Unit 2 -Water Chemistry and Cycles Intro

According to the diagram, what is the main source of ammonium (NH₄⁺) in a tank?

• Water changes

• Decomposing plant and animal matter & fish waste

• Sunlight

• Oxygen

Tags

NGSS.MS-LS2-3

Which bacteria convert ammonium (NH₄⁺) into nitrites (NO₂⁻)?

• Nitrosomonas

• Nitrospira

• Cyanobacteria

• Algae

Tags

NGSS.MS-LS2-3

Which bacteria convert nitrites (NO₂⁻) into nitrates (NO₃⁻)?

• Nitrosomonas

• Nitrospira

• Decomposers

• Zooplankton

Tags

NGSS.MS-LS2-3

What is the safest form of nitrogen for fish in tanks (at low levels)?

• Ammonium (NH₄⁺)

• Nitrite (NO₂⁻)

• Nitrate (NO₃⁻)

• None — all are equally harmful

Tags

NGSS.MS-LS2-3

Why are water changes an important part of the nitrogen cycle in aquariums?

• To add more ammonia for fish

• To remove excess nitrates

• To increase nitrite levels

• To eliminate all bacteria

Tags

NGSS.MS-LS2-3

Density is calculated using the formula:

• Mass ÷ Volume

• Volume ÷ Mass

• Mass × Volume

• Mass + Volume

An object with density of 0.8 g/mL will:

• Sink

• Float

• Dissolve

• Evaporate

Tags

NGSS.MS-PS1-2

Match the following effects of adding salt to water with their correct descriptions.

• Addition of salt causes water to become warmer

• Salt decreases water density

• Addition of salt makes water less dense

• Salt lowers pH

• Addition of salt makes water more acidic

• Salt increases water density

• Addition of salt makes floating easier in water

• Salt raises temperature

Tags

NGSS.MS-PS1-2

Fish use their swim bladders to:

• Control buoyancy

• Regulate oxygen

• Digest food

• Remove waste

The Buoyancy Lab helps students understand:

• How pH affects ecosystems

• How density relates to floating and sinking

• How osmosis moves water

• How nutrients cycle