UNIT 2 - KA4

Question 1

What can a variety of techniques be used to monitor

Answer 1

A variety of techniques can be used to monitor the health of the mother and developing foetus

Question 2

What is antenatal screening

Answer 2

Antenatal screening identifies the risk of a disorder so that further tests and prenatal diagnosis can be offered

Question 3

All pregnant women have two routine scans using ultrasound technology:

Answer 3

• a dating scan
• an anomaly scan

Question 4

What is a dating scan

Answer 4

A dating scan at 8-14 weeks determines the stage of pregnancy and due date. Dating scans are used with tests for marker chemicals which vary during pregnancy

Question 5

What is an anomaly scan

Answer 5

An anomaly scan at 18-20 weeks may detect serious physical abnormalities in the foetus

Question 6

Why are routine urine and blood tests carried out throughout pregnancy

Answer 6

Routine urine and blood tests are carried out throughout pregnancy to monitor the concentrations of marker chemicals.

Question 7

What can the marker chemicals found in routine urine and blood tests indicate

Answer 7

These marker chemicals may indicate a medical condition with the unborn foetus

Question 8

Why should biochemical tests be synchronised with information gained from ultra sound scans

Answer 8

As these markers may vary in concentration during pregnancy. It is important that any biochemical tests are synchronised with information gained from ultrasound scans to minimise the risk of false positive results and false negative results

Question 9

What is a false positive result

Answer 9

Suggesting a foetus has a condition when it does not

Question 10

What is a false negative result

Answer 10

Suggesting a foetus has not got a condition when it does

Question 11

When are further diagnostic tests which provide definitive results offered to pregnant women

Answer 11

• routine screening has highlighted a problem
• the individual is in a high risk category (women over the age of 35)
• there is a history of a harmful genetic disorder in the mothers family

Question 12

Why must a risk analysis be carried out

Answer 12

At this point, a risk analysis must be carried out because the diagnostic tests are invasive and may in few cases, cause damage to the foetus or trigger a miscarriage

Question 13

What are the two diagnostic tests

Answer 13

• Amniocentesis
• chronic villus sampling (CVS)

Question 14

What are the two screening tests

Answer 14

• dating scan
• anomaly scan

Question 15

Amniocentesis

Answer 15

Cells from amniocentesis can be used to make a karyotype which can detect chromosomal abnormalities

Question 16

Chorionic villus sampling

Answer 16

CVS from the placenta can be carried out earlier in pregnancy than amniocentesis. It has a higher risk of miscarriage but CVS karyotyping can be performed on the foetal cells immediately

Question 17

What are X and Y chromosomes in humans

Answer 17

In humans the X and Y chromosomes are the sex chromosomes

Question 18

What are all chromosomes apart from sex chromosomes in humans

Answer 18

All others are autosomes

Question 19

What can a pedigree allow

Answer 19

This then allows them to work out the chances of passing a genetic order on to their offspring

Question 20

Allele

Answer 20

An alternative form of a gene

Question 21

Homozygous

Answer 21

An individual with two identical alleles

Question 22

Heterozygous

Answer 22

An individual with two different alleles

Question 23

Genotype

Answer 23

The alleles which an organism carries, these are represented by letters

Question 24

Phenotype

Answer 24

The physical appearance of an organisms genotype

Question 25

Dominant

Answer 25

An allele which always shows in the phenotype

Question 26

Recessive

Answer 26

An allele which is masked by another unless the organism possesses two copies

Question 27

What is autosomal recessive inheritance

Answer 27

• the trait is expressed rarely and can skip generations
• sufferers are homozygous recessive (cc)
• non sufferers are homozygous dominant or heterozygous (CC, Cc)

Question 28

What is autosomal dominant inheritance

Answer 28

• the trait appears in every generation
• each sufferer of the trait has an affected parent
• all non sufferers are homozygous recessive, hh
• all sufferers are HH Hh

Question 29

How many inherited disorders can be successfully treated

Answer 29

None of these inherited disorders can be successfully treated except with the exception of phenylketonuria

Question 30

What is PKU

Answer 30

Phenylketonuria

Question 31

What does a substitution mutation mean in PKU

Answer 31

In PKU a substitution mutation means that the enzyme needed to convert phenylalanine to tyrosine is non functional

Question 32

What is the result of the non-functional enzyme

Answer 32

As a result there is a toxic build -up of the amino acid phenylalanine within the body. If untreated, it causes severe mental deficiency as the child grows

Question 33

Which type of diet are sufferers of PKU placed on .

Answer 33

PKU sufferers are screened for the presence of excess phenylalanine for the first few days after birth then placed on a restricted diet

Question 34

What can the restricted diet help for

Answer 34

Providing the diet is adhered to , particularly in early years when the brain is developing the mental deficiency is prevented

Question 35

What can an atypical chemical concentration lead to

Answer 35

An a typical chemical concentration can lead to diagnostic testing to determine if the fetus has a medicinal condition