Interactive Questions 07

7/31/2019 Interactive Questions 07

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Genetics

INTERACTIVE

MULTIPLE CHOICEQUESTIONS

The answers are provided.

Explanations of why the alternativesare unsatisfactory are also offered


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These multiple choice questions are similar to the ones

set by the GCSE and IGCSE Examination Boardsexcept that, in some cases, there may be more than one

acceptable answer

For this reason, even if you select a correct answer atyour first attempt, it is worth looking at all the

alternatives

(a) to see if there is a better answer and

(b) to see why some of the alternatives are

unacceptable


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Question 1

A fathers blood group isAB; the mothers is O.

Which of the following blood groups could appear in their

offspring?

(d) O

(c)AB

(b) B

(a)A

Question 2


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Yes

The fathers genome must be iAiB

The mothers genome will be iOiO

The combination iAiO is possible and will be expressed

as groupA because iA is the dominant allele


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The combination iB

iO

is possible andwill be expressed as group B

because iBis the dominant allele

Yes


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No



The offspring will all inherit either iA or iB from their

father and iO from their mother. Their genomes will be

either iAiO (expressed as groupA) or iBiO (expressedas

Group B. GroupAB is not possible


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No



The offspring will all inherit either iA or iB from

their father and iO from their mother. Their

genomes will be either iAiO or iBiO.The alleles

iA

and iB

are both dominant to iO

so group O isnot possible


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Question 2

A pure-breeding male black mouse is mated with a female brown

mouse and they produce a litter of 12. The allele for black fur is

dominant to the allele to brown fur.

What is the expected distribution of colour and sex in their litter?

(d) 12 black males

(c) 6 black males and 6 black females

(b) 9 black and 3 brown, all male

(a) 6 brown females and 6 black males

Question 3


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No

Black

maleBrown

femaleB B

b

b

Bb Bb

bB bB

gametes

The pure-breeding males genome must be BB and the brownmouses genome must be bb. The allele for black fur is

dominant over the brown allele. Therefore all the offspring

will be black (Bb)


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Black

maleBrown

femaleBX BY

bX

bX

BbXX BbXY

bBXX bBXY

gametes

Yes

Inheritance of colour is explained in the first answer. The malemouse carries the X and Y chromosomes. The female mouse

carries two X chromosomes. At meiosis, only one of each

chromosome pair goes to the gametes.


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No

Certainly all 12 mice will be black as explained in the first

answer, but the sex is inherited as explained in the third answer, so

the expectation is that there will be 6 males and 6 females in the

litter


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Question 3

A male heterozygous black mouse (Bb) is mated with a female

heterozygous black mouse (Bb) and the litter consists of 12

pups. B is the allele for the black colour. The allele for brown

colour is b. The dominant allele is B. Which of

these ratios is closest to the expected ratio for the distribution

of colour among the offspring?

X

(d) 8 black and 4 brown

(a) All black

(b) 6 black and 6 brown

(c) 4 black and eight brown

Question 4


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B

B b

b

BB Bb

Bb bb

gametes

From the Punned square you can see that the expected

ratio is 3 black (BB or Bb) to 1 brown (bb)

These are only the chance combinations. It would be

possible to produce 12 black pups, since black is the

dominant allele but this is not close to the expected ratio

Not very close


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These are only the chance combinations. It would be

possible to produce 6 black and 6 brown pups but this

is not very close to the expected ratio of 9:3

B

B b

b

BB Bb

Bb bb

gametes

From the Punnett square you can see that the expectedratio is 3 black (BB or Bb) to 1 brown (bb)

Not very close


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From the Punnett square you can see that the

expected ratio is 3 black (BB or Bb) to 1 brown (bb)

B

B b

b

BB Bb

Bb bb

gametes

These are only the chance combinations. A

combination of 4 black to 8 brown is close to the expected

ratio of 3:9 but since black is the dominant allele it seems to

be the wrong way round

Close but


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From the Punnett square you can see that the expected

ratio is 3 black (BB or Bb) to 1 brown (bb)

B

B b

b

BB Bb

Bb bb

gametes

These are only the chance combinations. A

combination of 8 black to 4 brown is closest to the expected

ratio of 9:3

The closest


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Question 4

a

b

c

d

e

The diagrams represent stages in cell

division by mitosis. (only one

chromosome is represented). What is

the correct sequence of events?

(d) d b a c e

(c) b a d c e

(b) b a c e d

(a) a b c d e

Question 5


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The chromosomes shorten and thicken (b) afterthey

have appeared in the nucleus (b). Similarly at the end

of cell division, the chromosomes extend and become

less visible (d) afterthe cell divides (e)

No


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Yes

This is the correct sequence


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The cell does not start to divide (d) until the chromatids

have separated (c). Also, cell constriction (e) precedes

cell division (d)

No


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No

Cell division (d) does not take place until the chromatids

have appeared (b) and separated (c). Also, cell

constriction (e) precedes cell division (d)


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Question 5

The process of cell division by meiosis takes place only

(d) in lymphocytes

(c) in reproductive organs

(b) in red bone marrow

(a) in skin cells

Question 6


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No

Although the cells in the basal layer of skin divide rapidly, it is

by mitosis


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Cells in the red bone marrow divide rapidly to produce

red and white blood cells, but this is by mitosis

No


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Yes

The cells in the reproductive organs which produce

gametes will undergo a meiotic division and produce

haploid gametes


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No

The lymphocytes are capable of dividing rapidly to

produce clones of cells but this involves only mitosis


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Question 6

In a DNA molecule, which of the molecules listed

below pairs with adenine?

(d) cytosine

(c) valine

(b) guanine

(a) thymine

Question 7


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thymine

Yes

adenine


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No

guanine cytosine

Guanine pairs with cytosine


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No

Valine is an amino acid and not an organic base


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No

cytosine guanine

Cytosine pairs with guanine


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Question 7

IfL is the allele for long hair and l is the allele for short hair,

B is the allele for black hair and b is the allele for white hair,S is the allele for straight hair and s is the allele for curly hair

What will be the phenotype for a small dog with the

genotype LLBbss?

(c) Long, white, curly fur

(d) Long, black, curly fur

(b) Short, black, straight fur

(a) Long, white, straight fur

Question 8


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No

The allele for black fur is dominant to the allele for

white fur


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No

The dog carries both dominant alleles for long hair


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The dog is heterozygous for the colour gene, but the allele

for black fur is dominant to the allele for white fur

No


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Yes

The dog is homozygous recessive for the curly allele,

homozygous dominant for hair length and heterozygous for the

colour gene but the black allele is dominant

Q ti 8


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(a) cutting out the insulin gene from human

DNA with restriction enzymes,

(b) extracting plasmids from the bacterium,

(c) returning the modified plasmid to the bacterium,

(d) inserting the insulin gene into the plasmid,

(e) cutting open the plasmid with the same restriction enzyme

(1) e, b, d, a, c

(2) b, c, e, a, d

(3) b, e, a, d, c

(4) b, d, e, a, c

Bacteria can be genetically modified to produce human

insulin. The steps involve

Question 9

Question 8

Which of the following is the correct sequence?


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No

The plasmids cannot be cut open (e) until they are

extracted from the bacterium (b)


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The insulin gene must be inserted in the plasmid (d)before it is returned to the bacterium (c)

No


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This is the correct sequence

b, a, e, d, c would also be acceptable because the

restriction enzyme can cut the plasmid DNA and humanDNA in any order

Yes


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No

The plasmid DNA must be opened (e) before the insulin

gene can be inserted (d)


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Question 9

Before natural selection can take place in an animal,

there has to be either

(d) a climate change

(c) a gene recombination or

(b) a change of habitat or

(a) a gene mutation or

Question 10


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Yes

A gene mutation which caused a change in the organism could

be subject to natural selection


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No

A change of habitat might favour a variation resulting

from a genetic change, such as a mutation, but selection

could not result from an organism simply changing its

habitat


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Yes

A new combination of genes could produce a variation that

had a selective advantage


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No

A climate change might favour some variants in a

population but could not, itself, produce those variants.

There has to be a genetic change for the climate change to

act upon


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Question 10

Which of the following can be inherited?

(d) Tuberculosis

(c) Sickle cell disease

(b) AIDS

(a) Cystic fibrosis


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Yes

Cystic fibrosis is caused by a gene mutation. The gene

controls the movement of salts and water into and out of the

cells. The mutated form of the gene causes thick mucus to be

secreted by the lungs, airways and pancreas, plus many othersymptoms. The

mutated gene is recessive to the normal gene..


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No

AIDS is caused by a virus, the human immunodeficiency

virus (HIV). The virus is transmitted by sexual intercourse

or by infected syringe needles.

An infected mother may pass the disease on to her baby, so

the disease may, superficially, appear to be inherited


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Yes

Sickle cell anaemia is caused by a mutation in a gene

controlling the composition of haemoglobin. This mutation

causes the red cells to become distorted in low oxygen

concentrations and so block small blood vessels.The mutated gene is recessive to the normal gene


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No

Tuberculosis is an infectious disease caused by a

bacteriumMycobacterium tuberculosis. The bacteria are

carried in the air.

In most cases, the disease affects the lungs.


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Interactive Questions 07