Download solutions

BIOLOGY Sem 2 Topic Test 2012 - ANSWERS
Use the following family tree for hemophilia, a sex linked trait, to answer question 1.
I
1
II
III
1.
2
1
2
3
4
2
1
5
3
6
4
Is the condition dominant or recessive? Give the evidence for your answer.
Recessive. Individual III3 receives an X chromosome from II6 and a Y chromosome from II5. Since the individual has the
disease, the X must contain the disease. Yet it does not show in III6 meaning it is recessive.
2. Write down the genotypes for each individual. If it cannot be determined, write all possibilities.
Xh – diseased chromosome, XH – normal chromosome
I1 - XhXh
I2 - XhY
H
II1 - X Y
II2 - XhXh
II3 - XhXh
II4 - XhXh
II5 - XhY
II6 - XhXH
h H
h
h
H
III1 - X X III2 - X Y
III3 - X Y
III4 - X Y
3.
If individual III2 married a carrier female, what are the chances that they would produce an offspring that would
suffer from hemophilia? What is the chance that a son would suffer? What is the chance that a daughter would
suffer?
Xh
Y
h
X
XhXh XhY
XH XhXH XHY
50% offspring suffer from disease. ½ The sons (others are fine). ½ the daughters (others are carriers).
4.
The following list has the steps in natural selection jumbled. Un-jumble them into the correct order.
i.
The environment changes which causes some
vi.
Variation in the gene pool
individuals to die
vii.
The individuals that are benefited by their
ii.
A greater proportion of the population
beneficial genes survive to a reproductive
now contain the beneficial genes
age.
iii.
Mutations that occur in a species leads to
viii.
The beneficial genes are passed on to the
iv.
If the environment changes in the same
next generation.
way in the future as it did in the past then
ix.
This has led to the species evolving
less individuals of the population will die out
v.
Order – III
A few individuals contain beneficial genes
that help them survive the environmental change
VI
I
V
VII
VIII
II
IV
IX
5.
Draw a labeled diagram to explain how an animal is cloned
6. What is gene splicing and how does it relate to the use of insulin for diabetics?
Gene splicing is taking a section of DNA from one organism and inserting it into the DNA of another. Insulin needed by
diabetics is made by bacterium which normally do not make it. The DNA sequence of base pairs which instructs a cell to
make insulin is spliced into bacterium’s normal DNA which changes how the cell operates.
7. What does IVF stand for?
In-vitro fertilisation
8. Name three issues relating to the use of IVF.
Age of recipient(s), same sex couples, costs, when does life begin (discarded embryos).
9. Give the 5 steps required for a cycle of IVF treatment
Ovaries are stimulates to release eggs by injection of hormones
Eggs are retrieved and placed in fertilization container
Sperm are added to fertilization container and left to fertilize eggs
Fertilized eggs are left to grow into embryos
One or two embryos are selected to be transferred to uterus of woman
10. What does the term mutation mean?
A sudden change in the DNA of an organism
11. What are the two causes of mutations?
Radiation and Chemicals
12. Give three examples of mutations and state whether they are beneficial or detrimental
Beneficial – resistance to antibiotics/toxins, fur colour (camouflage), ability to drink milk and others
Detrimental – seedless grapes, fur colour (not camouflaged), cancer and others
13. What genetic disorder is caused by i) too many body chromosomes ii)having an extra X chromosome in a female and a
male and iii) having only one X chromosome
I – down syndrome II – Triplo X in female, Klinefelter’s syndrome in males
III – Turner’s syndrome
14. What is the cause behind the above disorders? Draw a diagram showing how these can occur in an individual.
15. Rabbits are a pest in Australia. The rabbit proof fence was one attempt at controlling the spread of rabbits. What was
the other?
Introduction of myxomatosis; a disease which kills rabbits.
16. Describe why, after many generations, rabbits are now much more resistant to your answer to Q15.
Some rabbits already carried genes which made them resistant to the disease. These rabbits had a better chance at
surviving to reproduce and pass on these genes to their offspring than those that did not. Now a larger proportion of
rabbits are resistant to the disease.
Population
17. Show, using a graph how the population of rabbits would have changed over time, starting from just before the
introduction of the control measure from Q15.
Time
18. Provide one argument for, and one against GM foods.
GM foods can help solve world hunger, improve the production of food, make better versions of what nature has provided
GM foods are not ‘natural’, may do more harm than good, we cannot see the long term effects of changing the species.
19. What is meant by the term ‘genetic screening’ and how could it benefit parents?
Genetic screening is the process of checking the DNA of an offspring at the early stages of development and removing
those individuals with qualities not desired by the parents.
This can benefit parents who have, or carry a disease that could be passed on to their offspring which reduces the quality
of life. Parents can be certain their child is disease free, although at the expense of removing those offspring that do have
the disease.
20. The above pedigree chart is for a dominant/recessive type of inheritance pattern. Is the shaded
characteristic dominant or recessive? How can you tell?
Recessive as individuals 8 and 9 cannot have a shaded child unless shaded is recessive. (or individuals 3 and 4)
21. using G and g for the alleles, what is the genotype of individuals 5, 10 and 13
5 – Gg, 10 – gg, 13 – Gg or GG
22. Determine the genotypic ratio for the predicted offspring of individuals 3 and 4.
¼ GG, 2/4 Gg, ¼ gg
23. Using a punnet square, determine the % chance of a married couple having a son.
2/4 XY = 50% chance of a son
Planet Boop is filed with lush pink plants. There lives a population of Babbits (which look like a rabbit, but have
a few differences). Babbits are mostly blue, but some Babbits are pink. Most have short necks, but some have
elongated necks. They have looked this way for thousands of years.
24. Some Quolves (which look like wolves and eat Babbits) are introduced to the area the Babbits inhabit. How
and why does the allele frequency change in the Babbit population?
The pink allele will increase in frequency as pink Babbits will have better survival rates (camouflaged).
25. A flood washes away all the low lying pink grasses the Babbits generally eat. How and why does the allele
frequency change in the Babbit population?
The elongated neck allele will increase in frequency as longer necks allow for better survival rates (can eat
taller plants).
26. A population of purely green Boths (which look like sloths) are also preyed upon by the introduced Quolves.
Choose the most likely outcome of the Dares:
They will die out due to being easy and slow moving prey
27. Explain why the other two choices will not occur.
Mutations are random events that may be beneficial, detrimental or be neutral in their effect. Mutations must
occur to increase the variation within the population before a change in environment. Natural selection is a
guided process that chooses which variations survive. There is no variation in the green Boths so they will die
out.