back to index ofchaptersAnswers to questions from the text
1. What are plankton?
Ans. Plankton are the small animals and plants that live in the surfacelayers of the sea.
2. Plankton can either be temporary or permanent. Give an example ofa temporary and permanent plankton
Ans. Temporary - barnacle larvae. Permanent - jelly fish.
3. Why are there so many planktonic animals?
Ans. To increase the chance of immature barnacles growing to maturity.
4. What are the sex cells of a barnacle called?
Ans. Eggs and sperm
5. After fertilisation, name the first larval stage of a barnacle anddraw it.
Ans. A nauplius
See Figure
6. Name four other animals that have a larval stage as temporary plankton.
Ans. A rock lobster, prawn, sea snail or crab
7. Draw a fully labelled diagram to show the behaviour of the juvenilesettling behaviour of a barnacle.
Ans. See Figure
8. Where do adult prawns live?
Ans. On the continental shelf beside rivers.
9. What does the mysis stage of the prawn do 5 9 days after hatching?
Ans. Turns into a post larval stage
10. If you had a commercial fish hatchery, why would you need a marinescientist?
Ans. To identify the various stages of the animals being bread as wellas identify fish diseases and other competitors in the food chain at yourhatchery.
11. What is photosynthesis?
Ans. Photosynthesis is the process by which a plant uses the sun to makeits own food.
12. Give an example of a producer organism.
Ans. Marine algae, phytoplankton, diatoms.
13. What role do marine bacteria play in stabilising the marine ecosystem?
Ans. Marine bacteria play an important role in the recycling of wastematerial in the sea and are found at the surface as well as the ocean depths.
14. How should a coral cut be treated?
Ans. A coral cut need to be treated by removing all coral pieces witha toothbrush and then applying a drying solution such as betadine, to dryup the wound making it impossible for further bacteria to breed.
15. Name two zooplankton.
Ans. Copepods, arrow worms, snail larvae, prawn or crab larvae, jellyfish.
16. What is the main difference between phytoplankton and zooplankton?
Ans. Phytoplankters have chlorophyll
17. Name two planktonic adaptations giving reasons for your answers.
Ans.
1. Size. Most plankton are small which helps them float. Small size alsomeans that the individual can ingest and excrete straight through the bodywall and so reducing the need for a complicated digestive system which wouldadd weight to the body.
2. Shape. Most plankters use shape to stay afloat. They can be:
· long and flat or
· bell shaped or
· have long chains with air filled sacs or
· have a swimming antennae like copepods
18. What happens to plankton as night falls?
Ans. They move towards the surface.
19. What is the photic zone?
Ans. The photic zone is the depth of water that light can penetrate intothe sea (Figure 168.1). This is where phytoplankton live because they needthe sunlight for photosynthesis.
20. Why are upwellings important to phytoplankton?
Ans. Upwellings are currents that bring marine sediments to the surfaceand are very rich in nutrients which fertilise the phytoplankton (see Chapter12). Phytoplankton grow to very high numbers here, providing an enormousamount of food for marine animals.
21. Give an example of a marine food chain.
Ans.
Algae copepod fish fry cod tuna great white shark
22. What is the difference between a producer and a consumer?
Ans.
Producers are plants which make their own food using photosynthesis toconvert the Sun's energy to sugars.
Consumers are animals that consume other organisms plants, animals orboth to obtain their energy needs.
23. Name one herbivore that lives in the sea.
Ans. Dugong or abalone,
24. How much oxygen is produced by plankton?
Ans. Plankton form the basis for life on Earth they produce more than70 per cent of the Earth's oxygen and are a vital part of the food chainfor all living creatures in the sea.
25. Write definitions of the following terms and give an example of each:
a. First order consumer
Ans. Eats the producers..
b. Second order consumer
Ans. Eats the first order consumer
c. Carnivore
Ans. Animals that eat other animals
d. Predator
Ans. An animal that kills and eats other animals.
e. Scavenger
Ans. Special groups of animal consumers that eat dead animals and plants.
f. Decomposer organism
Ans. A decomposer organism breaks down the dead tissues of other organismsto release simple chemical substances such as minerals back into the sea.
g. Herbivore
Ans. Animals that eat only plants, such as dugong or abalone, are herbivores.
26. Draw a marine food web.
Ans. See Figure 1701.
27. What is the ultimate source for all energy on our planet?
Ans. The Sun
28. What do marine scientists use energy pyramids for?
Ans. Scientists often use an energy pyramid to demonstrate the energyflow through a community.
29. Only 10 per cent of energy is passed on in a food chain from oneconsumer to another.
a. Why is this so?
Ans. Only 10 percent can get locked up in chemical bonds.
b. What happens to the other 90 per cent of energy?
Ans. Use for normal body functions
c. Show how a seal, herring, zooplankton, small fish and phytoplanktonare related in a energy pyramid.
Ans. See Figure 171.1
30. Define the term biomass.
Ans. Biomass is the total amount of living matter per unit of surfaceor volume, expressed as a weight.
To be completed
1. Plankton
2. testis
3. ovary
4. hermaphrodite
5. reproductive cells
6. fertilised
7. Photosynthesis
8. Zooplankton
9. Phytoplankton
10. vertical migration
11. Producers
12. Consumers
13. Scavengers