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Biology Unit 5 Essay Cycles Of The Moon

Earth's natural satellite

This article is about Earth's natural satellite. For moons in general, see natural satellite. For other uses, see Moon (disambiguation).

The Moon is an astronomical body that orbitsplanetEarth, being Earth's only permanentnatural satellite. It is the fifth-largest natural satellite in the Solar System, and the largest among planetary satellites relative to the size of the planet that it orbits (its primary). Following Jupiter's satellite Io, the Moon is the second-densest satellite in the Solar System among those whose densities are known.

The Moon is thought to have formed about 4.51 billion years ago, not long after Earth. The most widely accepted explanation is that the Moon formed from the debris left over after a giant impact between Earth and a Mars-sized body called Theia.

The Moon is in synchronous rotation with Earth, always showing the same face, with its near side marked by dark volcanic maria that fill the spaces between the bright ancient crustal highlands and the prominent impact craters. As seen from the Earth, it is the second-brightest regularly visible celestial object in Earth's sky, after the Sun. Its surface is actually dark, although compared to the night sky it appears very bright, with a reflectance just slightly higher than that of worn asphalt. Its gravitational influence produces the ocean tides, body tides, and the slight lengthening of the day.

The Moon's average orbital distance at the present time is 384,402 km (238,856 mi),[10][11] or 1.28 light-seconds. This is about thirty times the diameter of Earth, with its apparent size in the sky almost the same as that of the Sun (due to it being 400x farther and larger), resulting in the Moon covering the Sun nearly precisely in total solar eclipse. This matching of apparent visual size will not continue in the far future, because the Moon's distance from Earth is slowly increasing.

The Soviet Union's Luna program was the first to reach the Moon with unmanned spacecraft in 1959; the United States' NASAApollo program achieved the only manned missions to date, beginning with the first manned lunar orbiting mission by Apollo 8 in 1968, and six manned lunar landings between 1969 and 1972, with the first being Apollo 11. These missions returned lunar rocks which have been used to develop a geological understanding of the Moon's origin, internal structure, and later history. Since the Apollo 17 mission in 1972, the Moon has been visited only by unmanned spacecraft.

Within human culture, both the Moon's natural prominence in the earthly sky, and its regular cycle of phases as seen from the Earth have provided cultural references and influences for human societies and cultures since time immemorial. Such cultural influences can be found in language, lunar based calendar systems, art, and mythology.

Name and etymology

See also: list of lunar deities

The usual English proper name for Earth's natural satellite is "the Moon", which in nonscientific texts is usually not capitalized.[12][13][14][15][16] The noun moon is derived from Old Englishmōna, which (like all Germanic language cognates) stems from Proto-Germanic*mēnô, which comes from Proto-Indo-European*mḗh₁n̥s "moon", "month", which comes from the Proto-Indo-European root *meh₁- "to measure", the month being the ancient unit of time measured by the Moon.[17][18] Occasionally, the name "Luna" is used. In literature, especially science fiction, "Luna" is used to distinguish it from other moons, while in poetry, the name has been used to denote personification of our moon.[19]

The modern English adjective pertaining to the Moon is lunar, derived from the Latin word for the Moon, luna. The adjective selenic (usually only used to refer to selenium) is so rarely used to refer to the moon that this meaning is not recorded in most major dictionaries.[20][21][22] It is derived from the Ancient Greek word for the Moon, σελήνη (selḗnē), from which is however also derived the prefix "seleno-", as in selenography, the study of the physical features of the Moon.[23][24] Both the Greek goddess Selene and the Roman goddess Diana were alternatively called Cynthia.[25] The names Luna, Cynthia, and Selene are reflected in terminology for lunar orbits in words such as apolune, pericynthion, and selenocentric. The name Diana comes from the Proto-Indo-European *diw-yo, "heavenly", which comes from the PIE root *dyeu- "to shine," which in many derivatives means "sky, heaven, and god" and is also the origin of Latin dies, "day".

Formation

Main articles: Origin of the Moon and Giant-impact hypothesis

Several mechanisms have been proposed for the Moon's formation 4.51 billion years ago,[f] and some 60 million years after the origin of the Solar System.[26] These mechanisms included the fission of the Moon from Earth's crust through centrifugal force[27] (which would require too great an initial spin of Earth),[28] the gravitational capture of a pre-formed Moon[29] (which would require an unfeasibly extended atmosphere of Earth to dissipate the energy of the passing Moon),[28] and the co-formation of Earth and the Moon together in the primordial accretion disk (which does not explain the depletion of metals in the Moon).[28] These hypotheses also cannot account for the high angular momentum of the Earth–Moon system.[30]

The prevailing hypothesis is that the Earth–Moon system formed as a result of the impact of a Mars-sized body (named Theia) with the proto-Earth (giant impact), that blasted material into orbit about the Earth that then accreted to form the present Earth-Moon system.[31][32]

The far side of the Moon has a crust that is 30 mi (48 km) thicker than the near side of the Moon. This is thought to be due to the Moon having been amalgamated from two different bodies.

This hypothesis, although not perfect, perhaps best explains the evidence. Eighteen months prior to an October 1984 conference on lunar origins, Bill Hartmann, Roger Phillips, and Jeff Taylor challenged fellow lunar scientists: "You have eighteen months. Go back to your Apollo data, go back to your computer, do whatever you have to, but make up your mind. Don't come to our conference unless you have something to say about the Moon's birth." At the 1984 conference at Kona, Hawaii, the giant impact hypothesis emerged as the most popular.

Before the conference, there were partisans of the three "traditional" theories, plus a few people who were starting to take the giant impact seriously, and there was a huge apathetic middle who didn’t think the debate would ever be resolved. Afterward there were essentially only two groups: the giant impact camp and the agnostics.[33]

Giant impacts are thought to have been common in the early Solar System. Computer simulations of a giant impact have produced results that are consistent with the mass of the lunar core and the present angular momentum of the Earth–Moon system. These simulations also show that most of the Moon derived from the impactor, rather than the proto-Earth.[34] More recent simulations suggest a larger fraction of the Moon derived from the original Earth mass.[35][36][37][38] Studies of meteorites originating from inner Solar System bodies such as Mars and Vesta show that they have very different oxygen and tungsten isotopic compositions as compared to Earth, whereas Earth and the Moon have nearly identical isotopic compositions. The isotopic equalization of the Earth-Moon system might be explained by the post-impact mixing of the vaporized material that formed the two,[39] although this is debated.[40]

The great amount of energy released in the impact event and the subsequent re-accretion of that material into the Earth-Moon system would have melted the outer shell of Earth, forming a magma ocean.[41][42] Similarly, the newly formed Moon would also have been affected and had its own lunar magma ocean; estimates for its depth range from about 500 km (300 miles) to its entire depth (1,737 km (1,079 miles)).[41]

While the giant impact hypothesis might explain many lines of evidence, there are still some unresolved questions, most of which involve the Moon's composition.[43]

In 2001, a team at the Carnegie Institute of Washington reported the most precise measurement of the isotopic signatures of lunar rocks.[44] To their surprise, the team found that the rocks from the Apollo program carried an isotopic signature that was identical with rocks from Earth, and were different from almost all other bodies in the Solar System. Because most of the material that went into orbit to form the Moon was thought to come from Theia, this observation was unexpected. In 2007, researchers from the California Institute of Technology announced that there was less than a 1% chance that Theia and Earth had identical isotopic signatures.[45] Published in 2012, an analysis of titanium isotopes in Apollo lunar samples showed that the Moon has the same composition as Earth,[46] which conflicts with what is expected if the Moon formed far from Earth's orbit or from Theia. Variations on the giant impact hypothesis may explain this data.

Physical characteristics

Internal structure

Main article: Internal structure of the Moon

The Moon is a differentiated body: it has a geochemically distinct crust, mantle, and core. The Moon has a solid iron-rich inner core with a radius possibly as small as 240 km (150 mi) and a fluid outer core primarily made of liquid iron with a radius of roughly 300 km (190 mi). Around the core is a partially molten boundary layer with a radius of about 500 km (310 mi).[48][49] This structure is thought to have developed through the fractional crystallization of a global magma ocean shortly after the Moon's formation 4.5 billion years ago.[50] Crystallization of this magma ocean would have created a mafic mantle from the precipitation and sinking of the minerals olivine, clinopyroxene, and orthopyroxene; after about three-quarters of the magma ocean had crystallised, lower-density plagioclase minerals could form and float into a crust atop.[51] The final liquids to crystallise would have been initially sandwiched between the crust and mantle, with a high abundance of incompatible and heat-producing elements.[1] Consistent with this perspective, geochemical mapping made from orbit suggests the crust of mostly anorthosite.[9] The Moon rock samples of the flood lavas that erupted onto the surface from partial melting in the mantle confirm the mafic mantle composition, which is more iron-rich than that of Earth.[1] The crust is on average about 50 km (31 mi) thick.[1]

The Moon is the second-densest satellite in the Solar System, after Io.[52] However, the inner core of the Moon is small, with a radius of about 350 km (220 mi) or less,[1] around 20% of the radius of the Moon. Its composition is not well defined, but is probably metallic iron alloyed with a small amount of sulfur and nickel; analyses of the Moon's time-variable rotation suggest that it is at least partly molten.[53]

Surface geology

Main articles: Geology of the Moon and Moon rocks

The topography of the Moon has been measured with laser altimetry and stereo image analysis.[54] Its most visible topographic feature is the giant far-side South Pole–Aitken basin, some 2,240 km (1,390 mi) in diameter, the largest crater on the Moon and the second-largest confirmed impact crater in the Solar System.[55][56] At 13 km (8.1 mi) deep, its floor is the lowest point on the surface of the Moon.[55][57] The highest elevations of the Moon's surface are located directly to the northeast, and it has been suggested might have been thickened by the oblique formation impact of the South Pole–Aitken basin.[58] Other large impact basins, such as Imbrium, Serenitatis, Crisium, Smythii, and Orientale, also possess regionally low elevations and elevated rims.[55] The far side of the lunar surface is on average about 1.9 km (1.2 mi) higher than that of the near side.[1]

The discovery of fault scarp cliffs by the Lunar Reconnaissance Orbiter suggest that the Moon has shrunk within the past billion years, by about 90 metres (300 ft).[59] Similar shrinkage features exist on Mercury.

Volcanic features

Main article: Lunar mare

The dark and relatively featureless lunar plains, clearly seen with the naked eye, are called maria (Latin for "seas"; singular mare), as they were once believed to be filled with water;[60] they are now known to be vast solidified pools of ancient basaltic lava. Although similar to terrestrial basalts, lunar basalts have more iron and no minerals altered by water.[61] The majority of these lavas erupted or flowed into the depressions associated with impact basins. Several geologic provinces containing shield volcanoes and volcanic domes are found within the near side "maria".[62]

Almost all maria are on the near side of the Moon, and cover 31% of the surface of the near side,[63] compared with 2% of the far side.[64] This is thought to be due to a concentration of heat-producing elements under the crust on the near side, seen on geochemical maps obtained by Lunar Prospector's gamma-ray spectrometer, which would have caused the underlying mantle to heat up, partially melt, rise to the surface and erupt.[51][65][66] Most of the Moon's mare basalts erupted during the Imbrian period, 3.0–3.5 billion years ago, although some radiometrically dated samples are as old as 4.2 billion years.[67] Until recently, the youngest eruptions, dated by crater counting, appeared to have been only 1.2 billion years ago.[68] In 2006, a study of Ina, a tiny depression in Lacus Felicitatis, found jagged, relatively dust-free features that, due to the lack of erosion by infalling debris, appeared to be only 2 million years old.[69]Moonquakes and releases of gas also indicate some continued lunar activity.[69] In 2014 NASA announced "widespread evidence of young lunar volcanism" at 70 irregular mare patches identified by the Lunar Reconnaissance Orbiter, some less than 50 million years old. This raises the possibility of a much warmer lunar mantle than previously believed, at least on the near side where the deep crust is substantially warmer due to the greater concentration of radioactive elements.[70][71][72][73] Just prior to this, evidence has been presented for 2–10 million years younger basaltic volcanism inside Lowell crater,[74][75] Orientale basin, located in the transition zone between the near and far sides of the Moon. An initially hotter mantle and/or local enrichment of heat-producing elements in the mantle could be responsible for prolonged activities also on the far side in the Orientale basin.[76][77]

The lighter-coloured regions of the Moon are called terrae, or more commonly highlands, because they are higher than most maria. They have been radiometrically dated to having formed 4.4 billion years ago, and may represent plagioclasecumulates of the lunar magma ocean.[67][68] In contrast to Earth, no major lunar mountains are believed to have formed as a result of tectonic events.[78]

The concentration of maria on the Near Side likely reflects the substantially thicker crust of the highlands of the Far Side, which may have formed in a slow-velocity impact of a second moon of Earth a few tens of millions of years after their formation.[79][80]

Impact craters

Further information: List of craters on the Moon

The other major geologic process that has affected the Moon's surface is impact cratering,[81] with craters formed when asteroids and comets collide with the lunar surface. There are estimated to be roughly 300,000 craters wider than 1 km (0.6 mi) on the Moon's near side alone.[82] The lunar geologic timescale is based on the most prominent impact events, including Nectaris, Imbrium, and Orientale, structures characterized by multiple rings of uplifted material, between hundreds and thousands of kilometres in diameter and associated with a broad apron of ejecta deposits that form a regional stratigraphic horizon.[83] The lack of an atmosphere, weather and recent geological processes mean that many of these craters are well-preserved. Although only a few multi-ring basins have been definitively dated, they are useful for assigning relative ages. Because impact craters accumulate at a nearly constant rate, counting the number of craters per unit area can be used to estimate the age of the surface.[83] The radiometric ages of impact-melted rocks collected during the Apollo missions cluster between 3.8 and 4.1 billion years old: this has been used to propose a Late Heavy Bombardment of impacts.[84]

Blanketed on top of the Moon's crust is a highly comminuted (broken into ever smaller particles) and impact gardened surface layer called regolith, formed by impact processes. The finer regolith, the lunar soil of silicon dioxide glass, has a texture resembling snow and a scent resembling spent gunpowder.[85] The regolith of older surfaces is generally thicker than for younger surfaces: it varies in thickness from 10–20 km (6.2–12.4 mi) in the highlands and 3–5 km (1.9–3.1 mi) in the maria.[86] Beneath the finely comminuted regolith layer is the megaregolith, a layer of highly fractured bedrock many kilometres thick.[87]

Comparison of high-resolution images obtained by the Lunar Reconnaissance Orbiter has shown a contemporary crater-production rate significantly higher than previously estimated. A secondary cratering process caused by distal ejecta is thought to churn the top two centimetres of regolith a hundred times more quickly than previous models suggested–on a timescale of 81,000 years.[88][89]

Lunar swirls

Main article: Lunar swirls

Lunar swirls are enigmatic features found across the Moon's surface, which are characterized by a high albedo, appearing optically immature (i.e. the optical characteristics of a relatively young regolith), and often displaying a sinuous shape. Their curvilinear shape is often accentuated by low albedo regions that wind between the bright swirls.

Presence of water

Main article: Lunar water

Liquid water cannot persist on the lunar surface. When exposed to solar radiation, water quickly decomposes through a process known as photodissociation and is lost to space. However, since the 1960s, scientists have hypothesized that water ice may be deposited by impacting comets or possibly produced by the reaction of oxygen-rich lunar rocks, and hydrogen from solar wind, leaving traces of water which could possibly persist in cold, permanently shadowed craters at either pole on the Moon.[90][91] Computer simulations suggest that up to 14,000 km2 (5,400 sq mi) of the surface may be in permanent shadow.[92] The presence of usable quantities of water on the Moon is an important factor in rendering lunar habitation as a cost-effective plan; the alternative of transporting water from Earth would be prohibitively expensive.[93]

In years since, signatures of water have been found to exist on the lunar surface.[94] In 1994, the bistatic radar experiment located on the Clementine spacecraft, indicated the existence of small, frozen pockets of water close to the surface. However, later radar observations by Arecibo, suggest these findings may rather be rocks ejected from young impact craters.[95] In 1998, the neutron spectrometer on the Lunar Prospector spacecraft showed that high concentrations of hydrogen are present in the first meter of depth in the regolith near the polar regions.[96] Volcanic lava beads, brought back to Earth aboard Apollo 15, showed small amounts of water in their interior.[97]

The 2008 Chandrayaan-1 spacecraft has since confirmed the existence of surface water ice, using the on-board Moon Mineralogy Mapper. The spectrometer observed absorption lines common to hydroxyl, in reflected sunlight, providing evidence of large quantities of water ice, on the lunar surface. The spacecraft showed that concentrations may possibly be as high as 1,000 ppm.[98] In 2009, LCROSS sent a 2,300 kg (5,100 lb) impactor into a permanently shadowed polar crater, and detected at least 100 kg (220 lb) of water in a plume of ejected material.[99][100] Another examination of the LCROSS data showed the amount of detected water to be closer to 155 ± 12 kg (342 ± 26 lb).[101]

In May 2011, 615–1410 ppm water in melt inclusions in lunar sample 74220 was reported,[102] the famous high-titanium "orange glass soil" of volcanic origin collected during the Apollo 17 mission in 1972. The inclusions were formed during explosive eruptions on the Moon approximately 3.7 billion years ago. This concentration is comparable with that of magma in Earth's upper mantle. Although of considerable selenological interest, this announcement affords little comfort to would-be lunar colonists—the sample originated many kilometers below the surface, and the inclusions are so difficult to access that it took 39 years to find them with a state-of-the-art ion microprobe instrument.

Gravitational field

Main article: Gravity of the Moon

The gravitational field of the Moon has been measured through tracking the Doppler shift of radio signals emitted by orbiting spacecraft. The main lunar gravity features are mascons, large positive gravitational anomalies associated with some of the giant impact basins, partly caused by the dense mare basaltic lava flows that fill those basins.[103][104] The anomalies greatly influence the orbit of spacecraft about the Moon. There are some puzzles: lava flows by themselves cannot explain all of the gravitational signature, and some mascons exist that are not linked to mare volcanism.[105]

Magnetic field

Main article: Magnetic field of the Moon

The Moon has an external magnetic field of about 1–100 nanoteslas, less than one-hundredth that of Earth. It does not currently have a global dipolar magnetic field and only has crustal magnetization, probably acquired early in lunar history when a dynamo was still operating.[106][107] Alternatively, some of the remnant magnetization may be from transient magnetic fields generated during large impact events through the expansion of an impact-generated plasma cloud in the presence of an ambient magnetic field. This is supported by the apparent location of the largest crustal magnetizations near the antipodes of the giant impact basins.[108]

Atmosphere

Main article: Atmosphere of the Moon

The Moon has an atmosphere so tenuous as to be nearly vacuum, with a total mass of less than 10 metric tons (9.8 long tons; 11 short tons).[111] The surface pressure of this small mass is around 3 × 10−15 atm (0.3 nPa); it varies with the lunar day. Its sources include outgassing and sputtering, a product of the bombardment of lunar soil by solar wind ions.[9][112] Elements that have been detected include sodium and potassium, produced by sputtering (also found in the atmospheres of Mercury and Io); helium-4 and neon[113] from the solar wind; and argon-40, radon-222, and polonium-210, outgassed after their creation by radioactive decay within the crust and mantle.[114][115] The absence of such neutral species (atoms or molecules) as oxygen, nitrogen, carbon, hydrogen and magnesium, which are present in the regolith, is not understood.[114] Water vapour has been detected by Chandrayaan-1 and found to vary with latitude, with a maximum at ~60–70 degrees; it is possibly generated from the sublimation of water ice in the regolith.[116] These gases either return into the regolith due to the Moon's gravity or are lost to space, either through solar radiation pressure or, if they are ionized, by being swept away by the solar wind's magnetic field.[114]

Dust

A permanent asymmetric moon dust cloud exists around the Moon, created by small particles from comets. Estimates are 5 tons of comet particles strike the Moon's surface each 24 hours. The particles strike the Moon's surface ejecting moon dust above the Moon. The dust stays above the Moon approximately 10 minutes, taking 5 minutes to rise, and 5 minutes to fall. On average, 120 kilograms of dust are present above the Moon, rising to 100 kilometers above the surface. The dust measurements were made by LADEE's Lunar Dust EXperiment (LDEX), between 20 and 100 kilometers above the surface, during a six-month period. LDEX detected an average of one 0.3 micrometer moon dust particle each minute. Dust particle counts peaked during the Geminid, Quadrantid, Northern Taurid, and Omicron Centauridmeteor showers, when the Earth, and Moon, pass through comet debris. The cloud is asymmetric, more dense near the boundary between the Moon's dayside and nightside.[117][118]

Past thicker atmosphere

In October 2017, NASA scientists at the Marshall Space Flight Center and the Lunar and Planetary Institute in Houston announced their finding, based on studies of Moon magma samples retrieved by the Apollo missions, that the Moon had once possessed a relatively thick atmosphere for a period of 70 million years between 3 and 4 billion years ago. This atmosphere, sourced from gases ejected from lunar volcanic eruptions, was twice the thickness of that of present-day Mars. The ancient lunar atmosphere was eventually stripped away by solar winds and dissipated into space.[119]

Seasons

The Moon's axial tilt with respect to the ecliptic is only 1.5424°,[120] much less than the 23.44° of Earth. Because of this, the Moon's solar illumination varies much less with season, and topographical details play a crucial role in seasonal effects.[121] From images taken by Clementine in 1994, it appears that four mountainous regions on the rim of Peary Crater at the Moon's north pole may remain illuminated for the entire lunar day

The evolution of the Moon and a tour of the Moon
GRAIL's gravity map of the Moon
Sketch by the Apollo 17 astronauts. The lunar atmosphere was later studied by LADEE.[109][110]

The following is a comprehensive list of essay questions that have been asked on past AP exams. The questions are organized according to units.

Unit 1 (Basic Chemistry and Water)

1.  The unique properties (characteristics) of water make life possible on Earth. Select three properties of water and:

    1. for each property, identify and define the property and explain it in terms of the physical/chemical nature of water.
    2. for each property, describe one example of how the property affects the functioning of living organisms.

Unit 2 (Organic Chemistry, Biochemistry, and Metabolism)

2.  Describe the chemical composition and configuration of enzymes and discuss the factors that modify enzyme structure and/or function.

3.  After an enzyme is mixed with its substrate, the amount of product formed is determined at 10-second intervals for 1 minute. Data from this experiment are shown below:

    Time (sec)

    0

    10

    20

    30

    40

    50

    60

    Product formed (mg)

    0.00

    0.25

    0.50

    0.70

    0.80

    0.85

    0.85

    Draw a graph of these data and answer the following questions.

    1. What is the initial rate of this enzymatic reaction?
    2. What is the rate after 50 seconds? Why is it different from the initial rate?
    3. What would be the effect on product formation if the enzyme where heated to a temperature of 100° C for 10 minutes before repeating the experiment? Why?
    4. How might altering the substrate concentration affect the rate of the reaction? Why?
    5. How might altering the pH affect the rate of the reaction? Why?

4.  Enzymes are biological catalysts.

    1. Relate the chemical structure of an enzyme to its specificity and catalytic activity.
    2. Design a quantitative experiment to investigate the influence of pH or temperature on the activity of an enzyme.
    3. Describe what information concerning the structure of an enzyme could be inferred from your experiments.

Unit 3 (Cell Structure and Function, Cell division)

5.  Describe the fluid-mosaic model of a plasma membrane. Discuss the role of the membrane in the movement of materials through it by each of the following processes:

    1. Active transport
    2. Passive transport

6.  Describe the structure of a eukaryotic plant cell. Indicate the ways in which a nonphotosynthetic prokaryotic cell would differ in structure from this generalized eukaryotic plant cell.

7.  Discuss the process of cell division in animals. Include a description of mitosis and cytokinesis, and of the other phases of the cell cycle. Do Not include meiosis.

     

8.  A laboratory assistant prepared solution of 0.8 M, 0.6 M, 0.4 M, and 0.2 M sucrose, but forgot to label them. After realizing the error, the assistant randomly labeled the flasks containing these four unknown solutions as flask A, flask B, flask C, and flask D.

    Design an experiment, based on the principles of diffusion and osmosis, that the assistant could use to determine which of the flasks contains each of the four unknown solutions. Include in your answer (a) a description of how you would set up and perform the experiment: (b) the results you would expect from your experiments: and (c) an explanation of those results based on the principles involved. (Be sure to clearly state the principles addressed in your discussion.)

9.  Cells transport substances across their membranes. Choose THREE of the following four types of cellular transport.

    • Osmosis
    • Active Transport
    • Facilitated Diffusion
    • Endocytosis/exocytosis

For each of the three transport types you choose,

    1. Describe the transport process and explain how the organization of cell membranes functions in the movement of specific molecules across membranes; and
    2. Explain the significance of each type of transport to a specific cell (you may use difference cell types as examples.)

Unit 4 (Photosynthesis and Cellular Respiration)

10.  Describe the similarities and differences between the biochemical pathways of aerobic respiration and photosynthesis in eukaryotic cells. Include in your discussion the major reactions, the end products, and energy transfers.

11.  The rate of photosynthesis may vary with changes that occur in environmental temperature, wavelength of light, and light intensity. Using a photosynthetic organism of your choice, choose only ONE of the three variables (temperature, wavelength of light, or light intensity) and for this variable

    • design a scientific experiment to determine the effect of the variable on the rate of photosynthesis for the organism;
    • explain how you would measure the rate of photosynthesis in your experiment;
    • describe the results you would expect. Explain why you would expect these results.

12.  Describe the light reactions of photosynthesis and, for both a C3 and a C4 plant, trace the path of a carbon dioxide molecule from the point at which it enters a plant to its incorporation into a glucose molecule. Include leaf anatomy and biochemical pathways in your discussion of each type of plant.

13.  Explain what occurs during the Krebs (citric acid) cycle and electron transport by describing the following:

    1. The location of the Krebs cycle and electron transport chain in mitochondria.
    2. The cyclic nature of the reactions in the Krebs cycle.
    3. The production of ATP and reduced coenzymes during the cycle.
    4. The chemiosmotic production of ATP during electron transport.

14.  Membranes are important structural features of cells.

    1. Describe how membrane structure is related to the transport of materials across the membrane.
    2. Describe the role of membranes in the synthesis of ATP in either cellular respiration or photosynthesis.

15. Energy transfer occurs in all cellular activities. For 3 of the following 5 processes involving energy transfer, explain how each functions in the cell and give an example. Explain how ATP is involved in each example you choose.

        • cellular movement
        • active transport
        • synthesis of molecules
        • chemiosmosis
        • fermentation

16. The results below are measurements of cumulative oxygen consumption by germinating and dry seeds. Gas volume measurements were corrected for changes in temperature and pressure.

    Cumulative Oxygen Consumed (mL)

    Time (minutes)

    0

    10

    20

    30

    40

    22° C Germinating Seeds

    0.0

    8.8

    16.0

    23.7

    32..0

    Dry Seeds

    0.0

    0.2

    0.1

    0.0

    0.1

    10° C Germinating Seeds

    0.0

    2.9

    6.2

    9.4

    12.5

    Dry Seeds

    0.0

    0.0

    0.2

    0.1

    0.2

    1. Using the graph paper provided, plot the results for the germinating seeds at 22° C and at 10° C.
    2. Calculate function the rate of oxygen consumption for the germinating seeds at 22° C, using the time interval between 10 and 20 minutes.
    3. Account for the differences in oxygen consumption observed between:
      1. germinating seeds at 22° C and at 10° C
      2. germinating seeds and dry seeds
    4. Describe the essential features of an experimental apparatus that could be used to measure oxygen consumption by a small organism. Explain why each of these features is necessary.

    Unit 5 (Meiosis, Mendelian Genetics, DNA Replication)

17.  State the conclusions reached by Mendel in his work on the inheritance of characteristics. Explain how each of the following deviates from these conclusions.

    1. Autosomal linkage.
    2. Sex-linked (X-linked) inheritance.
    3. Polygenic (multiple-gene) inheritance.

18.  Experiments by the following scientists provided critical information concerning DNA. Describe each classical experiment and indicate how it provided evidence for the chemical nature of the gene.

    1. Hershey and Chase- bacteriophage replication
    2. Griffith and Avery, MacLeod and McCarty- bacterial transformation
    3. Meselson and Stahl- DNA replication in bacteria

19.  Discuss Mendel’s laws of segregation and independent assortment. Explain how the events of meiosis I account for the observations that led Mendel to formulate these laws.

20.  An organism is heterozygous at two genetic loci on different chromosomes.

    1. Explain how these alleles are transmitted by the process of mitosis to daughter cells.
    2. Explain how these alleles are distributed by the process of meiosis to gametes.
    3. Explain how the behavior of these two pairs of homologous chromosomes during meiosis provides the physical basis for Mendel’s two laws of inheritance.

    Labeled diagrams that are explained in your answer may be useful.

    Unit 6 (Protein Synthesis, Gene Expression, DNA Technology)

21.  A portion of specific DNA molecule consists of the following sequence of nucleotide triplets.

    TAC GAA CTT GGG TCC

    This DNA sequence codes for the following short polypeptide.

    methionine – leucine – glutamic acid – proline – arginine

    Describe the steps in the synthesis of this polypeptide. What would be the effect of a deletion or an addition in one of the DNA nucleotides? What would be the effects of a substitution in one of the nucleotides?

22.  Describe the operon hypothesis and discuss how it explains the control of messenger RNA production and the regulation of protein synthesis in bacterial cells.

23.  Scientists seeking to determine which molecule is responsible for the transmission of characteristics from one generation to the next knew that the molecule must (1) copy itself precisely, (2) be stable but able to be changed, and (3) be complex enough to determine the organism’s phenotype.

  • Explain how DNA meets each of the three criteria stated above.
  • Select one of the criteria stated above and describe experimental evidence used to determine that DNA is the hereditary material.

 

24.  Describe the biochemical composition, structure, and replication of DNA. Discuss how recombinant DNA techniques may be used to correct a point mutation.

25.  Describe the production and processing of a protein that will be exported from a eukaryotic cell. Begin with the separation of the messenger RNA from the DNA template and end with the release of the protein at the plasma membrane.

26.  Describe the steps of protein synthesis, beginning with the attachment of a messenger RNA molecule to the small subunit of a ribosome and ending generalized with the release of the polypeptide from the ribosome. Include in your answer a discussion of how the different types of RNA function in this process.

27.  The diagram below shows a segment of DNA with a total length of 4,900 base pairs. The arrows indicate reaction sites for two restriction enzymes (enzyme X and enzyme Y).

    1. Explain how the principles of gel electrophoresis allow for the separation of DNA fragments.
    2. Describe the results you would expect from the electrophoresis separation of fragments from the following treatments of the DNA segment above. Assume that the digestions occurred under appropriate conditions and went to completion.
      1. DNA digested with only enzyme X
      2. DNA digested with only enzyme Y
      3. DNA digested with enzyme X and enzyme Y combined
      4. Undigested DNA
    3. Explain both of the following.
      1. The mechanism of action of restriction enzymes.
      2. The different results you would expect if a mutation occurred at the recognition site for enzyme Y.

28.  By using the techniques of genetic engineering, scientists are able to modify genetic materials so that a particular gene of interest from one cell can be incorporated into a different cell.

        • Describe a procedure by which this can be done.
        • Explain the purpose of each step of your procedure.
        • Describe how you could determine whether the gene was successfully incorporated.
        • Describe an example of how gene transfer and incorporation have been used in biomedical or commercial applications.

29.  Assume that a particular genetic condition in a mammalian species causes an inability to digest starch. This disorder occurs with equal frequency in males and females. In most cases, neither parent of affected offspring has the condition.

    1. Describe the most probable pattern of inheritance for this condition. Explain your reasoning. Include in your discussion a sample cross(es) sufficient to verify your proposed pattern.
    2. Explain how a mutation could cause this inability to digest starch.
    3. Describe how modern techniques of molecular biology could be used to determine whether the mutant allele is present in a given individual.

    Unit 7 (Evolution, Population Genetics, Speciation)

29.  Describe the special relationship between the two terms in each of the following pairs.

    1. Convergent evolution of organisms and Australia.
    2. Blood groups and genetic drift.
    3. Birds of prey and DDT.

30.  Describe the modern theory of evolution and discuss how it is supported by evidence from two of the following areas.

    1. population genetics
    2. molecular biology
    3. comparative anatomy and embryology

31.  Describe the process of speciation. Include in your discussion the factors that may contribute to the maintenance of genetic isolation.

32.  Do the following with reference to the Hardy-Weinberg model.

    1. Indicate the conditions under which allelic frequencies (p and q) remain constant from one generation to the next.
    2. Calculate, showing all work, the frequencies of the alleles and the frequencies of the genotypes in a population of 100,000 rabbits, of which 25,000 are white and 75,000 are agouti. (In rabbits the white color is due to a recessive allele, w, and the agouti is due to a dominant all, W.)
    3. If the homozygous dominant condition were to become lethal, what would happen to the allelic and genotypic frequencies in the rabbit population after two generations?

33.  Evolution is one of the major unifying themes of modern biology.

    1. Explain the mechanisms that lead to evolutionary change.
    2. Describe how scientists use each of the following as evidence for evolution.
      1. Bacterial resistance to antibodies.
      2. Comparative biochemistry.
      3. The fossil record.

34.  Genetic variation is the raw material for evolution.

    1. Explain three cellular and/or molecular mechanisms that introduce variation into the gene pool of a plant or animal population.
    2. Explain the evolutionary mechanisms that can change the composition of the gene pool.

35.  In a laboratory population of diploid, sexually reproducing organisms a certain trait is studied. This trait is determined by a single autosomal gene and is expressed as two phenotypes. A new population was created by crossing 51 pure breeding (homozygous) dominant individuals with 49 pure breeding (homozygous) individuals. After four generations, the following results were obtained.

    Number of Individuals

    Generation

    Dominant

    Recessive

    Total

    1

    51

    49

    100

    2

    280

    0

    280

    3

    240

    80

    320

    4

    300

    100

    400

    5

    360

    120

    480

    1. Identify an organism that might have been used to perform this experiment, and explain why this organism is a good choice for conducting this experiment.
    2. On the basis of the data, propose a hypothesis that explains the change in phenotypic frequency between generation 1 and generation 3.
    3. Is there evidence indicating whether or not this population is in Hardy-Weinberg equilibrium? Explain.

 Unit 8 (Chemical Evolution, Prokaryotes, Eukaryote Evolution, Protista)

36.  Scientists recently have proposed a reorganization of the phylogenetic system of classification to include the domain, a new taxonomic category higher (more inclusive) than the Kingdom category, as shown in the following diagram.

Universal Ancestor

Domain Bacteria             Domain Archaea Domain Eukarya

(Eubacteria)             (Archaebacteria) (Eukaryotes)

 

    • describe how this classification scheme presents different conclusions about the relationships among living organisms than those presented by the previous five-kingdom system of classification
    • describe three kinds of evidence that were used to develop the taxonomic scheme above, and explain how this evidence was used. The evidence may be structural, physiological, molecular, and/or genetic.
    • Describe
    • four of the characteristics of the universal ancestor.

Unit 9 (Introduction to Plants, Fungi, Invertebrates)

37.  In the life cycles of a fern and a flowering plant, compare and contrast each of the following:

    1. The gametophyte generation.
    2. Sperm transport and fertilization.
    3. Embryo protection.

38.  Describe the differences between the terms in each of the following pairs.

    1. Coelomate versus acoelomate body plan.
    2. Protostome versus deuterostome development.
    3. Radial versus bilateral symmetry.
    4. Explain how each of these pairs of features was important in constructing the phylogenetic tree shown below. Use specific examples from the tree in your discussion.

    Unit 10 (Vertebrates, Basic Animal Structure and Function)

39.  Select two of the following three pairs and discuss the evolutionary relationships between the two members of each pair you have chosen. In your discussion include structural adaptations and the functional significance.

    Pair A: green algae—vascular plants

    Pair B: prokaryotes—eukaryotes

    Pair C: amphibians—reptiles

    Unit 11 (Animal Nutrition, Circulation, Respiration, Immune System)

40.  Describe the structure of a mammalian respiratory system. Include in your discussion the mechanisms of inspiration and expiration.

41.  Describe the processes of fat and protein digestion and product absorption as they occur in the human stomach and small intestine. Include a discussion of the enzymatic reactions involved.

42.  Describe the following mechanisms of response to foreign materials in the human body.

    1. The antigen-antibody response to a skin graft from another person.
    2. The reactions of the body leading to inflammation of a wound infected by bacteria.

43.  Discuss the processes of exchange of O2 and CO2 that occur at the alveoli and muscle cells of mammals. Include in your answer a description of the transport of these gases in the blood.

44.  Many physioligical changes occur during exercise.

    1. Design a controlled experiment to test the hypothesis that an exercise session causes short-term increases in heart rat and breathing rate in humans.
    2. Explain how at least three organ systems are affected by this increased physical activity and discuss interactions among these systems.

45.  The graph below shows the response of the human immune system to exposure to an antigen. Use this graph to answer part a and part b of this question.

    1. Describe the events that occur during period I as the immune system responds to the initial exposure to the antigen.
    2. Describe the events that occur during period II following a second exposure to the same antigen.
    3. Explain how infection by the AIDS virus (HIV) affects the function of both T and B lymphocytes.

    Unit 12 (Homeostasis, Reproduction, Development)

47.  Discuss the processes of cleavage, gastrulation, and neurulation in the frog embryo; tell what each process accomplishes. Describe an experiment that illustrates the importance of induction in development.

48.  The evolutionary success of organisms depends on reproduction. Some groups of organisms reproduce asexually, some reproduce sexually, while others reproduce both sexually and asexually.

    1. Using THREE difference organisms, give an example of one organism that reproduces sexually, one that reproduces asexually, and one that reproduces BOTH sexually and asexually. For each organism given as an example, describe two reproductive adaptations. These adaptations may be behavioral, structural, and/or functional.
    2. What environmental conditions would favor sexual reproduction? Explain. What environmental conditions would favor asexual reproduction? Explain.

    Unit 13 (Endocrine System, Nervous System, Sensory and Motor Mechanisms)

49.  Discuss the sources and actions of each of the following pairs of hormones in humans and describe the feedback mechanisms that control their release.

    1. Insulin—glucagon
    2. Parathyroid hormone—calcitonin
    3. Thyrotropin (TSH)—thyroxine (T4)

50.  Beginning at the presynaptic membrane of the neuromuscular junction, describe the physical and biochemical events involved in the contraction of a skeletal muscle fiber. Include the structure of the fiber in your discussion.

52.  Describe the negative and positive feedback loops, and discuss how feedback mechanisms regulate each of the following.

    1. The menstrual cycle in nonpregnant human female.
    2. Blood glucose levels in humans.

53.  Discuss how cellular structures, including the plasma membrane, specialized endoplasmic reticulum, cytoskeletal elements, and mitochondria, function together in the contraction of skeletal muscle cells.

54.  Structure and function are related in the various organ systems of animals. Select two of the following four organ systems in vertebrates:

    • respiratory
    • digestive
    • excretory
    • nervous

For each of the two systems you choose, discuss the structure and function of two adaptations that aid in the transport or exchange of molecules (or ions). Be sure to relate structure to function in each example.

Unit 14 (Plant Structure and Function)

55. Relate the structure of an angiosperm leaf to each of the following:

    1. Adaptations for photosynthesis and food storage.
    2. Adaptations for food translocation and water transport.
    3. Specialized adaptations to a desert environment.

56.  Define the following plant responses and explain the mechanism of control for each. Cite experimental evidence as part of your discussion.

    1. Phototropism
    2. Photoperiodism

57.  Describe the structure of a bean seed and discuss its germination to the seedling stage. Include in your essay hormonal controls, structural changes, and tissue differentiation.

58.  Describe the effects of plant hormones on plant growth and development. Design an experiment to demonstrate the effect of one of these plant hormones on plant growth and development.

59.  Trace the pathway in a flowering plant as the water moves from the soil through the tissues of the root, stem, and leaves to the atmosphere. Explain the mechanisms involved in conducting water through these tissues.

60.  Discuss the adaptations that have enabled flowering plants to overcome the following problems associated with life on land.

    1. The absence of an aquatic environment for reproduction.
    2. The absence of an aquatic environment to support the plant body.
    3. Dehydration of the plant.

61.  A group of students designed an experiment to measure transpiration rates in a particular species of herbaceous plant. Plants were divided into four groups and were exposed to the following conditions.

    Group I-Room conditions (light, low humidity, 20° C, and little air movement.)
    Group II-Room conditions with increased humidity.
    Group III-Room conditions with increased air movement (fan)
    Group IV-Room conditions with additional light

    The cumulative water loss due to transpiration of water from each plant was measured at 10-minute intervals for 30 minutes. Water loss was expressed as milliliters of water per square centimeter of leaf surface area. The data for all plants in Group I (room conditions) were averaged. The average cumulative water loss by the plants in Group I is presented in the table below.

    Average Cumulative Water Loss by the Plants in Group I

    Time (minutes)

    Average Cumulative Water Loss (milliliter H2O centimeter2)

    10

    3.5 x 10-4

    20

    7.7 x 10-4

    30

    10.6 x 10-4

    1. Construct and label a graph using the data for Group I. Using the same set of axes, draw and label three additional lines representing the results that you would predict for Groups II, III, and IV.
    2. Explain how biological and physical processes are responsible for the difference between each of your predictions and the data for Group I.
    3. Explain how the concept of water potential is used to account for the movement of water from the plant stem to the atmosphere during transpiration.

62.  Numerous environmental variables influence plant growth. Three students each planted a seedling of the same genetic variety in the same type of container with equal amounts of soil from the same source. Their goal was to maximize their seedling’s growth by manipulating environmental conditions. Their data are shown below.

    Plant Seedling Mass (grams)
    Day 1Day 30
    Student A424
    Student B535
    Student C464
    1. Identify three different environmental variables that could account for differences in the mass of seedlings at day 30. Then choose one of these variables and design an experiment to test the hypothesis that your variable affects growth of these seedlings.
    2. Discuss the results you would expect if your hypothesis is correct. Then provide a physiological explanation for the effect of your variable on plant growth.

    Unit 15 (Ecology)

63.  Define and explain the role of each of the following in social behavior.

    1. Territoriality.
    2. Dominance hierarchies.
    3. Courtship behavior.

64.  Describe the trophic levels in a typical ecosystem. Discuss the flow of energy through the ecosystem, the relationship between the different trophic levels, and the factors that limit the number of trophic levels.

65.  Describe and give an example of each of the following. Include in your discussion the selection advantage of each.

    1. Pheromones.
    2. Mimicry.
    3. Stereotyped behavior (instinct).

66.  Describe the process of ecological succession from a pioneer community to a climax community. Include in your answer a discussion of species diversity and interactions, accumulation of biomass, and energy flow.

67.  Describe releasers, imprinting, and communications, as each of these terms relates to animal behavior. You may include in your answer a discussion of the classical studies of Niko Tinbergen, Konrad Lorenz, and Karl von Frisch.

68.  Describe the biogeochemical cycles of carbon and nitrogen. Trace these elements from the point of their release from a decaying animal to their incorporation into a living animal.

69.  Using an example for each, discuss the following ecological concepts.

    1. Succession
    2. Energy flow between trophic levels.
    3. Limiting factors.
    4. Carrying capacity.

70.  Living organisms play an important role in the recycling of many elements within an ecosystem. Discuss how various types of organisms and their biochemical reactions contribute to the recycling of either carbon or nitrogen in an ecosystem. Include in your answer one way in which human activity has an impact in the nutrient cycle you have chosen.

71.  Survival depends on the ability of an organism to respond to changes in its environment. Some plants flower in response to changes in day length. Some mammals may run or fight when frightened. For both of these examples, describe the physiological mechanisms involved in the response.

72.  Interdependence in nature is illustrated by the transfer of energy through trophic levels. The diagram below depicts the transfer of energy in a food web of an Arctic lake located in Alaska (J )

    1. Choosing organisms from four different trophic levels of this food web as examples, explain how energy is obtained at each trophic level.
    2. Describe the efficiency of energy transfer between trophic levels and discuss how the amount of energy available at each trophic level affects the structure of the ecosystem.
    3. If the cells in the dead terrestrial plant material that washed into the lake contained a commercially produced toxin, what would be the likely effects of this toxin on this food web? Explain.

     

     

    Noon

    174.0

    4 p.m.

    350.5

    8 p.m.

    60.5

    midnight

    8.0

For the data above, provide information on each of the following.

    • Summarize the pattern.
    • Identify THREE physiological or environmental variables that could cause the slugs to vary their distance from each other.
    • Explain how each variable could bring about the observed pattern of distribution.

Choose ONE of the variables that you identified and design a controlled experiment to test your hypothetical explanation. Describe results that would support or refute your hypothesis.

Cumulative Essays

74.  Describe how the following adaptations have increased the evolutionary success of the organisms that possess them. Include in your discussion the structure and function related to each adaptation.

    1. C4 metabolism
    2. Amniotic egg
    3. Four-chambered heart
    4. Pollen

75.  Describe the anatomical and functional similarities and difference within each of the following pairs of structures.

    1. Artery—vein
    2. Small intestine—colon
    3. Skeletal muscle—cardiac muscle
    4. Anterior pituitary—posterior pituitary

76.  Discuss how each of the following has contributed to the evolutionary success of the organisms in which they are found.

    1. seeds
    2. mammalian placenta
    3. diploidy

77.  Angiosperms (flowering plants) and vertebrates obtain nutrients from their environment in different ways.

    1. Discuss the type of nutrition and the nutritional requirements of angiosperms and vertebrates.
    2. Describe 2 structural adaptations in angiosperms for obtaining nutrients from the environment. Relate structure to function.
    3. Interdependence in nature is evident in symbiosis. Explain tow symbiotic relationships that aid in nutrient uptake, using examples from angiosperms and/or vertebrates. (Both examples may be angiosperms, both may be vertebrates, or one may be from each group.

78.  The problem of survival of animals on land are very different from those of survival of animals in an aquatic environment. Describe four problems associated with animal survival in terrestrial environments but not in aquatic environments. For each problem, explain an evolutionary solution.

79.  The survival of organisms depends on regulatory mechanisms at various levels. Choose THREE from the following examples. Explain how each is regulated.

    • The expression of a gene.
    • The activity of an enzyme.
    • The cell cycle.
    • The internal water balance of a plant.
    • The density of a population.

80.  Photosynthesis and cellular respiration recycle oxygen in ecosystems. Respond to TWO (and only two) of the following:

    1. Explain how the metabolic processes of cellular respiration and photosynthesis recycle oxygen.
    2. Discuss the structural adaptations that function in oxygen exchange between each of the following organisms and its environment: a plant; an insect; a fish.
    3. Trace a molecule of O2 from the environment to a muscle cell in a vertebrate of your choice.

81.  Biological recognition is important in many processes at the molecular, cellular, tissue, and organismal levels. Select three of the following, and for each of the three that you have chose, explain how the process of recognition occurs and give an example of each.

    1. Organisms recognize others as members of their own species.
    2. Neurotransmitters are recognized in the synapse.
    3. Antigens trigger antibody response.
    4. Nucleic acids are complementary.
    5. Target cells respond to specific hormones.

82.  Communication occurs among the cells in a multicellular organism. Choose THREE of the following examples of cell-to-cell communication, and for each example, describe the communication that occurs and the types of responses that result from this communication.

  • communication between two plant cells
  • communication between two immune-system cells
  • communication either between a neuron and another neuron, or between a neuron and a muscle cell
  • communication between a specific endocrine-gland cell and its target cell

 

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