Biology Today - February 2018

20. Refer to the given diagram of (FROL cloning vector pBR322.

Answer the following questions:
(a) Indicate the antibiotic resistant genes. State
the role of these genes.
(b) Indicate restriction site of (FRRI.
(c) Indicate the gene involved in the replication
of plasmid.

21. Explain any three methods to force 'alien' or recombinant
    DNA into host cells.


22. List and explain the factors due to which the density
    of a population in a given habitat during a given period
    fluctuates.
    SECTION - D


23. The air quality of your city has significantly improved now in
    comparison to what existed few years back. This is the result
    of a lot of conscious human efforts. You are being asked to
    conduct an awareness programme in your locality wherein
    you will comment on the steps taken by local Government
    to improve the air quality.

(a) Write any two of your comments.

(b) List any two ways that you would include in your programme
so as to ensure the maintenance of good quality of air.

(c) State any two values which your programme will inculcate
in the people of your locality.
SECTION - E

24. A flower of brinjal plant following the process of sexual
    reproduction produces 360 viable seeds. Answer the
    following questions giving reasons:

(a) How many ovules are minimally involved?

(b) How many megaspore mother cells are involved?

(c) What is the minimum number of pollen grains that must
land on stigma for pollination?

(d) How many male gametes are involved in the above case?

(e) How many microspore mother cells must have undergone
reduction division prior to dehiscence of anther in the above
case?
OR
(a) Explain the menstrual phase in a human female. State the
levels of ovarian and pituitary hormones during this phase.
(b) Why is follicular phase in the menstrual cycle also referred
to as proliferative phase? Explain.
(c) Explain the events that occur in a Graafian follicle at the
time of ovulation and thereafter.
(d) Draw diagram of Graafian follicle and label antrum and
secondary oocyte.

25. Describe Meselson and Stahl’s experiment that was conducted
    on (FROL in 1958.

P Q

2UL S

T

OR

(a) Differentiate between homology and analogy giving one

example each of plant and animal, respectively.

(b) Briefly explain how are they considered as an evidence in

support of evolution.

26. (a) Name the population growth pattern represented by
    the equation. What does “U” represent in the
    equation? Write its importance in population growth.
    (b) By using population Verhulst-Pearl logistic growth curve explain
    the principle of carrying capacity.
    OR
    (a) Explain how a hydrarch succession progresses from hydric
    to mesic condition and forms a stable climax community.
    (b) Why is the rate of secondary succession faster than that of
    primary succession?
    SOLUTIONS


27. Filiform apparatus of synergids plays a role in pollen tube
    guidance and pollen tube reception.


28. +RPRKDELOLV < +RPRHUHFWXV< Neanderthal man


29. Lysine and Arginine


30. Mother's milk contains antibodies which protect the infant
    against infections. The yellowish fluid, colostrum secreted by
    the mother during the initial days of lactation has abundant
    antibodies (IgA).


31. Separation of DNA fragments can be done by agarose gel
    electrophoresis. In this technique, the DNA molecules are
    separated according to their size, under the influence of an
    electric field.


32. Cleistogamous flowers do not open at all. In such flowers,
    the anthers and stigma lie close to each other. When anthers
    dehisce in the flower buds, pollen grains come in contact


33. with the stigma and pollination takes place.

Fig.: Schematic structure of a transcription unit

Transcription start site

Structural

gene

Template

strand Terminator

Coding strand

Promoter

3 c 5 c

5 c 3 c

OR

Coelacanth is the oldest among living fishes and is considered

a connecting link between fishes and amphibians that live

on both land and water.

8. Statins are blood-cholesterol lowering agents commercially
   produced by the yeast 0RQDVFXV SXUSXUHXV. Statins act
   by competitively inhibiting the enzyme responsible for
   synthesis of cholesterol.


9. In the given table, A is %UDVVLFD, B is Aphids, C is Pusa Sem 2
   and D is Shoot and fruit borer.