Cell structure - KERBOODLE (practice questions) Flashcards
The cytoskeleton is present throughout the cytoplasm of all eukaryotic cells.
Which of the following statements is/are correct with respect to the structure of the cytoskeleton?
Statement 1: Intermediate fibres - these fibres give mechanical strength to cells and help maintain their integrity.
Statement 2: Microtubules - contractile fibres formed from the proteins actin. Responsible for cell movement.
Statement 3: Microfilaments - formed from the cylindrical-shaped protein tubulin. They form a scaffold-like structure determining the shape of a cell.
A) 1,2 and 3 are correct
B) Only 1 and 2 are correct
C) Only 2 and 3 correct
D) Only 1 is correct
D
Serous cells are present in the salivary glands of animals. They are responsible for the production of the enzyme amylase which begins the breakdown of starch.
Identify the structures labelled in the diagram
X?
Y?
Z?
- X = endoplasmic reticulum or ribosome
- Y = golgi apparatus/body
- Z = vesicle
Serous cells are present in the salivary glands of animals. They are responsible for the production of the enzyme amylase which begins the breakdown of starch.
State whether the cell is eukaryotic or prokaryotic giving the reason for your decision.
- eukaryotic cell
- presence of membrane bound organelles
- name examples of membrane bound organelles
Serous cells are present in the salivary glands of animals. They are responsible for the production of the enzyme amylase which begins the breakdown of starch.
State which groups of enzymes contain amylase.
- carbohydrases or hydrolytic enzymes
Serous cells are present in the salivary glands of animals. They are responsible for the production of the enzyme amylase which begins the breakdown of starch.
Outline the stages and organelles involved in the production and release of amylase.
- nucleus
- production of mRNA or transcription
- ribosome
- protein synthesis or translation
- golgi apparatus
- protein modification
- vesicle
- transported to cell surface membrane
- describe exocytosis
Serous cells are present in the salivary glands of animals. They are responsible for the production of the enzyme amylase which begins the breakdown of starch.
Explain the process of exocytosis.
- vesicle (containing protein)
- fuses with cell surface membrane
- requiring energy from hydrolysis of ATP
- protein released from cell
Serous cells are present in the salivary glands of animals. They are responsible for the production of the enzyme amylase which begins the breakdown of starch.
Discuss the different roles of vesicles, vacuoles and lysosomes.
- vesicles have role in transport and secretion
- vacuoles have role in storage
- vacuoles contain mostly water
- vacuoles are larger than vesicles and lysosomes
- lysosomes have role in digestion
- lysosomes contain hydrolytic enzymes
The photo below shows a transmission electron micrograph of plankton. These single-celled marine micro-organisms are thought to be the most abundant photosynthetic organisms on Earth.
calculate the magnification of the Plankton labelled X. The actual diameter of the plankton is 2.6µm.
length of X = 15mm
- 15mm = 15 000µm
- 15 000/2.6
- Magnification = x5769
The amount of detail that can be seen with a microscope depends on both the magnification and resolution possible with the microscope being used. Any increase in magnification beyond the limit of resolution results in ‘empty magnification’.
Define resolution.
- ability to see two adjacent points as separate points
- higher resolution means more detail can be seen
The amount of detail that can be seen with a microscope depends on both the magnification and resolution possible with the microscope being used. Any increase in magnification beyond the limit of resolution results in ‘empty magnification’.
Define magnification
- degree by which the size of an image is larger than the size of the actual object
The amount of detail that can be seen with a microscope depends on both the magnification and resolution possible with the microscope being used. Any increase in magnification beyond the limit of resolution results in ‘empty magnification’.
Suggest what is meant by the term ‘empty magnification’
- magnification is increased without increase in resolution so no more detail is visible
Outline how a compound light microscope magnifies an image of a specimen
- objective lens
- magnifies image of object
- eyepiece lens
- magnifies image again
Describe three different ways of preparing microscope slides for light microscopy.
- dry mount
- sample sectioned
- cover slip placed over sample
- wet mount
- sample suspended in liquid
- cover slip placed on at an angle
- squash slide
- wet mount is pressed
- smear slide
- liquid sample is smeared to produce thin coating
Explain the meaning of the term artefact with reference to microscopy
- object visible in field of view
- produced during preparation of sample
- e.g. air bubble
Discuss the advantages and disadvantages of using an electron microscope to study the ultrastructure of cells.
- advantages:
- greater magnification
- greater resolution
- disadvantages
- sample must be dead
- expensive to set up
- expensive sample preparation
- large
- many artefacts
- technical skills required
- black and white images
Complete the table below.
The first row has been done for you.
- present
- membrane bound and non-membrane bound
- cellulose or chitin if present
- small, 70s
- present
