Q: Which equation would you use to calculate percent salinity by mass/volume for a salinometer test?

$$\text{Percent Salinity} = \frac{\text{Mass of Salt (g)}}{\text{Volume of Solution (mL)}} \times 100$$

Q: A team calibrates their salinometer using a 5% NaCl solution. If their device reads 4.5%, what is the percent error?

$$\text{Percent Error} = \frac{|4.5 - 5.0|}{5.0} \times 100 = 10\%$$

Question 1

Which of the following best describes the role of macroinvertebrates in assessing freshwater ecosystem health?

Accepted Answer

They serve as indicators of water quality due to their varying tolerance to pollution.

Question 2

A water sample has a dissolved oxygen (DO) concentration of 2 mg/L. Which of the following is the most likely implication for aquatic life?

Accepted Answer

Increased presence of pollution-tolerant species such as Tubifex worms.

Question 3

Which equation would you use to calculate percent salinity by mass/volume for a salinometer test?

Accepted Answer

$$	ext{Percent Salinity} = \frac{	ext{Mass of Salt (g)}}{	ext{Volume of Solution (mL)}} 	imes 100$$

Question 4

Which of the following macroinvertebrates is classified as pollution sensitive?

Accepted Answer

Mayfly

Question 5

A river is found to have high levels of nitrates and phosphates. What is the most likely ecological consequence?

Accepted Answer

Eutrophication leading to algal blooms and decreased oxygen levels.

Question 6

Which of the following is a correct application of Traditional Ecological Knowledge (TEK) in freshwater management?

Accepted Answer

Incorporating indigenous observations of seasonal fish migrations to guide conservation efforts.

Question 7

Which aquatic nuisance animal is known for clogging water intake pipes and outcompeting native mussels?

Accepted Answer

Zebra Mussel

Question 8

A student measures the density of a saltwater solution using a hydrometer and obtains a value of $$1.05 \ 	ext{g/mL}. If $$the density of pure water is $$1.00 \ 	ext{g/mL}$$, what does this indicate about the solution?

Accepted Answer

The solution contains dissolved salts, increasing its density.

Question 9

Which process in the water cycle is primarily responsible for returning water from the atmosphere to the Earth's surface?

Accepted Answer

Precipitation

Question 10

A stream is found to have a high population of leeches and blood midges. What does this most likely indicate about the water quality?

Accepted Answer

The water is moderately polluted and supports tolerant species.

Question 11

Which of the following best describes the relationship between biochemical oxygen demand (BOD) and dissolved oxygen (DO) in a freshwater system?

Accepted Answer

High BOD usually results in low DO.

Question 12

Which aquatic nuisance plant is known for forming dense mats that block sunlight and reduce oxygen levels in freshwater systems?

Accepted Answer

Eurasian Water Milfoil

Question 13

A team calibrates their salinometer using a 5% NaCl solution. If their device reads 4.5%, what is the percent error?

Accepted Answer

$$	ext{Percent Error} = \frac{|4.5 - 5.0|}{5.0} 	imes 100 = 10\%$$

Question 14

Which of the following is a correct sequence in a freshwater aquatic food web?

Accepted Answer

Algae → Mayfly nymph → Fish → Heron

Question 15

Which water quality parameter is most directly affected by increased sedimentation in a stream?

Accepted Answer

Turbidity

Question 16

A sample of water has a pH of 4.5. Which of the following statements is most accurate?

Accepted Answer

The water is acidic and may be harmful to sensitive species.

Question 17

Which of the following best explains why air-breathing snails can survive in polluted water?

Accepted Answer

They can breathe atmospheric oxygen, bypassing low dissolved oxygen levels.

Question 18

Which of the following is a primary goal of potable water treatment?

Accepted Answer

Remove pathogens and harmful chemicals to make water safe for drinking.

Question 19

A stream is monitored over time and shows a shift from mayflies and stoneflies to midge larvae and leeches. What does this shift most likely indicate?

Accepted Answer

Degradation of water quality.

Question 20

Which of the following best describes the function of a watershed in freshwater resource management?

Accepted Answer

A watershed is an area of land that drains all the streams and rainfall to a common outlet.

Water Quality and Freshwater Ecology: Study Guide

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