Biology: Cells, Systems, and Organ Functions

Cells, Tissues, Organs, Systems

• Building Blocks
  • Cells, tissues, organs, and systems are the foundational units of an organism.

Organisation of Plants

• Vascular Plants
  • Contain vascular tissue that transports water and minerals.
• Plant Tissues
  • Three main types:
  • Dermal
  • Ground
  • Vascular
• Plant Organs
  • Major organs include:
  • Leaves
  • Flowers
  • Stems
  • Roots
• Root and Shoot Systems
  • Root system absorbs water and nutrients.
  • Shoot system consists of reproductive and non-reproductive sections.

Organisation of Animals

• Complex Structure
  • Composed of various specialized cell types.
  • Common cell types include:
  • Skin cells
  • Muscle cells
  • Blood cells
  • Nerve cells
  • Fat cells
• Animal Tissues
  • Four main types:
  • Epithelial
  • Connective
  • Muscle
  • Nervous

5B – Plant Vascular Tissues

• Introduction
  • Overview of vascular tissues.
• Mechanisms of Transport
  • Water and nutrient movement in plants.
  • Regulated transpiration.
• Types of Vascular Tissues
  • Xylem: Transports water and minerals.
  • Phloem: Transports sugars and nutrients.
  • In dicots:
  • Vascular bundles are located in roots and below bark in stems/trunks, branching in leaves.

Mechanisms of Water and Nutrient Movement in Plants

• Xylem Structure
  • Composed of the remains of dead cells.
• Phloem Structure
  • Composed of living cells with sieve plates.
• Transpiration
  • Passive movement of water up the xylem and exit through stomata.
  • Lower air pressure in leaves compared to roots allows for water movement.
  • Adhesion of water molecules aids in movement.

Regulating Transpiration

• Factors Affecting Water Loss
  • Increased loss in hot, dry, and windy conditions.
• Guard Cells
  • Regulate stomatal openings.
  • Actively pump potassium ions:
  • Increase transpiration rate by uptake.
  • Decrease transpiration by outflow.
• Translocation
  • Movement of nutrients from leaves to other parts of the plant via phloem.

5C – The Digestive System

• Purpose
  • Digestive system breaks down food molecules for nutrients.
• Processes
  • Involves ingestion, digestion, absorption, and elimination.

Oral Cavity

• Functionality
  • Teeth break down food mechanically.
  • Salivary amylase starts carbohydrate digestion.

Oesophagus

• Function
  • Transports bolus to stomach via peristalsis (muscular contractions).

Stomach

• Processing Food
  • Churning and chemical breakdown creates chyme.
  • Acidic pH (1–3) aids in digestion.
  • Gastric juices secreted by stomach wall glands.

The Importance of pH

• Enzyme Activity
  • Different gut regions favor different pH for effective enzyme function.

Liver and Gallbladder

• Functions
  • Produce bile to emulsify fats.
  • Regulates metabolism and detoxifies substances.

Pancreas

• Roles
  • Produces digestive enzymes and bicarbonate to neutralize stomach acid.

Small Intestine

• Digestion and Absorption
  • Duodenum receives bile and enzymes; digestion completes here.
  • Absorption of nutrients (amino acids, monosaccharides, vitamins, and minerals) into blood.

Large Intestine

• Final Absorption
  • Absorbs water, vitamins, and minerals.
  • Stores and expels feces through anus.

Digestive Systems of Other Animals

• Diversity
  • Omnivores: Sharp and blunt teeth for mixed diets.
  • Carnivores: Sharp teeth for tearing flesh.
  • Herbivores: Long digestive systems and flat teeth for plant materials.
• Feeding Habits
  • Herbivores: Spend more time eating.
  • Carnivores: Less time feeding.

5D – The Excretory System

• Purpose
  • Removes waste and regulates water/ion balance.

The Kidneys and the Urinary Tract

• Urea Production
  • Ammonia converted to urea in the liver (less toxic).
  • Urea is excreted mixed with water as urine.
  • Urinary tract is involved in urine production and excretion.
• Kidney Functions
  • Filter blood, reabsorb useful substances, secrete waste.

Additional Excretory Organs

• Carbon Dioxide
  • Released from cells; carried to lungs for exhalation.
• Skin Role
  • Removes small nitrogenous wastes and ions via sweat.
• Liver Function
  • Detoxifies blood before excretion via the urinary tract.

5E – The Endocrine System

• Function
  • Specializes in cellular communication via signaling molecules (hormones).
  • Roles of Hormones:
  • Influence growth, metabolism, and homeostasis.
  • Crucial for sexual development and maturity.
• Mechanism of Action
  • Hormones bind to specific receptors on target cells to trigger responses.
• System Overview
  • The endocrine system consists of glands that produce hormones and regulate various body functions.