Monday, October 26, 2020

2017 March | HSE +2 Exam | BOTANY - ANSWERS

2017 March (+2) 

1. Seed Dormancy

2. (c) Bryophyllum


        Variety                          Crop
(a) Pusa Swarnim         (iv) Brassica
(b) Pusa Snowball        (iii) Cauliflower
(c) Pusa Sawani            (ii) Bhindi
(d) Pusa Sadabahar       (i) Chilly

4. Palindromic sequence

5. (a) Flowers do not open at all. The anthers and stigma lie close to each other. When the anther dehisces in the flower buds pollen grains come in contact with stigma.

(b) Geitonogamy is functionally cross pollination by pollinating agent/ pollination b/w different flowers of same plant.
Geitonogamy is genetically similar to autogamy because pollen grains come from the same plant.

6. Pericarp

7. (a) Antigen-antibody reaction     (i) ELISA
    (b) a-lactalbumin                         (ii) Rosie
    (c) a -1-antitrypsin                      (iii) Emphysema
    (d) Gene therapy                         (iv) ADA deficiency

8. Eli Lilly company prepared two DNA sequences corresponding to A & B chains of human insulin and introduced them in plasmids of E. coli to produce insulin chains. Chains A & B were produced separately, extracted and combined by creating disulfide bonds to form human insulin.

9. Carrying capacity.

10. (a) Jhum cultivation.

(b) the farmers cut down the forest trees and burn the plant remains. The ash is used as a fertiliser and the land is used for farming or grazing. After cultivation, the area is left for several years so as to allow its recovery.

11. (A) * Mutualism 
            * Commensalism/ mutualism 
            * Commensalism
            * Parasitism 
            * Parasitism 
            * Predation


(B) (a) Regulate: It is the maintenance of homeostasis by physiological & behavioural means. It ensures constant body temperature (thermoregulation), constant osmotic concentration (osmoregulation) etc. E.g. All birds & mammals, very few lower vertebrates and invertebrates.

(b) Conform: 99% of animals and nearly all plants cannot maintain a constant internal environment. Their body temperature or osmotic concentration change with the surrounding conditions.

(c) Migrate: Many animals like birds move away temporarily from stressful habitat to a more hospitable area and return when stressful period is over.

12. Biofortification.

13. (A) (a) Gel electrophoresis.
             (b) Staining the DNA with ethidium bromide followed by exposure to UV radiation.
             (c) 500 bp. DNA fragments separate according to their size. i.e. smaller fragments move farther.


(B) • Micro-injection: In this, recombinant DNA is directly injected into the nucleus of an animal cell.
• Biolistics (gene gun): In this, cells are bombarded with high velocity micro-particles of gold or tungsten coated with DNA. This method is suitable for plants.
• ‘Disarmed pathogen’ vectors: When it infects the cell, transfer the recombinant DNA into the host.

14. (b) Submerged plant stage 
      (d) Reed-swamp stage 
      (e) Marsh-meadow stage 
      (g) Forest/trees

15. The electrons released from electrode wires (at several thousand volts) attach to dust particles giving a negative charge. The collecting plates attract charged dust particles.

The velocity of air between the plates must be low enough to allow the dust to fall.
A scrubber removes gases like SO2. In this, the exhaust is passed through a spray of water or lime.

16. Mechanisms to promote outbreeding:

a. Avoiding synchronization: Here, the pollen is released before the stigma becomes receptive or stigma becomes receptive before the release of pollen. It prevents autogamy.

b. Arrangement of anther & stigma at different positions: This also prevents autogamy.

c. Self-incompatibility: It is a genetic mechanism to prevent self-pollen (from the same flower or other flowers of the same plant) from fertilization by inhibiting pollen germination or pollen tube growth in the pistil.


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