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IB NOS > Origin of Life > Flashcards

Origin of Life Flashcards

1
Q

When was the earth formed?

A

at least 4.6 billion years ago

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2
Q

How do we know when the earth was formed?

A

radioactive emissions from meteorites found on the Earth and the Moon leads us to infer that the Earth formed at
least 4.6 billion years ago

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3
Q

What techniques study the structure of the earth?

A

Advanced techniques in analysing seismic
waves, the Earth’s magnetic field, and geomagnetic
and gravity measurements

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4
Q

Why are rocks important to scientists?

A

Rocks can be dated by both absolute and relative

techniques

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5
Q

Why do living organisms affect changes in the Earth?

A

taking in liquid water and releasing water vapour to the atmosphere. Aquatic living organisms also affect the levels of dissolved gases and the levels of dissolved solids.

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6
Q

How did the concept of plate tectonics form?

A

gradually built up over the years based on:
- complementary shape of parts of the present continents
- similarities in rock formations and plant species,
though much of the scientific community was initially
sceptical

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7
Q

What led to the acceptance of plate tectonics?

A

paleomagnetism, especially critical evidence concerning the magnetic orientation of rocks from either side of the
mid-Atlantic ridge

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8
Q

What is paleomagnetism?

A

the branch of geophysics concerned with the magnetism in rocks that was induced by the earth’s magnetic field at the time of their formation

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9
Q

How are tectonic plates observed?

A

As a result of new technologies to measure distance

and position very precisely

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10
Q

What is the Earth’s crust made of?

A

The Earth’s crust is comprised of a number of
separate plates that gradually move relative to each
other.

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11
Q

What has happened to tectonic plates over time?

A

Over geological time the number and shape of the
plates, as well as the positions of these, have
undergone many changes.

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12
Q

What do tectonic plates cause?

A

Interactions of the plates are responsible for
earthquakes and physical features such as volcanoes
and mountain ranges.

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13
Q

What surrounds the Earth?

A

The Earth is surrounded by an atmosphere, the
composition of which has changed and continues to
change

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14
Q

What causes the ozone layer?

A

Radiation from the Sun, especially UV light, causes
chemical reactions between components of the
atmosphere

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15
Q

What causes gases in water?

A

Equilibrium exists between gases in the atmosphere
and gases dissolved in water on the surface of the
Earth, which hence acts as a reservoir of gases

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16
Q

What has a detailed study of the atmosphere enabled us to do?

A

develop models that can predict the effects of
changes in gas composition that may occur in the
future

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17
Q

Where do recent changes in Earth’s atmosphere come from?

A

ice core samples, especially from the Antarctic, which contain trapped air.

18
Q

What causes change in sea levels?

A

The total amount of water, and the ratio of water to

ice

19
Q

Where does most of Earth’s energy come from?

A

Most of the energy on Earth originates from the

Sun.

20
Q

What causes green house gases?

A

Solar radiation is absorbed by the Earth’s
surface and transferred to the atmosphere. The
Earth emits infrared radiation, some of which is absorbed and re-radiated by some gases in the
atmosphere, creating a greenhouse effect.

21
Q

What makes the surface temperature steady?

A

The balance between absorbed and emitted
radiation results in a surface temperature that
makes life possible.

22
Q

How does the sun affect the global climate?

A

Variations in solar activity are hypothesized to affect

global climate by 5%

23
Q

What objects provide information on how the Earth’s climate has changed over time?

A

Fossils and sediments

24
Q

Does human activity affect the climate?

A

Yes, Changes to the atmosphere that result from human

activity have a significant effect on the climate.

25
Q

How many greenhouse gases are there?

A

There are several greenhouse gases, each with a

different contribution to global warming

26
Q

What gases did Miller and Urey originally use in 1953 to show that amino acids could be made from simple inorganic molecules?

A

Hydrogen, methane and ammonia

27
Q

What was absent in Earth’s early atmosphere that allowed ultra violet light to shine on the Earth’s surface?

A

Ozone layer

28
Q

What did the electrodes simulate in the Miller Urey Experiment?

A

Lightening

29
Q

How many amino acids did Miller and Urey originally detect?

A

Five

30
Q

What gases did Miller and Urey use in their 1958 experiment?

A

Carbon dioxide, hydrogen sulphide, methane and ammonia

31
Q

What amino acid has been indirectly detected in nebula?

A

Glycine

32
Q

What does molecular Panspermia mean?

A

The first organic molecules originated from space

33
Q

How many strands does a RNA molecule have?

A

One

34
Q

What is RNA world theory?

A

RNA was the precursor to DNA as the molecule that held genetic information

35
Q

What is the primordial soup?

A

a solution rich in organic compounds in the primitive oceans of the earth, from which life is thought to have originated

36
Q

What are the main criticisms of Miller Urey’s experiment?

A

Results did not match the early earth

  • gases did not represent those in the atmosphere
  • only five amino acids found (compared to 20 in living things)
  • No methionine found (starter amino acid found in all proteins)
37
Q

What was Miller Urey’s experiment?

A

An experiment to show that conditions believed to exist in the early earth could create complex organic molecules. They created a primordial soup by:

  • Introducing gases
  • Recreating the water cycle by evaporating and condensing water
  • Keeping the environment warm
  • Exposing the chemicals to UV (no ozone layer in early atmosphere)
  • Recreating lightning by generating electrical sparks
38
Q

What happened when Miller and Urey’s ‘primordial soup’ was analysed 50 years later?

A

22 amino acids were found

39
Q

What is the endosymbiotic theory?

A

It proposes that 2 billion years, a prokaryote cell absorbed a smaller prokaryote cell. This smaller cell survived and the cells lived symbiotically (giving services to each other)

40
Q

What is the evidence for endosymbiosis?

A

Organelles that to be derived from engulfed prokaryotes:

  • have double membranes
  • have their own DNA
  • can replicate themselves within the host cell
  • can perform their own independent protein synthesis using small ribosomes

IB NOS (11 decks)

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