Monday, October 26, 2020

2017 March | HSE +2 Exam | ZOOLOGY- ANSWERS

 2017 March (+2) 

ZOOLOGY ANSWERS


1. Phenotype B. A: B: C: D = 3:1:9:3

2. 0.2

3. In situ conservation: It is the conservation of organisms in their natural habitats. E.g. National parks, Sanctuary etc.

Ex situ conservation: It is the conservation of organisms outside their habitats. E.g. genetic resource centres, zoological parks etc.

4. (3) Syphilis, Gonorrhea

5. (3) Bird female

6. Colostrum

7. Functions of LH & FSH: 

Hormones

In male

In female

LH

Acts on Leydig cells to stimulate release of androgens

Stimulates ovulation and development of corpus luteum

FSH

Acts on Sertoli cells to stimulate release of factors for spermiogenesis

Stimulates development of primary follicles to Graafian follicles.


8. Sickle cell anaemia

Reason: Replacement of glutamic acid with valine at the 6th position of b-globin chain. This is due to the single base substitution at the sixth codon of the β-globin gene from GAG to GUG.

9. (a) Frequency of M = 0.75 Frequency of N = 0.25

(b) These frequency values follow Hardy-Weinberg equilibrium. So, there will be no evolution in that population.

OR 

(a) Adaptive radiation.
(b) Adaptive radiation (evolution by adaptation) is the evolution of different species in a geographical area starting from a point. E.g. Australian marsupials (Marsupial radiation).

10. Advantages of biofertilizers: They are eco-friendly and improve soil. They prevent pollution.
      E.g. Rhizobium, Mycorrhiza, Cyanobacteria etc.

11. Assisted reproductive technologies (ART) are the technologies used to correct the infertility problems.
For male sterility: AI (artificial insemination) techniques.
For female sterility: GIFT (Gamete intra fallopian transfer)

12. (3) H2, CH4, NH3, H2O

13. (2) b and c

14.  

Reason: Poly adenylation always occurs at 3’ end.

15. (1) DNA fingerprinting
      (2) Steps:

a. Isolation of DNA.
b. Digestion of DNA by restriction endonucleases.
c. Separation of DNA fragments by gel electrophoresis.
d. Transferring (blotting) DNA fragments to synthetic membranes such as nitrocellulose or nylon.
e. Hybridization using radioactive labeled VNTR probe.
f. Detection of hybridized DNA by autoradiography.

OR 

(1) If lactose is provided, it is transported into the E. coli. Lactose (inducer) binds with repressor protein. So repressor protein cannot bind to operator gene. The operator gene becomes free and induces the RNA polymerase to bind with promoter gene. Then transcription starts.

(2) Lac operon remains switched off.

16. Use of Morphine: In medical field, it is used as pain killer or sedative.
      Abuse: It is abused as narcotic drugs. Produces temporary euphoria and addiction. Affects CNS.

17. Active immunity: It is the immunity in which antibodies are produced in a host body when the host is exposed to antigens (e.g. living or dead microbes or other proteins).

Passive immunity: Here, readymade antibodies are directly given to the body. E.g. Antibodies (IgG) from mother → Placenta → Foetus, Anti-tetanus serum (ATS) etc.

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