Diagram by Johann Dréo

Nitrogen Cycle

1. _______ is the vascular tissue that carries water and nutrients from the roots throughout the entire plant.

Vascular System

Xylem

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2. ________ is the vascular tissue that carries organic nutrients, primarily sugar, to all parts of the plant.

Phloem

Quick Review

The roots grow into the ground, and they serve 3 main roles for the plant:

1. Absorb water and nutrients from the soil/surroundings

2. Anchor the plant to the ground or surface it is growing on

3. Store energy, nutrients and water for future use by the plant.

Quick Review

Photo by Ingvar-fed

A new plant growth is known as a ______. The shoot system includes ______, _______, and _____________.

shootstems leaves

flowers/cones

Quick Review

A

T

G

C

Nitrogen is an essential nutrient for plants. Plants must make all of their own ______________ which are a part of every nucleotide. The also make their own ____________ which are linked together to form proteins. Nitrogen is also found in ____________ which is the molecule responsible for absorbing solar energy during photosynthesis.

nitrogen bases

amino acids

chlorophyll

Nitrogen gas (N2) is actually the most common element in the ____________, but plants cannot _______ and use this form of nitrogen. In order for plants to absorb nitrogen, it must first be __________ changed into a form that is absorbable.

atmosphere absorb

chemically

The process of converting nitrogen gas (N2) into ammonia (NH3) is known as _______________. This is the first step of the nitrogen cycle, and it can happen in a couple of different ways.

nitrogen fixation

Photo by Patrick Haney

Nitrogen fixation can begin in the air when _________ strikes. There is large amounts of energy in lightning, and this heat and radiation can cause nitrogen to react with hydrogen in ways it would not under normal conditions.

lightning

The most common method of nitrogen fixation occurs because of ________ and other microorganisms. These bacteria have _________ which convert the nitrogen in the air into _________. This ammonia will go on to be used by other bacteria.

bacteria

enzymes

ammonia

Soybean root nodules, containing Rhizobium bacteria

Soybean Plants

Many of theses bacteria actually live inside of the ______ of plants. Soybean plants and other ________ contain these bacteria inside of ____________. The bacteria are able to receive nutrients from the plant while the fix the nitrogen.

rootslegumes

root nodules

When plants and animals die, the nitrogen contained in these organisms is digested by ____________ and released into the soil as _________. Without these decomposers, the nitrogen would remain trapped in the dead animals. These decomposers _______ the nitrogen and are a key component of the cycle.

decomposersammonia

recycle

After the nitrogen gas (N2) has been converted into ammonia (NH3), it is converted once again by _________ bacteria. These bacteria absorb the ammonia and convert it into ________ (NO2

-) and ________ (NO3

-).

nitrifying

nitritesnitrates

Not all bacteria convert nitrogen into forms that plants can use. Some of them, known as ___________ bacteria, use the nitrites and ammonia themselves and convert it back into atmospheric nitrogen (N2). These bacteria are an important part of the nitrogen cycle that help replenish the N2 found in the air.

denitrifying

Once the nitrogen is converted into _______ (NO3-), it

can be absorbed through the ______ of the plant. Without the proper amount of nitrogen, the plant would not be able to survive.

nitratesroots

Many plants are grown by ________ in large quantities and this can deplete the nitrogen in the soil. After a few years of growing these crops, they can start to have trouble growing because there isn’t enough nitrogen.

farmers

Photo by Stan Shebs

CornWheat Oats

Photo by Rasbak

Soybean Plants Pea PlantsCloverAlfalfa

Because of this, farmers _______ their crops through their fields allowing _________ to grow in each field every few years. These legumes contain nitrogen fixing bacteria in their roots, and they help replenish the nitrogen available in the soil.

rotate

legumes