January 2012 units B1,B2,B3 Flashcards
All humans have different phenotypes.
Which word best explains the word phenotype?
genes; number of cells; nuclei; characteristic; chromosome [1]
characteristic.
Which description is correct for the word homozygous?
has more than 2 alleles for a gene
the alleles for the gene are the same
each chromosome has two alleles
the alleles for a gene are different
each cell has a different allele [1]
the alleles for the gene are the same
Which description is correct for the word heterozygous?
has more than 2 alleles for a gene
the alleles for the gene are the same
each chromosome has two alleles
the alleles for a gene are different
each cell has a different allele
[1]
the alleles for a gene are different
The Punnett square shows the inheritance of a characteristic caused by the recessive allele g
G g
G GG Gg
g Gg gg
Write down the genotype of a carrier [1]
Gg
The Punnett square shows the inheritance of a characteristic caused by the recessive allele g
G g
G GG Gg
g Gg gg
Write down the genotype that will show the characteristic [1]
gg
Some disorders are inherited.
One of these disorders is Huntington’s disease.
Complete the sentence to show how Huntington’s disease is inherited.
Put a ring around the correct word to complete each sentence.
Huntington’s disease is cause by a change in one /two/ multiple gene(s).
One one faulty allele is required to cause the disease, because the allele is dominant/recessive/powerful/weak. [2]
one; dominant
Genetic testing can be used for screening adult, children and embryos.
Describe uses of genetic testing and the implications of these tests for these people.
The quality of your written communication will be assessed in your answer. [6]
Note - you have to mention BOTH uses and implications, otherwise you will only get 2 out of 6 marks.
Implications must be linked to adult/child/embryo
Uses may include:
To find out whether a genetic disorder has been inherited
To find out reaction to a drug
To find out paternity
Implications may include:
To decide whether to terminate a pregnancy
To decide whether to have children
Insurance
Employment
Unreliable testing/false negatives/false positives
Miscarriage
Stress
Tailor made treatments
Embryo selection/gene therapy
Who else to tell in the family
Religious implications
Decision has been made for newborn, could affect the rest of his life
You are not expected to produce all - just enough for 6 marks!
Genetic testing is viewed differently by different people.
Write down one argument for and one argument against genetic testing. [2]
For:
Can plan ahead/make decisions
Right to know
Have the correct treatment
Might become ill in the future
Against:
Ethical/religious/God/unnatural
insurance implications
employment implications
false positive and negative
possible miscarriage or damage to embryo
Microorganisms can cause disease.
They can divide rapidly.
a. Bacteria are added to a Petri dish. The dish is sealed. After 24 hours the dish contains several colonies of bacteria.
i. (Look at the image). What is the smallest number of bacteria that could have been present in the Petri dish at the start of the 24 hours? [1]
i. 8
Microorganisms can cause disease.
They can divide rapidly.
a. Bacteria are added to a Petri dish. The dish is sealed. After 24 hours the dish contains several colonies of bacteria.
ii. A single bacterium can divide every 20 minutes.
One of the colonies has 4096 bacteria. Calculate how long this colony has been growing. Show your working. [2]
- 4096/2 = 2048
- 2048/2 = 1024
- 1024/2 = 512
- 512/2 = 256
- 256/2 = 128
- 128/2 = 64
- 64/2 = 32
- 32/2 = 16
- 16/2 = 8
- 8/2 = 4
- 4/2 = 2
- 2/1 = 1
12*20 = 240 minutes = 4 hours.
Microorganisms can cause disease.
They can divide rapidly.
a. Bacteria are added to a Petri dish. The dish is sealed. After 24 hours the dish contains several colonies of bacteria.
ii. A single bacterium can divide every 20 minutes. (previous question, to give context).
A similar colony takes longer than expected to grow to 4096 bacteria.
Which of these statements are possible reasons why? [2]
The Petri dish is too large
There is a shortage of food
They were left too long
There were not enough bacteria to start with
The temperature has been reduced
There is a shortage of food
The temperature has been reduced
(Need both for the mark)
Look at the graphs.
Flask A only contains a strain of bacteria (R–) that is not resistant to penicillin. Flask B only contains a strain of bacteria (R+) that is resistant to penicillin. Flask C contains a mixture of both strains of bacteria (R– and R+).
Penicillin was introduced to flask C at point X on the graph.
(i) Describe the effect on the number of bacteria after adding penicillin to flask C. [2]
The number of bacteria increased at first, then penicillin was added.
This killed some bacteria, so the number of bacteria went down, then started rising again.
(Must mention when penicillin was added to get 2 marks).
Look at the graphs.
Flask A only contains a strain of bacteria (R–) that is not resistant to penicillin. Flask B only contains a strain of bacteria (R+) that is resistant to penicillin. Flask C contains a mixture of both strains of bacteria (R– and R+).
Penicillin was introduced to flask C at point X on the graph.
(ii) The student drew these conclusions only from information in the three graphs.
Assume the vertical axis of each graph has the same scale.
1 After 2 hours there were more bacteria in flask B than in flask A.
2 The growth rate of bacteria in flask A was greatest at about 3 hours.
3 Resistant bacteria grew slower than non-resistant bacteria because they had less food.
4 After six hours, flask C mostly contained resistant bacteria.
5 The growth rate of bacteria in flask C increased after 5 hours because strain R– had become resistant to the penicillin.
Which of the student’s conclusions could be correctly drawn from the graphs? Choose from 1, 2, 3, 4 and 5. [2]
2 The growth rate of bacteria in flask A was greatest at about 3 hours.
4 After six hours, flask C mostly contained resistant bacteria.
Look at the graphs.
Flask A only contains a strain of bacteria (R–) that is not resistant to penicillin. Flask B only contains a strain of bacteria (R+) that is resistant to penicillin. Flask C contains a mixture of both strains of bacteria (R– and R+).
Penicillin was introduced to flask C at point X on the graph.
(iii) Another student said that the results for flask C clearly show why patients should complete a course of antibiotics.
State whether the student was correct. Explain your answer. [3]
NO - because (must give 3)
some bacteria may be resistant
not all bacteria killed
we do not know whether all non-resistant bacteria were killed
maybe a bigger dose would have killed them
maybe a longer dose would have killed them
4 Vaccinations help prevent disease.
(a) Edward Jenner discovered the first vaccine.
Read the article about Edward Jenner then answer the following questions.
Edward Jenner 1749 – 1823
Edward Jenner discovered the first vaccine in 1796. He noticed that milk maids who caught the mild disease of cowpox never caught the deadly disease of smallpox. He thought that cowpox must give protection against smallpox. To test his idea he injected a small boy called James Phipps with pus from a milk maid who had cowpox. James caught cowpox. When James had recovered, he injected James
with pus from a person who had smallpox. This would normally have resulted in James getting smallpox, but he did not. Edward Jenner had used cowpox pus to invent the first vaccine.
(i) Using ideas about vaccines, explain how Jenner’s treatment prevented James Phipps from getting smallpox. [6]
(ii) Use the example above to describe a correlation between a factor and an outcome. [1]
i. You must mention memory cells, and explain them; rapid response; antigens of smallpox and cowpox are similar; explanation of fit between antibody and antigen
ii. if you get cowpox you do not get smallpox
