Blood Components and Blood Vessels · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Blood parts and the pipes they travel in

Science · The Human Body · ages 15-16
Name ______________________   Date ____________

  1. Which vessel has thick muscular walls and a narrow middle?

    • Vein
    • Capillary
    • Artery

  2. Which blood part hauls oxygen around the body?

    • Platelets
    • Red blood cells
    • Plasma

  3. Capillary walls are only one cell thick.

    Circle one:   True   False

  4. Blood in the legs must flow upward against gravity at low pressure. Which feature makes this possible?

    • Valves in the veins
    • Thick artery walls
    • Thin capillary walls

  5. A cut stops bleeding after a few minutes. Which blood part did this?

    • White blood cells
    • Plasma
    • Platelets

  6. How does lacking a nucleus help a red blood cell?

    • It lets the cell divide faster
    • It leaves more room for haemoglobin
    • It helps the cell fight germs

  7. A tissue needs a faster supply of dissolved food. Which change to its capillaries would help most, and why?

    • Wider walls to hold more blood
    • Valves to raise the pressure
    • Thinner walls to shorten the diffusion path

  8. A student writes: veins carry blood away from the heart at high pressure, so they have thick walls. What is the error?

    • Veins carry blood toward the heart at low pressure with thin walls
    • Veins are one cell thick for fast exchange
    • Veins carry oxygen using haemoglobin
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Blood parts and the pipes they travel in W1-mt_aWZ2sGXGMn-s1

  1. Artery · Arteries take the full blast from the heart, so they need strong thick walls.
  2. Red blood cells · Red cells are packed with haemoglobin, the protein that carries oxygen.
  3. True · One thin layer keeps the diffusion path short so exchange is fast.
  4. Valves in the veins · Vein valves snap shut so low pressure blood cannot flow back down.
  5. Platelets · Platelets plug leaks by forming a clot at the wound.
  6. It leaves more room for haemoglobin · More haemoglobin per cell means more oxygen carried per cell.
  7. Thinner walls to shorten the diffusion path · Exchange speed depends on path length, so a thinner wall delivers faster.
  8. Veins carry blood toward the heart at low pressure with thin walls · Arteries carry blood away at high pressure. Veins return it at low pressure.
Worksheet · LightMySky