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Making food at deep-sea vents

Science · Ocean Life · ages 11-13

Name ______________________ Date ____________

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
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
Chemoautotrophic bacteria can form the producer base of a hydrothermal vent food web.
Circle one: True False
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.
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
Making food without sunlight means vent animals never use oxygen made by photosynthesis.
Circle one: True False
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
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

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

Photosynthesis in green plants · Photosynthesis uses light energy to make sugar from carbon dioxide and water.
Energy released by chemical reactions · Chemosynthesis uses chemical reaction energy. Some vent bacteria obtain it by reacting hydrogen sulphide with oxygen.
True · These bacteria make their own food using chemical energy. That food can support other organisms.
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.
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.
False · Food production and oxygen supply are separate questions. Vent animals can use oxygen made by photosynthesis near the surface.
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.
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.