Science 10 Assignment U3L5 (40 marks)
1. Explain the four points of the particle model of matter (4 marks)
1. All matter is made of particles but the particles in different
substances may be different size and composition.
2. The particles of matter are constantly moving or vibrating; particles
move least in solids and most in gases. Adding or taking away
energy will affect the movement of the particles.
3. The particles of matter are attracted to one another or are bonded
together.
4. Particles have spaces between them that are smallest in solids,
except for ice, and greatest in gases. The spaces may be occupied
by the particles of other substances.
2. Explain how the process of diffusion, facilitated diffusion, and active
transport occur and why each one is important to the cell. (6 marks)
Diffusion- occurs to provide a state of equilibrium. Diffusion is when
particles move from an area of high concentration to low
concentration.
Facilitated diffusion- Occurs to transport substances that are
soluble in water but not in lipids across the cell membrane. The
carrier proteins change shape and physically move the molecule
across the membrane into the cell. No added energy is needed
because the molecules are moving with the concentration gradient.
It is important in maintaining the proper levels of materials inside
and outside the cell.
Active transport- Occurs to molecules against the concentration
gradient. The process is like facilitated diffusion but the difference
is active transport goes against the concentration gradient and
requires energy from the cell. This is done to control actively the
concentrations of materials inside and outside of the cell.
3. Using your own words, explain what is meant by the terms “concentration
gradient” and “equilibrium” (2 marks)
Concentration gradient – the difference of concentration of a
specific substance of one area relative to another adjacent area.
Equilibrium- A state of balance between opposing actions.
4. Explain how you would ensure that the celery you bought three days ago will
be crisp and fresh for your dinner tonight. (1 mark)
Put the celery in a glass or bowl of water, so the water will restore
the cytoplasm and turgor pressure (deplasmolysis).
5. What are the differences between passive and active transport? (2 marks)
Passive transport is with the concentration gradient and requires
no energy input.
Active transport is against the concentration gradient and requires
a energy input.
6. Draw (or obtain a diagram from the internet) two diagrams showing the
processes of endocytosis and exocytosis. Indicate the similarities and
differences. (6 marks)
Similarities: The cell membrane surrounds the particles
Differences: Endocytosis brings the particles into the cell.
Exocytosis brings the particles out of the cell.
7. The transport of wastes out of the blood during dialysis depends on the
composition of the dialysis solution. Explain this statement. You should
include the particle model of diffusion and the role of the cell membrane in
your answer. (4 marks)
Dialysis makes use of concentration gradients across the dialysis membrane.
By controlling the concentration of certain substances (waste) on the filter
side of the membrane, you can control the rate and direction of diffusion
through the membrane. The membrane serves as a semi-permeable barrier
for waste materials to diffuse through and separated from the blood on the
other side of the membrane.
8. Draw and label (or obtain from the internet) a diagram of a liposome. how
are liposomes used in the treatment of HIV and cancer patients ? (3 marks)
HIV and cancer therapies use liposomes to deliver medication. The
spheres may circulate the blood stream then the medication on its
own.
9. Describe the role of membrane technologies in the following : (3 marks)
a) water purification –
Membranes can be used as sites of waste or impurity filtration for
the purpose of water purification
b) peritoneal dialysis – The role of membrane technology in
peritoneal dialysis is to rid the blood of toxins, wastes, and
excess fluid, produced by the cells of the body.
c) gene therapy for cancer –
Membranes can be used to target specific cells for chemical or
biological treatment by the use of protein markers.
10. List three differences between peritoneal dialysis and hemodialysis (3
marks)
Peritoneal dialysis is when waste products from the blood get
removed by a dialysate solution that is pumped into the peritoneal
cavity of the body and then removed.
Hemodialysis is when blood is pumped out of the body to be cleaned
by a machine and then returned.
11. Explain the term “reverse osmosis” as compared with “osmosis” (2 marks)
Reverse osmosis is the movement of water through a semipermeable membrane from a low concentration of solute to a high
concentration of solute.
Osmosis is the diffusion of water across a selectively permeable
membrane from high to low concentration.
12. Explain the importance of membrane binding to the action of insulin. (1
mark)
The binding to receptor sites on the cell membrane, stimulates the rate
of movement of the glucose into the cells through facilitated diffusion
with a carrier protein.
13. Describe some of the limitations of membrane technologies in the treatment
of HIV, diabetes, cancer and kidney disease. (4 marks)
Some they use the binding reaction to target human cells. The
binding reaction may also act like a molecular switch and trigger
many different activities in the cell.