This test is made up of four exercises on two pages.
Exercise 1: The blood cells (5 pts)
In order to study the role of the organs of the immune system; a scientist made many microscopic
observation of blood cells for three different mice A, B and C. One of these mice has a bone
marrow with abnormal function (not normal function), another one is without thymus.
The results of these microscopic observations are given in the following document.
1- Indicate, starting from the document 1, the mice that have white blood cells. Justify.
2- Name the cells 1, 2, 3 and 4 of the document 1. Justify.
3- Justify that the mouse C has abnormal function in the bone marrow.
Supplement studies on the mice A and B showed that:
- The B and T lymphocytes of the mouse A are mature.
- Only the B lymphocytes of the mouse B are mature.
4- Specify, starting from these results, the mouse that does not have a thymus.
Exercise 2: Immediate immune reaction
After a wound of the skin, we observe the variations that are undergone in the site of the wound.
The made observations are represented by the figures 1, 2, 3 and 4 given below.
1- Name the immune reaction represented by these figures.
2- Pick out from the figures: 2.1. The sign that is shown by the figures.
2.2. The change that occurs at the level of the blood capillary.
The figure 4 shows a decrease in this immune reaction.
3- Indicate the reason of the decrease of the reaction observed in the figure 4.
During this reaction the white blood cells make an important process called phagocytosis.
4- Name the steps A, B and C of phagocytosis shown by these figures.
5- Arrange the steps A, B and C in order. Justify.
Exercise 3: The rejection of grafts (5 pts)
In a scientific study the following problem is studied:
What are the elements of the body that are responsible for the
success or the rejection of the graft?
In order to answer this problem, scientists measured the
percentage of survival of the graft after one year for
individuals subjected to grafts of kidneys.
The results are given by the document 1.
1- Pick out, starting from the above text, the problem
studied by the scientists.
2- Formulate a hypothesis concerning this problem.
3- Copy and fill the following table starting from the
document 1.
HLA similarity
% of survival
Title:
4- Specify starting from the document 1 the group of
persons where all the grafts are rejected.
5- Draw out a conclusion about the elements that are
responsible for the rejection of the graft.
Exercise 4: Protection against microbes (5 pts)
In order to discover a technique of protection of hamsters against microbes, a scientist decides to
perform the experiment
schematized in the
document 1. He used in
this experiment the
tetanus bacteria that kills
normally the hamster
when it is injected to it.
1- Describe
the
experiment of document 1.
2- Draw out a conclusion concerning the protection of the hamster against the tetanus, starting
from this experiment and the above text.
The hamster that survived in the
experiment 1 is subjected to the
treatment shown in the document 2.
3- Justify the death of the hamster
A shown in the document 2.
4- Specify a technique that helps us
to protect the hamster from being
infected by the diphtheria.
The flu virus is a virus that infects
human and causes flu (disease). There
are 200 different kinds of flu virus. A scientific lab prepare a mixture of killed viruses from the
200 kinds of flu virus and use this mixture to treat humans.
5- Indicate the benefit of the injection of this mixture to humans.
Life science
Grade 8
Answer keys
Test 1 2016
Exercise 1: (5 pts)
1- The mice that have white blood cells are the mice A and B because they have cells with
nuclei. (1 pt)
2- Cell 1: Monocyte since it has U shaped nucleus.
Cell 2: granulocyte since it has multilobed nucleus.
Cell 3: lymphocyte since it has round nucleus.
Cell 4: red blood cell since it does not have a nucleus. (2 pt)
3- The mouse C has abnormal bone marrow because it does not have white blood cells and
the white blood cells are produced in the bone marrow. (1 pt)
4- The mouse B does not have a thymus since the T lymphocytes mature in the thymus and
in this case the T lymphocytes are not mature.
Exercise 2:
1- Inflammation reaction. (0.5 pt)
2- 2.1. Edema. (0.5 pt)
2.2. The blood capillary dilates. (0.5 pt)
3- The decrease in the number of bacteria in the skin leads to the decrease of the observed
reaction. (1 pt)
4- A: approach, B: Digestion, C: engulf. (1.5 pt)
5- A, C, B. since the white blood cell approach to the bacteria then it engulf it, after that it
digest it. (1 pt)
Exercise 3:
1- What are the elements of the body that are responsible for the success or the rejection of
the graft? ( 1 pt)
2- Hypothesis: The HLA molecules are responsible for the success or the rejection of the
graft. (1 pt)
3- .
HLA similarity % 100
50
0
% of survival
95
50
0
Title: Survival of the graft as a function of HLA similarity after one year. (1 pt)
4- The group of persons where all the graft are rejected is the group with 0 % of HLA
similarity since the percentage of survival is 0 %. (1 pt)
5- Conclusion: The HLA are the molecules of the body responsible for the success or the
rejection of the grafts. (1 pt)
Exercise 4: ( 5 pts)
1- Hamster is injected by killed tetanus bacteria, after 20 days, the survival of this hamster is
obtained, then live tetanus bacteria are injected to it, also its survival is obtained after 20
days. (1 pt)
2- The injection of killed tetanus bacteria protects the hamster form the live tetanus bacteria.
(1 pt)
3- The hamster dies since the immune response induced against the tetanus is specific. (1 pt)
4- We inject the killed diphtheria bacteria to the hamster since the immunity is specific. (1 pt)
5- The injection of this mixture to humans protect them from being infected by 200 kinds of
flu viruses. (1 pt)