Science Exam 2024

• Aerobic


  Full of oxygen
• Anaerobic


  Lacking of oxygen
• Breathing


  The mechanism that includes inhalation and exhalation
• Pathway for air to pass by


  1. nose

  2. trachea

  3. bronchus

  4. bronchiole

  5. alveolus

  6. bloodstream
• Pathway for exhalation


  1. bloodstream

  2. alveolus

  3. bronchiole

  4. bronchus

  5. trachea

  6. nose
• Respiration


  A process in the cell that oxides simple sugar to produce energy for life activities
• Mitochondria


  The powerhouse of the cell
• Life processes in a green plant during daytime

  1. Respiration

  2. Photosynthesis
• Gas exchange


  Occurs through the alveolus in the lungs
• Alveolus


  • Has a thin alveolar wall
• RBC


  Red Blood Cell
• Haemoglobin


  A special pigment in RBC which contains iron
• Solution


  Salt water
• Water is called Universal Solution
• For those insoluble in water can dissolve in organic solvent
• Blood plasma carries carbon dioxide in the body to the lungs
• Colorless solution


  • Salt solution
  • Sugar solution
• Colored solution


  • Copper sulfate solution (blue)
• Opaque


  Light cannot go through, not transparent
• One spot


  Sample is pure
• Three spots


  Sample is impure
• Retention time


  Time needed to separate the component from a dye in chromatography
• Balanced forces


  • Forces acting on an object can be balanced or unbalanced
  • Causes no change in the speed of an object
  • When acting on an object in opposite directions and equal in strength, it does not cause a change in the speed of a moving object
• Unbalanced forces


  • Occurs when one force is greater than the opposite force
  • Causes objects to speed up, slowdown or change direction
  • For an object: If its moving its speed could increase or decrease. If its moving its direction can change. Its shape can change. If its stationary it will start to move
• Examples of unbalanced forces

  • A car turning into a corner
  • Stretching an elastic band
  • A bike slowing down
• Since gravitational force is 9.8 N/kg, it means 1kg on Earth is 9.8 N, e.g: Nehan is 52kg, his weight is 52 x 9.8N = 509.6 N
• 1kg


  9.8 N
• Net force


  Same direction: add, different direction: subtract
• Pivot


  A supporting print that doesn't move
• Cactuses are filled with water
• Soils that form in arid climates are predominantly mineral soils with low organic content
• Most plants are drought-salt tolerant
• Rain does fall occasionally in deserts, and desert storms are often violent
• In the desert, it is very hot during the day and cold at night
• Desert temperatures

  • Day: 40°C
  • Night: 5°C or below
• Adaptation of desert plants (modification)


  1. Since the desert has a dry waterless weather, transpiration occurs easily (evaporation in water)

  2. In order to get enough water supply, desert plants have 2 types of roots (tap root: long and deep into the sand to get under water, fibrous root: to absorb water as soon as rain falls)
• Endangered


  Going to be extinct
• Nocturnal


  Active at night
• Poaching


  Illegal hunting
• Oxygen is carried by haemoglobin in the human body