Download B1 – You and your genes

B1 – You and your genes
Go to the BBC Bitesize website from the school homepage. Click on ‘science’, then scroll down to
‘Core Science’ and click on ‘OCR 21st Century Science’. Then under the ‘biology’ heading click on ‘You
and Your genes. Alternatively, click on this link (http://tinyurl.com/77n2tj5) to take you to the
correct web page.
By clicking through the revision pages on this website you will find the answers to the questions
below. Foundation students only need to do the questions in normal font. Higher tier students
should do all of the questions including those in bold font.
Genes
1.
2.
3.
4.
What does the nucleus in a cell do? ______________________________________________
Where are the chromosomes located in a cell? _____________________________________
What do genes make? ____________________________
Give two functions of proteins:
a. ______________________________________________
b. ______________________________________________
5. Name a characteristic caused by a number of genes working together. __________________
6. Other than genes, what other factor can cause variation? ____________________________
7. Why are identical twins a useful example of how environment affects a person’s
characteristics? ______________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
You should now test your understanding of this section by completing the Test Bite by clicking
on the link at the bottom of page 2 of the genes section.
Score = ______________
Inheritance
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
What do we call an egg cell after it has been fertilised? _____________________
How many chromosomes are there in an unfertilised egg? _____________
How many chromosomes are there in a zygote? _______________
What are different versions of the same gene called? ________________
What does homozygous mean? _________________________________________________
What does heterozygous mane? _________________________________________________
Why do different children in the same family have different features? __________________
___________________________________________________________________________
___________________________________________________________________________
What is different about the chromosomes a woman has compared to a man? ____________
___________________________________________________________________________
What sex chromosomes can an egg cell carry? _____________________
What sex chromosomes can a sperm cell carry? _____________________
Not all families have an equal number of boys and girls in them. Why is this?
19. Suggest two reasons why people may want to choose the sex of their children.
a. _____________________________________________________________________
b. _____________________________________________________________________
20. Why do people have different opinions on whether couples should be allowed to choose
the sex of their children? ______________________________________________________
___________________________________________________________________________
21. How does the Y chromosome make the embryo develop into a male? Outline the three
steps involved.
i.
_____________________________________________________
ii.
_____________________________________________________
iii.
_____________________________________________________
Now test your understanding of this section by completing the Test Bite by clicking on the link at the
bottom of page 2 of the inheritance section.
Score = ______________
Testing and treating genetic diseases
22. What is a ‘recessive allele’? _____________________________________________________
___________________________________________________________________________
23. If you are homozygous recessive for a gene, what type of alleles do you carry?
___________________________________________________________________________
24. What is the difference between an organism’s genotype and its phenotype?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
25. What type of allele causes cystic fibrosis? ______________________
26. What is the physical result of having cystic fibrosis? _________________________________
___________________________________________________________________________
27. What does it mean to be a ‘carrier’ of cystic fibrosis? ________________________________
___________________________________________________________________________
28. Look at the genetic diagram on the web page. If two carriers of cystic fibrosis have a baby,
what is the chance that:
a. It has cystic fibrosis? _________________
b. It does not have cystic fibrosis? _________________
c. It is a carrier of cystic fibrosis? _________________
29. In terms of genetics, how is Huntington’s disorder different to cystic fibrosis? ____________
___________________________________________________________________________
30. What does a Punnett square show? ______________________________________________
31. What does a genetic test analyse? ______________________________________________
32. When is an antenatal test carried out? ____________________________________________
33. Who is offered an antenatal test? _______________________________________________
34. When are neonatal tests carried out? ____________________________________________
35. Name a condition that can be tested for in a neonatal test. ___________________________
36. Pre-implantation genetic diagnosis allows an embryo to be tested before it begins growing in
the uterus. Give the steps involved in pre-implantation genetic diagnosis:
a. _____________________________________________
b. These eggs are collected by the doctor.
c. _____________________________________________
d. _____________________________________________
e. _____________________________________________
f. _____________________________________________
37. What is the benefit of using PGD? _______________________________________________
___________________________________________________________________________
38. Why might people want to know if they have the allele for Huntington’s disorder?
___________________________________________________________________________
39. What is the difference between a false positive and a false negative? ___________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
40. What is the difference between a scientific questions and an ethical question?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
41. Why might insurance companies want to know your genotype? ______________________
___________________________________________________________________________
42. A common argument made during an ethical debate is that the right decision is the one
that leads to the best outcome for ______________________________________________.
43. Why do ethical opinions change over time? _______________________________________
___________________________________________________________________________
Now go back to page six of this section and try the Test Bite which is linked at the bottom of that
page.
Score = ______________
Cloning Stem Cells
44. What are clones? _____________________________________________________________
45. What is asexual reproduction? __________________________________________________
46. Give an example of asexual reproduction in plants. __________________________________
___________________________________________________________________________
___________________________________________________________________________
47. How are identical twins formed? ________________________________________________
___________________________________________________________________________
48. What is the difference between adult stem cells and embryonic stem cells? Complete the
table below to show the differences.
Adult stem cell
Embryonic stem cell
Where is it found?
What type of cells can it
develop into?
49. What is a specialised cell? ______________________________________________________
50. What is unique about a stem cell? _______________________________________________
___________________________________________________________________________
51. Put the statements about therapeutic cloning below into the correct order.
a.
b.
c.
d.
e.
f.
Stem cells taken from the embryo.
Stem cells treated to develop into required cell types.
Egg cell stimulated to develop into an embryo.
Nucleus taken out of a human egg cell.
Nucleus from a patient's cell put into the egg cell.
Stem cells grown in a container of warm nutrients.
_____ _____ _____ _____ _____ _____
52. What are the four steps for weighing up an argument?
i.
_______________________________________________
ii.
_______________________________________________
iii.
_______________________________________________
iv.
_______________________________________________
Foundation tier students should click on the Test Bite link at the bottom of the web page.
Score = ______________
Higher tier students should carry on and complete question 53.
53. Dolly the sheep was cloned using adult stem cells. Label and complete the diagram below
to show how this was done:
Higher tier students now try the Test Bite which is linked at the bottom of the web page.
Score = ______________