Topic 3: the Chemistry of Life

Topic 4: Genetics (15 hours)

Assessment Statement Response Sample test question 4.1.1 State that eukaryote Page 102 2009 Specimen Paper chromosomes are made of 3. (a) State the two classes of DNA and proteins compounds that compose chromosomes in animal cells. [1] 3. (a) DNA and protein [1]

4.1.2 Define gene, allele, and Pg. 239 genome

4.1.3 Define gene mutation Pg. 328-329 IB says The terms point mutation or frameshift mutation will not be used.

4.1.4 Explain the consequence of Page 267 a base substitution mutation in relation to the processes of transcription and translation, using the example of sickle cell anemia 4.2.1 State that meiosis is a Page 243 2009 Specimen Paper reduction division of a 10. If the amount of DNA in a diploid nucleus to form haploid gamete is represented haploid nuclei by , what is the net quantity of DNA in a cell from the same organism at the start of meiosis? A. 0.5 B. C. 2 D. 4 4.2.2 Define homologous Page 240-241 chromosomes

4.2.3 Outline the process of Page 244-245 2009 Specimen Paper meiosis, including pairing of homologous chromosomes IB says: Limit crossing over to the exchange of 3(b) Outline how meiotic division and crossing over, followed genetic material between non-sister chromatids results in almost an infinite by two divisions, which during prophase I. Names of the stages are required. genetic variation in the results in four haploid cells gametes produced. [2]

3b (b) crossing over/chiasmata; shuffles alleles; random orientation of chromosomes; at metaphase I: at metaphase II; [2 max]

4.2.4 Explain that non-disjunction Page 285-288 2009 Specimen Paper can lead to changes in IB says: The characteristics of Down syndrome are chromosome number, not required. 3(d) State how chromosome illustrated by reference to number can increase in human Down syndrome (trisomy beings. 21) [1]

3[d] Nondisjunction [1] 4.2.5 State that, in karyotyping, Page 240 chromosomes are arranged in pairs according to their size and structure

4.2.6 State that karyotyping is Page 269-270 performed using cells collected by chorionic villus sampling or amniocentesis, for pre-natal diagnosis of chromosome abnormalities. 4.2.7 Analyse a human karyotype See Figure 13.3 on page 240 for a sample karyotype to determine gender and whether non-disjunction has occurred

4.3.1 Define genotype, phenotype, Page 239 2009 Specimen Paper dominant allele, recessive Page 251-266 11. A parent organism of unknown allele, codominant alleles, genotype is mated in a test cross. locus, homozygous, Half of the offspring have the heterozygous, carrier and same test cross. phenotype as the parent. What can be concluded from this result? A. The parent is homozygous dominant for the trait. B. The trait being inherited is polygenic. C. The parent is heterozygous for the trait. D. The parent is homozygous recessive for the trait.

4.3.2 Determine the genotypes and Page 254-257 2009 Specimen Paper phenotypes of the offspring IB says: The grid should be labeled to include 3(c) In a species of plant, tall is of a monohybrid cross using parental genotypes, gametes, and both offspring dominant to short and the a Punnett grid genotype and phenotype production of round seeds is dominant to that of wrinkled seeds. The alleles are unlinked. A plant heterozygous for both characteristics is crossed with a plant homozygous for tall with wrinkled seeds. Use the letters: T – allele for tall t – allele for short R – allele for round seed r – allele for wrinkled seed. Determine the phenotypes and genotypes of the offspring of this cross. [2]

3c. (c) all four genotypes shown: TTRr, TTrr, TtRr, Ttrr; phenotype individually identified/2 tall round and 2 tall wrinkled; [2] Cannot use genotype letters by themselves to mean phenotypes e.g. cannot state that the phenotype of a tall round plant is TR etc.

4.3.3 State that some genes have Page 262 more than two alleles (multiple alleles) 4.3.4 Describe ABO blood groups Page 262 as an example of codominance and multiple alleles

4.3.5 Explain how the sex Page 240 chromosomes control gender by referring to the inheritance of X and Y chromosomes in humans 4.3.6 State that some genes are Page 240 present on the X chromosome and absent from the shorter Y chromosome in humans 4.3.7 Define sex linkage Page 283-284

4.3.8 Describe the inheritance of Page 283-284 colour blindness and hemophilia as examples of sex linkage

4.3.9 State that a human female Page 283-284 can be homozygous or heterozygous with respect to sex-linked genes

4.3.10 Explain that female carriers Page 283-284 are heterozygous for X- linked recessive alleles

4.3.11 Predict the genotypic and phenotypic ratios of offspring of monohybrid crosses involving any of the above patterns of inheritance

4.3.12 Deduce the genotypes and Page 265-266 phenotypes of individuals in IB says: For dominant and recessive alleles, upper- pedigree charts case and lower-case letters, respectively, should be used. Letters representing alleles should be chosen with care to avoid confusion between upper and lower case. For codominance, the main letter should relate to the gene and the suffix to the allele, both upper case. For example, red and white codominant flower colours should be represented as CR and CW, respectively. For sickle-cell anemia, HbA is normal and Hbs is sickle cell.

4.4.1 Outline the use of Page 391-392, including Figure 20.7 polymerase chain reaction IB says: Details of methods are not required. (PCR) to copy and amplify minute quantities of DNA

4.4.2 State that, in gel Page 392-394, including Figure 20.8 electrophoresis, fragments of DNA move in an electric field and are separated according to their size.

4.4.3 State that gel electrophoresis Page 404-405 of DNA is used in DNA profiling 4.4.4 Describe the application of Page 402-405 DNA profiling to determine paternity and also in forensic investigations.

4.4.5 Analyse DNA profiles to Figure 20.17 on page 405, for example draw conclusions about paternity or forensic investigations

4.4.6 Outline three outcomes of Page 394-398 the sequencing of the complete human genome

4.4.7 State that, when genes are transferred between species, the amino acid sequence of polypeptides translated from them is unchanged because the genetic code is universal. 4.4.8 Outline a basic technique Pg. 386-388, including Figure 20.4 2009 Specimen Paper used for gene transfer 12. How are plasmids used in involving plasmids, a host biotechnology? cell (bacterium, yeast or A. For respiration in prokaryotes other cell), restriction B. For photosynthesis in enzymes (endonucleases), eukaryotes and DNA ligase C. For protein synthesis in prokaryotes and eukaryotes D. For gene transfer

4.4.9 State two examples of the Page 406-407 current uses of genetically modified crops or animals.

4.4.10 Discuss the potential benefits and possible harmful effects of one example of genetic modification

4.4.11 Define clone

4.4.12 Outline a technique for Pg. 415-417 cloning using differentiated See Figure 21.8—go on! Look at it!!! Awwww, what animal cells a cutie!!! 4.4.13 Discuss the ethical issues of therapeutic cloning in humans