Lecture 3

Question 1

Which 4 elements constitute >96% mass of living organisms?

Answer 1

O,C,H,N

Question 2

Approximately how many of the 92 elements does life use?

Answer 2

25.

Question 3

What are the three most likely origins of earths organic molecules and their energy sources?

Answer 3

1. Chemical reactions in the early atmosphere. Energy provided by sunlight, electricity
2. Chemical reactions in water. Most likely in deep oceans for thermal reasons. The energy was then provided by volcanic vents (black smokers)
3. Molecules brought to the Earth from space. The energy in this case is Sun- or starlight

Question 4

What are planetesimals?

Answer 4

Building blocks for planets, km to hundreds of km in size.

Question 5

What happens with organic molecules exposed to solar radiation?

Answer 5

They tend to be destroyed.

Question 6

Why should we start looking on solar systems where bodies have oceans and or atmospheres?

Answer 6

They can protect organic molecules from solar radiation.

Question 7

Sunlight diminishes by …?(1/R, 1/R^2, 1/R^3)

Answer 7

1/R^2

Question 8

What does chemical energy require to be present?

Answer 8

Some type of reactants. We need a gaseous or liquid medium in order to bring components together (Like an atmosphere or sea)

Question 9

Why is water so important? Big question ikr

Answer 9

It dissolves organic molecules -> Reactions can take place in cells

Transport of chemicals in and out of a cell possible.

Directly involved in the metabolic reactions that take place in the cell

It remains liquid over a wide range of temperatures

Less dense when it freezes. (“Snowball earth”)
‘
It is a polar molecule (Charge separation).

Question 10

What is the likely origin of water on the moon?

Answer 10

Comet impacts

Question 11

Why could Mercury still have sub-surface ice even though it’s way to close to the sun for that to form?

Answer 11

Mecury could have been formed elsewhere and migrated towards where it is now due to viscous drag or dynamical interactions.

Question 12

What is an exosphere?

Answer 12

Exosphere is a thin, atmosphere-like volume surrounding a planetary body where molecules are gravitationally bound to that body, but where the density is too low for them to behave as a gas by collisions

Question 13

“In the beginning Venus may have been more Earth-like than the Earth 4 Gyrs ago”. Describe what happened on Venus?

Answer 13

Venus had a runaway greenhouse effect from a 90 bar (Earth = 1 bar) atmosphere that consists almost exclusively from CO2