organisation paper 1

• how do cells form tissues, organs, and systems?

  by differentiating and working together
• what are the basic building blocks of all living organisms?

  cells
• what happens to cells as an organism develops?

  cells differentiate to form different types
• when do most types of animal cells differentiate?

  at an early stage of development
• can many types of plant cells differentiate throughout their life?

  yes, many types can differentiate continuously
• what changes occur as a cell differentiates?

  shape changes and new sub-cellular structures develop
• what is the function of a sperm cell's tail?

  to propel the sperm to fertilise the egg
• why do sperm cells have many mitochondria?

  to provide energy for their journey
• what does the nucleus of a sperm cell contain?

  one set of genetic material
• what is the function of the acrosome in a sperm cell?

  to allow the sperm to penetrate the egg
• what are the main components of a muscle cell?

  nucleus and protein fibres
• what is a tissue?

  • a group of cells with similar structure
  • cells work together to perform a job
  • examples: muscle tissue, glandular tissue, epithelial tissue
• what is the role of muscle tissue?

  to contract and produce movement
• what does glandular tissue produce?

  substances such as enzymes and hormones
• what is the function of epithelial tissue?

  to cover organs
• what are organs made of?

  groups of different tissues
• what tissues does the stomach contain?

  muscle, glandular, and epithelial tissues
• what is an organ system?

  a group of organs working together
• what do single-celled organisms lack?

  tissues
• what are enzymes?

  biological catalysts that speed up reactions
• what is the active site of an enzyme?

  a space within the protein molecule
• what does each enzyme catalyse?

  a specific reaction
• what is the optimum for enzymes?

  specific temperature and pH for best activity
• what is the lock and key theory?

  a model explaining enzyme-substrate interaction
• what happens to enzymes at high temperatures?

  they denature and change shape
• what occurs when an enzyme is denatured?

  the substrate cannot fit into the active site
• where are digestive enzymes produced?

  by specialised cells in glands and gut lining
• what do digestive enzymes do?

  break down large insoluble food molecules
• what is amylase?

  a carbohydrase that breaks down starch
• where is amylase produced?

  in the salivary glands and pancreas
• what does protease do?

  breaks down proteins into amino acids
• where is protease produced?

  in the stomach, pancreas, and small intestine
• what does lipase do?

  breaks down lipids into fatty acids and glycerol
• where is lipase produced?

  in the pancreas and small intestine
• what is bile?

  a liquid made in the liver and stored in the gall bladder
• what is the function of bile?

  to neutralise hydrochloric acid and emulsify fat
• how does bile increase the rate of fat digestion?

  by increasing surface area for lipase action
• what is the independent variable in the amylase experiment?

  the pH
• what is the dependent variable in the amylase experiment?

  the time taken for starch to digest
• what are control variables in the amylase experiment?

  temperature, concentration, and volume of solutions