Download BIOL1020 Semester 2, 2014 Deep Thought Questions

BIOL1020 Semester 2, 2014 Deep Thought Questions
The following pages list deep thought questions given by the course which require
‘beyond the surface level’ of thinking and really makes you think of the relationships
between different concepts at a deeper level. They are sorted into groups corresponding
to mini-tests. Some questions change each year so these questions may not necessarily
help you answer your deep thought questions specifically, but take note of how I
construct my answers, to get the most marks possible.
I have written a guide on the next page and included some tips to make the process
easier which would be a great help to you if you need it.
Note: These can apply to answer short answer/ essay style questions, not just these
deep thought questions for BIOL1020. These will set you up for higher-level
assessments.
I hope these would be of some help to you and good luck with your assessments. :D
Tiffany Lim’s BIOL1020 Deep Thought Questions
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BIOL1020_ Deep Thought Questions For Minitest 1Preparation (Week 1-4)
Note: The answer I have provided is just one of the many accepted answers. There are
several perspectives and points you can provide which will be accepted as well. Piazza
would also be very helpful for your study as many students contribute their ideas.
1. What are the common features of a tree and a dog, and how does the existence of these
features support the ideas of both evolution and a universal common ancestor?
ANSWER:
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Both dog + tree = eukaryotic organisms
Dog made up of animal cells, tree made up of plant cells.
Both types of cells have a plasma membrane, cytoplasm and organelles that have similar functions
and structure e.g. nucleus, mitochondria and ribosomes.
Both types of cells are similar in size and complexity.
Both cells’ genetic material are composed of DNA made up of four nucleotides, with the genetic
code comprising of three-nucleotide codons. Proteins are produced in these cells from the
expression of these genetic codes.
Cells found in both organisms multiply by cellular division.
Due to the existence of the similarities between a dog and tree, it is possible that these two
organisms descended from a universal common ancestor and evolved over time to adapt to
changes in the environment.
ANSWERS FROM ANOTHER PERSPECTIVE
DOTPOINT STYLE ANSWER:
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Dog = animal cells - contain mitochondria which creates the energy for dog to survive.
Plants = plant cells - contain chloroplasts which convert light energy into chemical energy for
plant to survive.
Both these organelles contain their own DNA.
Primitive prokaryotes have similar appearances to and are able to conduct cellular respiration
and photosynthesis respectively, much like the modern organelles.
This suggests the idea of common ancestor and evolution, as primitive eukaryotic cells couldn’t
produce own energy, therefore swallowed bacteria which could do so incorporated the bacteria
into their cells  over time evolved to contain these bacterial components in their structure.
ESSAY STYLE ANSWER:
The animal cells of a dog contain mitochondria, the organelle creates the energy needed to conduct the
processes for the dog to survive. Similarly in plant cells, the plant cells contain chloroplasts which convert
light energy into chemical energy needed for the plant to survive. Both these organelles contain their own
DNA. These two organelles support the idea of a universal common ancestor as primitive prokaryotes also
appear very similar in not only the appearance (they look like mitochondria and chloroplasts), but also
function, as they are able to conduct cellular respiration and photosynthesis respectively, much like the
modern organelles. This also suggests the idea of evolution, as primitive eukaryotic cells which were
unable to conduct cellular respiration by themselves, swallowed bacteria which could do so and though
symbiosis incorporated the bacteria into their cells and over time, evolved to contain these bacterial
components in their structure.
Tiffany Lim’s BIOL1020 Deep Thought Questions
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BIOL1020_ Deep Thought Questions For Minitest 2Preparation (Week 5-7)
1. Use your knowledge about the structure of microtubules to explain how these cytoskeleton
elements can be used to ‘pull’ the chromatids to the cell poles during cell division.
Use the following terms in your answer: filamentous structures, assembly, disassembly, dynamic and
shortening.
ANSWER: During prophase, the centrosome divides and assembles with the microtubules to form a
functional filamentous stricture called the mitotic spindle. This mitotic spindle stretches to the cell poles
during prophase. During prometaphase, some microtubules attach chromosomes at the kinetochores, while
others continue to stretch. This structure allows the dynamic ability of the microtubules to combine both
the push and pull mechanisms to work together to pull the chromatids to the cell poles during cell division.
The microtubules which attached the chromosomes, disassemble the sister chromatids by shortening its
microtubule length, while simultaneously, the microtubules which did not attach the chromosomes ensure
there’s enough distance by pushing the centrosomes away for efficient cell division.
2. Cyclins are proteins that control the cell cycle through binding to Cdks (cyclin-dependent kinases)
to form Maturation Promoting Factor (MPF). Draw a diagram showing the changes of cyclin
concentrations, Cdk concentrations and MPF concentrations during the different phases of the cell
cycle. Speculate on possible reasons why the formation of MPF does not fully coincide with the
production of cyclin.
Use the following terms in your explanation: ‘concentration-dependent binding’, free cyclin, Cdk-cyclin
complex, free Cdk concentrations and MPF concentrations.
ANSWER:
Cdk concentration
The formation of MPF doesn’t fully coincide with the production of cyclin because free cyclin and free cdk
concentrations must reach a high enough threshold to allow the concentration-dependent binding to
occur. Cdk concentrations remain constant throughout the cell cycle, while cyclin concentrations start
increasing in the S phase. Once it gets to G2 phase there is sufficient cyclin molecules to bind to cdk,
forming the cdk-cyclin complex (MPF). Only then do MPF concentrations increase. Hence, there is a lag
between the formation of MPF and production of cyclin.
Tiffany Lim’s BIOL1020 Deep Thought Questions
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Tiffany Lim’s BIOL1020 Deep Thought Questions
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