Physical Water Properties
Which property measures how cloudy water is?
A. pH
B. Turbidity
C. Conductivity
D. Dissolved oxygen
B. Turbidity ✅
A pH value of 7 is considered:
A. Acidic
B. Basic
C. Neutral
D. Alkaline
C. Neutral ✅
Dissolved oxygen (DO) is most important for:
A. Plant photosynthesis
B. Aquatic animal respiration
C. Water clarity
D. pH balance
B. Aquatic animal respiration ✅
Which organism primarily uses nitrates and phosphates?
A. Fish
B. Bacteria
C. Algae
D. Zooplankton
C. Algae ✅
Which organism is often used as a bioindicator of good water quality?
A. Leeches
B. Mayfly larvae
C. Mosquito larvae
D. Tubifex worms
B. Mayfly larvae ✅
What instrument is used to measure water turbidity in the field?
A. Secchi disk
B. Thermometer
C. pH probe
D. Titration kit
A. Secchi disk ✅
Which nutrient commonly causes eutrophication when present in excess?
A. Calcium
B. Sodium
C. Phosphate
D. Chloride
C. Phosphate ✅
Which process consumes dissolved oxygen?
A. Photosynthesis
B. Respiration
C. Diffusion
D. Precipitation
B. Respiration ✅
Eutrophication most often occurs in:
A. Fast-moving streams
B. Deep ocean waters
C. Nutrient-rich lakes
D. Polar regions
C. Nutrient-rich lakes ✅
Nonpoint source pollution is best described as pollution that:
A. Comes from factories
B. Is discharged through pipes
C. Has no single identifiable source
D. Is illegal
C. Has no single identifiable source ✅
High turbidity in water is most likely caused by:
A. Dissolved salts
B. Suspended sediments
C. High oxygen levels
D. Low temperature
B. Suspended sediments ✅
High nitrate levels in water are often linked to:
A. Road salt
B. Fertilizer runoff
C. Industrial cooling
D. Groundwater evaporation
B. Fertilizer runoff ✅
BOD stands for:
A. Biological Oxygen Demand
B. Baseline Oxygen Deficit
C. Bacterial Oxygen Density
D. Balanced Oxygen Distribution
A. Biological Oxygen Demand ✅
Which nutrient is usually the limiting factor in freshwater systems?
A. Nitrogen
B. Carbon
C. Phosphorus
D. Oxygen
C. Phosphorus ✅
Which land use is most likely to increase sediment runoff?
A. Forest
B. Wetland
C. Agriculture
D. Construction sites
D. Construction sites ✅
Which unit is commonly used to measure conductivity?
A. NTU
B. mg/L
C. µS/cm
D. °C
C. µS/cm ✅
Which form of nitrogen is most toxic to aquatic life?
A. Nitrate
B. Nitrite
C. Ammonia
D. Nitrogen gas
C. Ammonia ✅
High BOD levels usually indicate:
A. Clean water
B. Cold water
C. Organic pollution
D. High salinity
C. Organic pollution ✅
What is a common result of excessive algal growth?
A. Increased biodiversity
B. Higher pH stability
C. Oxygen depletion
D. Reduced temperature
C. Oxygen depletion ✅
Which water quality change most directly affects fish gill function?
A. pH shifts
B. Turbidity increase
C. Dissolved oxygen decrease
D. Nutrient enrichment
C. Dissolved oxygen decrease ✅
An increase in water temperature generally causes dissolved oxygen to:
A. Increase
B. Stay the same
C. Decrease
D. Fluctuate unpredictably
C. Decrease ✅
Which chemical parameter directly affects metal solubility in water?
A. Temperature
B. Turbidity
C. pH
D. Dissolved oxygen
C. pH ✅
A sudden drop in dissolved oxygen is most likely caused by:
A. Increased water flow
B. Algal die-off and decomposition
C. Reduced turbidity
D. Decreased nutrients
B. Algal die-off and decomposition ✅
Which human activity most contributes to cultural eutrophication?
A. Mining
B. Wastewater discharge
C. Agricultural runoff
D. Urban shading
C. Agricultural runoff ✅
A healthy aquatic ecosystem typically shows:
A. High nutrients and low DO
B. Low biodiversity
C. Stable pH and high DO
D. Frequent algal blooms
C. Stable pH and high DO ✅