Saturday, October 24, 2020

2018 March | HSE +2 Exam | Botany Answer Key

PART A: BOTANY (ANSWER KEY)

1.   (b) Parbhani kranti.


2.   Diapause.


3.   (a) Stratosphere or Troposphere.

(b) Dobson (Db).


4.     

A

B

1. Butterfly

c. 1-2 weeks

2. Crow

d. 15 years

3. Parrot

a. 140 years

4. Tortoise

b. 100 to 150 years


5.   (a)  Agarose gel.

(b)  Elution.


6.   (a) pBR322 (E. coli cloning vector).

(b) (i) Tetracycline resistance gene

(ii) Gene that codes for the proteins involved in the replication of plasmid.

(iii) Origin of replication.


7.   Filiform apparatus. It guides pollen tube into the synergids.


8.   Collected semen may be used immediately or can be frozen for later use.

Frozen semen can also be transported.


9.   ○ Vitamin A enriched carrots, spinach, pumpkin.

 Vitamin C enriched bitter gourd, bathua, mustard, tomato.

 Iron & calcium enriched spinach & bathua.

 Protein enriched beans.


10.  Purify air and water.

 Reduce global warming, droughts and floods.

 Maintain biodiversity.

 Pollinate crops.

 Provide aesthetic, cultural and spiritual values etc.


11.  Use of lead-free petrol or diesel.

 Use of catalytic converters.

 Phasing out of old vehicles.

 Use of low-sulphur petrol and diesel.

 Use of compressed natural gas (CNG) etc.


12.  Reduce the use of fossil fuel.

 Improve efficiency of energy usage.

 Reduce deforestation and plant trees.

 Slowing down the growth of human population


13.  Tolerant to abiotic stresses.

 Reduced use of chemical pesticides.

 Pest resistant crops.

 Reduce post-harvest losses

 Enhanced nutrient value of food.


14. They prepared two DNA sequences corresponding to A & B chains of human insulin and introduced in plasmids of E. coli to produce insulin chains. Chains A & B were combined by creating disulfide bonds to form human insulin.


15. When energy flows from a trophic level to the next higher trophic level, some energy is always lost as heat at each step.


16. (a) RNA interference (RNAi).

(b) Nematode specific genes were introduced into the host plant through the Agrobacterium vector.

This gene produces both sense and antisense RNA in host cells.

These are complementary to each other and form dsRNA.

dsRNA silences the specific mRNA of the nematode.


17. (a) Exponential (Geometric) growth curve and Logistic (Sigmoid) growth curve.

(b) Carrying capacity.


18. The functional megaspore develops into the female gametophyte.

Nucleus of the functional megaspore divides mitotically to form two nuclei. They move to the opposite poles, forming 2-nucleate embryo sac.

The nuclei again divide two times forming 4-nucleate and 8-nucleate stages of the embryo sac.

These divisions are free nuclear.

After the 8-nucleate stage, cell walls are laid down leading to the organization of the typical female gametophyte.

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