NEET UG Zoology Flashcards

24 sample cards from the Zoology deck

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

1. What are the phases of the human menstrual cycle (28 days)?

   Menstrual phase (days 1–5), Follicular/proliferative phase (days 6–13), Ovulatory phase (~day 14, LH surge), Luteal/secretory phase (days 15–28).

2. Which hormones control the menstrual cycle and ovulation?

   FSH stimulates follicle growth; LH triggers ovulation and corpus luteum formation; estrogen drives the proliferative phase; progesterone (from corpus luteum) maintains the luteal phase/endometrium.

3. Name two ART (Assisted Reproductive Technology) methods and what they involve.

   IVF-ET (in-vitro fertilisation, test-tube baby) — fertilisation outside the body, embryo transferred to uterus. GIFT — transfer of ovum + sperm into the fallopian tube. Others: ICSI, ZIFT, IUI.

4. List common contraceptive methods by category.

   Natural (rhythm, withdrawal, lactational amenorrhea), Barrier (condoms, diaphragm), IUDs (Cu-T, LNG-20), Oral pills (hormonal, e.g. Saheli), Injectables/implants, and Surgical (vasectomy, tubectomy).

5. What are STDs and name three common examples?

   Sexually Transmitted Diseases are infections spread through sexual contact. Examples: gonorrhoea, syphilis, chlamydiasis, genital herpes, HIV/AIDS, hepatitis-B.

6. Differentiate asexual and sexual reproduction.

   Asexual reproduction involves a single parent, no gamete fusion, and produces genetically identical offspring (clones). Sexual reproduction involves two parents, gamete fusion (fertilisation), and produces genetically variable offspring.

7. What were Griffith's and the Avery–MacLeod–McCarty experiments significant for?

   Griffith's experiment (1928) demonstrated bacterial transformation (a 'transforming principle'). Avery, MacLeod and McCarty (1944) identified that transforming principle as DNA — proving DNA is the genetic material.

8. State the key features of the Watson–Crick DNA double helix model.

   Two antiparallel polynucleotide strands coiled in a right-handed double helix; complementary base pairing (A=T with 2 H-bonds, G≡C with 3 H-bonds); ~10 bp per turn; pitch 3.4 nm; 0.34 nm between bases.

9. What is the central dogma of molecular biology?

   The flow of genetic information: DNA → (transcription) → RNA → (translation) → Protein. DNA replication copies DNA; reverse transcription (RNA→DNA) is an exception.

10. Why is DNA replication called semiconservative?

    Because each new DNA molecule retains one parental (old) strand and one newly synthesised strand. Demonstrated by Meselson and Stahl (1958) using N15/N14 in E. coli.

11. What are the salient features of the genetic code?

    It is triplet (3 bases = 1 codon), universal, degenerate (multiple codons per amino acid), non-overlapping, comma-less, and has a start codon (AUG) and stop codons (UAA, UAG, UGA).

12. What is the lac operon and its components?

    An inducible operon in E. coli controlling lactose metabolism. Components: regulatory gene (i), promoter (p), operator (o), and structural genes z (β-galactosidase), y (permease), a (transacetylase). Lactose acts as the inducer.

13. State Darwin's theory of evolution by natural selection.

    Organisms produce more offspring than can survive; individuals vary; those with favourable variations have higher fitness and survive/reproduce more ('survival of the fittest'), so beneficial traits accumulate over generations.

14. What is the Hardy–Weinberg principle and its equation?

    In an ideal population allele frequencies remain constant across generations. Equation: p² + 2pq + q² = 1 (where p + q = 1). Disturbing factors: mutation, gene migration, genetic drift, selection, recombination.

15. Give one example each of homologous and analogous organs.

    Homologous organs (same origin, different function, divergent evolution): forelimbs of whale, bat, human. Analogous organs (different origin, same function, convergent evolution): wings of butterfly and bird.

16. What is the difference between innate and acquired immunity?

    Innate (non-specific) immunity is present from birth — barriers, phagocytes, inflammation. Acquired (specific) immunity develops after exposure to a pathogen and shows specificity and memory (B-cells humoral, T-cells cell-mediated).

17. Name the causative organism and vector (if any) for malaria, filariasis and typhoid.

    Malaria: Plasmodium (vector: female Anopheles mosquito). Filariasis: Wuchereria (vector: Culex mosquito). Typhoid: Salmonella typhi (no insect vector; via contaminated food/water).

18. What is HIV and how does AIDS develop?

    HIV (Human Immunodeficiency Virus) is a retrovirus that infects helper T-cells (CD4+). It replicates, destroys T-cells, and progressively weakens immunity, leading to AIDS (Acquired Immuno Deficiency Syndrome) with opportunistic infections.

19. Differentiate active and passive immunity.

    Active immunity: body produces its own antibodies after exposure/vaccination — slow but long-lasting. Passive immunity: ready-made antibodies given from outside (e.g. mother's milk, antiserum) — fast but short-lived.

20. What is recombinant DNA technology and the key tool enzymes used?

    It is the technique of joining DNA from different sources to make recombinant DNA. Key enzymes: restriction endonucleases (cut DNA at specific sites), DNA ligase (joins fragments), and polymerases.

21. What are restriction enzymes and what do they recognise?

    Restriction endonucleases are 'molecular scissors' that cut DNA at specific palindromic recognition sequences, often leaving sticky (cohesive) ends. Example: EcoRI cuts at GAATTC.

22. What is PCR and what are its three steps?

    PCR (Polymerase Chain Reaction) amplifies DNA in vitro. Steps: Denaturation (strands separate ~94°C), Annealing (primers bind ~50–55°C), Extension (Taq polymerase synthesises new strands ~72°C).

23. Give two examples of GMOs/products of biotechnology in medicine and agriculture.

    Medicine: human insulin (Humulin), gene therapy for ADA deficiency. Agriculture: Bt cotton (pest-resistant via Bacillus thuringiensis cry genes), and RNAi-based pest resistance (e.g. against Meloidogyne).

24. What is the difference between an antigen and an antibody?

    An antigen is a foreign molecule that triggers an immune response; an antibody is a Y-shaped protein (immunoglobulin) produced by B-lymphocytes that specifically binds and neutralises the antigen.

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