KCET Biology - Botany Flashcards

24 sample cards from the Biology - Botany deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. State the Chargaff's rule and the base-pairing in DNA.

   Chargaff's rule: in DNA, A = T and G = C (purines = pyrimidines). Pairing: adenine with thymine (2 H-bonds), guanine with cytosine (3 H-bonds).

2. Define the central dogma of molecular biology.

   Genetic information flows DNA → RNA → protein (replication, transcription, translation). Reverse transcription (RNA → DNA) is an exception in retroviruses.

3. What are the three features of the genetic code (degeneracy, etc.)?

   The code is triplet, nearly universal, non-overlapping, comma-less, degenerate (most amino acids coded by more than one codon), and has start (AUG) and stop (UAA, UAG, UGA) codons; it is read in a fixed reading frame.

4. What is the role of the lac operon's repressor and inducer?

   In the lac operon, the i-gene makes a repressor protein that binds the operator and blocks transcription; lactose (allolactose, the inducer) binds the repressor, inactivating it, so RNA polymerase transcribes z, y, a genes (negative regulation).

5. Differentiate inbreeding and outbreeding in animal/plant improvement.

   Inbreeding: mating of closely related individuals — increases homozygosity, fixes desirable traits but may cause inbreeding depression. Outbreeding: mating of unrelated individuals — increases vigour (heterosis) and variability.

6. What is single cell protein (SCP) and give an example organism?

   SCP is protein-rich biomass obtained from microbes used as an alternative protein source (food/feed), e.g., Spirulina, Methylophilus methylotrophus, mushrooms (mycoprotein).

7. Define biofortification and give one example crop.

   Biofortification: breeding crops with higher levels of vitamins, minerals, proteins or healthier fats to improve public nutrition, e.g., iron-rich rice, Vitamin A-enriched carrots/spinach, protein-rich maize.

8. What is the difference between somatic hybridisation and micropropagation?

   Somatic hybridisation: fusion of protoplasts from two different plants to form a hybrid (somatic hybrid, e.g., pomato). Micropropagation: producing many plantlets through tissue culture, giving genetically identical somaclones.

9. Define ecological niche and habitat.

   Habitat: the physical place/environment where an organism lives. Niche: the functional role and total set of conditions/resources an organism uses (its 'profession') in the ecosystem.

10. Write the logistic (Verhulst-Pearl) population growth equation and name 'K'.

    dN/dt = rN[(K − N)/K], where r = intrinsic rate of increase, N = population size, K = carrying capacity (maximum population the environment can sustain); gives a sigmoid (S-shaped) curve.

11. Differentiate mutualism, commensalism and amensalism in population interactions.

    Mutualism: both species benefit (+/+). Commensalism: one benefits, other unaffected (+/0). Amensalism: one is harmed, other unaffected (−/0).

12. Name the trophic levels in a grazing food chain and the energy transfer law involved.

    Producers (T1) → primary consumers/herbivores (T2) → secondary consumers (T3) → tertiary consumers (T4). Energy transfer follows the 10 percent law (Lindeman): only ~10% passes to the next trophic level.

13. Define ecological pyramids and state which pyramid is always upright.

    Graphical representation of trophic structure (number, biomass, or energy). The pyramid of energy is always upright (energy decreases at each level); pyramids of number and biomass can be inverted.

14. Distinguish primary and secondary ecological succession.

    Primary succession: begins on bare, lifeless areas with no prior soil (e.g., bare rock, new lava); pioneer species are usually lichens — slow. Secondary succession: occurs where a community was destroyed but soil remains (e.g., abandoned farmland) — faster.

15. What are the three levels of biodiversity?

    Genetic diversity (variation within a species), species diversity (variety of species in a region/community), and ecological/ecosystem diversity (variety of habitats, communities and ecological processes).

16. State the species-area relationship equation given by Alexander von Humboldt.

    On a log scale: log S = log C + Z log A, where S = species richness, A = area, C = Y-intercept, Z = slope (regression coefficient, typically 0.1–0.2 for small areas, steeper 0.6–1.2 for large continents).

17. Differentiate in-situ and ex-situ conservation with examples.

    In-situ: protecting species in their natural habitat (national parks, sanctuaries, biosphere reserves, biodiversity hotspots). Ex-situ: protecting outside natural habitat (zoos, botanical gardens, seed banks, cryopreservation).

18. Name the 'Evil Quartet' — the four major causes of biodiversity loss.

    Habitat loss and fragmentation, over-exploitation, alien (invasive) species invasions, and co-extinctions.

19. What are the two core techniques that form the foundation of modern biotechnology?

    Genetic engineering (recombinant DNA technology — altering and transferring genes), and maintenance of sterile (contamination-free) microbial process control for large-scale growth of organisms/cells.

20. What is the role of restriction enzymes and DNA ligase in rDNA technology?

    Restriction endonucleases cut DNA at specific palindromic recognition sites (creating sticky ends). DNA ligase joins DNA fragments (e.g., insert into vector) by sealing the phosphodiester backbone.

21. Name the three steps of a PCR cycle and the enzyme used.

    Denaturation (~94°C, strands separate), annealing (~55°C, primers bind), extension (~72°C, synthesis). Enzyme: thermostable Taq polymerase (from Thermus aquaticus).

22. What is Bt cotton and how does the Bt toxin work?

    Bt cotton carries cry genes from Bacillus thuringiensis producing an inactive protoxin (crystal). In the insect's alkaline gut it is solubilised and activated, binding to midgut epithelium, creating pores that cause cell swelling, lysis and insect death.

23. What is RNA interference (RNAi) and its application against nematodes?

    RNAi is silencing of a specific mRNA by complementary double-stranded RNA. In tobacco, introducing nematode-specific genes producing dsRNA via host (RNAi) silences the parasite's mRNA, killing Meloidogyne incognita and protecting the plant.

24. What is Golden Rice and what trait was engineered into it?

    Golden Rice is a genetically engineered rice variety enriched with provitamin A (beta-carotene) in the grain to combat Vitamin A deficiency; the carotene gives it a golden colour.

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