LFSC P2 GR12 SEPT2014 MEMO ENG_hlayiso.com_.pdf

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE GRADE 12 SEPTEMBER 2014 LIFE SCIENCES P2 MEMORANDUM MARKS: 150 This memorandum consists of 8 pages.

Downloaded from hlayiso.com 2 LIFE SCIENCES P2 (SEPTEMBER 2014) SECTION A QUESTION 1 1.1 1.1.1 A  1.1.2 C  1.1.3 A  1.1.4 B  1.1.5 B  1.1.6 A  1.1.7 A  1.1.8 D  1.1.9 D  1.1.10 B  (10 x 2) (20) 1.2 1.2.1 Double Helix  1.2.2 Transcription  1.2.3 Hydrogen bonds 1.2.4 DNA replication  1.2.5 tRNA  1.2.6 Haploid  1.2.7 Alleles  1.2.8 Punctuated equilibrium  1.2.9 Geographic speciation  1.2.10 Genetic engineering/genetic modification  (10 x 1) (10) Copyright reserved Please turn over

Downloaded from hlayiso.com (SEPTEMBER 2014) LIFE SCIENCES P2 3 1.3 1.3.1 None  1.3.2 A only  1.3.3 Both A and B  1.3.4 A only  1.3.5 B only  1.3.6 A only  1.3.7 Both A and B  1.3.8 Both A and B  1.3.9 B only  1.3.10 A only  (10 x 2) (20) TOTAL SECTION A: 50 Copyright reserved Please turn over

Downloaded from hlayiso.com 4 LIFE SCIENCES P2 (SEPTEMBER 2014) SECTION B QUESTION 2 2.1 2.1.1 3 pairs (1) 2.1.2 Prophase 1  (1) 2.1.3 Crossing over  (1) 2.2 2.2.1 (a) 21  (1) (b) 6 (1) (c) 7 (1) 2.2.2 4 – ACU  5 – CCU  6 – GAG  (3) 2.2.3 4 – Threonine  5 – Proline  6 – Glutamate  (3) 2.2.4 valine  (1) 2.3 2.3.1 As the age of the mother increases,  the risk of having a Down syndrome child increases.  (2) 2.3.2 9 times  (2) 2.3.3 There are 3  copies of chromosome number 21 instead of just 2. (2) 2.4 2.4.1 B (1) 2.4.2 Organism A  (1) 2.4.3  Fast movement – to get away from danger   Ability to survey surroundings – to see where the dangers are   Freedom of forearm and hand – for tool use or for defence   Exposed to less UV light – for temperature regulation   Display of male genitals  – to attract a mate  (Any 3 x 2) (6) 2.4.4 Charles Darwin  (1) Copyright reserved Please turn over

Downloaded from hlayiso.com (SEPTEMBER 2014) LIFE SCIENCES P2 5 2.4.5 - As a result of genetic variation  in the giraffe population, some giraffe had longer necks than others.  - As a result of leaves being available, only higher up on trees,  giraffes competed for the leaves.  - Giraffes with shorter necks were outcompeted and died.  - Giraffes’ with longer necks survived.  - This is natural selection.  - The gene for longer necks was passed on to subsequent generations.  - Eventually all the giraffes had longer necks.  (Any 7 x 1) (7) 2.5 2.5.1 Bonobo  (1) 2.5.2 7 mya (million years ago) (1) 2.5.3 Orangutan  (1) 2.5.4 Humans and chimpanzees have a common ancestor  but are not in the same line of development.  (2) [40] Copyright reserved Please turn over

Downloaded from hlayiso.com 6 LIFE SCIENCES P2 (SEPTEMBER 2014) QUESTION 3 3.1 Individuals with RR will die before birth: Phenotypic ratio is therefore 2 red fur : 1 grey fur (rather than 3 red fur : 1 grey fur) Therefore: 200 / two thirds of the population has red fur 100 */ one third of the population has grey fur Any 6 points from diagram plus 1 compulsory point for the answer above (*) (7) 3.2 3.2.1 There are more than two alleles  possible at the one locus.  (2) 3.2.2 AB  (1) 3.2.3 (2) 3.3 3.3.1 60 arbitrary units  (1) 3.3.2 60 – 52  = 8 arbitrary units (2) 3.3.3 Grow wheat without insect poison gene.  (1) 3.3.4 It gave a higher yield in fields.  (1) 3.4 3.4.1 Four/4  (2) 3.4.2 (a) XHXh  (1) (b) XhY  (1) 3.4.3  The allele for the trait is carried on the X-chromosome /Y- chromosome does not carry the allele for the trait.  Males only have one X-chromosome   A male only needs one recessive allele  to be haemophiliac, whereas for a female to be haemophiliac both alleles must be recessive.  (Any 2 x 1) (2) Copyright reserved Please turn over

Downloaded from hlayiso.com (SEPTEMBER 2014) LIFE SCIENCES P2 7 3.4.4 50% / ½ (1) 3.4.5  To determine if the wife is a carrier.   To determine what the chances are of having a child with haemophilia.   Help them evaluate whether they would cope with such a child.   Help them to make an informed decision about whether to have children.  (Any 2 x 1) (2) 3.5 3.5.1 There are three bands of the child’s DNA,  which are identical to Mary’s.  (2) 3.5.2 Sam,  because four bands of his DNA matched those of the baby. /None of Johnny’s DNA matched the baby’s DNA. (2) 3.5.3 (a) blood testing  (1) (b)  Other people involved in the conflict can have the same blood type as the accused.   It can only show that the accused is not the father.  (Any 1 x 1) (1) 3.6 3.6.1 (a) Fewer resistant mosquitoes  / more susceptible mosquitoes (1) (b) Equal numbers of both type of mosquitoes.  (1) 3.6.2 Many of the susceptible/affected by DDT mosquitoes died because of the DDT application.  The resistant mosquitoes survived.  (2) 3.6.3 Those that survived the first DDT application reproduced  to form more offspring.  (2) 3.6.4 They were susceptible/affected by DDT  and were therefore killed off.  (2) [40] TOTAL SECTION B: 80 Copyright reserved Please turn over

Downloaded from hlayiso.com 8 LIFE SCIENCES P2 (SEPTEMBER 2014) SECTION C QUESTION 4 4.1 Trend towards bipedalism - The foramen magnum is at the base of the skull so that the head could be held vertically.  - The position of pelvic girdle/at the bottom of the core body is suitable to carry the weight of the body  - The pelvis is more cup-shaped which make it suitable to carry the core of the body.  - Their feet are directly under the body to carry the weight of the body.  - The decrease in the length of arms indicates a decreased dependency on its use in locomotion and therefore shows a more advanced stage of bipedalism.  - This is usually accompanied by an increase in the length of the legs.  - Humans have a lumbar curvature of the spine /S-shaped spinal column for better balance.  Change in diet from raw food to cooked food - Humans have smaller jaws  for eating cooked food.  - Ape-like beings have more prognathous jaws than human  for scooping the food /to reduce the dependency on arms.  - Ape-like beings have stronger jaws to break and chew raw food.  - Brow ridges became less developed in humans since the action of the smaller jaws did not create forces great enough for skull to have increased strength from the brow ridges.  - Humans have C-shaped jaws for increased chewing.  - Humans have flat nails and apes have claws to grab and grip their food.  - Absence of gaps (diastema) in humans between incisors and canines  indicating diet that is more refined.  - Humans have smaller teeth /incisors and canines for better chewing.  - Humans have flatter molars and pre-molars  for better chewing.  (17) Marking guidelines for the essay Relevance (R) Logical Sequence (L) Comprehensive (C) All information Ideas are arranged in a Both aspects required provided is relevant logical/cause-effect sequence. by the essay have been to the essay. sufficiently addressed. Only information Each significance is linked to Both aspects – relevant to the the relevant aspects. bipedalism and dietary development of change – are explained bipedalism and in a minimum of 13 change in diet is points. given. Synthesis (3) TOTAL SECTION C: 20 GRAND TOTAL: 150 Copyright reserved Please turn over