biology

• Sensory neurone


  These connect receptors to the coordinator
• Relay neurones


  These coordinate the correct response to the stimulus
• Motor neurone


  These send the signal from the coordinator to the effector
• Neurone


  A bundle of neurones is called a nerve
• Reflex arc


  A reflex arc is the pathway that a signal travels from the receptor to the effector, the brain is not included in the pathway and this makes the response faster
• Control variable


  Variables we keep the same to make the investigation valid
• What can influence your reaction time?


  •Age

  •Gender

  •Health

  •Training/preparation

  •Tired/stressed

  •Alcohol/drugs
• Genome


  All of the genetic material that is present in an organism
• Chromosomes


  23 pairs and 46 chromosomes
• Sperm cell adaptations


  •Mitochondria for energy

  •Tail for faster swimming
• When you exercise your blood sugar falls:

  •The pancreas detects the fall in blood glucose

  •The pancreas secretes glucagon into the blood stream

  •The glucagon travels to the liver

  •The liver converts glucagon into glucose and releases it into the blood

  •Blood glucose returns to normal
• When you eat your blood sugar rises:


  •The pancreas detects the rise in blood glucose

  •The pancreas secretes insulin into the blood stream

  •The insulin travels to the liver

  •The liver absorbs the glucose and converts it in to glycogen

  •Blood glucose returns to normal
• Catalysts

  Catalysts increase the rate of reaction by lowering the activation energy and providing an alternative pathway for the reaction without being used up
• Explain how catalysts speed up the rate of reaction:

  1. They lower the activation energy
  2. They create a pathway for the reaction
  3. They are not used up
• Meiosis

  •Produces non-identical cells

  •Daughter cells have one set of chromosomes

  •Includes two nuclear divisions

  •Produces 4 daughter cells
• Animal cell organelles:

  •Nucleus

  •Cell membrane

  •Cytoplasm

  •Mitochondria

  •Ribosomes
• Plant cell organelles

  •Cell membrane

  •Cell wall

  •Vacuole

  •Chloroplasts

  •Nucleus

  •Cytoplasm

  •Mitochondria

  •Ribosomes
• Nucleus

  Holds genetic information
• Ribosomes

  Creates proteins through protein synthesis
• Mitochondria

  Creates energy through respiration
• Plants

  Roots: where plants absorb water and mineral ions

  Stem: supports leaves and the flower

  Leaves: carries out photosynthesis

  Flower: reproductive part of the plant
• Diffusion

  Diffusion is the movement of particles from an area of high concentration to low concentration
• Phloem

  Phloem transports dissolved sugar from the leaves to the rest of the plant
• Xylem

  Xylem transports water and mineral ions from the roots to the rest of the plant
• Word equation for photosynthesis

  Carbon dioxide + water -> glucose + oxygen
• Symbol equation for photosynthesis

  Co2 + H2O -> C6H12O6 + O2
• Photosynthesis

  As light intensity increases, so does rate of photosynthesis. This is because there is more light which is the main part of photosynthesis
• Communicable disease


  •Infectious, can spread

  •Caused by pathogens such as viruses, bacteria, fungi and protists

  •Examples include measles, malaria and covid-19
• Non-communicable disease 


  •Not infectious

  •Caused by environment, lifestyle, genetic, or otherwise

  •Examples include coronary heart disease and cancer
• AIDS and tuberculosis 


  •AIDS damages the immune system and makes infections more likely and more dangerous

  •An AIDS sufferer will have fewer active white blood cells to fight infection

  •Bacteria are more likely to infect and harm an AIDS sufferer so tuberculosis is much more common
• The three types of blood vessels:


  •Arteries: carry blood away from the heart

  •Capillaries: tiny vessels involved in exchange of substances at the tissues

  •Veins: carry blood to the heart
• Arteries


  Artery walls are thick, strong and elastic. They have small lumen which helps to maintain the high pressure
• Veins


  Vein walls are thinner than artery walls. They have bigger lumen which helps to maintain blood flow
• Capillaries


  Capillaries are too small to see without a microscope. They are close to all body cells to allow substance exchange. They have thin permeable walls to allow whicker diffusion
• Factors of coronary heart disease:

  •Unhealthy food

  •Stress

  •Little exercise

  •Salty food

  •Smoking

  •Obesity

  •Genetics
• Coronary heart disease


  •Fatty deposits build up on the walls of the coronary artery

  •Blood flow is now restricted

  •Less oxygen reaches the heart muscle

  •The heart muscle cannot respire

  •Results in a heart attack
• Stents 


  Stents are metal grids that are placed into an artery to allow blood to flow. A catheter with a balloon is inserted in a blood vessel
• Disadvantages of stents

  •Infection

  •Blood clots
• Advantages of stents

  •Allows blood to flow

  •Keeps the artery open
• Statins

  A drug to lower the cholesterol in the blood