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biol 1103 unit 5 practice test
Terms in this set (100)
A mature maple tree can have a mass of 1 ton or more (dry biomass, after removing the water), yet it starts from a seed that weighs less than 1 gram. Which of the following processes contributes the most to this huge increase in biomass?
Incorporation of CO2 gas from the air by green leaves
A loaf of bread was left uncovered for two weeks on a scale measuring its mass. Mold grew on it, decomposing the bread. Assuming that the bread did not dry out, which of the following is a reasonable prediction of the weight of the bread and mold together?
The mass decreases as the mold converts the bread into biomass and gases.
On March 10, 2004, National Public Radio reported that "forests in a remote part of the Amazon are suddenly growing like teenagers in a growth spurt." Though, the radio report added, "This shouldn't be happening in old, mature forests." This unexpected growth could be caused by:
Increased levels of carbon dioxide such that the forests can conduct more photosynthesis
Fossil fuels are considered part of the "rock" pool of carbon on Earth. Burning fossil fuels moves that carbon into the atmosphere. Increased carbon in the atmosphere can lead to increased carbon:
on land and in the ocean
What would happen to the carbon cycle if all decomposers suddenly died and were not replenished?
carbon would accumulate in organic matter
Before the two years were up, however, the experiment failed. Supplemental oxygen was pumped into the facility and food supplies were provided through the airlocks. What caused the failure of the experiment? It was traced to nutrient pollution. The soil in some of the biosphere ecosystems was unusually rich in nutrients. These excess nutrients caused a huge population explosion in decomposer bacteria, which led to oxygen depletion.
How could a population explosion of bacteria lead to oxygen depletion?
The excess consumers used the oxygen for cell respiration.
To stabilize the environment in the Biosphere II habitat and enable it to become self-sufficient again, it would be helpful to
add plant producers to absorb excess carbon dioxide and produce oxygen.
Considering the global carbon cycle, where is the largest reservoir of carbon?
Carbon exists in the atmosphere. It could have come from what?
Cellular respiration by plants and animals, burning of biofuels, and burning of fossil fuels
Which process results in flux of carbon dioxide OUT OF the atmosphere?
Which molecule will yield more energy when combusted?
Saturated fat because energy is released when carbon switches from bonding with hydrogen to bonding with oxygen
Net energy balance is an important measure because it allows for comparison of biofuels based on the:
energy required to manufacture each biofuel and energy produced by each biofuel
Scientists believe that the average temperature of the earth's atmosphere has been increasing during the past 100 years. What is the major cause of this?
More carbon dioxide is in the atmosphere
The Keeling curve depicted here has an annual cycle. What is the primary cause of this cycle?
Fluctuations in amount of carbon being fixed by plants across seasons
Fertilizers increase plant growth by providing:
Nitrogen that can be taken up by plants
An ocean liner illegally dumps waste into the sea. This could result in?
Decrease in zooxanthellae population, decrease in coral population, increase in phytoplankton population
One strategy for reducing the need for application of fertilizer is to plant legumes such as alfalfa and non-legume plants such as corn in alternating years. This allows:
Corn to utilize nitrogen that was fixed by bacteria in the alfalfa
All of the following are consequences of excess carbon in the ocean:
increase acidification, increase temperature, dissolve the calcium in shells and coral
Which of the following is the most probable sequence of events when fertilizer runoff reaches a bay?
Phytoplankton population increases, decomposer population increases, decomposers consume oxygen via cellular respiration, fish and shellfish populations decrease because of lack of oxygen
done by autotrophs
requires sunlight, carbon dioxide, and water as starting reactants
releases oxygen, and some glucose
allows living things to access enormous amounts of energy
On a hot, dry day, plants close their stomata to conserve water. What impact will this have on photosynthesis?
Levels of carbon dioxide (a reactant) will fall, and levels of oxygen (a product) will rise. As a result, the rate of photosynthesis will slow down.
From where does a heterotroph directly obtain its energy?
eating other organisms
What is the overall purpose of the light reactions in photosynthesis?
to convert solar energy into chemical energy that cells can use to do work
absorption of light
Light energy enters the process of photosynthesis when pigments absorb the light. pigment molecules only absorb visible light for photosynthesis
different chlorophyll absorbs different wavelengths (different colors)
absorbs the energy of a photon in photosynthesis
light dependent reactions
converts light energy into chemical energy which is used by the calvin cycle to fuel the assembly of sugar molecules
grouping of pigment molecules and proteins
these are in the membranes of thylakoids
A pigment molecule in the photosystem absorbs one photon at a time
a quantity of light energy
travels until it reaches a molecule of chlorophyll
chlorophyll then "donates" an electron
this results in oxygen and hydrogen ions in the thylakoid space
strikes photosystem II to initiate photosynthesis
electron transport chain
As the electron passes along these proteins, energy from the electron fuels membrane pumps that actively move hydrogen ions against their concentration gradient from the stroma into the thylakoid space forming an electrochemical gradient
Plants produce oxygen when they photosynthesize. Where does the oxygen come from?
splitting water molecules
the reactions of photosynthesis that use the energy stored by the light-dependent reactions to form glucose and other carbohydrate molecules.
happens in the stroma
the conversion of CO2 to an organic compound
Explain the reciprocal nature of the net chemical reactions for photosynthesis and respiration.
Photosynthesis takes the energy of sunlight and combines water and carbon dioxide to produce sugar and oxygen as a waste product. The reactions of respiration take sugar and consume oxygen to break it down into carbon dioxide and water, releasing energy. Thus, the reactants of photosynthesis are the products of respiration, and vice versa.
plants consume carbon dioxide and release oxygen
animals consume oxygen and release carbon dioxide
how light energy gets converted to chemical energy during photosynthesis
1) Light energy is absorbed by chlorophyll
2) chlorophyll gets excited freeing up an electron
3) electrons move in a way that allows ATP to be generated
4) ATP is formed and can be used to power metabolic processes
RuBisCO is the key enzyme for carbon fixation because it:
Attaches carbon dioxide to a molecule containing 5 carbons
a major component of the matter that makes up your body
when plants are grown without soil
what plants are made of
cellulose molecules have a framework of carbon atoms
where plants get their carbon from
leaves have pores to let CO2 in through its stomata
get their carbon from the water
plants and phytoplankton
use 6 carbon molecules to make one glucose molecule
energy is required for this- solar radiation from the sun
plants transform light energy into chemical energy
and the energy is captured in the H-OH bonds
6CO2 + 6H2O = C6H12O6 + 6O2
carbon constantly moves from air to plants plants to air, air to plants to animals to air
growing plants requires a lot of CO2
carbon is trapped in living bodies and released when decomposers consume corpses which produces CO2
Where do plants get the sugar to run and build their bodies?
They make their own sugars internally, mainly from gas absorbed from the air.
A mature maple tree can have a mass of one ton or more (dry biomass, after removing the water), yet it starts from a seed that weighs less than one gram. Which of the following processes contributes the most to this huge increase in biomass?
Incorporation of CO2 gas from the atmosphere into molecules by the leaves
A potato is left outside and decays gradually. One of the main substances in the potato is the starch amylose (C6H10O5). What happens to the carbon atoms in the amylose molecules as the potato decays?
some of the atoms are incorporated into carbon dioxide and some of the atoms are transformed by decomposers to form other organic molecules that make up their bodies
once carbon enters a plant
exit the plant as CO2
Become a part of the plant cell walls, protein, and fat
be consumed by an insect feeding on the plant and become part of the insects body
What would happen to the fast carbon cycle if all decomposers suddenly died and were not replenished?
Carbon would accumulate in organic matter
contain energy, and many of these compounds come from plants and algae and have remained stored as fossilized carbon, which humans use as fuel
the amount of carbon dioxide in the atmosphere has increased as the fossil fuels are burned- resulting in climate change
carbon cycle diagram
exists in the atmosphere and is dissolved in water. Photosynthesis converts carbon dioxide gas to organic carbon, and respiration cycles the organic carbon back into carbon dioxide gas. Long-term storage of organic carbon occurs when matter from living organisms is buried deep underground and becomes fossilized. Volcanic activity and, more recently, human emissions bring this stored carbon back into the carbon cycle
acquire the high-energy carbon compounds from the autotrophs by consuming them and breaking them down by respiration to obtain cellular energy, such as ATP
atmosphere, bodies of liquid water (mostly oceans), ocean sediment, soil, rocks (including fossil fuels), and Earth's interior.
atmosphere- oceans- limestone
Carbon dioxide (CO2) from the atmosphere dissolves in water and, unlike oxygen and nitrogen gas, reacts with water molecules to form ionic compounds. Some of these ions combine with calcium ions in the seawater to form calcium carbonate (CaCO3), a major component of the shells of marine organisms. These organisms eventually form sediments on the ocean floor. Over geologic time, the calcium carbonate forms limestone, which comprises the largest carbon reservoir on Earth
carbon in the land
carbon is stored in soil as organic carbon as a result of the decomposition of living organisms or from weathering of terrestrial rock and minerals. Deeper under the ground, at land and at sea, are fossil fuels, the anaerobically decomposed remains of plants
enters the living world via free-living and symbiotic bacteria, which incorporate nitrogen into their macromolecules through nitrogen fixation (conversion of N2)
converts nitrogenous waste from living animals or from the remains of dead animals into ammonium (NH4+ ) by certain bacteria and fungi
human activity and nitrogen
release nitrogen into the environment by the combustion of fossil fuels, which releases different nitrogen oxides, and by the use of artificial fertilizers (which contain nitrogen and phosphorus compounds) in agriculture, which are then washed into lakes, streams, and rivers by surface runoff.
produces acid rain and greenhouse gas emissions- causing climate change
a process whereby nutrient runoff causes the overgrowth of algae and a number of consequential problems
Ammonification converts organic nitrogenous matter from living organisms into ammonium (NH4+).
Denitrification by bacteria converts nitrates (NO3-) to nitrogen gas (N2).
Nitrogen fixing bacteria convert nitrogen gas (N2) into organic compounds.
where can carbon be found on earth?
air, organic molecules, ocean water, plants, animals, and bacteria
called pools of carbon
Starting with carbon dioxide in the air, put the following steps in order to trace the path of carbon through the slow carbon cycle
1) carbon is fixed by phytoplankton (photosynthetic marine organisms) through photosynthesis
2) phytoplankton die and become fossilized
3) fossil fuels are harvested
4) carbon is released into the atmosphere through combustion
the largest carbon reservoir on the planet is
sediment, including limestone
Carbon dioxide can be released into the atmosphere by all of the following
burning of fossil fuels
the processes of generating energy from stored or eaten foods- the "waste product" of this is carbon dioxide
carbon is held in soil as organic matter which has not yet decomposed
how easily can carbon be dissolved in water
depends on solubility, concentration, and the amount of carbon
fast carbon cycle
carbon moving between living things, dead things, and the atmosphere
through photosynthesis and respiration
slow carbon cycle
carbon moving between living and dead things (land), the atmosphere, the ocean, and rocks (and fossil fuels embedded in rocks)
can you create or destroy carbon?
only change it- humans are changing where this carbon is located (aka why it's being emitted into the air and leading to global warming)
law conservation of mass
movement between pools of carbon
electricity production is the largest source
50% is coal
20% natural gas
transportation second largest
in order from which pools hold the greatest amount of carbon
planting to absorb carbon
atmospheric concentration of carbon dioxide
carbon dioxide and methane
absorbs infrared radiation that the earth emits
radiation causes gases to heat up- increasing temp
Imagine you leave a piece of bread out on the counter. After a week, you check back and it's moldy. How does the mass of the moldy bread compare to the mass of the original piece of bread?
The moldy bread has less mass
in plants, the total amount of carbon gained by photosynthesis must be greater than that respired over their lifetime because...
Plants need carbon to grow and therefore must take in more than they lose
all of the processes that cause flux of carbon into the atmosphere:
cellular respiration, burning of fossil fuels, and deforstation
all of the processes that remove carbon from the atmosphere:
photosynthesis, ocean absorption, and reforstation
in any chemical reaction, the overall energy change is
energy it takes to make the bonds - the energy it takes to break the bonds
high energy: carbon-carbon and carbon-hydrogen
lower energy: carbon-oxygen
as carbon switches from bonding with c or h to bonding with o, energy is released (cellular respiration)
the greater the h-c ratio, the more energy released
*when seeing which molecule should yield the most energy (be the best biofuel), count the h-c and c-c bonds
Ethanol is inferior compared to many energy sources because it has only:
7 bonds that can be changed by cellular respiration or combustion to release energy
organisms that can incorporate nitrogen directly from the atmosphere into their bodies
bacteria and cynobacteria
the majority of nitrogen is found
in the ocean
plants acquire nitrogen from
Ammonium (NH4+) from bacteria
Ammonium (NH4+) from fertilizers
The washing of fertilizer into bodies of water can lead to all of the following
Increased growth of aquatic microorganisms, higher concentrations of nitrogen in the water, decreased oxygen levels in the water, and decreased numbers of aquatic animals
Atmospheric nitrogen (N2 gases)
makes up 80% of the atmosphere
two nitrogen atoms triple bonded together- completely uses for most organisms
legumes (beans, peanuts, peas)
can convert n2 into ammonium (a form of nitrogen that plants can use)
mutually beneficial relationship between legumes and nitrogen fixing bacteria
bacteria benefit because plants fix carbon that the bacteria can use
the plant benefits because the bacteria fixed nitrogen
nitrogen fixing bacteria
commonly found in soil
legumes send out a signal that attracts them
where do other living things get the nitrogen they need?
lightning (n2 in rainwater)
waste and decaying organisms add some ammonium
is this enough nitrogen?
that's why people use fertilizer
15% ends up in streams and rivers
increases algae (ex phytoplankton) which depletes oxygen levels and blocks sunlight getting to the plants
excess nutrients (nitrogen from fertilizer) increases aquatic plant growth
more of this means more dead material which decomposes and further depletes oxygen levels
with so little oxygen, all plants and animals die (dead zone)
they need this oxygen to perform cellular respiration
ongoing decrease in the pH of the Earth's oceans, caused by the uptake of carbon dioxide (CO2) from the atmosphere. An estimated 30-40% of the carbon dioxide from human activity released into the atmosphere dissolves into oceans, rivers and lakes.
human impacts on the nitrogen cycle
dumping sewage into water increases nitrogen levels
results in coral reef decline
sewage consists of a lot of nutrients that clog up the water and coral reefs need clear water
also brings diseases into the water
creates algae and more plant life which takes away oxygen and coral lives at the bottom of the ocean so they die
Application of fertilizer results in plant growth because fertilizer provides the following critical nutrient:
all of the ways you could have acquired nitrogen that is now in your proteins, DNA, and RNA:
From plants that acquired nitrogen from a mutualistic relationship with bacteria
From animals that ate plants that took up ammonia from the soil
steps in order to trace the path of nitrogen into a protein in the turkey you ate for Thanksgiving:
1) lightning strikes, forming ammonia and nitrates
2) usable forms of nitrogen are absorbed from soil by plants
3) worms feed on decaying plant matter
4) the turkey acquires nitrogen by eating a decomposer
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