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Science 10

Science 10 · Worksheets

Final exam challenge

Ten questions of mixed difficulty, covering Cells, Compounds and equations, Energy and work, Global systems, Heat and energy transfer. Print it, or work through it on screen — the answer key starts on its own page.

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Final exam challenge

Science 10 · maddyhelps.com

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Circle the best answer for each question. Show your work in the space provided.

  1. Ice cores are useful evidence about past climate because

    1. a) ice reflects sunlight
    2. b) ice contains fossils
    3. c) trapped air bubbles preserve samples of ancient atmosphere
    4. d) ice grows one layer per century

  2. Energy leaves Earth almost entirely as

    1. a) conduction through the atmosphere
    2. b) convection into space
    3. c) visible light
    4. d) infrared radiation into space

  3. A cell's surface area to volume ratio limits its size because

    1. a) volume grows faster than surface area, so exchange cannot keep up
    2. b) the membrane gets thicker
    3. c) large cells have no nucleus
    4. d) DNA runs out

  4. Conduction transfers energy by

    1. a) chemical change
    2. b) the movement of a fluid
    3. c) direct contact between particles
    4. d) electromagnetic waves

  5. A motor takes in 500 J and produces 150 J of useful output. Its efficiency is

    1. a) 30%
    2. b) 70%
    3. c) 350%
    4. d) 3.3%

  6. The greenhouse effect warms Earth because greenhouse gases

    1. a) reflect sunlight to space
    2. b) absorb the infrared Earth re-emits and send some of it back
    3. c) produce heat themselves
    4. d) block incoming sunlight

  7. An ionic compound forms between

    1. a) two non-metals
    2. b) two metals
    3. c) two noble gases
    4. d) a metal and a non-metal

  8. Balanced, the equation ___H₂ + ___O₂ → ___H₂O is

    1. a) 2H₂ + O₂ → 2H₂O
    2. b) H₂ + 2O₂ → 2H₂O
    3. c) H₂ + O₂ → H₂O
    4. d) 2H₂ + 2O₂ → 2H₂O

  9. Diffusion is the movement of particles

    1. a) from higher to lower concentration, without energy
    2. b) only in living things
    3. c) only through a membrane
    4. d) from lower to higher concentration, using energy

  10. A ball bouncing lower each time has not destroyed energy, because

    1. a) gravity removed it permanently
    2. b) energy was created by the floor
    3. c) the missing energy became heat and sound in the ball and floor
    4. d) kinetic energy is not conserved

Answer key · Final exam challenge

Science 10 · maddyhelps.com

  1. c) trapped air bubbles preserve samples of ancient atmosphere — Each annual layer traps a little air, so a core is a dated record of atmospheric composition going back hundreds of thousands of years. Tree rings, sediment layers and coral give overlapping records that agree with it.
  2. d) infrared radiation into space — Space is a vacuum, so only radiation can carry energy away. Earth is far cooler than the Sun, so it radiates in the infrared rather than in visible light — and that is exactly the band greenhouse gases absorb.
  3. a) volume grows faster than surface area, so exchange cannot keep up — Doubling a cell's width gives four times the surface and eight times the volume. Beyond a certain size the membrane cannot supply the interior fast enough, so cells divide instead of growing.
  4. c) direct contact between particles — Fast particles collide with slower neighbours and pass energy along. Metals do this well because their free electrons carry energy through the material quickly.
  5. a) 30% — Efficiency = useful out ÷ total in × 100 = 150/500 × 100 = 30%. The other 350 J went to heat and sound, so 70% is what was <i>wasted</i>, not the efficiency.
  6. b) absorb the infrared Earth re-emits and send some of it back — Short-wavelength sunlight passes through and warms the surface, which re-radiates longer-wavelength infrared that the gases absorb. Without the effect Earth would average about −18 °C, so the effect itself is not the problem — the enhancement is.
  7. d) a metal and a non-metal — Metals give electrons up and non-metals take them, so the transfer produces oppositely charged ions that attract. Two non-metals share instead, which is a covalent bond.
  8. a) 2H₂ + O₂ → 2H₂O — Count each element on both sides: 4 hydrogens and 2 oxygens each way. Only the coefficients in front may be changed — altering a subscript would change the substance itself.
  9. a) from higher to lower concentration, without energy — Random motion spreads particles out until they are evenly distributed. It is passive, which means no ATP is spent — a rule that holds for non-living systems too.
  10. c) the missing energy became heat and sound in the ball and floor — Tracking where the energy went, rather than saying it was lost, is the habit this unit is really teaching. The total is unchanged; the useful, organised part is smaller.