Deep-sea life without sunlight · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Making food at deep-sea vents

Science · Ocean Life · ages 11-13
Name ______________________   Date ____________

  1. Which process uses light energy to build sugar from carbon dioxide and water?

    • Chemosynthesis in vent bacteria
    • Photosynthesis in green plants
    • Respiration in plants and animals

  2. What energy source do bacteria use for chemosynthesis?

    • Energy released by chemical reactions
    • Energy from the pressure of deep seawater
    • Energy carried by flashes of lightning

  3. Chemoautotrophic bacteria can form the producer base of a hydrothermal vent food web.

    Circle one:   True   False

  4. A vent crab eats small animals that feed only on bacterial mats. The mats shrink, and no other food replaces them. What may happen to the crab's food supply?

    • It may fall as the small animals lose food.
    • It must rise because fewer bacteria means more prey.
    • It must stay the same because crabs do not eat the mats.

  5. Adult giant vent tube worms have no mouth or stomach. How do they obtain food?

    • Their mouths filter drifting plankton
    • Their skin catches sunlight to make sugar
    • Bacteria inside them supply food

  6. Making food without sunlight means vent animals never use oxygen made by photosynthesis.

    Circle one:   True   False

  7. Maya says NASA studies Earth's vents to find sunlight beneath the ice of Europa and Enceladus. Which explanation should replace her idea?

    • Earth's vent animals prove that the same animals live on both moons
    • Studying Earth's vents proves that both moons already have active vents
    • Researchers test how chemical energy could support life

  8. Why are hydrothermal vents studied as one possible setting for the origin of life?

    • Their heat alone is known to turn seawater into living cells
    • Water and chemicals could help early reactions
    • Their living animals prove that the first cells formed there
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Answer key

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

Making food at deep-sea vents W1-mt_6Wx--Du8j3-s1

  1. Photosynthesis in green plants · Photosynthesis uses light energy to make sugar from carbon dioxide and water.
  2. Energy released by chemical reactions · Chemosynthesis uses chemical reaction energy. Some vent bacteria obtain it by reacting hydrogen sulphide with oxygen.
  3. True · These bacteria make their own food using chemical energy. That food can support other organisms.
  4. It may fall as the small animals lose food. · Less food for the small animals can reduce the prey available to the crab. A food shortage can affect animals more than one feeding link away.
  5. Bacteria inside them supply food · These worms host food-making bacteria inside their bodies. The bacteria use chemical energy and supply food to the worms.
  6. False · Food production and oxygen supply are separate questions. Vent animals can use oxygen made by photosynthesis near the surface.
  7. Researchers test how chemical energy could support life · Earth's vents help researchers investigate possible life supported by water and chemical energy. They do not prove life or active vents on both moons.
  8. Water and chemicals could help early reactions · Water, chemicals and reactions with rocks could have helped early living systems form. This possibility does not prove that life began at vents.
Worksheet · LightMySky