KCET Biology - Zoology Flashcards

24 sample cards from the Biology - Zoology deck

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

1. What is spermatogenesis and where does it occur?

   The formation of haploid sperm from diploid spermatogonia by meiosis, occurring in the seminiferous tubules of the testes; stimulated by FSH and testosterone, supported by Sertoli cells.

2. Describe the menstrual cycle phases and the dominant hormones.

   Menstrual phase (shedding of endometrium), follicular/proliferative phase (FSH, rising estrogen, follicle growth), ovulatory phase (LH surge causes ovulation ~day 14), and luteal/secretory phase (corpus luteum secretes progesterone).

3. What is the role of the placenta in human pregnancy?

   It connects the foetus to the uterine wall for exchange of nutrients, gases (O2/CO2) and wastes, and acts as an endocrine organ secreting hCG, progesterone, estrogen, and human placental lactogen.

4. List two barrier and two hormonal/IUD contraceptive methods.

   Barrier: condoms and diaphragms/cervical caps; Hormonal: oral contraceptive pills (e.g. Saheli) and injectables/implants; IUDs include Copper-T (Cu-releasing) and hormone-releasing (LNG-20).

5. What is amniocentesis and why is its misuse legally banned in India?

   A prenatal test analysing amniotic fluid to detect foetal genetic/chromosomal disorders; it is banned for sex determination because of its misuse for female foeticide.

6. What is the chromosomal basis of sex determination in humans?

   Humans have XX (female) and XY (male); the male is heterogametic (produces X or Y sperm) and determines the sex of the offspring; females are homogametic (XX).

7. Explain the inheritance pattern and cause of haemophilia.

   Haemophilia is an X-linked recessive disorder where blood fails to clot due to deficiency of a clotting factor; it is more common in males (XY) since one recessive allele is enough to express it.

8. What causes sickle-cell anaemia at the molecular level?

   An autosomal recessive point mutation (GAG to GTG) replacing glutamic acid with valine at the 6th position of the beta-globin chain of haemoglobin (HbS), causing RBCs to become sickle-shaped under low O2.

9. Name the chromosomal abnormality and karyotype of Down's syndrome.

   Trisomy of chromosome 21 (47 chromosomes); caused by failure of chromosomes to separate (non-disjunction).

10. Contrast Darwin's natural selection with Lamarck's theory of evolution.

    Lamarck proposed inheritance of acquired characters (use and disuse); Darwin proposed natural selection - variation exists, and individuals best adapted to the environment survive and reproduce ('survival of the fittest').

11. What is the Hardy-Weinberg principle and its equation?

    In a population at equilibrium, allele frequencies remain constant across generations (no evolution) when there is no mutation, migration, selection, genetic drift, or random mating. Equation: p^2 + 2pq + q^2 = 1, where p + q = 1.

12. Differentiate homologous and analogous organs with examples.

    Homologous organs have similar structure/origin but different functions (divergent evolution, e.g. forelimbs of whale, bat, human); analogous organs have different structure/origin but similar function (convergent evolution, e.g. wings of insect and bird).

13. Distinguish active and passive immunity.

    Active immunity is produced by the host's own body in response to antigens/vaccines (slow but long-lasting); passive immunity is ready-made antibodies given from outside (e.g. mother's milk, antivenom; fast but short-lived).

14. Name the causative organisms of malaria, typhoid, and amoebiasis.

    Malaria - Plasmodium (e.g. P. vivax, P. falciparum); typhoid - Salmonella typhi; amoebiasis (amoebic dysentery) - Entamoeba histolytica.

15. What are the two types of lymphocytes and their roles in immunity?

    B-lymphocytes produce antibodies (humoral/antibody-mediated immunity); T-lymphocytes mediate cell-mediated immunity (CMI) and help/regulate B cells (e.g. helper T, cytotoxic T cells).

16. How does HIV cause AIDS at the cellular level?

    HIV (a retrovirus) infects and destroys helper T-lymphocytes (CD4+ cells); their depletion cripples the immune system, leaving the body vulnerable to opportunistic infections.

17. Which microbes are used to produce curd and to make bread/wine respectively?

    Lactic Acid Bacteria (LAB, e.g. Lactobacillus) curdle milk into curd; Saccharomyces cerevisiae (baker's/brewer's yeast) is used for bread (CO2) and for alcohol/wine fermentation.

18. Name the microbial sources of penicillin, citric acid, and cyclosporin A.

    Penicillin - fungus Penicillium notatum/chrysogenum; citric acid - Aspergillus niger; cyclosporin A (immunosuppressant) - fungus Trichoderma polysporum.

19. What are biogas, its main component, and the microbes responsible?

    Biogas is a mixture of gases (mainly methane, CH4) produced by anaerobic microbial digestion of organic waste; methanogens such as Methanobacterium (found in cattle dung/gobar) produce it.

20. Give examples of biofertilizers and biocontrol agents.

    Biofertilizers: Rhizobium, Azospirillum, Azotobacter, cyanobacteria (e.g. Anabaena), mycorrhiza (Glomus). Biocontrol agents: Bacillus thuringiensis (Bt), Trichoderma, Baculoviruses (NPV), and ladybird/dragonfly.

21. What are the three key steps/tools of genetic engineering (recombinant DNA technology)?

    (1) Identifying and cutting DNA with restriction enzymes, (2) inserting the gene into a vector to form recombinant DNA, and (3) transferring it into a host and amplifying/expressing it (cloning).

22. What is the function of restriction endonucleases and what are 'sticky ends'?

    Restriction endonucleases (molecular scissors) cut DNA at specific palindromic recognition sequences; staggered cuts leave single-stranded overhangs called sticky ends that base-pair with complementary ends to join DNA fragments.

23. What is a cloning vector and name a commonly used one?

    A cloning vector is a DNA molecule (e.g. plasmid pBR322, bacteriophages, Ti plasmid of Agrobacterium) that carries the foreign gene into a host cell; it has an origin of replication (ori), selectable markers, and recognition sites.

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

    Polymerase Chain Reaction amplifies a DNA segment in vitro using primers and a thermostable Taq polymerase. Steps: denaturation (strand separation by heat), annealing (primers bind), and extension (Taq synthesises new strands).

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