GENETICS IBDP Biology 3.2 – Chromosomes May 24, 2021 Shveta 0 Comments Chromosomes, Genetics, IBDP Biology 1.The image shows a karyogram. [Source: https://commons.wikimedia.org/wiki/File:Karyotype_of_sheep_(Ovis_aries).png, by M. Singh, X. Ma, E. Amoah and G. Kannan] What information can be determined from this karyogram?The sex is femaleThe haploid number is 54Disjunction occurred during meiosisThe species is not human2. Cladograms can be created by comparing DNA or protein sequences. The cladogram on the left is based on DNA sequences and the cladogram on the right is based on comparing protein sequences. What is the reason that cladograms based on DNA sequences are more reliable predictors of the phylogenetic relationship of species than cladograms based on protein sequences?Amino acids are not as chemically stable as DNA nucleotidesDNA mutates but amino acids do notSeveral different triplets of bases can code for the same amino acidThere are 20 different amino acids but only 4 nucleotides3.Which is a characteristic of the pairs of sister chromatids that are visible during meiosis?They result from the replication of DNA before meiosisThey are only present in meiosis IThey split apart during metaphase I in meiosisThey are only present in meiosis II4. The bacterium Neisseria gonorrhoeae causes infections related to the human reproductive system. The graph shows the percentage of samples in which this bacterium showed resistance to six antibiotics over a period of ten years. What is a possible explanation for the total percentage resistance being larger than 100% in 2010?People do not take the antibiotics as prescribedMore people have been sampled in that yearThere was an epidemic of Neisseria gonorrhoeae in that yearSome bacteria are resistant to more than one antibiotic5. Which is a characteristic of the haploid number of eukaryotic chromosomes?It doubles in mitosisIt is fixed for each speciesIt is an even number for all speciesIt is positively correlated with an animal’s mass6. The diploid number of chromosomes in humans (Homo sapiens) is 46 and the diploid number of chromosomes in rice (Oryza sativa) is 24. What does this indicate about diploid chromosome numbers? Plant species have a lower diploid number of chromosomes than animalsMembers of a species have the same diploid number of chromosomesThe evolutionary progress of species is determined by the diploid number of chromosomesThe complexity of the organisms is correlated to the diploid number of chromosomes7. What is characteristic of homologous chromosomes?They have an identical DNA sequenceThey are of the same length in karyogramsThey form pairs in prokaryotesThey carry the same alleles8. What is a possible source of the chromosomes used for pre-natal karyotype diagnosis?The mother’s lymphocytes The mother’s cheek cells The cells from chorionic villi The fetal hair root cells 9. What causes the presence of three chromosomes 21 in Down syndrome? Crossing over Allele change Non-disjunction Gene mutation 10. What is a characteristic of the human Y chromosome?It is made of DNA and histones covered by phospholipidsIt contains some genes that are not present on the X chromosomeIt is the largest chromosome in the human karyotypeIt has a condensed length of approximately 100 µm11. What is the composition of eukaryotic chromosomes?DNA onlyDNA and riboseDNA and RNA DNA and proteins12. The image shows a human karyotype. According to the image, what conditions can be determined?Non-disjunction has occurred and the individual is maleNon-disjunction has occurred and the individual is femaleThe individual is female and has Down syndromeThe individual is male and has Down syndrome13. What information can be concluded from the karyotype? The person is a normal maleThe person is a normal femaleThe person is a male with Down syndromeThe person is a female with Down syndrome14. Which genetic condition can be diagnosed by karyotyping?Trisomy 21 Sickle-cell anemia Hemophilia Colour blindness 15. What commonly causes Down syndrome in humans?Non-disjunction Base substitution Amniocentesis Gene mutation 16. Which is a source of chromosomes for pre-natal diagnosis of abnormalities by karyotyping?Sperm Ovaries Erythrocytes Chorionic villi 17. Which is a source of chromosomes for pre-natal diagnosis of abnormalities by karyotyping?Sperm Ovaries Erythrocytes Chorionic villi 18. Which of the following statements about homologous chromosomes is correct?Each gene is at the same locus on both chromosomesThey are two identical copies of a parent chromosome which are attached to one another at the centromereThey always produce identical phenotypesThey are chromosomes that have identical genes and alleles19. What are homologous chromosomes?Identical chromosomes Non-identical chromosomes with different genes Non-identical chromosomes with the same genes in the same sequence but not necessarily the same allelesNon-identical chromosomes with the same genes in a different sequence and not necessarily the same alleles 20. What does the karyogram below correspond to? A normal male A normal femaleA female with Down syndromeA male with Down syndrome
