1.2 Cells: Origin & Ultrastructure

A student drew this eukaryotic cell.

Identify the structures E and G.

Distinguish between the function of the structures identified in part (a).

Spontaneous generation was once the widely accepted theory explaining the origin of life. It is now universally accepted that cells come from pre-existing cells. 

Outline the evidence that has allowed this change in universal acceptance. 

Miller and Urey’s experiments recreated the conditions thought to have existed on Earth prior to life.

Explain how the apparatus they used provided evidence for how the first cells could have formed.

Below are three electron micrographs showing organelles found within a cell.

Compare the structure and function of the organelles in micrographs K and L.

The electron micrograph below is of a salivary gland of a mosquito.

Identify the structures labelled P.

Draw a labelled biological diagram of the bacterial cell below.

Pradana Aumars, CC0, via Wikimedia Commons

The image below is an electron micrograph of some cells.

https://upload.wikimedia.org/wikipedia/commons/thumb/4/4d/Angiosperm_Morphology_Adaxial_Epidermis_in_Ligustrum_%2836845195186%29.jpg/800px-Angiosperm_Morphology_Adaxial_Epidermis_in_Ligustrum_%2836845195186%29.jpg?20180623001402

Deduce, with a reason, the function of cell H.

The image below is a 3D-printed model of a cell dividing.

Rosser1954, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Deduce, with a reason, whether this model represents an animal cell, plant cell or neither.

This is an electron micrograph of an immune cell, responsible for specific immunity.

[1]

[3]

One mark is available for clarity of communication throughout this question.

A student was examining this electron micrograph of a cell. They identified it as a plant cell.

Evaluate the student’s decision to identify this as a plant cell.

Explain the Oparin-Haldine hypothesis scientists proposed for the origin of the first cells.

Euglena gracilis is a unicellular eukaryotic cell that is both heterotrophic and autotrophic.

Discuss the theory that suggests how an organism could have evolved to be a eukaryotic cell that is both heterotrophic and autotrophic. 

The following statement describes some of Louis Pasteur’s findings:

Explain what these findings demonstrated.

The electron micrograph below shows part of a palisade mesophyll cell.

Identify structures A and D

The diagram below shows a drawing of part of an animal cell as seen through an electron microscope.

Suggest why the shapes of the two organelles labelled O in the diagram appear different.

State the function of organelle N in the diagram in part (c).

Phospholipids and peptidoglycan are two biological molecules, each of which are the  main constituent of structures found in prokaryotic cells. The drawing below shows part of a prokaryotic cell.

In certain conditions some prokaryotic cells can divide every 25 minutes.

With a starting population of 2.45 × 10³ cells, and assuming each cell divides every 25 minutes, calculate how many cells there will be after 3.75 hours. Assume no cells die during this time.

Identify structure R in the diagram in part (a).

Scientists used an electron microscope rather than an optical microscope to study the structure of a unicellular, eukaryotic organism known as an amoeba.

Explain why scientists used an electron microscope to study the structure of an amoeba.

State three structures in the amoeba cell that the scientists would not have been able to identify using a light microscope.

The electron micrograph below is of a spore from a fungus (Tilletia controversa), that affects wheat crops..Identify, with a reason, whether the electron micrograph above was produced using a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

 One mark is available for clarity of communication throughout this question.

The diagram below shows a drawing of part of an animal cell as seen through an electron microscope.

Large numbers of organelle O are found in small intestine epithelial cells. Explain why these cells are adapted in this way.

Describe the process shown in the diagram below.

Compare and contrast the structures of prokaryotic and eukaryotic cells.