Ant and post

Question 1

Summary

Answer 1

A variety of techniques can be used to monitor the health of the mother, developing fetus and baby.

Question 2

Antenatal Screening

Answer 2

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

Question 3

Ultrasound imaging

Answer 3

Ultrasound imaging

Pregnant women are given two ultrasound scans.

Question 4

Dating Scan detail

Answer 4

Dating scans which determine pregnancy stage and due date are used with tests for marker chemicals which vary normally during pregnancy.

Question 5

Anomaly Scan

Answer 5

Anomaly scans may detect serious physical abnormalities in the fetus.

Question 6

Dating Scan and an Anomaly Scan dates

Answer 6

A dating scan takes place between 8 and 14 weeks and an anomaly scan between 18 and 20 weeks.

Question 7

Blood and Urine Tests

Answer 7

Blood and urine tests

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

Question 8

Blood urine tests and Measuring chemical at wrong stage

Answer 8

Measuring a chemical at the wrong time could lead to a false positive result. An atypical (unusual) chemical concentration can lead to
diagnostic testing to determine if the fetus has a medical condition

Question 9

Amniocentesis and chorionic villus sampling (CVS) and the advantages and disadvantages of their use.

Answer 9

Amniocentesis and chorionic villus sampling (CVS) and the advantages and disadvantages of their use.
CVS can be carried out earlier in pregnancy than amniocentesis, although it has a higher risk of miscarriage.

Question 10

Cells from samples can…

Answer 10

C ells from samples can be cultured to obtain sufficient cells to produce a karyotype to diagnose a range of conditions.

Question 11

Karyotype

Answer 11

A karyotype shows an individual’s chromosomes arranged as homologous pairs.

Question 12

Decision tests

Answer 12

In deciding to proceed with these tests, the element of risk will be assessed, as will the decisions the individuals concerned are likely to make if a test is positive.

Question 13

Postnatal Screening

Answer 13

Diagnostic testing for phenylketonuria (PKU).
In PKU a substitution mutation means that the enzyme which converts phenylalanine to tyrosine is non-functional.
Individuals with high levels of phenylalanine are placed on a restricted diet.

Question 14

Autosomal Dominance inheritance

Answer 14

The trait appears in every generation.
Each sufferer has one affected parent.
If a branch of the family does not express the trait, the trait fails to appear in future generations.
Males and females affected in approximately equal numbers.

Question 15

Autosomal recessive inheritance

Answer 15

An autosomal recessive pattern of inheritance is recognisable because usually:
The trait is relatively rare.
The trait may skip generations.
Trait is expressed in some of the offspring on a consanguineous marriage (e.g. cousins)
Males and females affected in approximately equal numbers.

Question 16

Autosomal incomplete dominance

Answer 16

The fully expressed form of the disorder is relatively rare.
The partially expressed form occurs more frequently.
Each sufferer of the fully expressed form has 2 parents who suffer from the partly expressed form of the disorder.
Males and females affected in approximately equal numbers.

Question 17

Sex linked

Answer 17

A sex linked recessive pattern of inheritance is recognisable because usually:

Many more males affected than females (if any)
No sons of an affected male show the trait
Some grandsons of an affected male may show the trait

Genotypes can be added to family tree –
All sufferers are homozygous recessive (normally male XhY, very rarely female XhXh)
Non sufferers are homozygous dominant (XHY or XHXH) or heterozygous carrier females (XHXh)

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