Biology Notes

Biology

  • Biology is the study of life.
  • Biologists study the structure, function, growth, origin, evolution, and distribution of living organisms.
  • Biology helps us understand how living organisms work and interact on multiple levels.

Fields of Biology

  • Biochemistry: Study of the chemistry of compounds and processes in organisms.
  • Ecology: Study of environment and relationships between organisms.
  • Botany: Study of plants.
  • Physiology: Study of how the human body works.
  • Nutrition: Study of food, nutrients, and their effects.
  • Genetics: Study of heredity.
  • Microbiology: Study of microorganisms.
  • Palaeontology: Study of fossils.

Characteristics of Living Organisms (Vital Functions)

  • Living organisms exhibit 7 characteristics:
    • Movement
    • Reproduction
    • Sensitivity
    • Growth
    • Respiration
    • Excretion
    • Nutrition

Movement

  • Ability to alter position for food or to avoid danger.
  • Animals move from one place to another or move parts of their body.
  • Plants move parts of their body (e.g., leaves and petals towards the sun).

Reproduction

  • Formation of new organisms (offspring) to increase numbers and prevent extinction.
    • Asexual Reproduction: One parent; offspring identical to parent.
    • Sexual Reproduction: Two parents; offspring different from parents.

Sensitivity

  • Ability to respond to changes (stimuli) inside or outside the body.
  • Animals have receptors to detect stimuli.
  • Example: Removing hand from a hot object.

Growth

  • Ability to increase the number of cells, leading to an increase in size.

Respiration

  • Process by which food is broken down to release energy (ATP).
    • Aerobic Respiration: Requires oxygen; releases more energy.
    • Anaerobic Respiration: No oxygen required; releases less energy.

Excretion

  • Removal of waste products from metabolism.
    • Examples: Sweat, urea, carbon dioxide.
  • Egestion is NOT Excretion: It's the removal of undigested material.

Nutrition

  • Process by which an organism obtains food for growth, repair, and energy.
    • Autotrophic Nutrition: Organism makes its own food from simple substances.
    • Heterotrophic Nutrition: Organism takes in ready-made food.