IAT Biology Flashcards

24 sample cards from the Biology deck

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

1. What is the expected phenotypic ratio of a monohybrid and a dihybrid cross in the F2 generation?

   Monohybrid: 3:1. Dihybrid: 9:3:3:1.

2. What are the key structural features of DNA according to the Watson-Crick double helix model?

   Two antiparallel polynucleotide strands coiled into a right-handed helix; complementary base pairing (A=T with 2 H-bonds, G≡C with 3 H-bonds); ~10 base pairs per turn (pitch 3.4 nm, 0.34 nm between bases); sugar-phosphate backbone outside, bases inside.

3. What is the central dogma of molecular biology?

   Genetic information flows from DNA --> RNA (transcription) --> Protein (translation). (Reverse transcription, RNA --> DNA, occurs in retroviruses.)

4. What is adaptive radiation? Give an example.

   Adaptive radiation is the evolution of different species from a common ancestor in a given geographical area, each adapted to a different niche. Example: Darwin's finches of the Galapagos Islands; Australian marsupials.

5. State the Hardy-Weinberg principle and name factors that disturb it.

   In an ideal population, allele and genotype frequencies remain constant across generations (p^2 + 2pq + q^2 = 1, with p + q = 1). It is disturbed by gene flow/migration, genetic drift, mutation, genetic recombination, and natural selection.

6. Differentiate between active and passive immunity.

   Active immunity: the body produces its own antibodies after exposure to an antigen (infection or vaccine); slow but long-lasting. Passive immunity: ready-made antibodies are given from outside (e.g., mother's milk, antiserum); fast but short-lived.

7. Name the causative organisms for malaria, typhoid, and AIDS.

   Malaria: Plasmodium (protozoan). Typhoid: Salmonella typhi (bacterium). AIDS: HIV (retrovirus).

8. What are the differences between inbreeding and outbreeding in animal husbandry?

   Inbreeding: mating of closely related individuals; increases homozygosity and accumulates desirable genes but can cause inbreeding depression. Outbreeding: mating of unrelated animals; increases heterozygosity/vigour (e.g., out-crossing, cross-breeding, interspecific hybridization).

9. Name microbes used in producing curd, bread/alcohol, and the antibiotic penicillin.

   Curd: Lactobacillus (lactic acid bacteria). Bread/alcohol: Saccharomyces cerevisiae (yeast). Penicillin: Penicillium notatum (fungus).

10. What are the two core techniques that form the basis of biotechnology?

    Genetic engineering (recombinant DNA technology—altering the chemistry of genetic material to introduce them into host organisms) and maintenance of sterile (microbe-free) conditions for growing only the desired microbe/cell in large quantities (bioprocess/chemical engineering).

11. What is the role of restriction enzymes in recombinant DNA technology?

    Restriction endonucleases are 'molecular scissors' that recognize specific palindromic DNA sequences and cut the DNA, often producing sticky ends that allow joining of DNA fragments from different sources by DNA ligase.

12. What is Bt cotton, and what makes it pest-resistant?

    Bt cotton is a transgenic crop carrying cry genes from the bacterium Bacillus thuringiensis. These genes produce Bt toxin (a crystal protein) that is lethal to specific insect pests (e.g., bollworms), giving built-in pest resistance.

13. What is gene therapy, and name a disease it was first used to treat.

    Gene therapy is the correction of a genetic defect by introducing a normal/functional gene into the patient's cells or tissues. It was first used to treat ADA (adenosine deaminase) deficiency (a form of SCID).

14. Define a population and name three of its key attributes studied in ecology.

    A population is a group of individuals of the same species living in a defined geographical area, sharing/competing for resources and capable of interbreeding. Attributes: birth rate (natality), death rate (mortality), sex ratio, age distribution/pyramids, and population density.

15. What is the difference between exponential and logistic population growth?

    Exponential growth (J-shaped curve) occurs with unlimited resources: dN/dt = rN. Logistic growth (S-shaped/sigmoid curve) occurs with limited resources and a carrying capacity (K): dN/dt = rN((K-N)/K).

16. What is an ecological pyramid, and which pyramid is always upright?

    An ecological pyramid is a graphical representation of trophic levels in terms of number, biomass, or energy. The pyramid of energy is always upright (energy decreases at each successive trophic level, per the 10% law).

17. State the 10 percent law of energy transfer in an ecosystem.

    Only about 10% of the energy at one trophic level is transferred to the next higher trophic level; the rest (~90%) is lost as heat (metabolism) and through other processes (Lindeman's 10% law).

18. What are the three levels of biodiversity?

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

19. Distinguish between in-situ and ex-situ conservation with examples.

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

20. What are the major greenhouse gases and the primary effect of their accumulation?

    CO2, methane (CH4), nitrous oxide (N2O), and CFCs/water vapour. Their accumulation traps long-wave (infrared) radiation, enhancing the greenhouse effect and causing global warming.

21. What causes ozone layer depletion, and why is the ozone layer important?

    Chlorofluorocarbons (CFCs) release chlorine atoms that catalytically destroy stratospheric ozone (the 'ozone hole'). The ozone layer is important because it absorbs harmful UV-B radiation, protecting living organisms from skin cancer, mutations, and eye damage.

22. What is biological magnification (biomagnification)? Give an example pollutant.

    Biomagnification is the progressive increase in concentration of a non-degradable toxicant (e.g., DDT, mercury) at successive trophic levels of a food chain, because it is accumulated and not metabolized/excreted.

23. What are the kingdom-level features of Fungi (mode of nutrition, cell wall, reserve food)?

    Fungi are heterotrophic (saprophytic/parasitic), absorptive feeders; cell wall is made of chitin; reserve food is glycogen; body is usually filamentous (hyphae forming mycelium); mostly multicellular except yeast.

24. What is the difference between an open and a closed circulatory system?

    Open circulatory system: blood (hemolymph) flows through open spaces/sinuses bathing tissues directly (e.g., arthropods, molluscs). Closed circulatory system: blood flows within vessels at all times (e.g., annelids, vertebrates), allowing more efficient, regulated transport.

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