4.2 Study Guide Flashcards
Define and explain the differences between nitrogen fixation, nitrification, and denitrification.
Nitrogen fixation is the transformation of gaseous nitrogen molecules (N2) into different chemical compounds like ammonium that plants can absorb and utilize. Nitrification is the transformation of compounds like ammonium into nitrates, which are nitrogen compounds that plants can use even better than ammonium. Denitrification is the transformation of these nitrogen compounds back into gaseous nitrogen, which is released into the atmosphere. All 3 processes are generally performed by bacteria living in soil.
State the inputs and outputs of photosynthesis. Explain how they relate to the inputs and outputs of cellular respiration.
For photosynthesis to occur, the inputs of carbon dioxide, water, and sunlight/light energy are required. The process produces the outputs of oxygen and glucose molecules. Cellular respiration, on the other hand, is essentially the opposite and requires the inputs of oxygen and glucose while producing the outputs of carbon dioxide, water, and ATP (a different form of energy).
Regarding the processes of photosynthesis and cellular respiration, state what types of organisms perform only one process and what types perform both as well as which processes.
Producers, which are mostly composed of plants but also include some animals and bacteria, can perform both photosynthesis and cellular respiration, which allows them to produce their own energy using nutrients and sunlight. Consumers, which are mostly composed of animals but also include some plants and other organism kingdoms, can only perform cellular respiration and must acquire energy through the consumption of other organisms.
Explain how human activity has a negative impact on the nitrogen and carbon cycles. Describe some of the consequences of the activity.
Plants thrive off of high nitrogen levels. Because of this, one way for humans to increase crop growth is through the addition of high-nitrogen fertilizer into soil. However, this often breaks the mutualistic equalibrium between plants and the bacteria that process and transform nitrogen for them to use and can create parasitic bacteria that only feed off of plants without needing to supply them with anything. As well as this, excess fertilizer that becomes run-off through rainwater sometimes flows into bodies of water, where it causes extreme overabundances of algae growth that blocks sunlight underwater and uses up high amounts of dissolved oxygen, which is imperative for the survival of most aquatic organisms.
Humanity requires energy to power modern technology, but unfortunately our currently most common method of acquiring such energy is through the burning of fossil fuels, which are high in carbon dioxide gas as well as other compounds. This burning releases these gases into the atmosphere, where they naturally trap heat energy and prevent it from flowing into space to keep the earth at a habitable temperature. However, the excess of these gases caused by the burning of fossil fuels is slowly making it so that too much heat is being trapped, and the global temperature is rising too high and imbalancing climates and ecosystems worldwide.
Explain what BTB (bromothymol blue) highlights and how.
Bromothymol Blue is a chemical that highlights a liquid’s pH by changing its color based on whether the liquid is acidic, neutral, or basic. If the liquid is acidic, BTB turns it yellow; if it is neutral, it becomes green; if it is basic, it becomes blue.
Describe 2 similarities and 2 differences in how carbon and energy cycle through ecosystems.
The carbon and energy cycles are similar in that they follow many of the same pathways through consumption, decomposition, excretion, etc. and generally have a direct relationship within organisms due to one being used to ‘produce’ the other. They are different in that they originate from different sources - carbon from the atmosphere and energy from the sun - and are lost to different sources through cellular respiration - carbon back to the atmosphere and energy to heat.
4 test tubes full of regular water are being observed as BTB (bromothymol blue) is added. Tube A has aquatic snails within it and no light source. Tube B has aquatic plants within it and a light source. Tube C has aquatic plants in it and no light source. Tube D has both aquatic snails and aquatic plants in it and no light source. Explain how the colors of the water in each tube will differ when BTB is added and explain why.
Because Tube A has only aquatic snails, the cellular respiration performed by the snails will release relatively high amounts of CO2 into the water, which will dissolve into carbonic acid and turn the water yellow due to the BTB (whether a light source is present is irrelevant in this tube).
With plants, water, light, and carbon released by the plants’ cellular respiration, all the requirements for photosynthesis are met within
Tube B, meaning its plants will be able to re-absorb its carbon dioxide outputs and keep the tube’s water at its natural neutrality to slight acidity and, thus, green-blue BTB color.
On the other hand, with no light source, Tube C’s plants will not be able to photosynthesize and will slowly make the tube’s water more and more acidic due to carbon dioxide released from cellular respiration, meaning the water in Tube C’s color will be yellow.
Tube D would have essentially the same cycle as Tube B, just with a few extra steps, if it were to have a light source. Instead, its plants cannot photosynthesize just like Tube C’s, and the combined carbon dioxide outputs of the snails and the plants will cause an even swifter result of high carbonic acid levels and yellow water.
