Download Science 1.3 Questions 10

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QUESTION ONE: ON THE HIGH SEAS
Several cruise ships have been in the news recently with outbreaks
of gastrointestinal illness caused by the virus group Norovirus.
This virus is spread easily and causes nausea, vomiting, stomach
pains and diarrhoea for 1-2 days.
A number of bacteria species can cause very similar illnesses, so doctors must find out
which microorganism type is responsible to be able to treat it. Bacteria can be identified by
culturing a sample of vomit in agar, but viruses cannot.
(a)
Explain why viruses cannot be cultured on a nutrient agar plate, but bacteria can.
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(b)
Compare and contrast how the Norovirus infects a person and causes illness, with
how a bacterial species (that causes similar illness) would. In your answer consider:

how they are spread

their relevant life processes
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QUESTION TWO: YOGHURT MAKING
Fresh yoghurt can be easily made in the home, using a sachet of mix purchased from the
supermarket. These dried mixes include milk powder and various bacteria, eg.
Lactobacillus bulgaricus. The steps to use them include:
1. Fill a clean jar with fresh, clean cold tap water.
2. Add the contents of the yoghurt sachet and mix thoroughly, topping the jar up
with water to ensure it is completely full before screwing the lid on tightly.
3. Place the jar in a special insulated plastic container full of hot water. Place the
lid on the container and leave for 8-12 hours until set.
4. Store in the fridge for no longer than one week.
(a)
Explain why the dried sachet can be stored in a cupboard for years, but the prepared
yoghurt must be stored in the fridge for only one week.
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(b)
Discuss how each of the steps 1-3 above contributes to the successful production of
safe-to –eat yoghurt in your home. Include in your answer

Life processes of Lactobacillus bulgaricus bacteria involved in making
yoghurt

How each step helps to provide the conditions needed by bacteria
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QUESTION THREE: SMILE!
Facial dimples are a dominant genetic trait, caused by shortened facial muscles which pull
on the overlying skin when a person smiles. The recessive trait produces longer muscles,
so no dimples appear. D = dimples, d = not.
A married couple, both with dimples, have four children. One child has dimples, the other
three do not.
(a)
Give the genotypes for both parents, and explain why you chose this answer.
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(b)
The parents are surprised that only one of their children has dimples like they do,
and wonder what they will get if they have another baby.
Discuss how the process of meiosis functions to produce children both with
dimples and without. Include why the parents are surprised and state the likely
outcome if another child was born. Include a punnet square in your answer.
Diagram/s may be used.
PUNNET SQUARE
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QUESTION FOUR: CAT GENETICS
There are many genes used by pedigree cat breeders to get a range of colours, fur length
and body shapes. Several genes can control coat colour in cats.
One of these produces the Agouti pattern, where each hair has a black tip but bands of light
and dark towards the hair root. This pattern is dominant, and denoted by the letter A. The
recessive allele for this trait gives plain black hairs.
(a)
Give the genotype and phenotype of the cat pictured. Explain why you chose these
answers.
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(b)
A breeder wishes to have a pure breeding group with the Agouti coat colour. He
has a group of the Oriental breed pictured, some of which are black and some of
which are Agouti.
Discuss how he would go about developing a pure breeding Agouti group. Include
punnet square(s) in your answer.
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Extra paper for continuation of answers if required. Clearly number the
question.Agouti
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