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.