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Holiday homework assignment

DAV Public School, Kailash Hills

Holiday Homework (2017-18)

                                                               Class XII (Biology)

HOTS

 1. If a branch “dasheri mango” is grafted on a tree producing “desi mangoes” what type

  of mangoes will be borne on grafted branch& other branches of the plant?                             1

       

2. Most sugarcane varieties cultivated today are aneuploids and are sterile. But they grow

  and perform extremely well. Sterility in sugarcane is not of any disadvantage. Why?            1

3. Why do organisms like algae and fungi which normally adopt asexual reproduction

   switch over to sexual method of reproduction just before the onset of adverse conditions?   1

4. If a certain plant when introduced into a new environment neither produces seeds nor it

  responds to vegetative propagation. How can more plants be produced?                                2

5. Even though each pollen grain has two male gametes. Why are at least 10 pollen grains and         

   not 5 pollen grains required to fertilise 10 ovules present in a particular carpel?                   2

6. “Apomictic genes are trying to be inserted in hybrid varieties” –Explain                         3

7. a) “Dehydration of seed increases their shelf life” – Explain                                            2

   b) Cleistogamous flowers are strictly self pollinating,” Explain. What is the disadvantage                 

      of this phenomenon?                                                                                                        2

   c) Even after killing the generative cell with a laser beam, the pollen grain of a flowering           

        plant germinates and produces normal pollen tube. How does it happen?                    1

8. Suppose the acrosome of mammalian spermatozoa does not function normally, how would              

   it affect fertilization? Give reasons.                                                                                    2                                                     

9. Fill the blank spaces a, b, c, and d given in the following table.

               S. No.        Organism                   Organ                    Gamete

                 (i)                 a                            Testes                 Spermatozoa                            2

                 (ii)         Human female                 b                         Ovum

                 (iii)      Plant (Angiosperm)           c                     Pollen grains

                 (iv)      Plant (pteridophytes)    antheridium                d

10. a) In which part of human female reproductive system do the following events take place?    1x5

   i. Release of 1st polar body

  ii. Release of 2nd polar body

  iii. Fertilization

  iv. Implantation

  b) From where do the signals for parturition originate and what does maternal pituitary release

  for simulating uterine contraction for child birth?

11. A woman who was pregnant (8 weeks), on clinical examination was found to have conceived

     a defective foetus with a serious genetic defect.

   1) With what test would the doctor have confirmed the genetic defect.

   2) What suggestive measure would you recommend?                                                                            2

12. Study the following diagram and answer the following questions:

                                   

                           

a) Label the parts A,B,C,D,E and F                                                                                                             3

b) How does D differ from F?                                                                                                                     1

            

13. State which law of Mendelian inheritance is expressed in the following

      diagram?

                      To different gamete        To different gamete                         1

14. Assume that no new mutations have arisen in the family.                                                   2

   Answer each question with either ‘Yes’ or ‘No’

i) Could this be inherited as recessive trait?

ii) Could this be inherited as dominant trait?

15. The map distance between A & B genes is 18 unit; between B & C is 20                         2

   unit and C & A is 2 unit.(a)What is the order of genes on a linkage group?(b)                               

   Write the unit of map distance.

16 . Colour blindness is a recessive trait. A couple with normal vision has two sons,             2

    one colour blind and one with normal vision. If the couple also has daughters what

    proportion of them will have normal vision?

18. From the given monohybrid ratio identify the type of inheritance and give one               3

     example each.

      i) Both phenotypic and genotypic ratio is 1:2:1

      ii) Phenotypic ratio is 3:1 and genotypic ratio is 1:2:1

17. Mention the steps involved in the following Pea plant cross                                               3

    

     Removal of anthers---------------------- A

              

   Transfer of Pollen------------------------ B

 

   Raising the next generation-------------C

19. Mention whether the male individuals of the following organisms are homozygous/  

    heterozygous.                                                                                                                   1x5

   i) Human = XY-XX

   ii) Hen = ZW-ZZ

   iii) Drosophila = XY-XX

   iv) Grasshopper = XO-XX

   v) Birds = ZZ-ZW

20. Mention the type of error in the following diseases:

   1. Sickle cell anaemia

   2. Haemophilia

   3. Phenylketonuria

   4. Down’s syndrome

   5. Klinefelter’s syndrome

Chapter 2: Reproduction in plants- Gametogenesis ( Male & Female)

Microsporogenesis and pollen grain formation

                                        

Megasporogenesis and embryo sac formation