Astronomy Chapter 18

The key advantage of Carbon over Silicon as the base element for life is

carbon forms more stable compounds

The oxygen atom in a water molecule

carries a negative charge

The hydrogen atoms in a water molecule

carry a positive charge.

An advantage of carbon dioxide as the starting form of carbon for use by living things is that it

dissolves in water

A spectrum is defined to be the set of

frequencies or colors present in a light source.

The most common element in the universe is

hydrogen

Carbon is

one of the four most common elements in the universe

If we wish to find life with a carbon-return process similar to the one here on Earth, we should look for planets

with thin, unstable surfaces

Compared to the frequency of photons absorbed during a transition from a -5ev state to a -4ev state, transitions from the -5ev state to a -2ev state would correspond to absorbing photons whose frequency is

3 times as high. 5-4=1, 5-2=3, 3 is 3 times as large as 1.

Which of the following comments about the energy needed to separate the hydrogen and oxygen in water is correct?

It is the same as the energy released when the hydrogen is burned, so we get no net gain of energy.

Which system is closest to the plan of most current Earth life-forms?

One DNA molecule is used to make RNA molecules which, in turn, make proteins and enzymes that construct and operate a life-form.

What is the order of frequencies from lowest to highest?

Radio Waves, TV, microwaves, heat, infra-red, visible, ultra-violet, x-rays, gamma rays

Which model for the formation of life on Earth would apply if it turns out the first step of forming a self-copying molecule is extremely improbable?

The Panspermia Model

The early Earth probably had carbon

in the form of amino acids and other complex hydrocarbons

If the frequency of electromagnetic radiation goes from 2×10^14Hz to 6×10^14Hz, the energy of each individual photon in the radiation

is multiplied by 3. 6/2=3

The role of DNA in current Earth life is to

provide the patterns for the enzymes that carry out the chemical processes of life.

The chlorophyll in plants uses sunlight to

split water into hydrogen and oxygen

A hydrogen bond is the result of

the electrical attraction between a hydrogen atom on one molecule and an oppositely charged part of another molecule.

A DNA molecule consists of

two sugar phosphate chains connected by pairs of nitrogenous bases

The strongest evidence that Earth life is all descended from a single self copying molecule is that all life

uses the same 4 nitrogenous bases to code for the same 20 amino acids