Biology · Sample Paper 3

General instructions

Section A · Objective

1. Question 11 mark

   The male gametophyte in angiosperms is the

   1. A.ovule
   2. B.pollen grain
   3. C.embryo sac
   4. D.anther wall
2. Question 21 mark

   Formation of more than one embryo in a seed is

   1. A.apomixis
   2. B.polyembryony
   3. C.parthenocarpy
   4. D.cleistogamy
3. Question 31 mark

   The corpus luteum secretes mainly

   1. A.oestrogen
   2. B.progesterone
   3. C.FSH
   4. D.LH
4. Question 41 mark

   Which part of the sperm contains mitochondria?

   1. A.head
   2. B.neck
   3. C.middle piece
   4. D.tail
5. Question 51 mark

   Mendel chose the garden pea because it

   1. A.had many contrasting traits and short life cycle
   2. B.was a tree
   3. C.could not self-pollinate
   4. D.had large seeds only
6. Question 61 mark

   Haemophilia is an example of

   1. A.autosomal dominant disorder
   2. B.sex-linked recessive disorder
   3. C.chromosomal disorder
   4. D.Mendelian dominant disorder
7. Question 71 mark

   Which nitrogenous base is found only in RNA?

   1. A.adenine
   2. B.thymine
   3. C.uracil
   4. D.guanine
8. Question 81 mark

   The Human Genome Project found that humans have about

   1. A.3000 genes
   2. B.20 000–25 000 genes
   3. C.1 lakh genes
   4. D.1 million genes
9. Question 91 mark

   The yeast used in making bread is

   1. A.Saccharomyces cerevisiae
   2. B.Lactobacillus
   3. C.Aspergillus
   4. D.Rhizopus
10. Question 101 mark

    Which disease is caused by a virus?

    1. A.typhoid
    2. B.common cold
    3. C.malaria
    4. D.ringworm
11. Question 111 mark

    The enzyme used to join DNA fragments in rDNA technology is

    1. A.restriction endonuclease
    2. B.DNA ligase
    3. C.Taq polymerase
    4. D.lysozyme
12. Question 121 mark

    Which of these is an example of amensalism?

    1. A.Penicillium inhibiting bacteria
    2. B.lichens
    3. C.cattle egret and cattle
    4. D.tapeworm in humans
13. Question 131 mark

    Assertion (A): Lactational amenorrhoea is a natural method of contraception.

    Reason (R): Ovulation and menstruation do not occur during intense lactation after childbirth (up to about six months).

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.
14. Question 141 mark

    Assertion (A): Bt cotton is resistant to bollworms.

    Reason (R): The Cry protein becomes toxic in the alkaline gut of the insect.

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.
15. Question 151 mark

    Assertion (A): In a grassland, the pyramid of numbers is upright.

    Reason (R): Producers in a grassland are more numerous than herbivores, which in turn outnumber carnivores.

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.
16. Question 161 mark

    Assertion (A): Darwin's finches of the Galápagos are an example of adaptive radiation.

    Reason (R): Adaptive radiation is the evolution of different species from a common ancestor in a given area.

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.

Section B · Very short answer

1. Question 172 marks

   What is the function of the tapetum? Where is it found?

2. Question 182 marks

   What is IVF? Name the technique in which the embryo is transferred into the uterus at the 8-cell stage or later.

3. Question 192 marks

   What is a pedigree analysis? Why is it useful in humans?

4. OR

   Question 192 marks

   Differentiate between Turner's syndrome and Klinefelter's syndrome.

5. Question 202 marks

   Name two antibiotics and the organisms that produce them.

6. Question 212 marks

   What is the difference between gross primary productivity and net primary productivity?

Section C · Short answer

1. Question 223 marks

   Describe the structure of a human sperm with a labelled (described) diagram.

2. Question 233 marks

   Explain the three steps of translation.

3. Question 243 marks

   Explain the steps involved in recombinant DNA technology.

4. OR

   Question 243 marks

   What is a bioreactor? Name its main components.

5. Question 253 marks

   What is cancer? How do cancer cells differ from normal cells? Name two methods of diagnosis.

6. Question 263 marks

   What is RNA interference? How is it used to make tobacco plants resistant to nematodes?

7. Question 273 marks

   Explain the different ways in which organisms respond to abiotic stresses.

8. Question 283 marks

   What are biodiversity hotspots? Name the hotspots found in India.

Section D · Case-based

1. Question 294 marks

   Case study — Vaccination drive. A district health team runs a vaccination camp for children against polio, measles and hepatitis B. Some parents worry about side effects. The doctor explains that vaccines contain weakened or killed pathogens or their proteins, which train the immune system.

   (i) What type of immunity is developed by vaccination? (1 mark)

   (ii) Which cells retain the 'memory' of the pathogen? (1 mark)

   (iii) Explain how vaccination protects a person from a future infection. (2 marks)

   OR

   (iii) Differentiate between innate and acquired immunity. (2 marks)

2. Question 304 marks

   Case study — Antibiotic resistance. In a hospital, doctors found that a strain of bacteria that used to be killed easily by an antibiotic now survives treatment. Over years of antibiotic use, the resistant bacteria multiplied while the sensitive ones were killed.

   (i) Which evolutionary process explains this observation? (1 mark)

   (ii) Is this an example of evolution by anthropogenic action? Why? (1 mark)

   (iii) Explain the role of variation and selection in the rise of resistant bacteria. (2 marks)

   OR

   (iii) Give two ways to slow down antibiotic resistance. (2 marks)

Section E · Long answer

1. Question 315 marks

   Describe the structure of DNA as proposed by Watson and Crick (double helix). What is the role of hydrogen bonds in it?

2. OR

   Question 315 marks

   Explain the process of DNA replication.

3. Question 325 marks

   Describe the events from fertilisation to implantation in humans.

4. Question 335 marks

   What is ecological succession? Describe hydrarch succession.

5. OR

   Question 335 marks

   Explain the patterns of biodiversity: latitudinal gradients and the species–area relationship.