thrombocytes (Platelets): Help in clot formation.

Circulation Pathways

Systemic Circulation:

Heart (Left Ventricle) → Arteries → Arterioles → Capillaries (tissue exchange) → Venules → Veins → Heart (Right Atrium)

Pulmonary Circulation:

Heart (Right Ventricle) → Pulmonary Arteries → Lungs (gas exchange) → Pulmonary Veins → Heart (Left Atrium)

The Excretory System

Key Organs of the Excretory System

• Kidney
• Ureter
• Bladder
• Urethra
• External Urethral Orifice (Meatus)