IGCSE Biology Paper-4: Specimen Questions with Answers 58 - 59 of 279

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Question 58


Describe in Detail


What are the major disorders related to hearing.


Presbycusis- It causes due to aging. The occurrence of presbycusis increases exponentially with age.

  • Presbycusis reduces the ability of the ears to alert a person to desirable factors and harmful factors in his or her surroundings.
  • Presbycusis makes understanding speech hard primarily.
  • People affected with Presbycusis may fail to respond or respond incorrectly when others speak to them.
  • Presbycusis may also alter speaking ability.

Tinnitus- It is the perception or thought of sound when there is no sound in reality external to the person. Tinnitus can occur due to many causes including obstruction of the ear canal, abnormality of any of the parts of the middle ear, inner ear, or infection in the ear or CNS, high blood pressure; atherosclerosis; diabetes mellitus, hormone imbalances, headaches, medications, and toxic chemicals.

Question 59

Describe in Detail


The diagram shows amniocentesis. What is the procedure of this method?

The Diagram Shows Amniocentesis


Amniocentesis (AFT) is a medical process in which prenatal diagnosis of chromosomal abnormalities and fetal infections, and used for sex determination in which a small amount of amniotic fluid, which contains fetal tissues, is sampled from the amniotic sac surrounding a developing fetus, and the fetal DNA is inspected for genetic deviations


  • Before the start of the procedure, an anesthetic can be given to the mother in order to relieve the pain
  • After this a needle is usually inserted through the mother՚s abdominal wall, then through the wall of the uterus, and finally into the amniotic sac.
  • With the help of ultrasound-guidance, a physician punctures the sac in a part away from the fetus and extracts approximately 20 ml of amniotic fluid.
  • Under a microscope the chromosomes are examined for abnormalities
  • The most common abnormalities detected are Down syndrome, Edwards՚s syndrome, and Turner syndrome.
  • In regard to the fetus, the puncture seals and the amniotic sac replenishes the liquid over the next 24 – 48 hours

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