• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Cycles in Biology.

Extracts from this document...

Introduction

Cycles in Biology A cycle is an interval during which a recurring sequence of events occurs. Cycles are a hugely relevant component of biology. Practically everything has to be recycled as every resource, to some extent, is a non-renewable resource. There are cycles in all aspects of biology that can be explored. Life-materials are the basic particles of Earth, called elements, that all living organisms build their bodies from. They are sometimes called "bio-elements." All living organisms are made primarily of six elements, all in the same proportion: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus and Sulphur. Most organisms require small, often tiny, amounts of additional such as iron, copper and iodine. Most plants require a total of twenty-three different nutrients to flourish. Essential nutrients are limited. We use them for energy to power our bodies (food for metabolism) and as materials to build and renew our bodies. We renew or rebuild our bodies over and over, every day. Nutrients are all recycled so organisms can share them over time. This sharing process is called the Nutrient Cycle. These nutrients have been shared over and over for billions of years. Every organism alive on earth is made of nutrients that have been used and re-used over and over again. ...read more.

Middle

Organic forms of carbon in the lithosphere include litter, organic matter, and substances found in soils. Some carbon dioxide is released from the interior of the lithosphere by volcanoes. The nitrogen cycle is the complex series of reactions by which nitrogen is slowly but continually recycled in the atmosphere, lithosphere and hydrosphere. The nitrogen cycle represents one of the most important nutrient cycles found in the earths ecosystems and almost all of the nitrogen found in any ecosystem originally came from the atmosphere. Nitrogen is used by living organisms to produce a number of complex organic molecules such as amino acids, proteins, and nucleic acids. The largest store of nitrogen is found in the atmosphere where it exists as a gas. Other major stores of nitrogen include organic matter in soil and the oceans. Despite its abundance in the atmosphere, nitrogen is often the most limiting nutrient for plant growth as they can only take up nitrogen in certain forms. Most plants obtain the nitrogen they need as inorganic nitrate from the soil solution. Animals receive the required nitrogen they need for metabolism, growth, and reproduction by the consumption of living or dead organic matter containing molecules composed partially of nitrogen. ...read more.

Conclusion

Most of the energy made available by the oxidative steps of the cycle is transferred as energy-rich electrons to NAD+, forming NADH. For each acetyl group that enters the Krebs cycle, three molecules of NAD+ are reduced to NADH. In Step 6, electrons are transferred to the electron acceptor FAD rather than to NAD+. In one turn of the citric acid cycle, two molecules of carbon dioxide and eight hydrogen atoms are removed, forming three NADH and one FADH2. The carbon dioxide produced accounts for the two carbon atoms of the acetyl group that entered the citric acid cycle. These hydrogens come from water molecules that are added during the reactions of the cycle. Because two acetylcholine molecules are produced from each glucose molecule, the cycle must turn twice to process each glucose. At the end of each turn of the cycle, the four-carbon oxaloacetate is left, and the cycle is ready for another turn. After two turns of the cycle, the original glucose molecule has lost all of its carbons and may be regarded as having been completely consumed. Only one molecule of ATP is produced directly with each turn of the citric acid cycle. The rest of the ATP that is formed during aerobic respiration is produced by the electron transport system. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Energy, Respiration & the Environment section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Energy, Respiration & the Environment essays

  1. Marked by a teacher

    Effect of nitrate concentration on the growth of Duckweeds

    5 star(s)

    At this point the cell is turgid (very firm), which is the healthiest state for the plants generally; this is why the fronds in this condition looked very healthy and green. This is also the reason why maximum amount of growth did not occur in the 0% concentration and it

  2. Nitrogen Cycle

    as a solid rock known as calcium carbonate (limestone). Corals and algae encourage this reaction and build up limestone reefs in the process. On land and in the water, plants take up carbon dioxide and convert it into carbohydrates through photosynthesis. This carbon in the plants now has 3 possible fates.

  1. The Pancreas is a large gland that forms part of the Endocrine System, but ...

    This stops the pancreatic enzymes from working. Lipase, which digests fats, is mainly affected. Therefore, people with pancreatitis have trouble digesting and absorbing fatty foods. There are a few different theories about how the enzymes can become activated and start digesting the tissue and start to cause inflammation.

  2. Field trip report Mangrove ecosystem

    They are mosses, Aegiceras corniculatum and Kandelia candel. Note that both Kandelia candel and Aegiceras corniculatum are quite short (they always below 1.3m), since the substratum in Sai Keng is hard (the soil is composed of nearly 56 % gravel). Here are some of the description and their distribution. i.

  1. the effect of bile concentration on the activity of the enzyme lipase during the ...

    Put the pH probe in the buffer of 7 and then set it as 7 and then test with the pH buffer of 4 and repeat if it is not accurate. It is important that the pH probe is accurate as this affects our results directly if it's inaccurate.

  2. chemistry of renewable resources

    and are not usually used as a source of energy, except in times of starvation. The cause of death in people suffering from "slimmers' disease" - anorexia nervosa - is heart failure, because the body begins to obtain energy from the protein in heart muscle Typical values Per 100g (3.5 OZ)

  1. Why the Body Needs Energy? Every living cell within the ...

    is divided into two lobes which are the superior and inferior lobes, as fore the fight lungs is divided into three which are the superior, middle and inferior. * The lobes are subdivided into lobules. * The lung tissues are made of bronchioles, alveoli, blood vessels, nerves, connective tissues and elastic tissues.

  2. The Homeostatic Mechanisms

    Also, the body?s temperature increases as this is happening due to the amount of energy being burnt. Homeostatic mechanisms maintain the body temperature at a stable level to prevent the person from overheating. This is known as thermoregulation, which is controlled by the hypothalamus within the brain.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work