Life Sciences Grade 12 Eastern Cape June 2022 Memo (English)

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE GRADE 12 JUNE 2022 LIFE SCIENCES MARKING GUIDELINE MARKS: 150 This marking guideline consists of 9 pages.

Downloaded from hlayiso.com 2 LIFE SCIENCES (EC/JUNE2022) SECTION A QUESTION 1 1.1 1.1.1 D ✓✓ 1.1.2 B ✓✓ 1.1.3 A ✓✓ 1.1.4 A ✓✓ 1.1.5 C ✓✓ 1.1.6 B ✓✓ 1.1.7 A ✓✓ 1.1.8 C ✓✓ 1.1.9 A ✓✓ 1.1.10 C ✓✓ (10 x 2) (20) 1.2 1.2.1 Internal ✓ fertilisation 1.2.2 Umbilical vein ✓ 1.2.3 Mitochondrion ✓/Mitochondria 1.2.4 Pinna ✓ 1.2.5 Acrosome ✓ 1.2.6 Puberty ✓ 1.2.7 Chromatin ✓ network 1.2.8 Amniotic ✓egg (8 x 1) (8) 1.3 1.3.1 A only ✓✓ 1.3.2 B only ✓✓ 1.3.3 None ✓✓ (3 x 2) (6) 1.4 1.4.1 DNA profiling ✓ (1) 1.4.2 Adult C ✓ (1) 1.4.3 • All bands of adult B and C together ✓ • match all the children’s bands ✓ OR • He is the only adult that can provide all the DNA bands ✓ with adult B that the children have ✓ (2) Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/JUNE 2022) LIFE SCIENCES 3 1.4.4 • Child 1 and 2 ✓✓ (2) 1.4.5 • Tracing missing persons ✓ • Identify crime suspects ✓ • Identification of genetic disorders ✓ • Establishing family relations ✓ • Matching tissues for organ transplants ✓ • Identifying dead persons ✓/animals (Mark first TWO only) (2) 1.5 1.5.1 (a) Dihybrid cross ✓ (1) (b) Involves the inheritance of two characteristics ✓ (1) 1.5.2 1✓ (1) 1.5.3 FfBb ✓ (1) 1.5.4 (a) Fluffy tails and brown fur ✓ (1) (b) ffBb ✓ (1) 1.5.5 12 3 ✓✓ OR 4 OR 75% (2) 16 TOTAL SECTION A: 50 Copyright reserved Please turn over

Downloaded from hlayiso.com 4 LIFE SCIENCES (EC/JUNE2022) SECTION B QUESTION 2 2.1 2.1.1 (a) Deoxyribose ✓ (1) (b) Nucleotide ✓ (1) 2.1.2 • The DNA (double helix) unwinds✓and • unzips ✓/hydrogen bonds break • to form two separate strands ✓ • Both DNA strands serve as templates ✓ • to build a complementary DNA ✓/(A to T and C to G) using free (DNA) nucleotides from the nucleoplasm • This results in two identical (DNA) molecules ✓ • Each molecule consists of one original strand and one new strand ✓ (Any 6 x 1) (6) 2.1.3 Met ✓- Phe ✓- Cys ✓ (3) 2.1.4 • Codon AUG (on the mRNA) changed to AAG ✓ • Anticodon UAC (on tRNA) changed to UUC ✓ • which resulted in Lys ✓ being picked by tRNA and • a different protein was formed ✓ (4) 2.2.1 (a) Locus ✓ (1) (b) Centromere ✓ (1) 2.2.2 Heterozygous ✓ (1) 2.2.3 The alleles/letters representing the gene are different. ✓ (1) 2.2.4 Similarity: • They carry the same genes at the same loci ✓/positions/locations Difference: • They carry different alleles ✓ • because of crossing over ✓ during meiosis and • mutations ✓/copying errors during DNA replication 1 similarity + Any 2 differences (3) 2.3 2.3.1 (a) Zygote ✓ (1) (b) Morula ✓/ Blastula (1) 2.3.2 Fertilisation ✓ (1) 2.3.3 In the fallopian tubes ✓/Oviducts (1) Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/JUNE 2022) LIFE SCIENCES 5 2.3.4 • The process is oogenesis ✓ • Diploid cells in the ovary undergo mitosis ✓ • to form numerous follicles ✓ • At the onset of puberty ✓ • and under the influence of FSH ✓ • one cell inside a follicle enlarges and undergoes meiosis ✓ • Of the four cells that are produced, only one survives ✓ • to form a mature, haploid ovum ✓ (Any 6 x 1) (6) 2.3.5 • Amniotic fluid acts as a shock absorber and protect the foetus from mechanical injury ✓ /temperature changes/dehydration • The placenta serves as a barrier protecting the foetus from certain diseases ✓ (2) 2.4 P1 Phenotype White patch x White patch  Genotype Hh x Hh  Meiosis G/gametes H, h x H, h Fertilisation F1 Genotype HH; Hh; Hh hh  Phenotype 3 White patch: 1 Without white patch * P1 and F1  Meiosis and fertilisation  *Compulsory 1 + Any 5 OR P1 Phenotype White patch x White patch  Genotype Hh x Hh  Meiosis Gametes H h H HH Hh Fertilisation h Hh hh 1 mark for correct gametes 1 mark for correct genotypes F1 Phenotype 3 White patch: 1 Without white patch * P1 and F1  Meiosis and fertilisation  *1 Compulsory + Any 5 (6) 2.5.1 Karyotype ✓ (1) 2.5.2 Autosomes ✓ (1) 2.5.3 Female ✓ (1) Copyright reserved Please turn over

Downloaded from hlayiso.com 6 LIFE SCIENCES (EC/JUNE2022) 2.5.4 • The last pair ✓/chromosome pair 23/gonosomes • consist of two X chromosomes ✓/XX (2) 2.5.5 • During Anaphase ✓ I/II • Chromosome pair 21/chromosome failed to separate ✓/ nondisjunction occurred at position 21 • Resulting in a gamete (daughter cell) with an extra chromosome ✓ at position 21 • When this gamete was fertilised by a normal gamete ✓ • The zygote ended up with 3 chromosomes at position 21 ✓ (5) [50] Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/JUNE 2022) LIFE SCIENCES 7 QUESTION 3 3.1 3.1.1 (a) Centriole ✓/ Centrosome (1) (b) Spindle fibre ✓ (1) 3.1.2 Anaphase I ✓ (1) 3.1.3 Each chromosome of each homologous pair is being pulled to the opposite poles ✓ (1) 3.1.4 3✓ (1) 3.1.5 • The chromosomes show swapped segments of genetic material ✓ (1) 3.1.6 • Introduces genetic variation ✓ in offspring thereby • improving the chances of survival ✓ (2) 3.2 3.2.1 (a) Menstruation ✓ (1) (b) Ovulation ✓ (1) 3.2.2 (a) Follicle stimulating hormone ✓/FSH (1) (b) Progesterone ✓ (1) 3.2.3 • Stimulates the development of primary follicles into mature Graafian follicle ✓ (1) 3.2.4 • The endometrial lining will no longer be maintained ✓ • This will result in the lining being broken down and shed ✓ • during menstruation ✓ • preventing possible implantation of the fertilised egg ✓ • and pregnancy ✓ • new follicle ✓ being formed (Any 5 x 1) (5) 3.3 3.3.1 (a) D ✓– Eustachian tube ✓ (2) (b) E ✓– Round window ✓ (2) 3.3.2 Transmits sound vibrations to the middle ear. ✓ (1) 3.3.3 • They lie on three different planes ✓ • to detect movement in any direction ✓ • fluid moves in at least one of the semi-circular canals ✓ • to stimulate receptors ✓ (Any 3 x 1) (3) Copyright reserved Please turn over

Downloaded from hlayiso.com 8 LIFE SCIENCES (EC/JUNE2022) 3.4 • The receptor receives the stimulus ✓ and • converts it into an impulse ✓ • which is transmitted by the sensory neuron ✓ • through the dorsal root ✓ • of the spinal nerve ✓ • to the spinal cord ✓ • where the impulse is transferred via the interneuron ✓ • to the motor neuron ✓ • which carries the impulse via the ventral root ✓ • to the effector ✓/muscle/gland • The impulse is transferred from one neuron to the next via a synapse ✓ (Any 7 x 1) (7) 3.5 3.5.1 X = 292 + 301 + 297 ✓ 3 = 297 ✓mm ✓ (Accept 296,67/ 296,7) (3) 3.5.2 (a) Accommodation ✓ (1) (b) • Ciliary muscles contract ✓ • Suspensory ligaments slacken ✓/loosen • Tension on the lens decreases ✓ • Lens becomes more convex ✓/more rounded/bulging • Light rays are focused on the retina ✓ (5 x 1) (5) 3.5.3 Effect of age on the average focusing distance 350 Average focusing distance (mm) 309 300 279 258 250 200 40 150 45 55 100 50 0 Age (6) Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/JUNE 2022) LIFE SCIENCES 9 Guideline for assessing the graph CRITERIA ELABORATION MARK Correct type of graph Bar graph drawn 1 (T) Caption of graph (C) Both variables included 1 Axes labels (L) X- and Y-axis correctly labelled 1 Scale for X-and Y- - Equal space between bars and axis(S) width of bars for X-axis and 1 - Correct scale for Y-axis Plotting of bars (P) - 1 to 2 bars plotted correctly 1 - All 3 bars plotted correctly 2 3.5.4 As the age of the volunteers increase, the longer is the average focusing distance. ✓✓ OR As the age of the volunteers decreases, the shorter is the average focusing distance ✓✓ (2) [50] TOTAL SECTION B: 100 GRAND TOTAL: 150 Copyright reserved Please turn over