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IB Bio > A2.1 Origin of Cells > Flashcards

A2.1 Origin of Cells Flashcards

1
Q

What are all cells and organisms constructed from?

A

Complex carbon-based macromolecules called organic compounds

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2
Q

Why can organic compounds vary greatly in structure and diversity?

A

Due to the chemical properties of carbon (can form four covalent bonds)

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3
Q

What is considered a fundamental requirement in the initial formation of cells?

A

The generation of organic compounds from inorganic sources

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4
Q

What does the large variety of organic compounds allow cells to do?

A

Undertake a greater range of chemical processes needed to sustain life

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5
Q

What was a key requirement for the spontaneous formation of simple organic compounds?

A

A lack of free oxygen in the atmosphere

This absence of free oxygen contributed to the lack of ozone.

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6
Q

What resulted from the lack of ozone in the early atmosphere?

A

Higher levels of ultraviolet light penetration

Ultraviolet light could penetrate more deeply without the protective ozone layer.

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7
Q

What were the atmospheric concentrations of carbon dioxide and methane like in early Earth?

A

Significantly higher concentrations

This increase contributed to higher temperatures on early Earth.

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8
Q

What was the effect of higher atmospheric concentrations of carbon dioxide and methane?

A

Resulted in significantly higher temperatures

These temperatures facilitated the chemical processes necessary for organic compound formation.

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9
Q

Why do the chemical processes required for carbon compounds to form spontaneously not occur now?

A

These conditions no longer exist on Earth

Modern atmospheric conditions are different from those in early Earth.

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10
Q

What does the cell theory state about living things?

A

All living things are composed of cells

This principle emphasizes the cellular basis of life.

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11
Q

What is the smallest unit of life according to the cell theory?

A

The cell

This highlights that cells are the fundamental building blocks of all organisms.

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12
Q

How do cells arise according to the cell theory?

A

Cells only arise from pre-existing cells

This principle indicates that new cells are formed through the division of existing cells.

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13
Q

What does it mean for living organisms to be self-sustaining?

A

They are able to maintain the conditions needed to continue their existence

This refers to the ability to carry out essential life processes.

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14
Q

List the conditions necessary for living organisms to sustain life.

A
  • Metabolism
  • Reproduction
  • Sensitivity (responsiveness)
  • Homeostasis
  • Excretion
  • Nutrition
  • Growth (movement)

These conditions are fundamental for the survival and functioning of living organisms.

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15
Q

According to the cell theory, what is the smallest unit capable of self-sustaining life?

A

The cell

Cells can undertake all the functions of life.

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16
Q

True or False: All living organisms can perform metabolism.

A

True

Metabolism is a key condition for life.

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17
Q

Fill in the blank: The smallest unit capable of self-sustaining life is the _______.

A

cell

This is a fundamental concept in biology.

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18
Q

What is homeostasis in the context of living organisms?

A

The ability to maintain stable internal conditions

This is crucial for the survival of organisms.

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19
Q

Define excretion as it relates to living organisms.

A

The process of removing waste products from the body

Excretion is essential for maintaining internal balance.

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20
Q

What is the role of sensitivity in living organisms?

A

Responsiveness to environmental stimuli

This allows organisms to adapt to changes in their environment.

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21
Q

What does nutrition refer to in the context of living organisms?

A

The intake of substances necessary for growth and energy

Nutrition is vital for sustaining life processes.

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22
Q

How does reproduction contribute to the survival of living organisms?

A

It ensures the continuation of a species

Reproduction can be sexual or asexual.

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23
Q

What is growth in the context of living organisms?

A

The increase in size and mass of an organism

Growth can also involve movement and development.

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24
Q

Why are viruses not considered living?

A

Because they cannot carry out all life functions independently

Viruses do not have the characteristics that define living organisms.

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25
What do viruses lack that prevents them from being classified as living organisms?
Metabolism ## Footnote Viruses do not perform metabolic processes on their own.
26
How do viruses generate their component parts?
By relying on metabolic events in a host cell ## Footnote Viruses need a host to utilize its cellular machinery.
27
Can viruses reproduce autonomously?
No ## Footnote Viruses must infect a cell to replicate.
28
Fill in the blank: A virus must _______ a cell in order to replicate.
[infect]
29
What is the primary method by which cells are produced?
Cells are produced via the division of pre-existing cells.
30
What is abiogenesis?
Abiogenesis is the process by which the first cells arose from non-living material.
31
List the four key stages theorized for the process of abiogenesis.
* Catalysis * Self-Assembly * Self-Replication * Compartmentalisation
32
What occurs during the Catalysis stage of abiogenesis?
Simple organic molecules were synthesised from primordial inorganic molecules.
33
What happens in the Self-Assembly stage of abiogenesis?
More complex polymers were constructed from simple organic molecules.
34
Define the Self-Replication stage in the context of abiogenesis.
Certain polymers formed the capacity to be duplicated, enabling inheritance.
35
What is the significance of Compartmentalisation in abiogenesis?
Molecules became packaged into membranes with unique internal chemistry.
36
What is abiogenesis?
The theory that life originated from non-living matter.
37
Why has testing the theory of abiogenesis been difficult for scientists?
Due to the following reasons: * The exact conditions on pre-biotic Earth no longer exist * The first protocells did not form fossils
38
Fill in the blank: The exact conditions on pre-biotic Earth ______.
[no longer exist and cannot be replicated under controlled settings]
39
What evidence is limited for testing hypotheses about abiogenesis?
Fossil evidence of the first protocells.
40
True or False: The first protocells left behind abundant fossils.
False
41
What was the purpose of the Miller-Urey experiment?
To demonstrate the non-living synthesis of organic materials under pre-biotic Earth conditions ## Footnote The experiment aimed to recreate the conditions thought to exist on early Earth.
42
What were the initial conditions recreated in the Miller-Urey experiment?
High temperatures and a reducing atmosphere (no oxygen) ## Footnote These conditions reflect the hypothesized environment of pre-biotic Earth.
43
What gases were mixed with water vapour in the Miller-Urey experiment?
H2, CH4, NH3 ## Footnote These gases were chosen to simulate the reducing atmosphere of early Earth.
44
What energy source was simulated in the Miller-Urey experiment?
Electrical discharge (simulating lightning) ## Footnote This was used to drive chemical reactions in the mixture.
45
What was done to the mixture after it was exposed to electrical discharge?
It was allowed to cool and concentrate components for ~1 week ## Footnote This step was crucial for the subsequent analysis of the condensed mixture.
46
What were the findings after analyzing the condensed mixture in the Miller-Urey experiment?
It contained traces of simple organic molecules ## Footnote This indicated that organic synthesis was possible under the simulated conditions.
47
What conclusion did Miller and Urey draw from their experiment?
Organic molecules can form from inorganic compounds ## Footnote This supports the idea that such molecules could have formed on prebiotic Earth.
48
Fill in the blank: The Miller-Urey experiment recreated the conditions of _______ Earth.
[pre-biotic]
49
True or False: The Miller-Urey experiment proved that life could arise from non-living materials.
False ## Footnote The experiment demonstrated the potential for organic molecules to form, but did not prove the origin of life.
50
What are the two main components of fatty acids?
Hydrophobic tail and hydrophilic head
51
List the types of structures that fatty acids can form.
* Vesicles * Micelles * Bilayers
52
What facilitated the spontaneous formation of membranes?
The production of simple organic molecules
53
In water, how do non-polar fatty acids arrange themselves?
They form micelles, with hydrophobic tails coalescing
54
What happens when polar organic monomers are produced?
They attract the hydrophilic glycerol heads of fatty acids, forming a spherical bilayer
55
What does the formation of membrane-bound containers create?
A hydrophobic barrier
56
What is the significance of the hydrophobic barrier created by vesicles?
It allows the internal chemistry of the vesicle to differ from the exterior
57
What does the ordered aggregation of non-living components lead to?
The development of the first cells
58
Fill in the blank: Fatty acids can form _______ in water.
micelles
59
True or False: The hydrophilic heads of fatty acids repel water.
False
60
What is considered a fundamental requirement in the initial formation of cells?
The capacity for certain organic compounds to self-replicate ## Footnote This allows for chemical processes to be reproduced in successive cells as the necessary organic compounds are effectively inherited.
61
Why is RNA presumed to have been the first genetic material?
Due to two key qualities: * RNA can self-replicate * RNA can act as a catalyst
62
What does RNA's ability to self-replicate involve?
RNA can form a complementary template sequence that can be used to produce new identical molecules ## Footnote This property is essential for the replication of genetic material.
63
What role do RNA catalysts (ribozymes) play in modern cells?
Involved in peptide bond formation and intron splicing ## Footnote Ribozymes demonstrate that RNA can have enzymatic functions.
64
Fill in the blank: RNA can act as a _______.
catalyst
65
True or False: RNA cannot self-replicate.
False
66
What is the only molecule capable of both self-replication and catalytic functioning?
RNA
67
Which molecule has taken over RNA's role due to its superior chemical stability?
DNA
68
What is the structural form of DNA that contributes to its stability?
double helical structure
69
Which molecule has taken over as the catalytic form due to its greater variability?
Protein
70
How many amino acids are involved in protein variability?
20
71
Fill in the blank: DNA has taken over as the data storage form due to its superior _______ stability.
chemical
72
Fill in the blank: Protein has taken over as the catalytic form due to its greater _______.
variability
73
True or False: RNA has a double helical structure.
False
74
What are the four bases that make up RNA?
Adenine, Uracil, Cytosine, Guanine
75
What are the components of the catalytic function provided by proteins?
amino acids

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