Download Investigating Cells

Investigating Cells
Interactive Summaries
This is an interactive exercise were you can fill in the correct
blanks as you go! The Investigating Cells unit is divided into 4
sub-units:
o
o
o
o
Investigating Living Cells
Investigating Diffusion
Investigating Enzymes
Investigating Cell Division
The first sets of summaries in each sub-unit are all at CREDIT
LEVEL!
To select an answer for each blank simply click on the grey box
and choose your answer. You can check your answer by using
the F1 key.
Investigating Living Cells
The summaries for this section are all at General level!
Investigating
Diffusion
The Importance of Diffusion in Living Things
o In a multicellular animal like a human being, diffusion
plays a very important role.
o For example, blood returning to the lungs from the cells
contains a higher concentration of
and lower concentration of
than in the
air sac. Carbon dioxide therefore diffuses out of the
blood and oxygen diffuses in.
Air sa
o In living cells oxygen and
is
constantly being used up during respiration. Therefore
the oxygen and glucose concentration inside the cell will
be
than in the surrounding blood.
o Oxygen and glucose will therefore diffuse into the cell
from a
concentration to a
concentration.
oxygen
oxygen
o At the same time carbon dioxide is constantly being
during respiration and will build up in
the cell.
o Therefore there will be a
concentration
inside the cell and a
concentration in the
surrounding blood. Therefore carbon dioxide will diffuse
the cell.
Carbon dioxide
Carbon dioxide
o Diffusion is important so that
substances can diffuse into cells and
products and can diffuse out of cells during respiration.
Diffusion in Cells
o The difference in concentration that exists between two
regions before diffusion is known as the
.
o During diffusion molecules always move along a
concentration gradient from
to
concentration.
Cell membrane
High concentration
Osmosis in Plant Cells
o If a plant cell was placed in pure water, water would
the cell by osmosis. This is because the pure
water has a
water concentration than the
contents of a normal plant cell.
o The vacuole
against the
o The
cell
.
wall
.
stretches
o The cell is said to be
and pushes the cytoplasm
slightly
but
does
not
.
o If a plant cell is placed in concentrated sugar solution
water will
the cell by osmosis.
This is
because
there
is
a
water
concentration inside the cell compared to the surrounding
solution.
o The
rigid.
vacuole
and
the
cytoplasm
from the cell wall which is still fairly
o The cells is said to be
flaccid.
or has become
o Dilute sucrose solution would have the same water
concentration as the contents of a normal cell so net
movement of water would occur.
Osmosis in Animal Cells
o If red blood cells are placed in pure water, water will
by osmosis until the cell bursts. This is
because there is a
water concentration
outside the cell compared to inside the cell.
o The cell bursts because animal cells do not have a
.
o If red blood cells are placed in
, water
will exit the cell by osmosis. This is because there is a
higher water concentration inside the cell compared to
outside the cell. This will cause the cell to
.
o As 0.85% salt solution has the same water
concentration as the red blood cell contents,
there is no net flow of water into or out of the
cell by osmosis.
Investigating Enzymes
Specificity of an Enzyme
o Each enzyme only acts on one type of
.
o Catalase, for example, will only breakdown
and no other substrate.
o Each enzyme is said to be
substrate.
to its
o The shape of a molecule of enzyme exactly matches
the shape of a molecule of its substrate. This is known
as the
theory. This allows the two
molecules to combine briefly bringing about the
reaction.
o Each enzyme will also work best at a specific pH and
temperature.
o The particular condition at which an enzyme works
best is called the
condition.
Mitosis
o Stage (a): the nucleus containing long uncoiled
chromosomes each double to form two identical
o Stage (b): Short coiled up
visible.
are
o Stage (c): Chromosomes become attached at the
equator. A
forms and each
chromosome becoames attached by its
.
o Stage (d): Pairs of identical
are
separated and move to opposite ‘poles’ of the cell.
o Stage (e) –(f): The nuclear membrane and
divides. Separated chromatids are
now called chromosomes. Two
cells are
formed each containing the same number of
chromosomes as the original cell.
Maintaining Chromosome Number
o Chromosomes contain the main source of genetic
information typical of a particular species.
o It is essential that each cell formed as a result mitosis
recieves a
complement of
chromosomes so that during
the cells of
multicellular organism will beable to provide the
species with all of its characteristics.
This is the end of the Credit section. Well done!!
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