Biology today

MTMTBIOLOGY TODAYBIOLOGY TODAY || march ‘16march ‘16 3333

25. Assertion : histamine causes constriction of blood
    capillaries resulting in inflammatory response.

Reason : administration of antihistamines results in
the dilation of blood capillaries and provides relief from
inflammation.

26. Assertion : In spite of exposure to large number of
    infectious agents, humans are resistive to diseases.
    Reason : humans are able to defend against most of
    the foreign agents due to the ability to fight disease-
    causing organisms.


27. Assertion : IgG is the most abundant class of Igs in
    the body.
    Reason : IgG is mainly found in sweat, tears, saliva,
    mucus, colostrum and gastro intestinal secretions.


28. Assertion : Tobacco contains a large number of alkaloids
    including nicotine.
    Reason : Nicotine stimulates adrenal gland which
    decreases blood pressure and increase heart rate.
    figure Based Questions


29. refer to the given figure and answer the following
    questions.
    Retro virus
    Virus infects
    normal cell

Cytoplasm

E Nucleus DNA

D

B

A

C

Animal cell

Plasma

membrane

(a) Identify the steps a, B, c, D and E labelled in it.

(b) Describe briefly the mode of transmission of the virus

mentioned in the figure.

30. refer to the given figure and
    answer the following questions.

(a) Name the parts labelled

a, B and c.

(b) What is the function of

part labelled c?

(c) What is the function of B?

chAPTer-9 : sTrATeGIes fOr

enhAncemenT In fOOD PrODucTIOn

multiple choice Questions

1. Which one of the following pairs is mismatched?
   (a) Apis indica - honey
   (b) Kenia lacca - lac
   (c) Bombyx mori - silk
   (d) Pila globosa - pearl


2. In cloning of cattle, a fertilised egg is taken out of the
   mother’s womb and
   (a) in the eight cell stage, cells are separated and cultured
   until small embryos are formed which are implanted
   into the womb of other cows
   (b) in the eight cell stage the individual cells are separated
   under electrical field for further development in culture
   media
   (c) from this upto eight identical twins can be produced
   (d) the egg is divided into 4 pairs of cells which are
   implanted into the womb of other cows.


3. heterosis is referred to as the phenomenon of attainment
   of
   (a) increased vigour in a hybrid
   (b) organogenesis in plant
   (c) production of spores
   (d) localised over growth.


4. honey of bee is sweet as it contains
   (a) sucrose (b) glucose
   (c) fructose (d) mannose.


5. Polyploidy leads to rapid formation of new species, because
   of
   (a) isolation behaviour
   (b) genetic recombination
   (c) development of multiple sets of chromosomes
   (d) mutation therapy.


6. In high yielding hybrid crop varieties, to exploit hybrid vigour,
   the farmers need to purchase fresh hybrid seed every year,
   because
   (a) it is cheaper to purchase fresh seed
   (b) hybrid vigour is lost due to inbreeding depression
   (c) they are not allowed to grow their own seed
   (d) government has accepted Dunkel’s proposals.


7. Which of the following statements is not true about somatic
   embryogenesis?
   (a) The pattern of development of a somatic embryo is
   comparable to that of a zygotic embryo.
   (b) Somatic embryos can develop from microspores.
   (c) Somatic embryo is induced usually by an auxin such
   as 2, 4-D.
   (d) a somatic embryo develops from a somatic cell.