Cell Structure Exam Questions Flashcards
(22 cards)
Name the structures labelled W to Z in the diagram.
cell surface membrane
cell wall
capusle
flagellum
what is inside of the cell surface membrane
phospholipids
what is inside of the cell wall
murein, glycoproteins
Some prokaryotic cells can divide every 30 minutes. A liquid culture contained a starting
population of 1.35 × 104 cells.
Assuming each cell divides every 30 minutes, calculate how many cells there will be after 3
hours. Assume no cells die during this time.
8.64 × 10 to the power of 5
Name two structures present in plant cells that are not present in animal cells.
chloroplast
cell wall
Explain why the solution the biologist used was ice-cold, buffered and the same water
potential as the liver tissue (step 1).
ice cold to prevent enzyme activity preventing damage to organelles
buffered to reduce the pH so proteins dont denature
same water potential - to prevent osmosis and lysis from the cell bursting
Explain why the biologist used a blender and then filtered the mixture (steps 2 and 3)
to homegenise break down the cell to filter out any large debris
Name the organelle that made up most of the first pellet after centrifuging at a low speed
nuclei
The second centrifuge tube was spun at a higher speed to obtain the sample of organelles
labelled C in the diagram (step 5).
to obtain mitochrondria which is more dense than the nucleus
Outline the role of organelles in the production, transport and release of proteins from
eukaryotic cells.
Golgi Appartus
they add carbohydrates to proteins to make glycoproteins
they form lysosomes
Ribosomes /RER
Protein synthesis
Mitochrondia
Site of aerobic respiration
produce ATP for protein synthesis
DNA in nucleus codes for protein
Suggest why a nucleus is not visible in above image.
Nucleus is not stained
name organelle S and T
S - vacuole
T - chloroplast
Give one advantage of viewing a biological specimen using a transmission electron
microscope compared with using a scanning electron microscope.
Higher resolution to view internal structures
The cells in the diagram below are part of a continuous layer of cells forming the upper
surface of a leaf.
The shaded area of cell U is 150 µm2
The total area of the upper surface of the leaf is 70.65 cm2
Calculate the number of cells in the upper surface
4.71 x 10 to the power of 7
Describe how you could make a temporary mount of a piece of plant tissue to observe the
position of starch grains in the cells when using an optical (light) microscope
add a drop of water to the slide
obtain a thin layer of the cells and place on the slide
stain the cells with iodine
use a cover slip and push to prevent any bubbles from forming
with the mounting needle lower the cover slip
A transmission electron microscope was used to produce the image in the figure above.
Explain why.
it has a high resolution so it can see the internal structure of organelles
This photograph was taken using a transmission electron microscope. The structure of the
organelles visible in the photograph could not have been seen using an optical(light)
microscope. Explain why.
optical microscope has a low resolution because it has a low wavelength of light its too weak /short
The ground liver was centrifuged at low speed. The pellet that formed at the bottom of
the centrifuge tube was thrown away and the supernatant centrifuged again at higher
speed. Explain why it was necessary to first centrifuge the ground liver at low speed
in order to obtain a suspension of organelle D.
TO REMOVE Nuclei which is more dense at the bottom
Explain the link between.
mitochondria and muscle cells (lines 6 - 7);
in relation due to muscle contraction
mitochrondia is the site of aerobic respiration and it produces ATP which releases energy for muscle contraction
rough endoplasmic reticulum and enzyme-secreting cells from salivary glands
(lines 7 - 8).
enzymes are proteins
produces protein / protein synthesis
Use information in the passage to explain how a tadpole’s tail is absorbed as a tadpole
changes into a frog. (LYSOSOMES)
LYSOSOMES BREAK DOWN/DIGEST CELLS
THEY CONTAIN ENZYMES
Starting with some lettuce leaves, describe how you would obtain a sample of undamaged
chloroplasts. Use your knowledge of cell fractionation and ultracentrifugation to answer this
question.
homogenise / break down the food
place in ice cold, isotonic, buffered solution
ice cold to prevent enzyme activity and to prevent damage to organelles
isotonic to prevent osmosis and the cell from bursting / swelling
buffered to maintain pH level and to prevent protein from denaturing
centrifuge at low speed to filter out and to remove debris
the first pellet will form nuclei at the bottom
then spin centrifuge at higher speed and mitochrondria, chloroplast will be obtained
remove any supertanant
