bio

• Characteristics of living organisms

  • Nutrition
  • Respiration
  • Excretion
  • Growth and development
  • Irritability (sensitivity)
  • Reproduction
  • Movement
  • Control of internal conditions
• Nutrition


  Obtaining organic substances and minerals (i.e. food) from which organisms get their energy essential for growth
• Respiration


  Breaking down (or burning) of food to release energy
• Excretion


  Removal of waste products of metabolism (made inside the body), excess substance & toxic materials
• Growth


  Irreversible increase in size (dry mass) or number of cells or both
• Development


  Increase in complexity of an organism or change from one stage to another
• Irritability (sensitivity)


  Ability of an organism to detect (feel) and respond (react) to different stimuli
• Reproduction


  Ability of an organism to give offspring with the same basic characteristics of their parents
• Movement


  Change in position or direction or both of an organism either the whole organism or part of it
• Control of internal conditions


  Ability of an organism to keep their internal environment constant
• Eukaryotic


  Cells having a nucleus
• Prokaryotic


  Cells before nucleus
• The main groups of classification or the kingdoms

  • Animals
  • Plants
  • Fungi
  • Protoctists
  • Bacteria
  • Viruses
• Animals


  • Multicellular organisms
  • Do not contain chloroplasts, so are not able to carry photosynthesis
  • Do not have cell wall
  • Usually have nervous coordination
  • Able to move from one place to another
  • Often store carbohydrates as glycogen
• Plants


  • Multicellular organisms
  • Contain chloroplasts, so they can photosynthesis
  • Have cellulose cell walls
  • Store carbohydrates in form of sucrose or starch
• Fungi


  • Either multicellular (mold) or unicellular (yeast)
  • Not able to carry photosynthesis
  • Body is usually organized into a mycelium made from thread like structures called hyphae, which contain many nuclei
  • Have chitin cell walls
  • Feed by extracellular secretion of digestive enzymes on to food
  • May store carbohydrates as glycogen
• Protoctists


  • Unicellular organisms
  • Some like amoeba, that live in pond water (fresh water), have features as an animal cell
  • Others like chlorella, have chloroplasts and more like plants
  • A pathogenic example is plasmodium, responsible for causing malaria
• Bacteria


  • Unicellular microorganism
  • Have a simple cell structure that lacks nucleus but contain a circular chromosome of DNA
  • Have cell wall made of polysaccharides and proteins, cell membrane and cytoplasm and plasmids
  • Some can carry out photosynthesis but most feed on living or dead organisms by exchanging benefits
  • Take several shapes
• Viruses


  • Simple particles, smaller than bacteria, seen only by electron microscope
  • Can only reproduce inside living cells (host cells)
  • Parasites and can infect every type of living organisms
  • Lack all the cellular structures, but have a protein coat and contain one type of nucleic acid either DNA or RNA
• Comparison between the kingdoms

  • Multicellular/Unicellular
  • Cell wall/No cell wall
  • Photosynthesis/No photosynthesis
  • Nervous coordination/No nervous coordination
  • Movement/No movement
  • Carbohydrate storage

  
• Organelles


  Small compartments within the cell, surrounded by membrane and have special function
• Cell


  Structural and functional unit of all living organisms
• Tissue


  Group of similar cells to perform certain function
• Organ


  Group of tissues of different structure and perform one uniform function
• System (organ system)


  Group of organs, each has different structure with combined related function
• Organelles found in plant and animal cells

  • Cell membrane
  • Cytoplasm
  • Nucleus
  • Ribosomes
• Cell membrane


  Surrounds the cell, made up of proteins & fats, partially or selectively permeable
• Cytoplasm


  Jelly like, made of proteins, water and salts, holds organelles in place and site of most metabolic reactions
• Nucleus


  Made up of chromosomes enclosed by nuclear membrane, controls cell division & activities, carries genetic information, controls protein synthesis
• Ribosomes


  Found in the cytoplasm, for synthesis of proteins
• Organelles found in plant cells

  • Cell wall
  • Vacuole
  • Chloroplasts

  
• Cell wall in plant cells

  Made up of cellulose, keeps shape of plant cells, protects the cell, prevents its rupture, and keeps cell turgidity
• Vacuole in plant cells


  Large, permanent, contains sap, surrounded by membrane, food storage, supports plant cell, keeps turgidity with cell wall
• Chloroplasts in plant cells

  Large bodies contain pigment called chlorophyll, trap sunlight energy & convert it to chemical energy for photosynthesis, storage of starch
• Mitochondria are organelles present in animal & plant cells, they are called power house, as they are sites for aerobic respiration and energy storage
• Similarities between animal & plant cells

  • Cell membrane
  • Cytoplasm
  • Mitochondria
  • Nucleus
• Differences between animal & plant cells

  • Plant cell has cell wall, vacuole & chloroplasts while animal cell has not
  • Plant cell stores starch granules while animal cell stores glycogen
  • Plant cell is regular in shape while animal cell is irregular
  • Plant cell has side nucleus (pushed by the central vacuole) while animal cell has central nucleus
• Cell Division and Differentiation

  1. Multicellular organisms begin life as a single fertilized egg cell, called a zygote

  2. This divides into two cells, then four, then eight and so on, until the adult body contains countless millions of cells

  3. As the developing embryo grows, cells become specialized to carry out particular roles

  
• Stem cell


  A cell that has the ability to divide many times by mitosis while remaining undifferentiated
• Embryonic stem cells


  • Found in the early stage of development of the embryo, can differentiate into any type of cell