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 64 codons of mRNA code for the same amino acids in almost all species. A rare exception is found in Paramecium where one of the "stop codons" actually codes for the amino acid glutamine.
What does this suggest about the origin of cells?
The 64 codons in the genetic code give rise to the same amino acids in nearly all organisms, There is very little variation. If the genetic code had evolved several times in the history off life, there would be many differences.
The 64 codons in the genetic code give rise to the same amino acids in nearly all organisms.
There is very little variaion. 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.
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. If the solution was hypertonic, the tissue would lose water (and gain ions).
The electron microscope image below shows an organelle found in eukaryotic plant cells.
What is the name of the organelles?
A mitochondrion (pleural = mitochondria) has an outer membrane and inner membrane folded into cristae. They are present in all eukaryotic cells.
How does compartmentalisation by their internal membranes benefit eukaryotic cells?
Eukaryote cells (approx. 100µm in diameter) are much larger than prokaryote cells (approx 1µm) and so the concentration of reactants in the cytoplasm would be more dilute if all the metabolism happened in the cytoplasm.
Specialist organelles, like mitochondria keep the enzymes for aerobic respiration in one place, which increases their concentration, and increases the rate of reactions.
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
Convert the ruler measurement to the same units written on the scale bar, in this case 25mm is 25000µm
Divide the ruler measurement of image size 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 white cell (with a nucleus) as being 2 cm in diameter.
Estimate the actual size of this white blood cell.
First change the size measurement into µm = 20000µm
Then divide the image size by the magnification. 20000 / 3000 = 20 / 3 = 6.6 µm
Explain the significance of the following terms in Biology; Metabolism, response, growth, reproduction, excretion, nutrition, homeostasis.
Remember MR H GREN. These letters represent the seven characteristics of living things.
Cells are often stored in isotonic conditions because they can be damaged in other concentrations, hypertonic, or hypotonic. Which of the descriptions of hypertonic is the most accurate?
Hypertonic solutions have a higher concentration of solutes, and lower water potentials than cells.
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 of the following could be used to distinguish a living from a non- living object
Comment: Inanimate objects can move, produce and utilise energy but the process of respiration is exclusive to living systems
Human red blood cells are circular and 0.6 μm in diameter. A photograph of red blood cells is shown as an illustration in a book. They have a mean diameter of 1.2mm in the image. 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 blood, a mixed 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. Blood has red cells and a variety of white cells with specific functions.
The image shows a transverse section of a plant cell seen using an electron microscope.
What is the main function of the large organelle (A) seen in the cell?
The organelle shown is the nucleus, it stores the genetic information, DNA and is the location of DNA replication and Transcription.
The diagram is of a plasma membrane. Which label corresponds to a protein channel?
Protein channels cross the membrane to allow hydrophilic substances to pass through the membrane.
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.
Which of the following are believed to be endosymbiotic structures involved in cell locomotion in both prokaryotes and eukaryotes?
Flagellae are locomotory structures found in some Monera (bacteria), and some eukaryotic cells such as male gametes and Protoctista. Mitochondria are not found in prokaryotes. Pseudopodia are involved in locomotion but only in cells without an external wall. Fimbriae in bacteria allow for binding to a host or substrate, the same name is given to projections in the oviduct that aid movement of the ovum towards the uterus.
The theory of spontaneous generation has been disproved by Pasteur's experiment. Is there a point in evolution when spontaneous generation did occur?
The first cells must have arisen spontaneously from non-living matter, probably in volcanic vents, but the universal nature of cell ultrastructure and of the genetic code makes it likely that this only happened once.
A tissue is placed in an isotonic bathing solution. Which of the following is the best description of water movement between the tissue and the bathing solution?
There is no net water movement, gain and loss from the tissue is equal in both directions.
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