Hots Xii Biology

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  • 7/25/2019 Hots Xii Biology


    Chapter 1.



    1) No two individuals, especially in mammals (except monozygotic twins) look

    alike. What distinguishes them from the rest 1

    !) " plant was introduced in #ndia $ecause of its $eautiful flowers % shape of

    leaves. #t propagates vegetatively at a phenomenal rate and spread all over the

    water $odies and has $ecome a threat. Which plant is $eing referred to 1

    &) " few plants exhi$it unusual flowering phenomena which flowers once in

    their life time and die. 'uggest an evidence of the same from monocotyledon.1

    ) #dentify " and *a$el (1) and (!) in the given figure 1

    +) he Nilgiris $elt form the large $lue stretches in the hilly areas of -erala,

    -arnataka, % amilnadu and attracted a large num$er of tourists. What reason

    do you attri$ute to this phenomenal change of nature once in 1! years 1

    ) Why estrous cycle is not seen in humans 1

    /) "ll papaya and date palm plants produce flowers yet only few papaya and

    date palm seen to produce fruit. What could $e the possi$le reason for the rest

    not producing them 10) ften the num$er of male gametes produced in an organism is in large

    num$er as compared to female. Why has nature taken up this developmental

    disparity 1
  • 7/25/2019 Hots Xii Biology


    2) his figure shows fruit containing seed inside. *a$el ' % 3 shown in fig. 1

    14) #n nature for $oth plants % animals, hormones are responsi$le for transitions

    $etween the three phases of reproduction. Which & phases are $eing referred tohere1

    ! marks

    11) *a$el " and and write the type of the vegetative propagule. !


    1!. (i) hough ginger is found under the soil. 5et it is not a root, $ut stem. 6ustify your answer with two reasons.

    (ii) What are the specialised cells which undergo meiosis in the diploid

    organisms, called as

    1&) Why can7t man $e oviparous 6ustify the statement. !

    1) (i) Name the process of development of em$ryo from the zygote. !

    (ii) What are the two changes which the zygote undergoes during this


    1+) *a$el the figures " and and also mark 8 and 5. !


    8 5
  • 7/25/2019 Hots Xii Biology


    1) Why dogs and cats have oestrus cycle $ut human $eings have menstrual

    cycle, though all are mammals !

    1/) #n $isexual flowers, why is the transfer of pollen grains easier than in

    unisexual flowers Name the specialized event in unisexual flowers which helps

    in transfer of pollen. !

    10) 9an we refer the off :springs formed $y asexual reproduction, as a clone

    #f yes, why !

    12) he posterior end of cockroach shows the following structures. ;ention if it

    is a male or female. "lso la$el the part marked 787.



    !4) "rrange the following events in proper sem$ryogenesis

    ($) ?ertilization

    (c) @ametogenesis

    (d) Aygote formation.

    What will happen if meiosis does not take place during gametogenesis
  • 7/25/2019 Hots Xii Biology





    1) Bo pollen grains survive in adverse conditions 1

    !) Non: al$uminons seeds do not have endosperm, then from where do they take the

    food during germination 1

    &) .'. of anther shows four layers in the wall:epidermis, endothelium, tapetum and

    middle layer, "rrange them from outermost to innermost. 1

    ) #dentify the figure given $elow and la$el the parts indicated in the figure. 1

    +) 9omplete the flow chart. 1

    ) #f the num$er of chromosomes in the leaf cell of a flowering plant is !0, What

    num$er would you expect in the em$ryo and endosperm 1

    ! marks

    /) (a) Che microspore is haploid while that of microspore mother cell is diploidC

    comment. !

    ($) Dow many male gametes and female gamets are produced $y

    (i) ?ive microspore mother cell (ii) ?ive megaspore mother cell
  • 7/25/2019 Hots Xii Biology


    0) (a) what is the process shown in the diagram given $elow

    ($)Name the structure at (a) of the figure given $elow !


    2) Why do you think that the zygote is dormant for some time in a fertilized ovule !

    14) What will $e the fate of ovule if the synergids are a$sent in the em$ryo sac !

    11) 5our friend would like to cross:pollinate the $isexual flower. Dow can you guide

    him to $e successful in his experiment !
  • 7/25/2019 Hots Xii Biology


    1!) Dow does the flower of maize and canna$is are pollinated What are the features

    found in these flowers for such type of pollination !

    & marks

    1&) @enerally nucellus does not persist in mature seeds. 9ite two examples which show

    persistence of nucellus in the seed and what name is given to the persistent nucellulus&

    1) #f one can induce parthenocarpy through the application of phytohormones, which

    fruit would you select to induce parthenocarpy and why &

    + marks

    1+) " student wants to know the ploidy of coconut. "fter studying its different parts he

    inferred the ploidy of the following parts. 9heck whether the student is correct. +

    (a) Water inside the fruit:n

    ($) White -ernal:!n(c) 'eed coat:n

    (d) >m$ryo:&n

    (e) epal:!n
  • 7/25/2019 Hots Xii Biology



    1 mark

    1) Aygote undergoes mitosis to form 1 celled stage of em$ryo. What is it

    known as 1

    !) Name the important mammary gland secretions that h