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.
Huntington's Disease (HD) is a brain disorder that affects a person's ability to talk, and move. HD is caused by a faulty protein. The job of the protein is to direct vesicles containing important molecules to the outside of the cell. The chemicals are released when the vesicle reaches the membrane.
What is the name given to the release of chemicals by a cell in this way?
This is a type of secretion, the vesicle fuses with the plasma membrane and its contents are released. This is called "exocytosis".
Cells today come from pre-existing cells. The origin of the fist cell must be different.
Where do biologists think the first cell came from?
The first cell must have come from non-living material. This material must have contained molecules which today we consider as organic, carbon containing molecules.
What is the best definition of endosymbiosis?
Endosymbiosis is where a cell engulfs another cell and it continues to live inside the cell.
The engulfed cell provides something for the host cell, and gets something in return. Both cells benefit.
The image below was taken in 1825 and shows part of the cell cycle.
What type of cells is this and at which stage of the cell cycle?
Cytokinesis occurs after mitosis in plant and animal cells. The chromosomes are uncoiled.
Plant cells build a new cell wall which divides the cytoplasm.
Animal cells form a cleavage furrow (likes a wasps waist) as they don't have cell walls.
The image below shows two cells undergoing mitosis.
Which of the following correctly identifies the stage of mitosis for each of the cells?
Identification of the phase of mitosis is an important skill.
The position of the chromosomes gives the best clue.
In Prophase, they are spread around the cell, and double stranded.
In Metaphase, the chromosomes are lined up on the spindle equator.
In Anaphase, the chromosomes are moving to opposite poles of the cell.
In Telophase, the two groups of chromosomes are separate, sometimes with a nuclear membrane.
Which property of phospholipid molecules describes the fact that they have both hydrophobic and hydrophilic parts?
Phospholipids form bilayers in water due to the amphipathic properties of phospholipid molecules. The hydrophobic tails attract each other and the hydrophilic phosphates are attracted to the water.
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.
The electron microscope image below shows an organelle found in both animal and plant cells.
What is the name of the organelle?
Know how to idenfity the organelles in eukaryotes and draw their compartmentalised structure.
The rER has parallel membranes covered in dots, which are ribosomes, used for making proteins, for secretion from the cell.
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.
Cell theory covers most, but not all cases.
Which one of these statements is an exception?
Exceptions to cell theory are : multinucleated striated muscle the giant single celled Acetabularia algae?
Also, organisms consisting of only one cell carry out all functions of life in that cell. e.g. Paramecium, Chlorella.
When nerve cells form brain tissue they can; store memories, create thoughts and coordinate movement.
If you only ever studied individual nerve cells you would never see these abilities which the brain has.
What is this type of property called?
Multicellular organisms have properties that emerge from the interaction of their cellular components. (Emergent properties)
Stargardts disease is vision loss caused by the death of both cone cells and rod cells in the part of the retina around the fovea. One potential treatment for Stargardts disease is the use of human embryonic stem cells.
What are the properties of these stem cells, which other cells don't have, that makes them so useful for this treatment?
Stem cells can divide and this help researchers to grow them in the lab.
They can differentiate along different pathways in embryonic development which makes stem cells useful for therapeutic uses (e.g. Stargart's disease) because they can be grown into many different tissues.
The electron microscope image below shows a scale bar marked with 100µm.
The large 'goblet cell' in the centre is producing mucous which will protect the surface of the epithelium.
What is the diameter of the goblet cell?
Accurately, measure the scale bar length in mm, measure the diameter of the cell, in mm
divide cell diameter by scalebar and multiply by 100µm.
You can often estimate the size using the scale bar and your thumb or a pen.
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 blood cells below were imaged using an electron microscope.
The magnification is x3000 and the ruler measures the central cell as being 2 cm in diameter.
Estimate the actual size of this white blood cell.
Calculate specimen size using magnification?
First change the size measurement into µm units = 20000µm
Then divide by the magnification. 20000 / 3000 = 20 / 3 = 6.6 µm
The 64 codons in the genetic code give rise to the same amino acids in nearly all organisms.
There is very little variation. This is evidence for a single common origin of life.
Differences in the frequency of amino acid use reflects the different genes in the two organisms.
Which means of transport across a plasma membrane requires the molecule shown in the picture?
Which is the best description of the genetic code?
The genetic code is universal (the codons code for the same amino acid in all organisms) but there are a very few exceptions, mostly in Archaea. A mutation does not alter the genetic code, it alters the base sequence of DNA.
What is the name of the process by which a white blood cell can engulf a pathogenic bacterium?
Endocytosis ("into the cell") is the process by which cells can engulf particles.
How do integral proteins remain within the phospholipid bilayer?
Integral proteins have a hydrophobic centre that associates with the fatty acid inner layer of the bilayer and a hydrophilic head that associates with the phospholipid heads.
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