PRELIMINARY STAGE 2025
Our Lady of Grace SHS: 71 points
Benkum SHS: 50 points
Prampram SHS: 31 points
QUESTION
What term is used to describe the zone where fresh water and salt water mix?
ANSWER: Estuary
EXPLANATION
An estuary is a partially enclosed coastal water body (often where a river meets the sea) where fresh water from rivers mixes with salt water from the ocean, creating a distinctive brackish-water ecosystem with fluctuating salinity, rich in nutrients and biodiversity.
PRACTICE QUESTIONS
1. What is brackish water?
ANSWER: Water that is saltier than fresh water but less salty than sea water.
2. About how salty is sea water?
ANSWER: About 35 parts per thousand.
3. Name a plant community found in tropical estuaries.
ANSWER: Mangroves.
4. Why are estuaries called nurseries?
ANSWER: Many young fish and shellfish grow up there.
5. What causes the changing salinity in an estuary?
ANSWER: The tides and the flow of river water.
6. Name an estuary or lagoon in Ghana.
ANSWER: The Volta estuary (or the Keta Lagoon).
7. What are euryhaline organisms?
ANSWER: Organisms that tolerate a wide range of salinity.
8. Why are estuaries rich in nutrients?
ANSWER: Rivers bring nutrients and sediments.
9. What problem do estuarine animals face in osmoregulation?
ANSWER: The salinity changes, so they must adjust their water and salt balance.
10. What is a delta?
ANSWER: A fan-shaped deposit of sediment where a river enters the sea.
11. What is a salt marsh?
ANSWER: A coastal wetland with plants tolerant of salt.
12. State one threat to estuaries.
ANSWER: Pollution from land.