4.3 Cycles of Matter

The process of plants losing water through their leaves is called ____.

• condensation

• evaporation

• transpiration

• exhaling

Answer explanation

The process of plants losing water through their leaves is called transpiration. This is not condensation, which is the change of water from a gas to a liquid, or evaporation, which is the change from a liquid to a gas. It's also not exhaling, as plants do not breathe in the same way animals do. Instead, transpiration is a vital process for plant life, allowing them to transport water from roots to leaves.

What is the most abundant gas in the atmosphere?

• hydrogen

• oxygen

• helium

• nitrogen

Answer explanation

The most abundant gas in the atmosphere is nitrogen. It makes up about 78% of the Earth's atmosphere. The other options, hydrogen, oxygen, and helium, are also present in the atmosphere but in much smaller quantities. Oxygen is the second most abundant gas, but it only makes up about 21% of the atmosphere. Therefore, the correct answer to the question is nitrogen.

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NGSS.MS-PS1-1

Why do living things need nitrogen?

• To get energy

• To breathe

• To make proteins

• To release waste

Answer explanation

Living things need nitrogen primarily to make proteins. Proteins are essential for growth and development in all organisms. Nitrogen is a key component of amino acids, the building blocks of proteins. Therefore, the correct answer to the question is 'To make proteins'.

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NGSS.MS-LS2-3

What happens during the process of nitrogen-fixation?

• Nitrogen compounds turn into N₂

• N₂ turns into nitrogen compounds

Answer explanation

Nitrogen fixation is the process where atmospheric nitrogen (N2) is converted into ammonia (NH3). This process is crucial for life because it provides the nitrogen that is required by plants for protein synthesis. Therefore, the correct answer is that N2 turns into nitrogen compounds during nitrogen fixation.

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NGSS.MS-LS2-3

What happens during the process of denitrification?

• Nitrogen compounds turn into N₂

• N₂ turns into nitrogen compounds

Answer explanation

The process of denitrification involves the conversion of nitrogen compounds into nitrogen gas (N₂). This is a biological process carried out by certain types of bacteria in the absence of oxygen. Therefore, the correct answer is 'Nitrogen compounds turn into N₂'.

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Which is NOT a way that nitrogen compounds are added to the soil?

• Decay of dead organisms

• Denitrification

• Animal waste

• Nitrogen-fixation

Answer explanation

Denitrification is not a way that nitrogen compounds are added to the soil, but rather a process where nitrate in the soil is converted back into nitrogen gas, thereby removing nitrogen from the soil. The other options, decay of dead organisms, animal waste, and nitrogen-fixation, all contribute to adding nitrogen compounds to the soil.

Tags

NGSS.MS-LS2-3

What is the only process that removes carbon from the atmosphere?

• combustion

• cellular respiration

• photosynthesis

• decomposition

Answer explanation

The process of photosynthesis is the only one among the given options that removes carbon from the atmosphere. During photosynthesis, plants absorb carbon dioxide from the atmosphere and convert it into glucose and oxygen. The other options, such as combustion, cellular respiration, and decomposition, actually release carbon into the atmosphere.

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Animals obtain the nitrogen they need directly from the

• soil in their habitat

• air they breathe

• plants they eat

• bacteria living within them

Answer explanation

Animals cannot directly absorb nitrogen from the air or soil. Instead, they obtain the nitrogen they need by consuming plants. These plants have already converted atmospheric nitrogen into a usable form through a process called nitrogen fixation. Therefore, the correct answer to the question is 'plants they eat'.

Tags

NGSS.MS-LS2-1

What converts nitrogen gas into a useable form for plants and animals?

• bacteria

• fungi

• rain

• car exhaust 

Answer explanation

Bacteria, specifically nitrogen-fixing bacteria, are responsible for converting nitrogen gas into a usable form for plants and animals. These bacteria live in the soil and on the roots of certain plants, where they convert atmospheric nitrogen into ammonia, which can then be taken up by plants and eventually make its way into the food chain for animals.

How do  animals get nitrogen?

• the atmosphere 

• eating other organisms

• bacteria

• lightning 

Answer explanation

Animals obtain nitrogen by consuming other organisms. Nitrogen is an essential component of amino acids, which are the building blocks of proteins. When animals eat plants or other animals, they break down the proteins and incorporate the nitrogen into their own tissues. This process allows them to obtain the nitrogen they need for growth and other vital functions.

Tags

NGSS.MS-LS2-3