Final pt 4

Question 1

Light from a star passes through an exoplanet’s ____ atmosphere. Our telescopes capture the light and an instrument called a ____ splits it into a rainbow spectrum. The black bars where slices are missing, are where the sodium in the exoplanet’s atmosphere has _____ it, revealing its presence

Answer 1

sodium-rich, spectrometer, absorbed

Question 2

_____ yield a broad range of metabolic byproducts. In an environment different from earth’s these byproducts may accumulate to produce ______ ____ different from those on past and present earth.

Answer 2

microorganisms, biosignature gasses

Question 3

reactions in which electrons are transferred between molecules or compounds, or both

Answer 3

redox reactions

Question 4

redox reactions are used by life to exploit ___ ___ ___ and are also a key part of the chemistry of metabolism, which includes production of _____ materials. Some of the products in redox reactions end up as ____ or ____ and can accumulate in the atmosphere as biosignature gasses

Answer 4

chemical energy gradients, energy-storing, waste, byproducts

Question 5

the number of electrons that an atom loses, gains, or appears to use when joining with another atom in compounds

Answer 5

Oxidation state

Question 6

Elements with lower oxidation states have ___ electrons, will ____ electrons, and get ____.

Answer 6

more, donate, oxidized

Question 7

Elements with higher oxidation states have ____ electrons, are electron ____, and get ____

Answer 7

fewer, acceptors, reduced

Question 8

In the electrochemical cell, the anode ____ electrons and the cathode ____ electrons.

Answer 8

supplies, consumes

Question 9

any pair of electron donor and acceptor that is mediated by an electron transport chain

Answer 9

respiration

Question 10

Reactions can be ___ possibly but very slow due to ___ ___. ___ catalyze reactions with enzymes. Enzymes can be ___ and allow reactions to take place in nature

Answer 10

activation energy, microbes, recycled

Question 11

A high temperature ____ ___ ___ at endeavour site on the Juan de Fuca Ridge has ___ that supplies the microbial symbionts inside _____.

Answer 11

black smoker vent, sulfide, tubeworms

Question 12

On early mars, there was ample _____ ____ (Fe2+), production of ___, and ___ ___ ___ ____

Answer 12

ferrous iron, nitrate, nitrate dependent iron oxidation

Question 13

The ___ ___ illustrates how different microorganisms perform their ____ roles: the activities of one organism enable another to grow and ____. These are ___ recycling systems, driven only by energy and from _____.

Answer 13

winogradsky column, interdependent, vice-versa, self-contained, light

Question 14

In the oceans there are many ___ ____

Answer 14

coupled metabolisms

Question 15

___ is the most familiar and ___ stripper of electrons.

Answer 15

oxygen, powerful

Question 16

As electrons go from willing donor to willing acceptor, they go down a ____ gradient and the electrons ___ energy. In respiring cells, the energy from this flow of electrons is used to build up a gradient of ____ across membranes. When the protons flow down this artificially created gradient back across the membrane, ___ is created through ____ of ADP

Answer 16

thermodynamic, lose, protons, ATP, phosphorylation

Question 17

In the case of _____ respiration, used by most animals and many ___ the electron acceptor is oxygen. However, it can be anything that has a hunger for electrons, such as ___, ___ and ____. All that matters is that the recipient’s ___ ____ is higher than that of the donor. The greater the ____ in potentials, the more energy is released

Answer 17

aerobic, bacteria, CO2, NO3, perchlorate, redox potential, difference

Question 18

In 1977 Engelbert Broda determined that __ and ___ can and will react together in the way that oxygen and ____ ___ molecules do. This predicts that it would be possible for a creature to make a living by breathing nitrate and eating _____, just as we do by breathing oxygen and eating proteins, ___ or ____. In 1990s, there was discovery of bacteria capable of this ___ __ _____ or annammox reaction, in which ___ is oxidized, and ___ is reduced

Answer 18

NO3, NH4+, organic carbon, ammonia, fats, carbohydrates, anaerobic ammonia oxidation, NH4+, NO3

Question 19

A strategy for finding life on another planet is to look for ____ environments. Requirements for organisms to exist include the elements ___, __, ___, ___, and ___, liquid water, and appropriate ___ and ___ conditions

Answer 19

habitable, C, H, N, O, P, S, chemical, physical

Question 20

habitability is conservative term limited by our knowledge of the range of possible ____ their environmental and ___ capabilities, and their ___ requirements. A habitable environment could exist for a very short period of time as a ____ environment, or sustain over billions of years. This is determined by many interconnected factors such as __ ___, the ___ cycle, and planetary ___ ___

Answer 20

life-forms, metabolic, energy, transient, plate tectonics, hydrological, temperature regimens

Question 21

There are potentially ____ habitable environments, containing the requirements for life, as well as _____ ____.

Answer 21

subsurface, redox pairs

Question 22

____ enzymes are less efficient with ____ isotopes. These depleted carbon isotope compositions were observed at ___ ___, Mars. It is possible that this is due to _____ of biological methane released from the subsurface, the ___ of atmospheric CO2, or the deposition of __ ___ during passage through a galactic molecular cloud. All of these scenarios are ____, unlike processes common on Earth

Answer 22

catalytic, heavy, gale crater, photolysis, photoreduction, cosmic dust, unconventional

Question 23

Methane is chemically ___ in the current ___ atmosphere of Mars. It would quickly break down due to ___ __ from the sun and chemical reactions with other gasses. Therefore, a persistent or episodic presence of methane in the atmosphere may imply the exist of a source to continually ___ the gas.

Answer 23

unstable, oxidizing, UV radiation, replenish

Question 24

Thus far, solar system exploration has found compounds of interest, but often in locations where the gas sources are ____, such as the martian ___ and water reservoirs inside ___ ___. However, the geochemical sources for carbon compounds may exist and _____/ ___ anomalies can be hard to reconcile.

Answer 24

inaccessible, subsurface, icy moons, temporal, spatial

Question 25

An ideal biosignature gas would be ___. Living organisms should be its ___ source and it should have intrinsically strong, precisely characterized __ ____ unblended with ___ lines.

Answer 25

unambiguous, sole, spectral transitions, contaminant

Question 26

Venus is ____% CO2, with a ___km thick troposphere. It has a runaway ___ effect and had a permanent loss of water as shown by the high ___ ratio. It also has __ ___ that are temperate but ____

Answer 26

95.3, 50, greenhouse, D/H, cloud decks, hyperacidic

Question 27

The ___ abundance on venus could not be reconciled based on our current knowledge of ____ chemistry on venus.

Answer 27

phosphine, abiotic

Question 28

DAVINCI is NASA’s proposed mission for a __ ___ venus investigation of __ ___, chemistry and imaging, using both an orbiter and a descent probe.

Answer 28

deep atmosphere, noble gasses