biology

• stem cells-

  cells that have not undergone differentiation (an unspecialised cell become a specialised cell type)
• embryonic- early stages of life
• adult stem cells found in:

  brain, eyes, heart, liver, bone marrow
• embryo's-

  formed after the fertilised (nucleus of each cell fused together) egg cell divides
• 2 kinds of stem cells:

  embryonic- useful in medicine

  adult- limited types of cells
• use of stem cells-

  treat paralysis, diabetes, blindness

  issues-

  concerns about it causing cancer

  concerns regarding viruses

  ethical issues-

  disagree with the use of stem cells from embryos (obtained from IBF clinics)
• therapeutic cloning-

  a way of producing embryonic stem cells to treat patients

  process:

  1. egg from donor
  2. remove nucleus (discharged)
  3. egg cell with no nucleus
  4. cell from patients body removed nucleus to put into egg cell
  5. zap of electricity (divides it)
  6. forms embryos (form of stem cell)
• advantage of therapeutic cloning-

  patients body won't reject the cells or tissue or organs produced
• diffusion-

  the movement of particles from an area of high to low concentration (no membrane required)

  move in both directions
• osmosis-

  high to low concentration with water particles only with partially permeable membrane

  concentration of water same on both sides of membrane, movement of water molecules will be the same in both directions.
• plant cells (osmosis)-

  cell wall cytoplasm and vacuole push against the cell wall and become turgid (swollen)

  more concentrated solution:

  cell cytoplasm and vacuole lose water by osmosis (shrink and pull away from cell wall)

  highly concentrated solution:

  cell undergoes plasmolysis as cells lose more water
• animal cells (osmosis)-

  take in and lose water

  do not have a cell wall- change size and shape when put into solutions that are at different concentration levels to the cells contents
• active transport-

  moved from high to low concentration against the concentration gradient (opposite direction) and requires energy.

  cells with AT need a lot of microconidia (happens in s. intestine)
• plants (AT)-

  AT occurs across the root so the plant takes in ions needed from soil
• animals (AT)-

  all glucose in gut needs to be absorbed in intestine

  movement of glucose involves AT

  process requires energy by respiration
• digestive system-

  order:

  1. cells
  2. tissue
  3. organ
  4. organ system
  5. organism
• functions-

  cell- single cell

  tissue- group of cells, similar structure, working together to carry out a specific function

  organ- group of different tissues working together to carry out a specific function

  organ system- groups of organs working together to perform a specific function

  organism- different organ systems working together
• absorption-

  surface of s. intestine has projections called villi

  villi increase surface area
• enzymes-

  has region called active site

  substrate- molecule taking part in the chemical reaction (fits into active site- once connected, reaction start to happen)
• broken down by enzymes-

  proteins- amino acids

  carbs- simple sugars

  lipids- fatty acids/ glycerol
• food tests-

  starch:

  iodine

  change from red- brown to blue- black, starch is present

  protein:

  biurets solution

  light blue turns to lilac, protein is present

  lipids:

  use ethanol and water

  put in test tube and shake- put in another

  cloudy emulsion, lipids is present

  reducing sugars:

  benedict's solution:

  put both in water bath (test tube)

  bright blue turns to green- orange, reducing sugars is present
• heart-

  right side- pumping deoxygenated blood to lungs

  left side- pumps oxygenated blood around body
• labels of heart-

  1. vena cava (R)- blood comes through pulmonary artery, down to the right atrium, then right ventricle (deoxygenated blood)
  2. pulmonary artery- carry blood away from heart to lungs
  3. pulmonary vein- carry blood to heart (oxygenated blood)
  4. aorta (L)- blood through pulmonary vein, through the L atrium, then left ventricle
• blood vessels-

  coronary artery (major B.V)

  blood and glucose to heart so it can pump/ relax/ contract

  red blood:

  transport oxygen around the body

  white blood:

  fights infection

  platelets:

  clot to prevent blood loss in an injury

  plasma:

  liquid part of the blood
• arteries-

  carry blood away from heart

  thick, muscular

  muscular walls to withstands blood flowing at high pressure as it leaves the heart.

  large lumen
• vein-

  carry blood to the heart

  thinner walls

  large lumen

  valves to prevent back flow of blood
• capillary-

  allows diffusion of gases and nutrients from blood into the body cells

  one cell thick, thin

  very small lumen

  allows transport of gases and nutrients into and out of blood
• coronary heart disease-

  layers of fat build up in arteries

  reducing blood flow to the heart

  stents used to open arteries

  statin medicines used to reduce blood cholesterol levels (reduces the rate of fat building up)
• causes for coronary heart disease-

  poor diet

  stress and smoking

  salt

  lack of exercise

  genetic factors
• role of mitochondria in an animal cell-

  release energy in the cell through aerobic respiration
• magnification definition-

  how many times larger the image is from the object
• to find image size in magnification-

  I=AM (image= actual (object)x magnification)
• magnification-

  M= image/ actual
• actual size in mag-

  actual = image/ mag
• plant cell stem cells -

  are found in meristem leaves
• carbs are broken down by amylase

  proteins broken down by protease

  fats (lipids) broken down by lipases into glucerol
• 2 main roles of the digestive system-

  Digestion - process of breaking down large food molecules into smaller molecules 

  Absorption - process of absorbing these small food molecules into the body