Topic 1 Cell Biology Paper 1 questions

Topic 1: Cell biology

This page contains multiple choice questions in the style of Paper 1 of the Biology exams.
They test the breadth of your knowledge of the understandings and skills about cell biology.

To spend more time reviewing the topic before answering these questions, use the revision resources.


Cell biology revision resources

This page lists the understandings and skills expected for Topic 1 and links to the sub-topic pages which contain detailed revision notes, activities and past paper style questions. Great for revision.

Learn from any mistakes. Every question has an examiner's explanation that appears when you check your answers.


The microscope image shows cells in a tissue sample taken from a growth suspected of being cancerous.

What is the best estimate of the mitotic index of this tissue?
Assume that there are exactly 60 cells (for simplicity).

Skill: Determination of a mitotic index from a micrograph
There are 3 cells in stages of mitosis.
So the mitotic index = 3 divided by 60 cells total.
Keeping it simple = 1 / 20 or 0.05


Identify the stage of mitosis for the two cells X and Y.

Skill: Identification of phases of mitosis in cells viewed with a microscope or in a micrograph
(prophase, metaphase, anaphase and telophase).


This box contains a lung waiting for a transplant operation.

What is special about the solution inside the box which surrounds the tissue?

Tissues and organs must be kept in a solution with the same osmolarity as the cytoplasm of the cells to prevent osmosis. If they were kept in pure water, osmosis would carry water into the cells and they would burst, causing damage to the cells.


The electron microscope image below shows three organelles found in an animal cell.

What is the name of the organelles?

Know how to idenfity the organelles in eukaryotes and draw their compartmentalised structure.
A mitochondrion (pleural = mitochondria) has an outer membrane and inner membrane folded into long thing 'flaps' called cristae.


This electron microscope image shows a group of prokaryotes.

What structures are most likely to be found inside these cells?

Skill: you should know how to draw prokaryotic cells (with a cell wall, plasma membrane, cytoplasm, pili, flagella, 70s ribosomes and nucleoid.) and eukaryotic cells (free 80s ribosomes, rough endoplasmic reticulum (rER), lysosome, Golgi apparatus, mitochondrion and nucleus)


The 'Cell theory' explains the nature of living things.
Which statement best describes Cell theory?

According to cell theory, living organisms are composed of cells.
Cells come from pre-existing cells and cells are the smallest using of life.


What is the importance of surface area to volume ratio to cells?

Surface area to volume ratio is important in the limitation of cell size. The lager the volume, the greater the need for materials which have to be exchanged over the surface of the cell.


The image below shows erythrocytes and leucocytes.l.

Using the scale bar and the ruler placed on the image, estimate the magnification of the image.
Which answer is the best estimate

Calculate the magnification of an electron microscope image from a scale bar?

Convert the ruler measurement to the same units written on the scale bar, in this case 25mm is 25000µm

then divide the ruler measurement 25000 by the number on the scalebar, 25.


The diagram shows the transport of sodium ions across a membrane.

Which explanation gives the best description of the type of membrane transport shown?.

Facilitated diffusion does not require energy from ATP so this process is active transport. It can move sodium ions against the concentration gradient, but this is not always the case.


Which label in the image below shows the process of endocytosis?

Endocytosis is the process where a substance is surrounded by the plasma membrane which forms a vesicle inside the cell that then moves into the cytoplasm, separating from the plasma membrane.


The image below shows a eukaryotic cell.

Which structure, visible in the image, could be used as evidence supporting endosymbiosis?

The mitochondria provide evidence supporting endosymbiosis because they have:

  • a double membrane
  • 70S ribosomes
  • DNA

Human red blood cells are circular and 0.6 μm in diameter. A photograph of a red blood cell is shown as an illustration in a book with a diameter of 1.2mm. What is the magnification of the diagram?

Comment: Convert 1.2 mm into μm by multiplying x 1000 = 1200 μm (so that both units are the same). Then you can see that 0.6 x 2000 = 1200. Or use the formula Magnification = Image size/true size. If the photograph is larger than the cell, the magnification could not be 0.5x which would make it smaller. Eliminate obviously incorrect answers.


The image shows a cross section of trachea epithelium tissue. What is the best definition of a tissue?

A tissue may have one cell type or several and may have one or more functions. Tracheal epithelium has goblet cells to secrete mucus and columnar epithelial cells with cilia to remove contaminants and pathogens from the air and sweep them away from the lungs.


Why is a fungal hypha an exception to the cell theory?

A fungal hypha has many nuclei in a hypha but no cross walls to divide the hypha into cells.


Which organelle is visible in an electron microscope but not in a light microscope?

The ribosome is too small to be seen in the electron microscope, the other organelles were seen in the light microscope before the electron microscope was invented.


Which organelles are found in large numbers in secretory cells in animals? I Vesicles II Golgi Body III Mitochondria IV Rough endoplasmic reticulum.

Secretory cells synthesise proteins for exocytosis so have large numbers of mitochondria to supply energy, RER to synthesise the proteins for packaging into vesicles by the Golgi Body.


Which process is involved in white blood cells engulfing bacteria (arrowed in the photomicrograph)?

White blood cells engulf bacteria by endocytosis, the intake of solid particles by a cell membrane.


Louis Pasteur used sterile broth and swan necked flasks to disprove which theory?

Pasteur demonstrated that broth would go cloudy only when air was allowed to contact the broth, bringing microbes. He disproved Spontaneous Generation.


Which organelles in a plant cell are believed to have originated as free-living prokaryotic cells?

Both the mitochondria and the chloroplast in plant cells are thought to have been free-living prokaryotes which evolved in a symbiotic relationship with a eukaryotic cell.


Which component of the plasma membrane varies in function between differentiated cells?

The protein component of the membrane varies in structure and function.

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