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. Compared with a vein of similar size, which vessel has a thicker muscular, elastic wall and a narrower lumen?

    • A vein carrying blood back from a body organ
    • A capillary exchanging substances in body tissue
    • An artery carrying blood away from the heart

  2. Which blood component carries most of the oxygen around the body?

    • White blood cells
    • Red blood cells
    • Blood platelets

  3. Capillary walls are only one cell thick.

    Circle one:   True   False

  4. Blood returns from the legs towards the heart at low pressure. Which feature helps stop it flowing back down?

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

  5. At a damaged blood vessel, which component gathers to form a plug and helps blood clot?

    • White blood cells
    • Plasma alone
    • Platelets

  6. How does lacking a nucleus help a mature human red blood cell carry oxygen?

    • It lets the mature cell divide to make more cells
    • It leaves more room inside the cell for haemoglobin
    • It lets the cell produce antibodies against pathogens

  7. At a tissue, glucose concentration is higher in blood plasma than in the surrounding tissue fluid. Which description explains how glucose reaches that fluid?

    • Glucose is carried by red cells and diffuses through thick artery walls.
    • Glucose travels in plasma and diffuses across thin capillary walls.
    • Glucose travels in plasma and is pushed through valves in vein walls.

  8. A student writes: veins carry blood away from the heart at high pressure, so they have thick walls. Which correction fits veins in the body loop?

    • Veins return blood at lower pressure and have thinner walls than comparable arteries.
    • Veins carry blood away at higher pressure and have narrower lumens than comparable arteries.
    • Veins exchange substances at tissues and have walls only one cell thick, like capillaries.
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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. An artery carrying blood away from the heart · An artery has a thicker muscular, elastic wall to withstand higher pressure. Its lumen is narrower than that of a vein of similar size.
  2. Red blood cells · Red cells are packed with haemoglobin, the protein that carries oxygen.
  3. True · A capillary wall is one cell thick. This gives substances a short diffusion path between blood and tissues.
  4. Valves in the veins · Valves in leg veins limit backward flow. They do not pump blood; nearby muscle contractions help move it towards the heart.
  5. Platelets · Platelets gather at the damaged vessel to form a plug. They help clotting together with proteins in plasma.
  6. It leaves more room inside the cell for haemoglobin · Without a nucleus, a mature human red blood cell has more room for haemoglobin, so it can carry more oxygen.
  7. Glucose travels in plasma and diffuses across thin capillary walls. · Glucose travels in plasma. It diffuses across capillary walls from the higher concentration in plasma to the lower concentration in tissue fluid.
  8. Veins return blood at lower pressure and have thinner walls than comparable arteries. · The student has used artery features to describe veins. Veins return blood towards the heart at lower pressure and have thinner walls.
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