Origins of Cells (HL IB Biology)

The Miller–Urey experiment, illustrated below, recreated the conditions thought to have existed on early Earth.

Describe the main observation from the Miller-Urey experiment.

Evaluate the Miller Urey-experiment. Do not use any points covered in part (a).

Identify the conditions present on early Earth that enabled successful pre-biotic formation of carbon compounds.

The image below shows a vesicle. 

Describe the spontaneous formation of vesicles.

Explain the importance of the formation of a membrane-bound compartment during the development of early cells.

Vesicles can be used to transport small molecules, such as ions, via membrane transport protein known as antiports. Researchers investigated the effect of temperature on the transport of sodium ions (Na⁺) through antiports in 100 isolated vesicles from the leaves of Chinese white poplar, Populus tomentosa. Their results are shown in the graph below.

Describe the results shown in the graph. 

Scientists claimed that vesicles optimise the transport of ions across membranes at 30 °C.

Use the information provided to evaluate this claim. 

State the features of RNA that mean it is presumed to have been the first genetic material. 

Scientists investigated the effect of ribozyme on population growth in yeast, Saccharomyces cerevisiae.

Describe ribozyme.

[1]

(ii)

State the specific role of ribozyme. 

[1]

A growth curve analysis of S. cerevisiae was carried out; S. cerevisiae cells were treated with a control substance (pGAD), with ribozyme (pGADRz) or with a mutant ribozyme (pGADmRz) at 30 °C. The results are shown in the graph below.

Note that N is number of cells after the given time period and N₀ is the initial number of cells.

Describe the effect of ribozyme on the growth of the S. cerevisiae population at 30 °C.

A student suggested that the results of the experiment shown in part (c) were surprising. 

Explain why the student came to this conclusion.