mod 2

• unicellular; only one cell, meaning its responsible for its own life processes. Its simple structure limits the number of metabolic reactions that can occur at any particular time
• colonial organisms; collections of cells sharing resources and physically connected but all perform different roles
• some cells have specialised functions which coordinate with others to increase efficiency of the colony
• multicellular; made up of more than one cell which different cells are specialised to perform different functions for the benefit of the whole
• similar cells will be grouped together for the efficient functioning of the organism
• the groups of cells will concentrate on a particular function
• cell differentiation; after mitosis, where the cell becomes specialised to perform different functions
• digestion is the breaking down of large complex food particles into smaller and simpler particles that can be absorbed through the intestinal wall and into the bloodstream
• mechanical digestion; physically broken down
• chemical digestion; broken down by chemical agents such as enzymes
• mouth; teeth mechanically break down food, saliva lubricates the food and contains enzymes to start to chemically break down
• epiglottis


  small flap at the back of throat to prevent food going into lungs and down oesophagus
• stomach


  food churned up by muscles, gastric juice chemically digest to be broken down by chemical agents
• pancreas


  makes pancreatic juice to add to duodenum, contains all 3 enzymes to chemically break down carbs, protein fat
• liver


  makes bile
• gall bladder


  bile is stored here and added to duodenum via bile duct to emulsify fat and lipids
• small intestine


  food and water is absorbed into the walls to the bloodstream
• villi structure


  increase SA, meaning food can be absorbed more efficiently
• large intestine


  undigested and unabsorbed food is passed into here and water vitamin, mineral are absorbed into the bloodstream
• gaseous exchange


  movement between gases between internal and external environments by diffusion
• respiratory systems

  organs made up of gaseous tissues allowing an organism to take in oxygen and remove carbon dioxide
• common characteristics for efficient function and maximum exchange of gases

  large SA; faster rate of diffusion

  moist+thin; dissolves easily across the membrane and less distance to travel

  close proximity; gases to be taken to and from

  concentration gradient: occurs in the right direction
• stem cells

  biological cells found in all multicellular organisms, which can divide through mitosis and differentiate into diverse specialised cells
• embryonic stem cells


  are pluripotent, can differentiate in specialised cells, give rise to every cell type in a fully formed body, are in very low number in adults
• adult stem cells

  most specialised cells, identified in many organs and tissue, replenish dying cells and regenerate damaged tissue
• autotrophs


  produce their own organic compound
• heterotrophs


  rely on consuming other organisms, must have a supply of organic molecules, consumers and decomposes in the food chain/web,
• non-vascular plants

  do not have xylem and phloem, instead have simpler tissues that have specialised functions for internal transport of water, constant supply of water needed to live and reproduce to absorb through the surface of their leaves, nutrients absorbed / waste removed by diffusion and osmosis
• vascular plants


  contain leaves, stems, roots, flowers, seeds, shoot, vascular system
• vascular system


  responsible for the transport and distribution of organic compounds, water, minerals and gases
• xylem


  transport water from the roots to leaves, only upwards direction
• phloem

  transports sugar (sucrose and glucose) made by the leaves to any part of the plant
• root system

  anchor the plant and absorb water and inorganic nutrients from the soil, has a large surface area
• epidermal cells in the roots


  responsible for absorption of water and dissolved inorganic nutrients from the soil
• water moves through the roots via osmosis
• shoot system

  provides structural support and a transport pathway and its located above ground
• shoot layers

  dermal, vascular, ground tissue
• dermal layer

  outer layer provides protection, waterproofing and control of gas exchange
• vascular layer

  composed of the xylem and the phloem within the vascular bundle
• ground tissue

  fills in around the vascular tissue