A level Biology OCR Exam Questions AND Correct Answers
Antibodies are made by plasma cells. Explain how plasma cells
are specialised for their role - ✔✔Plasma cells have a lot of
ribosomes, rough endoplasmic reticulum, Golgi apparatus and
mitochondria.
As more solute is added to a solution, what happens to the
solute potential and hence the water potential? - ✔✔Solute
potential decreases, hence water potential decreases
Briefly outline the events of atrial systole - ✔✔Left and right
atria contract together; blood is squeezed from the atria
through the atrioventricular valves into the ventricles, down a
pressure gradient.
Briefly outline the events of diastole - ✔✔Once ventricular
contraction is complete, heart muscle starts to relax, heart
starts to fill with blood again and semilunar valves close
Briefly outline the events of ventricular systole -
✔✔Ventricular blood pressure rises very quickly to a level
above the arteries; semilunar valves open and blood rushes
out of ventricles into the arteries
,Cacti are succulents. What does this mean? - ✔✔They store
water in their stems which become fleshy and swollen
Channel proteins and carrier proteins have what main role
within the membrane? - ✔✔Transport
Define and describe exocytosis - ✔✔The bulk transport of
particles too large to pass through the membrane, out of the
cell. It works like a reversal of pinocytosis. A vesicle containing
the substance fuses with the plasma membrane. The fused
site opens, releasing the contents of the secretory vesicle.
Define and describe phagocytosis - ✔✔The intake of solid
particles into the cell by engulfing. Pseudopodia surround the
particles, the membrane fuses together, to form a vesicle.
Define and describe pinocytosis - ✔✔The intake of liquids into
the cell by engulfing. The plasma membrane invaginates, and
the membrane fuses around the substance, forming a vesicle.
Define bulk transport and give two examples - ✔✔The
movement of large molecules that are too big to pass across
,the plasma membrane. Endocytosis (phagocytosis or
pinocytosis) brings large molecules INTO the cell, enclosed in a
vesicle. Exocytosis transports large molecules OUT of cells.
Define the term active transport - ✔✔Movement of
molecules, against their concentration gradient (using energy
liberated from ATP hydrolysis) using specific protein channels
or carriers
Define the term diffusion. - ✔✔The net movement of a
substance from an area of high concentration to an area of
low concentration. It is passive, does NOT require ATP.
Define the term epidemic - ✔✔A rapid spread of disease
through a high proportion of a population (usually within a
country)
Define the term facilitated diffusion - ✔✔Movement of
molecules from a high concentration to a low concentration,
across a partially permeable membrane, via specific channel
or carrier proteins. It is passive, does NOT require ATP
, Define the term osmosis - ✔✔The movement of water
molecules from a region of higher water potential to a region
of lower water potential, across a partially permeable
membrane
Define the term tissue - ✔✔A group of cells working together
to perform a particular function
Define the term translocation - ✔✔Transport of assimilates
from source to sink (tissue that needs them)
Describe 2 major pathways taken by water to move between
cells - ✔✔Apoplast - through spaces in cell walls and between
cells (mass flow...not osmosis); symplast - moves through
cytoplasm and between cells via plasmodesmata
Describe 3 adaptations of marram grass (xerophyte) and
explain their importance - ✔✔Leaf rolled longitudinally
trapping air inside (air becomes humid and reduces water loss
from the leaf); thick waxy cuticle on upper epidermis (reduces
evaporation); stomata on lower epidermis inside rolled leaf
(protected by enclosed air space); stomata are in pits in lower
epidermis which is folded and covered by hairs (reduces air
movement and hence water loss); spongy mesophyll very
Antibodies are made by plasma cells. Explain how plasma cells
are specialised for their role - ✔✔Plasma cells have a lot of
ribosomes, rough endoplasmic reticulum, Golgi apparatus and
mitochondria.
As more solute is added to a solution, what happens to the
solute potential and hence the water potential? - ✔✔Solute
potential decreases, hence water potential decreases
Briefly outline the events of atrial systole - ✔✔Left and right
atria contract together; blood is squeezed from the atria
through the atrioventricular valves into the ventricles, down a
pressure gradient.
Briefly outline the events of diastole - ✔✔Once ventricular
contraction is complete, heart muscle starts to relax, heart
starts to fill with blood again and semilunar valves close
Briefly outline the events of ventricular systole -
✔✔Ventricular blood pressure rises very quickly to a level
above the arteries; semilunar valves open and blood rushes
out of ventricles into the arteries
,Cacti are succulents. What does this mean? - ✔✔They store
water in their stems which become fleshy and swollen
Channel proteins and carrier proteins have what main role
within the membrane? - ✔✔Transport
Define and describe exocytosis - ✔✔The bulk transport of
particles too large to pass through the membrane, out of the
cell. It works like a reversal of pinocytosis. A vesicle containing
the substance fuses with the plasma membrane. The fused
site opens, releasing the contents of the secretory vesicle.
Define and describe phagocytosis - ✔✔The intake of solid
particles into the cell by engulfing. Pseudopodia surround the
particles, the membrane fuses together, to form a vesicle.
Define and describe pinocytosis - ✔✔The intake of liquids into
the cell by engulfing. The plasma membrane invaginates, and
the membrane fuses around the substance, forming a vesicle.
Define bulk transport and give two examples - ✔✔The
movement of large molecules that are too big to pass across
,the plasma membrane. Endocytosis (phagocytosis or
pinocytosis) brings large molecules INTO the cell, enclosed in a
vesicle. Exocytosis transports large molecules OUT of cells.
Define the term active transport - ✔✔Movement of
molecules, against their concentration gradient (using energy
liberated from ATP hydrolysis) using specific protein channels
or carriers
Define the term diffusion. - ✔✔The net movement of a
substance from an area of high concentration to an area of
low concentration. It is passive, does NOT require ATP.
Define the term epidemic - ✔✔A rapid spread of disease
through a high proportion of a population (usually within a
country)
Define the term facilitated diffusion - ✔✔Movement of
molecules from a high concentration to a low concentration,
across a partially permeable membrane, via specific channel
or carrier proteins. It is passive, does NOT require ATP
, Define the term osmosis - ✔✔The movement of water
molecules from a region of higher water potential to a region
of lower water potential, across a partially permeable
membrane
Define the term tissue - ✔✔A group of cells working together
to perform a particular function
Define the term translocation - ✔✔Transport of assimilates
from source to sink (tissue that needs them)
Describe 2 major pathways taken by water to move between
cells - ✔✔Apoplast - through spaces in cell walls and between
cells (mass flow...not osmosis); symplast - moves through
cytoplasm and between cells via plasmodesmata
Describe 3 adaptations of marram grass (xerophyte) and
explain their importance - ✔✔Leaf rolled longitudinally
trapping air inside (air becomes humid and reduces water loss
from the leaf); thick waxy cuticle on upper epidermis (reduces
evaporation); stomata on lower epidermis inside rolled leaf
(protected by enclosed air space); stomata are in pits in lower
epidermis which is folded and covered by hairs (reduces air
movement and hence water loss); spongy mesophyll very
