2019 June (SAY) | HSE +2 Exam | Zoology - Answers

ZOOLOGY (2019 June)


1. (d) Fertilisation → Zygote → Cleavage → Morula → Blastula → Implantation.

2. (a) Mating (b) Mating between relatives

3. Erwin Chargaff

4. (a) 

(b) It is used to find out the unknown genotype of a character.

5. (a) AIDS
    (b) Advocate safe sex and free distribution of condoms.
          Make blood (from blood banks) safe from HIV.




(a) Citric Acid

(b) Acetic acid

(c) Lactic acid

(d) Butyric acid

III. Aspergillus niger

I. Acetobactor aceti

IV. Lactobacillus

Il. Clostridium butylicum

7. (a) Gynaecomastia: Klinefelter’s syndrome.
          Rudimentary ovary and lack of secondary sexual characters: Turner’s syndrome.
    (b) Klinefelter’s syndrome: Presence of an additional copy of X-chromosome in male.
          Turner’s syndrome: Absence of one X chromosome in female

8. A= Hydrogen bond
    B= Ester bond
    C= Phosphodiester bond
    D= N-glycosidic bond

9. (a) Pituitary gland. 14th day of the Menstrual cycle.
    (b) LH acts on the Leydig cells and stimulates secretion of androgens.

10. They can fix nitrogen from the atmosphere. Also absorb phosphorous. E.g. Rhizobium, Cyanobacteria, Mycorrhiza etc.

11. (a) 500 mya: Plants.
      (b) 350 mya: Jawless fishes, fish with stout fins.
      (c) 320 mya: Sea-weeds. Plants.
      (d) 200 mya: Reptiles

12. The process is Translation (Protein synthesis).

      It includes 4 steps:
  1. Charging (aminoacylation) of tRNA.
  2. Initiation.
  3. Elongation.
  4. Termination.
13. Over production → Struggle for existence → Variation → Survival of the fittest → Natural selection → Origin of species.

14. (a) Antibody (Immunoglobulin)
      (b) Humoral immune response (AMI) and Cell mediated immune response (CMI).

15. (a) Opioids: Depressants. Affect CNS.
      (b) Cannabinoids: Acts in brain. Affects cardiovascular system.
      (c) Coca alkaloids: Stimulates CNS.

16. (a) Test Tube Baby Programme.
      (b) ZIFT (Zygote Intra Fallopian Transfer): Transfer of zygote or early embryo (with up to 8 blastomeres) into fallopian tube.

      IUT (Intra Uterine Transfer): Transfer of embryo with more than 8 blastomeres into the uterus.

17. In situ conservation (on site): It is the conservation of genetic resources within natural or human-made ecosystems in which they occur. E.g. National Parks, Sanctuaries, Biosphere reserves, Sacred groves etc.

Ex situ conservation (off site): It is the conservation of organisms outside their habitats. E.g. genetic resource centres, zoological parks, wildlife safari parks, botanical gardens etc.

18. a. There are 3 RNA polymerases: RNA polymerase I, II & III.
      b. Primary transcripts (hnRNA) contain exons & introns. To remove introns, it undergoes processing (splicing, capping & tailing) and becomes mRNA.
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