In Matric Life Sciences (DNA: Code of Life), who discovered the double-helix structure of DNA in 1953 using X-ray diffraction photographs taken by Rosalind Franklin and Maurice Wilkins?

James Watson and Francis Crick.

In Matric Life Sciences (Cradle of Humankind Fossils), match the famous South African and East African hominid fossils to their species, discoverers, and sites.

'Taung Child' (Australopithecus africanus): Raymond Dart (1924, Taung, North West); 'Mrs Ples' (Australopithecus africanus): Robert Broom (1947, Sterkfontein Caves); 'Little Foot' (Australopithecus prometheus/africanus): Ron Clarke (Sterkfontein); 'Karabo' (Australopithecus sediba): Lee Berger (2008, Malapa); 'Homo naledi': Lee Berger (Rising Star Cave); 'Lucy' (Australopithecus afarensis): Donald Johanson (Ethiopia); 'Turkana Boy' (Homo erectus): Richard Leakey/Kamoya Kimeu (Kenya).

In Matric Life Sciences (Evolution), contrast Punctuated Equilibrium (Eldredge & Gould, 1972) with Phyletic Gradualism (Darwin).

Gradualism proposes that species evolve slowly and continuously through small cumulative changes over long geological periods (predicting many transitional fossils). Punctuated Equilibrium proposes that species remain largely unchanged for long periods of stasis, interrupted ('punctuated') by relatively brief bursts of rapid speciation—explaining the scarcity of transitional fossils in the fossil record.

In Matric Life Sciences (Human Reproduction), what are the structures of a human sperm cell (acrosome, nucleus, middle piece, tail) and the functions of the seminal vesicles, prostate gland, and Cowper's glands?

Acrosome: contains hydrolytic enzymes to penetrate the ovum membrane; Nucleus: carries 23 haploid chromosomes; Middle piece: packed with mitochondria to supply ATP for swimming; Tail (flagellum): propulsion. Seminal vesicles: secrete fructose-rich fluid for sperm energy; Prostate gland: secretes alkaline fluid to neutralize acidic vaginal secretions; Cowper's glands: secrete mucus for lubrication and motility.

In Matric Life Sciences (Endocrine Disorders), distinguish between Type 1 and Type 2 Diabetes Mellitus, Hyperthyroidism (Graves' disease), and Hypothyroidism (Goitre/Myxoedema).

Type 1 Diabetes: autoimmune destruction of beta cells in the Islets of Langerhans resulting in little/no insulin production (treated with daily insulin injections). Type 2 Diabetes: body cells become resistant to insulin (linked to obesity/lifestyle). Hyperthyroidism: over-secretion of thyroxin causing high metabolic rate, weight loss, hyperactivity, and exophthalmos. Hypothyroidism: under-secretion of thyroxin causing low metabolic rate, weight gain, lethargy, and goitre (iodine deficiency).

In Matric Life Sciences (Genetics Pedigree Diagrams), how do you determine whether a trait on a pedigree chart is Autosomal Dominant, Autosomal Recessive, or Sex-Linked (X-linked) Recessive?

If two unaffected parents have an affected child, the disorder MUST be recessive (parents are heterozygous carriers). If two affected parents have an unaffected child, the trait MUST be dominant. If the trait is recessive and affects predominantly males (passed from carrier mothers to sons, never from father to son), it is X-linked recessive (e.g., haemophilia, red-green colour blindness).

In NSC Matric Life Sciences (Paper 2), how is the curriculum split between Paper 1 (150 marks) and Paper 2 (150 marks) under the DBE CAPS examination guidelines?

Paper 1 (150 marks): Reproduction in Vertebrates, Human Reproduction, Responding to the Environment (Humans & Plants), Endocrine System, and Homeostasis in Humans. Paper 2 (150 marks): DNA: The Code of Life, Meiosis, Genetics and Inheritance, and Evolution.

In Matric Life Sciences (Scientific Investigation Questions), how do you identify the Independent Variable, Dependent Variable, Fixed/Controlled Variables, Reliability, and Validity?

Independent variable: the factor deliberately manipulated by the investigator (plotted on X-axis). Dependent variable: the effect measured/observed (plotted on Y-axis). Validity: improved by keeping all other controlled variables constant (same age, temperature, species). Reliability: improved by increasing sample size or repeating the investigation and calculating an average.

In Matric Life Sciences (Human Reproduction), what are the functions of the Amniotic Fluid, Umbilical Artery, Umbilical Vein, and Placenta during gestation?

Amniotic fluid (inside amnion): acts as a shock absorber, prevents dehydration, maintains constant temperature, and allows free fetal movement. Umbilical vein: carries oxygenated, nutrient-rich blood FROM the placenta TO the fetus. Umbilical arteries (two): carry deoxygenated blood and nitrogenous waste/CO2 FROM the fetus TO the placenta. Placenta: site of gas/nutrient/waste exchange by diffusion, secretes progesterone after week 12, and passes maternal antibodies (passive immunity).

In Matric Life Sciences (Homeostasis), how does the body respond when blood Carbon Dioxide (CO2) levels increase during strenuous exercise?

High CO2 lowers blood pH (making blood more acidic as carbonic acid forms). Chemoreceptors in the carotid and aortic bodies detect the drop in pH and send impulses to the medulla oblongata, which sends impulses to the diaphragm and intercostal muscles to contract faster and deeper (increasing rate and depth of breathing) and to the heart to beat faster, expelling excess CO2.

In Matric Life Sciences (Homeostasis), how do ADH (Antidiuretic Hormone) and Aldosterone regulate Osmoregulation (water) and Salt (Sodium) balance in the kidney?

When blood water content is low (dehydration/sweating): osmoreceptors in the hypothalamus stimulate the pituitary gland to secrete MORE ADH, which increases the permeability of the distal convoluted tubules and collecting ducts, reabsorbing more water into the blood (producing a small volume of concentrated urine). When blood sodium (Na⁺) is low: the adrenal cortex secretes MORE Aldosterone, increasing Na⁺ reabsorption from the renal filtrate into the blood.

In Matric Life Sciences (Evolution), what is the difference between Artificial Selection (Selective Breeding) and Natural Selection?

In Natural Selection, the environment acts as the selective pressure, selecting traits that increase the organism's survival and reproductive fitness in the wild (maintaining genetic diversity). In Artificial Selection, HUMANS act as the selective agent, breeding organisms for traits that benefit human needs (e.g., high milk yield in cattle, drought-tolerant maize), which reduces genetic variation and increases homozygosity.

In Matric Life Sciences (Human Eye), compare the Pupillary Mechanism (Light Reflex) in bright light vs. dim light, and Accommodation for near ( 6 m) vision.

Pupillary Mechanism in Bright Light: circular muscles of the iris CONTRACT, radial muscles RELAX, pupil CONSTRICTS to let less light in (opposite in dim light). Accommodation for Near Vision (<6 m): ciliary muscles CONTRACT, suspensory ligaments SLACKEN, tension on lens decreases, and the elastic lens becomes MORE CONVEX (rounder) with greater refractive power.

In Matric Life Sciences (Human Evolution), list the anatomical differences in the skull, spine, pelvis, and foramen magnum between African Apes (Chimpanzees) and Homo sapiens (Bipedalism).

Homo sapiens vs. African Apes: 1. Foramen magnum is in a forward (central) position under the skull (vs. backward in apes) for upright bipedal balance; 2. Spine is S-shaped for shock absorption (vs. C-shaped in apes); 3. Pelvis is short and wide/cup-shaped to support internal organs (vs. long and narrow in apes); 4. Larger cranium/brain volume, flatter face (non-prognathous), smaller canines with no diastema, U-shaped to parabolic dental arcade, and no cranial/brow ridges.

In Matric Life Sciences (Biotechnology), distinguish between Stem Cells, Reproductive Cloning, Therapeutic Cloning, and Genetic Modification (GMOs).

Stem cells are undifferentiated cells (embryonic, umbilical cord blood, or bone marrow) capable of differentiating into specialized tissues. Reproductive cloning produces a genetically identical whole organism (e.g., Dolly the sheep via somatic cell nuclear transfer). Therapeutic cloning produces embryonic stem cells to repair damaged organs/tissues. Genetic modification inserts a desirable gene (e.g., human insulin gene into bacterial plasmids) using restriction enzymes and DNA ligase.

In Matric Life Sciences (Meiosis), what is Non-disjunction, and how does it cause Down Syndrome (Trisomy 21)?

Non-disjunction is the failure of homologous chromosomes (in Anaphase I) or sister chromatids (in Anaphase II) to separate properly during meiosis. If a gamete with an extra chromosome 21 (n + 1 = 24) fuses with a normal gamete (n = 23), the resulting zygote has 47 chromosomes with three copies of chromosome 21 (Trisomy 21 / Down Syndrome).

In Matric Life Sciences (Human Reproduction), trace the hormonal control of the 28-day Menstrual Cycle involving FSH, Oestrogen, LH, and Progesterone.

1. Pituitary gland secretes FSH, which stimulates development of a primary follicle into a Graafian follicle in the ovary. 2. Developing Graafian follicle secretes Oestrogen, which thickens the endometrium and, at high levels, triggers a surge of LH (while inhibiting FSH). 3. LH (from pituitary) triggers Ovulation (Around Day 14) and converts the ruptured follicle into the Corpus Luteum. 4. Corpus Luteum secretes Progesterone, which maintains the thick vascular endometrium for implantation and inhibits FSH and LH (negative feedback).

In Matric Life Sciences (Endocrine System & Homeostasis), explain the Negative Feedback mechanism regulating Thyroxin levels via TSH and Thyroxin.

When blood thyroxin levels drop below normal, the pituitary gland detects this and secretes MORE TSH (Thyroid-Stimulating Hormone) into the blood. TSH stimulates the thyroid gland to secrete more thyroxin, raising metabolic rate back to normal; high thyroxin then inhibits the pituitary gland from secreting TSH.

In Matric Life Sciences (Meiosis), during which phase does Crossing Over occur, and how does it together with Random Arrangement of chromosomes introduce genetic variation?

Crossing Over occurs in Prophase I: homologous chromosomes pair up to form bivalents, and non-sister chromatids overlap at chiasmata to exchange genetic material. Random Arrangement occurs at the equator during Metaphase I (homologous pairs) and Metaphase II (single chromosomes), producing genetically distinct haploid gametes.

In Matric Life Sciences (Human Ear), how does the ear carry out Hearing (via the Organ of Corti in the cochlea) versus Balance (via the Cristae and Maculae)?

Hearing: Tympanic membrane -> ossicles (malleus, incus, stapes) -> oval window -> pressure waves in endolymph stimulate hair cells of the Organ of Corti -> auditory nerve -> cerebrum. Balance: Cristae in the ampullae of the three semicircular canals detect changes in SPEED and DIRECTION of head movement; Maculae in the utriculus and sacculus detect the position of the head relative to GRAVITY -> vestibular nerve -> cerebellum.

In Matric Life Sciences, if a DNA template strand has the base triplet 3'-TAC-5', what is the corresponding mRNA codon and the tRNA anticodon?

mRNA codon = AUG (start codon coding for Methionine); tRNA anticodon = UAC.

In Matric Life Sciences (Plant Hormones), what are the roles of Auxins in Apical Dominance, Phototropism, and Geotropism, and what are the roles of Gibberellins and Abscisic Acid?

Auxins produced at the apical bud inhibit the growth of lateral buds (apical dominance—removing the tip causes lateral branches to grow bushy). Gibberellins stimulate stem elongation (bolting) and seed germination. Abscisic Acid promotes seed/bud dormancy during winter and triggers stomatal closure during drought stress.

In Matric Life Sciences, why is mitochondrial DNA (mtDNA) used to trace maternal ancestry (such as 'Mitochondrial Eve' in Out-of-Africa evolution questions)?

During fertilization, only the nucleus of the sperm enters the ovum while the sperm's mitochondria in the middle piece are discarded outside; therefore, zygotes inherit mtDNA exclusively from the mother's ovum, and mtDNA mutates at a known, steady rate without crossing over.

In Matric Life Sciences (Human Evolution), what are the two main lines of evidence supporting the 'Out of Africa' Hypothesis?

1. Fossil evidence: Ardipithecus, Australopithecus, and Homo habilis fossils are found ONLY in Africa (Rift Valley and South Africa), and the oldest Homo erectus and Homo sapiens fossils are also found in Africa. 2. Genetic evidence (mtDNA): analysis of mutations in mitochondrial DNA shows the highest genetic diversity—and therefore the oldest ancestral populations—in Africa.

In Matric Life Sciences (Thermoregulation), write the DBE sequence explaining how the hypothalamus and skin blood vessels respond on a COLD day.

1. Thermoreceptors in the skin and hypothalamus detect a drop in temperature. 2. The hypothalamus sends nerve impulses to the blood vessels of the skin. 3. Vasoconstriction occurs (arterioles supplying skin capillaries narrow). 4. Less warm blood flows to the surface of the skin and sweat glands become inactive. 5. Less heat is lost from the body by radiation, convection, Conduction, and evaporation.

In Matric Life Sciences (Speciation), write the standard 6-point DBE template for Allopatric Speciation (Speciation through Geographic Isolation).

1. If a population of a single species becomes separated by a geographical barrier (mountain, river, ocean, continental drift), 2. the population splits into two and there is NO GENE FLOW between them. 3. Because each population is exposed to different environmental conditions, 4. Natural Selection occurs independently in each population, selecting for different favourable traits. 5. Over many generations the populations become genotypically and phenotypically different. 6. Even if they mix again, they cannot interbreed to produce fertile offspring—a new species has formed.

In Matric Life Sciences, describe the two stages of Protein Synthesis: Transcription and Translation.

Transcription (in the nucleus): Double-stranded DNA unwinds and unzips as weak hydrogen bonds break; one strand acts as a template to form a complementary mRNA strand using free RNA nucleotides (with Uracil pairing with Adenine). Translation (at the ribosome in the cytoplasm): mRNA attaches to the ribosome; tRNA molecules carrying specific amino acids match their anticodons to the complementary mRNA codons, and peptide bonds form between adjacent amino acids to build a polypeptide chain.

In Matric Life Sciences (Genetics), distinguish between Complete Dominance, Incomplete Dominance, and Co-dominance using Punnett crosses.

Complete dominance: heterozygous phenotype is identical to homozygous dominant (Red RR × White rr -> all Red Rr). Incomplete dominance: neither allele dominates, producing an intermediate blended phenotype in heterozygotes (Red RR × White WW -> Pink RW). Co-dominance: both alleles are equally and distinctly expressed in the heterozygote (Red RR × White WW cattle -> Roan RW patches of both red and white hairs; or Blood Group AB = I^A I^B).

In Matric Life Sciences, state the structural differences between DNA and RNA regarding sugar, strands, nitrogenous bases, and cellular location.

DNA contains deoxyribose sugar, is double-stranded (double helix), has Thymine (A-T, G-C), and is found in the nucleus (nuclear DNA), mitochondria (mtDNA), and chloroplasts. RNA contains ribose sugar, is single-stranded, has Uracil instead of Thymine (A-U, G-C), and occurs as mRNA, tRNA, and rRNA in the nucleus and cytoplasm/ribosomes.

In Matric Life Sciences (Vertebrate Reproduction), distinguish between Ovipary, Ovovivipary, and Vivipary, and between Precocial and Altricial development.

Ovipary: eggs laid outside the female's body (fish, amphibians, birds); Ovovivipary: eggs retained inside the female's body nourished by yolk and hatch just before/at birth (some sharks, puff adder); Vivipary: embryo develops inside the uterus nourished via a placenta (mammals). Precocial young are born with eyes open, covered in down/fur, and able to move/feed independently (ostrich, buck); Altricial young are born blind, hairless, and helpless, requiring intensive parental care (humans, songbirds).

In Matric Life Sciences (Human Nervous System), trace the pathway of a Reflex Arc from stimulus to effector, and explain the significance of a reflex action.

Receptor -> Sensory (afferent) neuron -> Dorsal root of spinal nerve (with cell body in dorsal root ganglion) -> Synapse -> Interneuron (connector neuron in grey matter of spinal cord) -> Synapse -> Motor (efferent) neuron via ventral root -> Effector (muscle/gland). Reflex actions provide rapid, automatic protection from bodily harm without waiting for conscious processing by the cerebrum.

In Matric Life Sciences (Evolution), how do bacteria evolve resistance to antibiotics (or insects to DDT) through Darwin's Theory of Natural Selection?

1. There is natural variation in the bacterial population—some bacteria have a gene/mutation for antibiotic resistance while others do not. 2. When exposed to the antibiotic, non-resistant bacteria die, 3. while antibiotic-resistant bacteria survive. 4. The surviving resistant bacteria reproduce rapidly and pass the allele for resistance to their offspring, 5. increasing the proportion of resistant bacteria in future generations.

South Africa NSC Matric Life Sciences (Paper 1 & 2): DNA/RNA Protein Synthesis, Meiosis, Human Reproduction, Nervous/Endocrine, Homeostasis & Evolution

Covers South Africa CAPS Grade 12 NSC Matric Life Sciences Paper 1 & Paper 2: DNA Code of Life, Protein Synthesis (Transcription & Translation), Meiosis, Human Reproduction, Nervous & Endocrine Systems, Homeostasis, Plant Responses, Genetics, and Human Evolution (Cradle of Humankind).

Level: basic
Languages: en → en
Cards: 32
Markdown: South Africa NSC Matric Life Sciences (Paper 1 & 2): DNA/RNA Protein Synthesis, Meiosis, Human Reproduction, Nervous/Endocrine, Homeostasis & Evolution (.md)

Flashcards (32)

#	Front (Term / Question)	Back (Definition / Answer)
1	In Matric Life Sciences (DNA: Code of Life), who discovered the double-helix structure of DNA in 1953 using X-ray diffraction photographs taken by Rosalind Franklin and Maurice Wilkins?	James Watson and Francis Crick.
2	In Matric Life Sciences (Cradle of Humankind Fossils), match the famous South African and East African hominid fossils to their species, discoverers, and sites.	'Taung Child' (Australopithecus africanus): Raymond Dart (1924, Taung, North West); 'Mrs Ples' (Australopithecus africanus): Robert Broom (1947, Sterkfontein Caves); 'Little Foot' (Australopithecus prometheus/africanus): Ron Clarke (Sterkfontein); 'Karabo' (Australopithecus sediba): Lee Berger (2008, Malapa); 'Homo naledi': Lee Berger (Rising Star Cave); 'Lucy' (Australopithecus afarensis): Donald Johanson (Ethiopia); 'Turkana Boy' (Homo erectus): Richard Leakey/Kamoya Kimeu (Kenya).
3	In Matric Life Sciences (Evolution), contrast Punctuated Equilibrium (Eldredge & Gould, 1972) with Phyletic Gradualism (Darwin).	Gradualism proposes that species evolve slowly and continuously through small cumulative changes over long geological periods (predicting many transitional fossils). Punctuated Equilibrium proposes that species remain largely unchanged for long periods of stasis, interrupted ('punctuated') by relatively brief bursts of rapid speciation—explaining the scarcity of transitional fossils in the fossil record.
4	In Matric Life Sciences (Human Reproduction), what are the structures of a human sperm cell (acrosome, nucleus, middle piece, tail) and the functions of the seminal vesicles, prostate gland, and Cowper's glands?	Acrosome: contains hydrolytic enzymes to penetrate the ovum membrane; Nucleus: carries 23 haploid chromosomes; Middle piece: packed with mitochondria to supply ATP for swimming; Tail (flagellum): propulsion. Seminal vesicles: secrete fructose-rich fluid for sperm energy; Prostate gland: secretes alkaline fluid to neutralize acidic vaginal secretions; Cowper's glands: secrete mucus for lubrication and motility.
5	In Matric Life Sciences (Endocrine Disorders), distinguish between Type 1 and Type 2 Diabetes Mellitus, Hyperthyroidism (Graves' disease), and Hypothyroidism (Goitre/Myxoedema).	Type 1 Diabetes: autoimmune destruction of beta cells in the Islets of Langerhans resulting in little/no insulin production (treated with daily insulin injections). Type 2 Diabetes: body cells become resistant to insulin (linked to obesity/lifestyle). Hyperthyroidism: over-secretion of thyroxin causing high metabolic rate, weight loss, hyperactivity, and exophthalmos. Hypothyroidism: under-secretion of thyroxin causing low metabolic rate, weight gain, lethargy, and goitre (iodine deficiency).
6	In Matric Life Sciences (Genetics Pedigree Diagrams), how do you determine whether a trait on a pedigree chart is Autosomal Dominant, Autosomal Recessive, or Sex-Linked (X-linked) Recessive?	If two unaffected parents have an affected child, the disorder MUST be recessive (parents are heterozygous carriers). If two affected parents have an unaffected child, the trait MUST be dominant. If the trait is recessive and affects predominantly males (passed from carrier mothers to sons, never from father to son), it is X-linked recessive (e.g., haemophilia, red-green colour blindness).
7	In NSC Matric Life Sciences (Paper 2), how is the curriculum split between Paper 1 (150 marks) and Paper 2 (150 marks) under the DBE CAPS examination guidelines?	Paper 1 (150 marks): Reproduction in Vertebrates, Human Reproduction, Responding to the Environment (Humans & Plants), Endocrine System, and Homeostasis in Humans. Paper 2 (150 marks): DNA: The Code of Life, Meiosis, Genetics and Inheritance, and Evolution.
8	In Matric Life Sciences (Scientific Investigation Questions), how do you identify the Independent Variable, Dependent Variable, Fixed/Controlled Variables, Reliability, and Validity?	Independent variable: the factor deliberately manipulated by the investigator (plotted on X-axis). Dependent variable: the effect measured/observed (plotted on Y-axis). Validity: improved by keeping all other controlled variables constant (same age, temperature, species). Reliability: improved by increasing sample size or repeating the investigation and calculating an average.
9	In Matric Life Sciences (Human Reproduction), what are the functions of the Amniotic Fluid, Umbilical Artery, Umbilical Vein, and Placenta during gestation?	Amniotic fluid (inside amnion): acts as a shock absorber, prevents dehydration, maintains constant temperature, and allows free fetal movement. Umbilical vein: carries oxygenated, nutrient-rich blood FROM the placenta TO the fetus. Umbilical arteries (two): carry deoxygenated blood and nitrogenous waste/CO2 FROM the fetus TO the placenta. Placenta: site of gas/nutrient/waste exchange by diffusion, secretes progesterone after week 12, and passes maternal antibodies (passive immunity).
10	In Matric Life Sciences (Homeostasis), how does the body respond when blood Carbon Dioxide (CO2) levels increase during strenuous exercise?	High CO2 lowers blood pH (making blood more acidic as carbonic acid forms). Chemoreceptors in the carotid and aortic bodies detect the drop in pH and send impulses to the medulla oblongata, which sends impulses to the diaphragm and intercostal muscles to contract faster and deeper (increasing rate and depth of breathing) and to the heart to beat faster, expelling excess CO2.
11	In Matric Life Sciences (Homeostasis), how do ADH (Antidiuretic Hormone) and Aldosterone regulate Osmoregulation (water) and Salt (Sodium) balance in the kidney?	When blood water content is low (dehydration/sweating): osmoreceptors in the hypothalamus stimulate the pituitary gland to secrete MORE ADH, which increases the permeability of the distal convoluted tubules and collecting ducts, reabsorbing more water into the blood (producing a small volume of concentrated urine). When blood sodium (Na⁺) is low: the adrenal cortex secretes MORE Aldosterone, increasing Na⁺ reabsorption from the renal filtrate into the blood.
12	In Matric Life Sciences (Evolution), what is the difference between Artificial Selection (Selective Breeding) and Natural Selection?	In Natural Selection, the environment acts as the selective pressure, selecting traits that increase the organism's survival and reproductive fitness in the wild (maintaining genetic diversity). In Artificial Selection, HUMANS act as the selective agent, breeding organisms for traits that benefit human needs (e.g., high milk yield in cattle, drought-tolerant maize), which reduces genetic variation and increases homozygosity.
13	In Matric Life Sciences (Human Eye), compare the Pupillary Mechanism (Light Reflex) in bright light vs. dim light, and Accommodation for near (<6 m) vs. distant (>6 m) vision.	Pupillary Mechanism in Bright Light: circular muscles of the iris CONTRACT, radial muscles RELAX, pupil CONSTRICTS to let less light in (opposite in dim light). Accommodation for Near Vision (<6 m): ciliary muscles CONTRACT, suspensory ligaments SLACKEN, tension on lens decreases, and the elastic lens becomes MORE CONVEX (rounder) with greater refractive power.
14	In Matric Life Sciences (Human Evolution), list the anatomical differences in the skull, spine, pelvis, and foramen magnum between African Apes (Chimpanzees) and Homo sapiens (Bipedalism).	Homo sapiens vs. African Apes: 1. Foramen magnum is in a forward (central) position under the skull (vs. backward in apes) for upright bipedal balance; 2. Spine is S-shaped for shock absorption (vs. C-shaped in apes); 3. Pelvis is short and wide/cup-shaped to support internal organs (vs. long and narrow in apes); 4. Larger cranium/brain volume, flatter face (non-prognathous), smaller canines with no diastema, U-shaped to parabolic dental arcade, and no cranial/brow ridges.
15	In Matric Life Sciences (Biotechnology), distinguish between Stem Cells, Reproductive Cloning, Therapeutic Cloning, and Genetic Modification (GMOs).	Stem cells are undifferentiated cells (embryonic, umbilical cord blood, or bone marrow) capable of differentiating into specialized tissues. Reproductive cloning produces a genetically identical whole organism (e.g., Dolly the sheep via somatic cell nuclear transfer). Therapeutic cloning produces embryonic stem cells to repair damaged organs/tissues. Genetic modification inserts a desirable gene (e.g., human insulin gene into bacterial plasmids) using restriction enzymes and DNA ligase.
16	In Matric Life Sciences (Meiosis), what is Non-disjunction, and how does it cause Down Syndrome (Trisomy 21)?	Non-disjunction is the failure of homologous chromosomes (in Anaphase I) or sister chromatids (in Anaphase II) to separate properly during meiosis. If a gamete with an extra chromosome 21 (n + 1 = 24) fuses with a normal gamete (n = 23), the resulting zygote has 47 chromosomes with three copies of chromosome 21 (Trisomy 21 / Down Syndrome).
17	In Matric Life Sciences (Human Reproduction), trace the hormonal control of the 28-day Menstrual Cycle involving FSH, Oestrogen, LH, and Progesterone.	1. Pituitary gland secretes FSH, which stimulates development of a primary follicle into a Graafian follicle in the ovary. 2. Developing Graafian follicle secretes Oestrogen, which thickens the endometrium and, at high levels, triggers a surge of LH (while inhibiting FSH). 3. LH (from pituitary) triggers Ovulation (Around Day 14) and converts the ruptured follicle into the Corpus Luteum. 4. Corpus Luteum secretes Progesterone, which maintains the thick vascular endometrium for implantation and inhibits FSH and LH (negative feedback).
18	In Matric Life Sciences (Endocrine System & Homeostasis), explain the Negative Feedback mechanism regulating Thyroxin levels via TSH and Thyroxin.	When blood thyroxin levels drop below normal, the pituitary gland detects this and secretes MORE TSH (Thyroid-Stimulating Hormone) into the blood. TSH stimulates the thyroid gland to secrete more thyroxin, raising metabolic rate back to normal; high thyroxin then inhibits the pituitary gland from secreting TSH.
19	In Matric Life Sciences (Meiosis), during which phase does Crossing Over occur, and how does it together with Random Arrangement of chromosomes introduce genetic variation?	Crossing Over occurs in Prophase I: homologous chromosomes pair up to form bivalents, and non-sister chromatids overlap at chiasmata to exchange genetic material. Random Arrangement occurs at the equator during Metaphase I (homologous pairs) and Metaphase II (single chromosomes), producing genetically distinct haploid gametes.
20	In Matric Life Sciences (Human Ear), how does the ear carry out Hearing (via the Organ of Corti in the cochlea) versus Balance (via the Cristae and Maculae)?	Hearing: Tympanic membrane -> ossicles (malleus, incus, stapes) -> oval window -> pressure waves in endolymph stimulate hair cells of the Organ of Corti -> auditory nerve -> cerebrum. Balance: Cristae in the ampullae of the three semicircular canals detect changes in SPEED and DIRECTION of head movement; Maculae in the utriculus and sacculus detect the position of the head relative to GRAVITY -> vestibular nerve -> cerebellum.
21	In Matric Life Sciences, if a DNA template strand has the base triplet 3'-TAC-5', what is the corresponding mRNA codon and the tRNA anticodon?	mRNA codon = AUG (start codon coding for Methionine); tRNA anticodon = UAC.
22	In Matric Life Sciences (Plant Hormones), what are the roles of Auxins in Apical Dominance, Phototropism, and Geotropism, and what are the roles of Gibberellins and Abscisic Acid?	Auxins produced at the apical bud inhibit the growth of lateral buds (apical dominance—removing the tip causes lateral branches to grow bushy). Gibberellins stimulate stem elongation (bolting) and seed germination. Abscisic Acid promotes seed/bud dormancy during winter and triggers stomatal closure during drought stress.
23	In Matric Life Sciences, why is mitochondrial DNA (mtDNA) used to trace maternal ancestry (such as 'Mitochondrial Eve' in Out-of-Africa evolution questions)?	During fertilization, only the nucleus of the sperm enters the ovum while the sperm's mitochondria in the middle piece are discarded outside; therefore, zygotes inherit mtDNA exclusively from the mother's ovum, and mtDNA mutates at a known, steady rate without crossing over.
24	In Matric Life Sciences (Human Evolution), what are the two main lines of evidence supporting the 'Out of Africa' Hypothesis?	1. Fossil evidence: Ardipithecus, Australopithecus, and Homo habilis fossils are found ONLY in Africa (Rift Valley and South Africa), and the oldest Homo erectus and Homo sapiens fossils are also found in Africa. 2. Genetic evidence (mtDNA): analysis of mutations in mitochondrial DNA shows the highest genetic diversity—and therefore the oldest ancestral populations—in Africa.
25	In Matric Life Sciences (Thermoregulation), write the DBE sequence explaining how the hypothalamus and skin blood vessels respond on a COLD day.	1. Thermoreceptors in the skin and hypothalamus detect a drop in temperature. 2. The hypothalamus sends nerve impulses to the blood vessels of the skin. 3. Vasoconstriction occurs (arterioles supplying skin capillaries narrow). 4. Less warm blood flows to the surface of the skin and sweat glands become inactive. 5. Less heat is lost from the body by radiation, convection, Conduction, and evaporation.
26	In Matric Life Sciences (Speciation), write the standard 6-point DBE template for Allopatric Speciation (Speciation through Geographic Isolation).	1. If a population of a single species becomes separated by a geographical barrier (mountain, river, ocean, continental drift), 2. the population splits into two and there is NO GENE FLOW between them. 3. Because each population is exposed to different environmental conditions, 4. Natural Selection occurs independently in each population, selecting for different favourable traits. 5. Over many generations the populations become genotypically and phenotypically different. 6. Even if they mix again, they cannot interbreed to produce fertile offspring—a new species has formed.
27	In Matric Life Sciences, describe the two stages of Protein Synthesis: Transcription and Translation.	Transcription (in the nucleus): Double-stranded DNA unwinds and unzips as weak hydrogen bonds break; one strand acts as a template to form a complementary mRNA strand using free RNA nucleotides (with Uracil pairing with Adenine). Translation (at the ribosome in the cytoplasm): mRNA attaches to the ribosome; tRNA molecules carrying specific amino acids match their anticodons to the complementary mRNA codons, and peptide bonds form between adjacent amino acids to build a polypeptide chain.
28	In Matric Life Sciences (Genetics), distinguish between Complete Dominance, Incomplete Dominance, and Co-dominance using Punnett crosses.	Complete dominance: heterozygous phenotype is identical to homozygous dominant (Red RR × White rr -> all Red Rr). Incomplete dominance: neither allele dominates, producing an intermediate blended phenotype in heterozygotes (Red RR × White WW -> Pink RW). Co-dominance: both alleles are equally and distinctly expressed in the heterozygote (Red RR × White WW cattle -> Roan RW patches of both red and white hairs; or Blood Group AB = I^A I^B).
29	In Matric Life Sciences, state the structural differences between DNA and RNA regarding sugar, strands, nitrogenous bases, and cellular location.	DNA contains deoxyribose sugar, is double-stranded (double helix), has Thymine (A-T, G-C), and is found in the nucleus (nuclear DNA), mitochondria (mtDNA), and chloroplasts. RNA contains ribose sugar, is single-stranded, has Uracil instead of Thymine (A-U, G-C), and occurs as mRNA, tRNA, and rRNA in the nucleus and cytoplasm/ribosomes.
30	In Matric Life Sciences (Vertebrate Reproduction), distinguish between Ovipary, Ovovivipary, and Vivipary, and between Precocial and Altricial development.	Ovipary: eggs laid outside the female's body (fish, amphibians, birds); Ovovivipary: eggs retained inside the female's body nourished by yolk and hatch just before/at birth (some sharks, puff adder); Vivipary: embryo develops inside the uterus nourished via a placenta (mammals). Precocial young are born with eyes open, covered in down/fur, and able to move/feed independently (ostrich, buck); Altricial young are born blind, hairless, and helpless, requiring intensive parental care (humans, songbirds).
31	In Matric Life Sciences (Human Nervous System), trace the pathway of a Reflex Arc from stimulus to effector, and explain the significance of a reflex action.	Receptor -> Sensory (afferent) neuron -> Dorsal root of spinal nerve (with cell body in dorsal root ganglion) -> Synapse -> Interneuron (connector neuron in grey matter of spinal cord) -> Synapse -> Motor (efferent) neuron via ventral root -> Effector (muscle/gland). Reflex actions provide rapid, automatic protection from bodily harm without waiting for conscious processing by the cerebrum.
32	In Matric Life Sciences (Evolution), how do bacteria evolve resistance to antibiotics (or insects to DDT) through Darwin's Theory of Natural Selection?	1. There is natural variation in the bacterial population—some bacteria have a gene/mutation for antibiotic resistance while others do not. 2. When exposed to the antibiotic, non-resistant bacteria die, 3. while antibiotic-resistant bacteria survive. 4. The surviving resistant bacteria reproduce rapidly and pass the allele for resistance to their offspring, 5. increasing the proportion of resistant bacteria in future generations.