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📗 Nayab Subba syllabus: Paper I, General Knowledge, Units 1.8.2 and 1.8.3 · Open the full Nayab Subba course
This note covers the science units of Paper I that are not about the body or chemistry: evolution and heredity (1.8.3) and biotechnology and alternative energy (1.8.2).
1. Evolution (क्रमविकास)
- Evolution is the slow change in living things over many generations, by which new species arise from older ones.
- Jean-Baptiste Lamarck (France) proposed the inheritance of acquired characters (use and disuse): for example, the giraffe’s neck became long by stretching. This idea is now rejected.
- Charles Darwin (England) gave the theory of natural selection in his book On the Origin of Species (1859):
- Living things produce more offspring than can survive.
- There is variation among them.
- There is a struggle for existence.
- Those best suited to the environment survive and reproduce (survival of the fittest, a phrase first used by Herbert Spencer).
- Over time, useful variations add up and new species form.
- Evidence of evolution: fossils, homologous organs (same structure, different use, e.g. human arm and bat wing), analogous organs, vestigial organs (appendix), embryology and DNA similarity.
- Hugo de Vries explained sudden changes as mutations.
2. Heredity and genetics (वंशाणु)
- Heredity is the passing of characters from parents to offspring. Genetics is the science of heredity.
- Gregor Mendel (Austria), the father of genetics, experimented on pea plants and gave the laws of dominance, segregation and independent assortment.
- Characters are carried by genes, which are parts of DNA on chromosomes in the nucleus.
- DNA (deoxyribonucleic acid) has a double-helix structure, described by Watson and Crick (1953).
- Humans have 46 chromosomes (23 pairs): 22 pairs of autosomes and 1 pair of sex chromosomes.
- Females are XX and males are XY; the father’s chromosome decides the sex of the child.
- Genetic disorders: haemophilia and colour blindness (linked to X chromosome), Down syndrome (an extra chromosome 21), thalassaemia, sickle-cell anaemia.
3. Biotechnology (जैविक प्रविधि)
- Biotechnology is the use of living organisms or their parts to make useful products.
- Old (traditional): making curd, cheese, bread, alcohol and vinegar by fermentation using microbes (yeast, bacteria).
- Modern: genetic engineering (recombinant DNA), tissue culture, cloning, gene therapy.
| Application | Example |
|---|---|
| Medicine | Human insulin made by bacteria, vaccines, antibiotics, gene therapy |
| Agriculture | GM crops (Bt cotton), disease-free plantlets by tissue culture (banana, potato, orchids in Nepal) |
| Forensics | DNA fingerprinting to identify criminals and parents |
| Animal science | Cloning: Dolly the sheep (1996) was the first mammal cloned from an adult cell |
| Environment | Bacteria that clean oil spills (bioremediation), biogas |
- Concerns: safety of GM food, loss of biodiversity, ethical questions about cloning.
4. Alternative (renewable) energy (वैकल्पिक ऊर्जा)
- Alternative energy means energy from sources other than fossil fuels (coal, petroleum) and large hydropower: solar, wind, biogas, micro-hydro, biomass, geothermal and hydrogen.
| Source | Note for Nepal |
|---|---|
| Solar | Solar home systems, solar water heaters, solar irrigation pumps |
| Micro-hydro | Small plants for remote villages |
| Biogas | Made from cow dung and kitchen waste; methane is the main gas; Nepal is a leader in household biogas |
| Wind | Small pilot projects; good potential in some high areas |
| Improved cooking stoves | Reduce firewood use and indoor smoke |
| Biomass | Firewood is still a major household energy source |
- Alternative Energy Promotion Centre (AEPC), set up in 2053 BS (1996), promotes renewable energy in Nepal.
- Benefits: clean, renewable, reduces imports of petroleum, reaches remote areas, cuts greenhouse gases.
- ICT (information and communication technology) and emerging technology are covered in Emerging Technologies.
📌 Key points to remember
- Lamarck: inheritance of acquired characters (rejected); Darwin: natural selection, On the Origin of Species (1859).
- “Survival of the fittest” was first used by Herbert Spencer; de Vries explained mutations.
- Mendel (pea plants) is the father of genetics; DNA double helix by Watson and Crick (1953).
- Humans: 46 chromosomes (23 pairs); female XX, male XY; father’s chromosome decides sex.
- Biotechnology: insulin, vaccines, GM crops, tissue culture, DNA fingerprinting, cloning (Dolly, 1996).
- Alternative energy: solar, micro-hydro, biogas (methane), wind, improved stoves; AEPC (2053 BS) promotes it.
📝 Quiz
Test yourself: Evolution, Heredity, Biotechnology and Alternative Energy
50 questions check what you read about Evolution (क्रमविकास), Biotechnology (जैविक प्रविधि) and Alternative (renewable) energy (वैकल्पिक ऊर्जा). Each attempt picks 25 at random.
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