Author: Anonymous

2.3.5 Behalwe vir die ovulasie gesien in die diagram hierbo, beskryf die gebeure wat sal moet plaasvind vir ‘n ovum om bevrug te word.   (4)

QUESTION 3 3.1 Read the case below and answer the questions that follow: Lesh-Nyhan Syndrome (LNS) is a rare but fatal human genetic disorder caused by a recessive allele found on the X-chromosome. Individuals with this disorder have a specific enzyme deficiency which causes a build-up of uric acid in all the body fluids. At birth, infants with the syndrome function normally, but as uric acid increases in their systems, delays in motor development occurs, leading to weak muscles, involuntary muscle spasms and moderate mental retardation. By 2 to 3 years of age, individuals often show self-mutilation behaviour, such as biting of fingers and lips, and the inside of the mouth. Death is usually due to infection, renal failure or uraemia (high levels of uric acid in the blood) between the ages of 10 and 30. After Anne and Mike, who are both healthy, had their only son diagnosed with LNS, the couple went to their families to investigate. Mike’s family had no history of the disorder. Much to Anne’s surprise, her mother told her that Anne’s uncle had suffered from the disorder and died before Anne was born. Adapted from: Lesch-Nyhan Syndrome Information Page | National Institute of Neurological Disorders and Stroke (2021). Available at: https://www.ninds.nih.gov/Disorders/All-Disorders/Lesch-Nyhan-Syndrome-Information-Page (Accessed: 3 May 2021).

3.1.1 (b) Quote a phrase from the text to provide a reason for your answer in 3.1.1 (a). (1)

1.1.4 Which statement regarding DNA and RNA is correct?  A.  There are three types of DNA and one type of RNA.B.  DNA is a helical molecule that is wrapped around histones, while RNA is a linear molecule that is not wrapped around histones.C.  DNA is a single helix, while RNA is a double helix.D.  DNA is a short, linear molecule, while RNA is a long, helical molecule. (2)

3.2.3  Which inheritance pattern do these traits follow? Choose the correct option: A.  Complete dominanceB.  Co-dominanceC.  Incomplete dominance  (2)

3.2.1 How many alelles are involved in the traits outline above?Only type the number (numerical). No letters, no punctuation. (1)

Dit is ‘n ekstra lêer oplaai opsie. Gebruik dit SLEGS as ‘n vorige vraag vermis of foutief was. As jy wel ‘n lêer hier oplaai, noem of nommer dit duidelik en volgens die betrokke vraagnommer.

2.2 ‘n Wetenskaplike het ‘n studie gedoen om vas te stel of  ʼn  vasektomie (die afsny van die vas deferens) ‘n invloed sal hê op testosteroonproduksie.  Hy het twaalf volwasse, manlike Reuse Afrika rotte gebruik. Hy het hulle in drie groepe ingedeel. Aan die begin van die eksperiment was al die rotte getoets – almal het dieselfde testikulêre gewig, spermtelling, sperm-beweeglikheid en testosteroonvlakke gehad.  ‘n Vasektomie was gedoen slegs op die regter testes van die rotte in Groep 1 en Groep 2. Hulle linker testes het onbehandeld gebly. Die rotte in Groep 3 het heeltemal onbehandeld gebly.  Na 6 en 8 weke was die testosteroonvlakke in die rotte se bloed getoets. Semen van beide testes was onttrek en geanaliseer. Die resultate word in die tabel hieronder getoon. Resultate van ‘n vasektomie op testosteroonvlakke in Reuse Afrika rotte Groep Behandeling Hoeveelheid weke tussen vasektomie en toetsing Testikulêre gewig (g) Spermtelling (x 106/ml) Beweeg-baarheid van sperm (%) Testosteroon vlakke (ng/ml) Rtestis L testis R testis L testis 1 Vasektomie aan regter testis 8 weke 1.75 2.26 0.25 0.35 22 0.65 2 Vasektomie aan regter testis 6 weke 2.53 3.22 7.2 14.1 19 1.1 3 Onbehandeld 8 weke 5.51 5.35 71.0 68.2 83 1.4   Aangepas vanaf:  Makerere Medical School, Uganda 2013 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3824497/

3.2.2 Explain what an allele is. (2)

1.4.2 Provide labels for parts numbered A, B, C, D, and E. (5)