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IB Biology HLA2.1 Origins of cellsQuestion Bank

A2.1 Origins of cells

Question D1

[Maximum number: 5]

The synthesis of complex organic molecules in sea water is believed to be an important step in the evolution of life on Earth. Researchers investigated whether the evaporation of sea water containing amino acids could catalyse the formation of dipeptides such as divaline (valine-valine) under prebiotic Earth conditions. They placed different amino acid combinations in a chamber to simulate the evaporation cycles between high tides in shallow seas. In one investigation the amino acid valine was used as the substrate and the percentage yield of divaline was measured after different numbers of evaporation cycles. The experiment was repeated without a catalyst and with either glycine or histidine as catalysts.

Question image

Question D1(b)

(a)

This investigation was performed in a chamber at 85∘C85^{\circ} \mathrm{C} leading to total evaporation of the salt water within one day. The atmosphere inside the chamber consisted of nitrogen, carbon dioxide and water vapour. Evaluate the experiment on the basis of similarity with conditions that existed on the prebiotic Earth.

[ 3 ]

Question D1(c)

(b)

Outline other possible locations where conditions could have allowed the synthesis of organic molecules under prebiotic conditions.

[ 2 ]

Question 3

[Maximum number: 1]

Which cell component arose first during the formation of the earliest cells?

A

Chloroplast

B

Plasma membrane

C

Mitochondria

D

Cell wall

Question 2

Question 2(a)

Question 2(a)(ii)

(a)
(i)

Outline the methods used for dating fossils and rocks using 40 K{ }^{40} \mathrm{~K}.

[ 2 ]

Question 2

Question 2(a)

(a)

State the name for primitive, phospholipid-enclosed structures that may have preceded cells.

[ 1 ]

Question 2

Question 2(b)

(a)

Identify two properties of RNA which may have contributed to the origin of life.
1.
2.

[ 2 ]

Question 2(d)

(b)

Describe how 14C{ }^{14} \mathrm{C} can be used to estimate the age of a fossil.

[ 3 ]

Question D2

Question D2(a)

(a)

State one activity of RNA necessary for it to have had a role in the origin of life.

[ 1 ]

Question 12

[Maximum number: 1]

The Miller-Urey experiment carried out in 1952 tested the hypothesis of the chemical origin of life. What were the key findings?

A

Living cells could be produced from a mixture of chemicals.

B

Complex organic molecules could form under simulated primordial conditions.

C

Life could spontaneously emerge without external influence.

D

DNA and RNA could self-replicate in a prebiotic environment.

Question 10

[Maximum number: 5]

There is evidence that RNA was used as a genetic material in living organisms before DNA.

Question 10(a)

(a)

Describe the structure of RNA and the evidence that it was the first genetic material used to store information.

[ 5 ]
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