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 variaion. If the genetic code had evolved several times in the history off life, there would be many differences.
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.
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
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).
The four cells shown below have each been surrounded by a solution for 1 hour.
Which cells have been in a hypertonic solution ?
Cell A is swollen turgid, it is in a hypotonic solution or an isotonic solution.
The cells B, C and D show increasing signs of plasmolysis, and so they must be in hypertonic solutions.
Skill: Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions. (Practical 2)
Which of the following is true of peripheral proteins in cell membranes?
Membrane proteins are diverse in terms of structure, position in the membrane and function.
Peripheral proteins are attached to the membrane but found on its surface.
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.
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)
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.
The image below is of Dracaena leaf upper epidermis cells.
Which of the following is the best estimate of the length (from top to bottom) of an epidermal cell?
Comment: The cells are approximately the same size as the scale bar.
This would make 70µm the closest estimate.
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.
What is the sequence of events that occur in a cell that is secreting a protein hormone?
1 Exocytosis
2 Vesicle formed by Golgi Body
3 Fusion of vesicle to plasma membrane
4 RER manufactures protein.
Ribosomes on the RER manufacture protein. This is packaged in vesicles by the Golgi Body and moves to the surface of the cell where the vesicle and plasma membrane fuse and exocytosis of the protein occurs.
What is the structure of the genetic material found in a mitochondrion?
Mitochondrial DNA is a single helical molecule, not associated with protein and circular in shape. The same as prokaryote nucleoid DNA.
Which property of stem cells is important for embryonic development?
Stem cells can divide and differentiate along different pathways. For a single fertilised egg cell to grow into an embryo both these processes are necessary.
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.
In which ways is a plasma membrane fluid?
I The shape is flexible
II Proteins can move in and out of the membrane
III Proteins can move within the membrane
IV It can reseal a small puncture.
The membrane can reseal if slightly damaged and the shape is flexible. Proteins cannot move in and out of the membrane but can move within the membrane.
Why is the cell component in the image regarded as an organelle?
The organelle is a cell component with a membane, the mitochondrion, it is adapted to aerobic respiration.
There are twenty complete cells in this microphotograph (with complete nuclear material). Estimate the number of complete cells in prophase of mitosis.
There are 3 complete cells in prophase (chromosomes visible in a nucleus..
The image below was taken in 1825 and shows part of the cell cycle.
What is shown in the image?
Cytokinesis occurs after mitosis in plant and animal cells.
Animal cells form a cleavage furrow (looks like a wasps waist) as they don't have cell walls.
The two daughter cells are the same size, so cytokinesis is equal.
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