University of Africa - General Biology 1 Study Notes

UNIVERSITY OF AFRICA, TORU-ORUA, BAYELSA STATE, NIGERIA

FACULTY OF BASIC & APPLIED SCIENCES

DEPARTMENT OF BIOLOGICAL SCIENCES

Course Code: BIO 101
Course Title: General Biology 1
Lecturer: Dr Ifeanyichukwu W. Nwankwo

Characteristics of Living Things

There are seven activities which make organisms different from non-living things. These are the seven characteristics of living organisms.

1. Nutrition

  • Definition: Nutrition is the process by which organisms obtain energy and raw materials from nutrients such as proteins, carbohydrates, and fats.
  • Function: Living things take in materials from their surroundings that they use for growth or to provide energy.

2. Respiration

  • Definition: Respiration is the release of energy from food substances in all living cells.
  • Function: Living things break down food within their cells to release energy for carrying out various biological processes.

3. Movement

  • Concept: All living things exhibit movement.
  • Examples:
    • A leopard moves, just as a tree or plant carries out subtler forms of movement.
    • Plants also exhibit movement, albeit often imperceptibly.

4. Excretion

  • Definition: Excretion is the process defined as the removal of toxic materials, the waste products of metabolism, and substances in excess from the body of an organism.
  • Function: Due to the various chemical reactions occurring in cells, all living organisms must excrete waste to avoid poisoning their own cells.

5. Growth

  • Definition: Growth refers to the permanent increase in cell number and size.
  • Process: It involves using food to produce new cells.

6. Reproduction

  • Concept: All living organisms can produce offspring.

7. Sensitivity

  • Concept: All living organisms can sense and respond to stimuli around them, such as light, temperature, gravity, and chemical substances.

Classification of Living Things

Living things are classified into a hierarchical system with eight levels: domain, kingdom, phylum, class, order, family, genus, and species. This system, known as taxonomy, organizes organisms from the broadest to the most specific based on shared characteristics.

  • Current Model:
    • Three domains:
    • Prokarya (Bacteria)
    • Archaea
    • Eukarya
    • Five kingdoms:
    • Monera
    • Protista
    • Fungi
    • Plantae
    • Animalia

The Eight Levels of Classification

  1. Domain: The most general category based on fundamental cell structure and genetic makeup.
    • Examples: Prokarya, Archaea, Eukarya
  2. Kingdom: Broad group within a domain. For example, animals, plants, fungi, and protists are kingdoms within the Eukarya domain.
  3. Phylum: Subdivision of a kingdom; e.g., Chordata includes all animals with a backbone.
  4. Class: Subdivision of a phylum; humans belong to the class Mammalia.
  5. Order: Subdivision of a class; humans are in the order Primates.
  6. Family: Subdivision of an order; the family for humans is Hominidae.
  7. Genus: Subdivision of a family; the genus for humans is Homo.
  8. Species: The most specific level, a group of organisms that can interbreed; the species for humans is Sapiens.
Key Principles
  • Each level of classification becomes more specific, with organisms sharing more traits as you move from domain to species.
  • The classification is hierarchical, meaning each level contains smaller groups from the level below it.
  • The scientific name of an organism is a combination of its genus and species (e.g., Homo sapiens).

Classification by R.H. Whittaker

  • Proposal: R.H. Whittaker organized organisms into five kingdoms based on cell structure, mode, and source of nutrition, and body design.
  • The Five Kingdoms:
    • Monera
    • Protista
    • Fungi
    • Plantae
    • Animalia

Reproduction in Living Things

  • Definition: Reproduction is the biological process by which organisms create new individuals, ensuring the continuation of their species.
  • Types of Reproduction:
    1. Asexual Reproduction:
      • A single parent creates genetically identical offspring.
      • Example: Binary fission in bacteria.
    2. Sexual Reproduction:
      • Two parents contribute genetic material (via gametes like sperm and eggs) to create genetically diverse offspring.

Kingdom Classification and General Reproduction

Kingdom Monera (Bacteria)

  • Description: Monerans are prokaryotic unicellular microscopic organisms composed of organelles lacking membranes.
  • Habitat: Found in diverse environments, some are free-living and some are parasitic.
  • Examples: Different species of bacteria.
Mode of Reproduction
  • Asexual Reproduction: Primarily through binary fission; one bacterial cell divides into two identical daughter cells.
  • Other Reproductive Methods:
    • Budding
    • Formation of endospores under unfavourable conditions
  • Sexual Reproduction:
    • Via genetic recombination methods:
    • Conjugation: Transfer of DNA between bacteria
    • Transduction: Gene transfer by bacteriophages
    • Transformation: Uptake of DNA from the environment
  • Example: Escherichia coli reproduces by binary fission; conjugation is observed in species like Streptococcus.

Kingdom Protista (Algae, Paramecium, Amoeba, etc.)

  • Description: Includes single-celled and multicelled eukaryotes, such as protozoans and algae, which are neither plants, animals, nor fungi.
  • Cell Structure: Characterized by cells with a defined nucleus and membrane-bound organelles.
  • Habitat: Found in various habitats, including aquatic, moist terrestrial, and as symbionts or parasites.
Mode of Reproduction
  • Asexual Reproduction: Commonly occurs via binary fission or multiple fission.
  • Sexual Reproduction: Can involve conjugation or the formation of gametes.
  • Examples:
    • Amoeba reproduces asexually by binary fission.
    • Paramecium reproduces sexually by conjugation.

Kingdom Fungi (Yeasts, Moulds, Mushrooms)

  • Description: A diverse group of eukaryotic organisms characterized by heterotrophic nutrition, absorption of food, chitinous cell walls, spore reproduction, and vital decomposition roles.
Mode of Reproduction
  • Asexual Reproduction: Occurs via spore formation (e.g., conidia, sporangiospores).
  • Sexual Reproduction: Involves the fusion of specialized sexual structures leading to spores formed through meiosis.
  • Example: Bread mould (Rhizopus) reproduces asexually by sporangiospores and sexually by zygospores.

Kingdom Plantae (Thallophytes, Bryophytes, Pteridophytes, Gymnosperms, Angiosperms)

  • Description: Major groups are classified based on body structure and reproductive features.
  • Main Categories:
    • Bryophytes: Non-vascular plants (e.g., liverworts, hornworts, mosses).
    • Pteridophytes: Seedless vascular plants (e.g., true ferns, horsetails).
    • Gymnosperms: Vascular seed-producing plants with