BIOL 2070 - LECTURE 11 EXAM QUESTIONS AND ANSWERS
WITH COMPLETE SOLUTIONS VERIFIED
FITB: Multicellular organisms are built from organized collections of ____.
Cells
FITB: Cells are organized into _____ which are then assembled into organs.
tissues
How are the organized assembly of cells within mammalian intestinal tissue held
together?
Cell-cell adhesions and the extracellular matrix
True or False: Plant cells have weak external walls
False. They have tough external walls that strengthen the cells.
Name two common plant cell wall polysaccharides.
Cellulose and pectin
Where would you predominately find pectin in plant cells?
Outer layers of cells which have only primary cell walls
Where would you find an abundant amount of cellulose in plant cells?
inner layers with thicker, more rigid secondary cell walls
What provides plant cell walls tensile strength?
Cellulose microfibrils
What is a cellulose microfibril composed of?
,A bundle of unbranched chains of glucose where each glucose subunit is inverted with
respect to its neigbours and joined to them via a beta 1,4-linkage
True or False: In cellulose molecules, there are hundreds of disaccharide repeats
True
How many cellulose molecules are held together in a single cellulose microfibril
and how does this occur?
16 cellulose molecules held together via hydrogen bonds
While other polysaccharides cross-link cellulose microfibrils, what is pectin
doing?
Providing resistance to compression by filling space between microfibrils
FITB: The middle lamella is rich in ____ and is the layer that cements one cell wall
to another.
Pectin
True or False: The size of cellulose microfibrils affects the direction in which the
cell elongates.
False. It is the orientation
True or False: Cells start with identical shapes and identical orientations of
cellulose microfibrils in their walls.
False. They have different orientations
FITB: _____ pressure is uniform in all directions
Turgor
What determines the direction in which cells elongate in relation to the
orientation of microfibrils?
, Each cell tends to elongate in a direction perpendicular to the orientation of the
microfibrils and is determined by the direction in which its cells expand
True or False: Microtubules help direct the deposition of cellulose in the plant cell
wall.
True
How is the orientation of extracellular cellulose microfibrils determined?
The orientation of underlying intracellular microtubules
Why are cellulose synthase enzyme complexes important membrane proteins?
They continuously synthesize cellulose microfibrils on the outer face of the plasma
membrane
How does elongation affect the cellulose synthase enzyme complex?
It pushes the synthase complex along in the plane of the plasma membrane
Correct this statement: Animal connective tissues consist largely of an
intracellular matrix.
Animal connective tissues consist largely of an extracellular matrix.
What provides tensile strength in animal connective tissues?
Collagen
What are the stages of collagen assembly?
Individual polypeptide chains --> Triple-Stranded collagen molecules --> fibrils --> fibres
FITB: Fibrils are bundled into ____
Fibres
True or False: Fibres ONLY run in the plane of the section
False. They can also run approximately at right angle to the section
WITH COMPLETE SOLUTIONS VERIFIED
FITB: Multicellular organisms are built from organized collections of ____.
Cells
FITB: Cells are organized into _____ which are then assembled into organs.
tissues
How are the organized assembly of cells within mammalian intestinal tissue held
together?
Cell-cell adhesions and the extracellular matrix
True or False: Plant cells have weak external walls
False. They have tough external walls that strengthen the cells.
Name two common plant cell wall polysaccharides.
Cellulose and pectin
Where would you predominately find pectin in plant cells?
Outer layers of cells which have only primary cell walls
Where would you find an abundant amount of cellulose in plant cells?
inner layers with thicker, more rigid secondary cell walls
What provides plant cell walls tensile strength?
Cellulose microfibrils
What is a cellulose microfibril composed of?
,A bundle of unbranched chains of glucose where each glucose subunit is inverted with
respect to its neigbours and joined to them via a beta 1,4-linkage
True or False: In cellulose molecules, there are hundreds of disaccharide repeats
True
How many cellulose molecules are held together in a single cellulose microfibril
and how does this occur?
16 cellulose molecules held together via hydrogen bonds
While other polysaccharides cross-link cellulose microfibrils, what is pectin
doing?
Providing resistance to compression by filling space between microfibrils
FITB: The middle lamella is rich in ____ and is the layer that cements one cell wall
to another.
Pectin
True or False: The size of cellulose microfibrils affects the direction in which the
cell elongates.
False. It is the orientation
True or False: Cells start with identical shapes and identical orientations of
cellulose microfibrils in their walls.
False. They have different orientations
FITB: _____ pressure is uniform in all directions
Turgor
What determines the direction in which cells elongate in relation to the
orientation of microfibrils?
, Each cell tends to elongate in a direction perpendicular to the orientation of the
microfibrils and is determined by the direction in which its cells expand
True or False: Microtubules help direct the deposition of cellulose in the plant cell
wall.
True
How is the orientation of extracellular cellulose microfibrils determined?
The orientation of underlying intracellular microtubules
Why are cellulose synthase enzyme complexes important membrane proteins?
They continuously synthesize cellulose microfibrils on the outer face of the plasma
membrane
How does elongation affect the cellulose synthase enzyme complex?
It pushes the synthase complex along in the plane of the plasma membrane
Correct this statement: Animal connective tissues consist largely of an
intracellular matrix.
Animal connective tissues consist largely of an extracellular matrix.
What provides tensile strength in animal connective tissues?
Collagen
What are the stages of collagen assembly?
Individual polypeptide chains --> Triple-Stranded collagen molecules --> fibrils --> fibres
FITB: Fibrils are bundled into ____
Fibres
True or False: Fibres ONLY run in the plane of the section
False. They can also run approximately at right angle to the section
