Answer:
Because they don't have fertilizer.
Explanation:
Well, if this was a long time ago, then farmers did not have fertilizer. So, there are bacteria on the roots of plants that convert nitrogen into a usable form. It's very important for growing, and when farmers harvest the crop, not much of the nitrogen is returned to the land, so it is not as fertile. Fertilizer is largely consisted of nitrogen, so that is why farmers use fertilizers today. But "a long time ago," farmers did not have fertilizer.
The three scientific principles of sustainability are: (1) dependence on solar energy, (2) Biodiversity, and (3) chemical cycling.
dependence on solar energy - the energy imparted to the earth system by the sun. The sun warms the planet and provides energy that plants use to produce nutrients. The sun also powers indirect forms of solar energy such as wind and flowing water.
biodiversity -
The average expiratory reserve volume or ERV is 810.
<h3>What is expiratory reserve volume?</h3>
- Expiratory reserve volume or ERV is the amount of air that is exhaled forcibly.
- This can be measured using a spirometer and is used to detect restrictive lung diseases.
- It is the maximum amount of air that can be exhaled after normal tidal volume is exhaled.
- Respiratory volume is the volume of air which is either inhaled, exhaled or stored in your lungs.
- The doctors estimate the reserve volume with the help of spirometer to determine some lung diseases.
- Once diagnosed with a lung disease, spirometry is used to monitor it.
- Here, 3 readings of ERV are taken, calculate the sum of the these and divide by 3 to calculate the average ERV.
- ERV= (800+ 850+ 780)/ 3= 810
Learn about tidal volume here:
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Answer:
The minimum mass of dissolved cholesterol that the new system must be able to detect is 0.43 milligrams.
Note: The question is incomplete. The complete question is:
<em>GenAlex Medical, a leading manufacturer of medical laboratory equipment, is designing a new automated system that can detect borderline high levels of dissolved cholesterol (170, to 200. mg/dL), using a blood sample that is as small as 250 μL Calculate the minimum mass in milligrams of cholesterol that the new system must be able to detect Be sure your answer has the correct number of significant digits.</em>
Explanation:
Range of the equipment to detect cholesterol in blood = 170.0 to 200.0 mg/dL
Minimum amount of cholesterol that can be detected by instrument = 170 mg/dL
Volume of blood sample = 250 <em>μ</em>L= 0.0025 dL (1 dL = 100000 <em>μL)</em>
Amount of dissolved cholesterol in 250 <em>μL</em> sample of blood =
170 mg/dL * 0.0025 dL = 0.425 mg
The minimum mass of cholesterol that the new system must be able to detect is 0.43 milligrams.
Answer:
tundra plants, caribou and grizzly bear, and lichens.
Explanation:
