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Important Questions For You!

Chapter 2: Sexual Reproduction in Flowering Plants

1. What is the role of tapetum in the pollen grain wall formation? [1]

2.  Fill in the missing words: [1]

Pollen mother cell → Pollen tetrad → Pollen grain → Vegetative cell, ___?____

3.  In the following events, indicate the stages where mitosis and meiosis occur. [1]

Megaspore mother cell →(1)→Megaspores→(2)→Embryo sacs→(3)→Egg

4.  Outer envelope of a pollen grain is made of a highly resistant substance. What is that substance and at which particular point is it absent? [2]

5. A bilobed and dithecous anther has 100 microspore mother cells per microsporangium. How many male gametophytes can it produce? [2]

6. What is apomixis? Comment on its significance. How can it be commercially used? [3]

7. What are the characteristics of wind, water and insect-pollinated flowers? [5]

8. Explain about the pollination occurring in the chasmogamous flowers. [5]

9.                                                                                                         [5]

(a)  Draw a diagram of a mature embryo sac of an angiosperm and label its following parts:    

  1. Filiform apparatus
  2. Synergids
  3. Central cell
  4. Egg
  5. Polar nuclei
  6. Antipodals

(b) Write the fate of the egg cell and polar nuclei after fertilisation.


Chapter 3: Human Reproduction

1.  Which structure is formed after the release of ova from Graafian follicles? [1]

2.  What happens if pregnancy is not maintained in the human female? [1]

3.  From where do the signals for parturition originate? [1]

4.  Why are male testes located outside the abdominal cavity? [2]

5.  What are the similarities between spermatogenesis and oogenesis? [3]

6.  Differentiate between spermatocytes and oocytes. [3]

7.  Enlist any three functions of a female placenta. [3]

8.  What is spermiogenesis? Write the various changes which occur during this process? [5]

9.  Write the function of the following: [5]

  1. Corpus luteum
  2. Endometrium
  3. Acrosome
  4. Sperm tail
  5. Fimbriae

 

Chapter 4: Reproductive Health

1.  What is the significance of amniocentesis? [1]

2.  How are test tube babies different from the normally produced babies? [2]

3.  What is the advantage of Saheli?  [2]

4.  “Removal of gonads cannot be a contraceptive option”. Why? [3]

5.  What are the different methods of contraception in human beings? [5]

 

Chapter 5: Principles of Inheritance and Variation

1.  Non-disjunction may lead to a zygote containing XXY sex chromosomes, what sex would this produce in Drosophila and in humans? [1]

2.  Assertion: Down’s syndrome is caused due to the presence of an additional copy of the chromosome number 21 (trisomy of 21).[1]

Reason: The affected individual is short statured with small round head, furrowed tongue and partially open mouth.

a. Both assertion and reason are true, and reason is the correct explanation of the assertion.
b. Both assertion and reason are true, and reason is not the correct explanation of the assertion.
c. Assertion is true but reason is false.
d. Both assertion and reason are false.                                                     

3.  Assertion: Sickle-cell anaemia is an autosome linked recessive trait that can be transmitted from parents to the offspring when both the partners are carrier for the gene (or heterozygous). [1]

Reason: Sickle-cell anaemia is caused by a mutation or change, in one of the genes, that provides instructions for making the clotting factor proteins needed to form a blood clot.

a. Both assertion and reason are true, and reason is the correct explanation of the assertion.
b. Both assertion and reason are true, and reason is not the correct explanation of the assertion.
c. Assertion is true but reason is false.
d. Both assertion and reason are false.                                              

4.  What is aneuploidy? Give an example. [2]

5.  A single pea plant in your kitchen garden produces pods with viable seeds, but the individual papaya plant does not. Explain. [2]

6.  A pea plant with purple flowers was crossed with a plant with white flowers producing 40 plants with only purple flowers. On selfing, these plants produced 470 plants with purple flowers and 162 with white flowers. What genetic mechanisms account for these results? [3]

7.  Read the following and answer any four questions from (i) to (v) given below: [4]

The chromosomal disorders are caused due to absence or excess or abnormal arrangement of one or more chromosomes. Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s), called aneuploidy. Examples of chromosomal disorders include Down’s syndrome and Turner’s syndrome. Failure of cytokinesis after telophase stage of cell division results in an increase in a whole set of chromosomes in an organism and, this phenomenon is known as polyploidy. This condition is often seen in plants.

The total number of chromosomes of a normal human being is 46 (23 pairs). Out of these 22 pairs are autosomes and one pair of chromosomes are sex chromosomes.

Sometimes, though rarely, either an additional copy of a chromosome may be included in an individual or an individual may lack one of any one pair of chromosomes. These situations are known as trisomy or monosomy of a chromosome.

(i)   Down’s syndrome is due to:

  1. Linkage
  2. Sex-linked inheritance
  3. Crossing over
  4. Non-disjunction of chromosome

(ii)   The cause of Down’s syndrome is the presence of an additional copy of the chromosome number:

  1. 21
  2. 15
  3. 16
  4. 8

(iii)   Which of the following is NOT correct symptom of Down’s syndrome?

  1. Short statured
  2. Small round head
  3. Partially open mouth
  4. Rudimentary ovaries

(iv)   _______________ is caused due to the presence of an additional copy of X-chromosome resulting into a karyotype of 47, XXY.

  1. Down’s Syndrome
  2. Klinefelter’s Syndrome
  3. Turner’s Syndrome
  4. Haemophilia

(v)   ______________ is caused due to the absence of one of the X chromosomes.

  1. Down’s Syndrome
  2. Klinefelter’s Syndrome
  3. Turner’s Syndrome
  4. Haemophilia

8. Read the following and answer any four questions from (i) to (v) given below: [4]

Sickle cell anemia is a genetic disorder where the body produces an abnormal hemoglobin called hemoglobin S. Red blood cells are normally flexible and round, but when the hemoglobin is defective, blood cells take on a “sickle” or crescent shape. Sickle cell anemia is caused by mutations in a gene called HBB.

It is an inherited blood disorder that occurs if both the maternal and paternal copies of the HBB gene are defective. In other words, if an individual receives just one copy of the defective HBB gene, either from mother or father, then the individual has no sickle cell anemia but has what is called “sickle cell trait”.

People with sickle cell trait usually do not have any symptoms or problems but they can pass the mutated gene onto their children. There are three inheritance scenarios that can lead to a child having sickle cell anemia:

- Both parents have sickle cell trait

- One parent has sickle cell anemia and the other has sickle cell trait

- Both parents have sickle cell anemia                                                                                                             

(i)   Sickle cell anemia is a/ an ______________________ disease.

  1. X linked
  2. autosomal dominant
  3. autosomal recessive
  4. Y linked

(ii) If both parents have sickle cell trait, then there is _______________of the child having sickle cell anemia.

  1. 25 % risk
  2. 50 % risk
  3. 75% risk
  4. No risk

(iii) If both parents have sickle cell trait, then there is _______________of the child having sickle cell trait.

  1. 25 % risk
  2. 50 % risk
  3. 75% risk
  4. No risk

(iv)   If one parent has sickle cell anemia and the other has sickle cell trait, there is __________that their children will have sickle cell anemia and ___________will have sickle cell trait.

  1. 25 % risk, 75% risk
  2. 50 % risk, 50% risk
  3. 75% risk, 25% risk
  4. No risk

(v)

The following statements are drawn as conclusions from the above data (Kenya).

I. Patients with SCD (Sickle Cell Disease) are less likely to be infected with malaria.

II. Patients with SCD (Sickle Cell Disease) are more likely to be infected with malaria.

III. Over the years the percentage of people infected with malaria has been decreasing.

IV. Year 2000 saw the largest percentage difference between malaria patients with and without SCD.

Choose from below the correct alternative.

  1. Only I is true
  2. I and IV are true
  3. III and II are true
  4. I and III are true


Chapter 6: Molecular Basis of Inheritance

1.  Assertion: Lactose is the substrate for the enzyme beta-galactosidase in lac operon.

Reason: It regulates switching on and off of the operon.

  1. Both assertion and reason are true, and reason is the correct explanation of the assertion.
  2. Both assertion and reason are true, and reason is not the correct explanation of the assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false. [1]

2.  Assertion: In Eukaryotes, the nucleosomes in chromatin are seen as ‘beads-on-string’ structure when viewed under electron microscope.

Reason: Nucleosomes constitute the repeating unit of a structure in nucleus called chromatin.

  1. Both assertion and reason are true, and reason is the correct explanation of the assertion.
  2. Both assertion and reason are true, and reason is not the correct explanation of the assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false. [1]

3. If the base sequence of one strand of DNA is CAT, TAG, TAC, GAC, what will be the base sequence [2]

  1. Of complementary DNA strand
  2. Of its complementary RNA strand

4.  Mention two functions of the codon AUG. [2]

5.  Describe in brief the process of transcription. [5]

6.  Describe briefly the mechanism of DNA replication. [5]

7.  Write the full names of the different types of RNA. State only how each type is involved in protein synthesis. [5]


Chapter 8: Human Health and Disease

 1.  Mention any two symptoms of AIDS. [2]

2.  Name the infective stage of Plasmodium. Give any two symptoms of the disease caused by this pathogen. [2]

3.  A wife donated one of her kidneys to her husband whose both the kidneys have failed. He has been given immunosuppressive agents/drugs.                       

Now, answer the questions accordingly:

  1. What are immunosuppressive agents?
  2. Why immunosuppressive agents are given to the recipient during an organ transplant?
  3. Name one immunosuppressive agent and its source. [3]

4.  Surveys and statistics show that use of drugs and alcohol has been on the rise especially among the youth which is really a cause of concern as it could result in many harmful effects. Answer the following questions with reference to the above passage:

i. Identify the type of drug obtained from the inflorescence shown in the given figure. 

ii. How are these drugs taken and their effect?

iii. Name any two drugs obtained from these plants. [3]

5.  Read the following and answer any four questions from (i) to (v) given below: [4]

Cancer is one of the most dreaded diseases of human beings and is a major cause of death all over the globe. More than a million Indians suffer from cancer and a large number of them die from it annually. The mechanisms that underlie development of cancer or oncogenic transformation of cells, its treatment and control have been some of the most intense areas of research in biology and medicine. In our body, cell growth and differentiation is highly controlled and regulated. In cancer cells, there is breakdown of these  regulatory mechanisms. Normal cells show a property called contact inhibition by virtue of which contact with other cells inhibits their uncontrolled growth. Cancer cells appears to have lost this property. As a result of this, cancerous cells just continue to divide giving rise to masses of cells called tumors.

(i)   The chemical carcinogens present in tobacco smoke have been identified as a major cause of _______________ cancer.

  1. Lung
  2. Skin
  3. Breast
  4. Prostate

(ii)   In ___________________, a piece of the suspected tissue cut into thin sections is stained and examined under microscope.

  1. X-ray
  2. Biopsy
  3. CT Scan
  4. MRI

(iii)   In which type of cancer treatment, the tumor cells are irradiated lethally?

  1. Immunotherapy
  2. Surgery
  3. Radiotherapy
  4. Chemotherapy

(iv)   Which substances help in activating the immune system and destroying the tumor in cancer patients?

  1. α-interferon
  2. antibiotics
  3. analgesics
  4. Tranquilisers

(v)   Assertion: Several chemotherapeutic drugs are used to kill cancerous cells. Some of these are specific for particular tumors.

Reason: Majority of drugs have side effects like hair loss, anemia, etc.

  1. Both assertion and reason are true, and reason is the correct explanation of the assertion.
  2. Both assertion and reason are true, and reason is not the correct explanation of the assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false.

6.

(a) Name the stage of Plasmodium which gains entry into the human body.

(b) Trace the stages of Plasmodium in the body of female Anopheles after its entry.

(c) Explain the cause of periodic recurrence of chill and high fever during malarial attack in humans. [5]


Chapter 10: Microbes in Human Welfare

1.  Write the scientific name of the microbe used for fermenting malted cereals and fruit juices. [1]

2.  Name the source of cyclosporin-A. How does this bioactive molecule function in our body? [2]

3.  Name any two species of fungus which are used in the production of antibiotics. [2]

4.  Bacillus thuringiensis produces insecticidal protein. Why does this toxin not kill Bacillus? [2]

5.  What is biological control? How Baculoviruses acts as biological control agents? [3]

6.   

  1. What is single cell protein (SCP)?
  2. Name any two organisms which provide SCP.
  3. What is the significance of SCP? [3]

7.  Describe the structure of a biogas plant. Give various steps involved in obtaining biogas. [5]

 

Chapter 11: Biotechnology: Principles and Processes

1.  A restriction enzyme digests DNA into fragments. Name the technique used to check the progression of this enzyme and separate DNA fragments. [1]

2.  Name two commonly used vectors in genetic engineering. [1]

3.  What is the function of gel electrophoresis? [1]

4.  An extra chromosomal segment of circular DNA of a bacterium is used to carry gene of interest into the host cell. What is the name given to it? [1]

5.  Which enzymes are known as “molecular Scissors”? [1]

6.  Assertion: The cut pieces of DNA are linked with plasmid DNA.

Reason: Plasmid DNA fails to act as vectors.

  1. Both assertion and reason are true, and reason is the correct explanation of the assertion.
  2. Both assertion and reason are true, and reason is not the correct explanation of the assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false. [1]

7.  Differentiate between plasmid DNA and chromosomal DNA? [2]

8.  What is the role of enzyme “Ligase” in genetic Engineering? [2]

9.  What are sticky ends? Why are they named so? [2]

10.   Name two commonly used bioreactors. State the importance of using a bioreactor. [2]


Chapter 12: Biotechnology And Its Applications

1.  Name the bacterium which produces Bt toxin. [1]

2.  What is the function of ADA? [1]

3.  Expand PCR. List its two uses. [2]

4.  Explain why children eating golden rice are unlikely to suffer from ‘night blindness’? [2]

5.  Bacillus thuringiensis produces insecticidal protein. Why does this toxin not kill Bacillus? [2]

6.  How does the RNA interface help in developing resistance in tobacco plant against nematode infection? [3]

7.  Agrobacterium tumefaciens is used in natural genetic engineering of plants. How is it so? [3]

8.  With the help of an example, explain the role of transgenic animals in

  1. Vaccine safety
  2. Biological products [3]

9.  Describe briefly the structure of insulin. How is genetically engineered insulin synthesised? [3]

 

Chapter 13: Organisms and Population

1.  Why are some organisms called as eurythermals and some other as stenohaline? [1]

2.  Why are green plants not found beyond a certain depth in the ocean? [1]

3.  Name the type of interaction seen between whale and barnacles growing on its back. [1]

4.  State Gause’s ‘Competitive Exclusion Principle’. [1]

5.  Name and explain the type of interaction between big trees and certain species of wasps. [2]

6.  Explain why very small animals are rarely found in polar region. [2]

7.  Construct an age pyramid which reflects an expanding growth status of human population. [2]

8.  How do organisms like fungi, zooplanktons and bears overcome the temporary short-lived climatic stressful conditions? Explain. [3]

9.  Define the following terms and give one example for each: [5]

  1. Commensalism
  2. Parasitism
  3. Camouflage
  4. Mutualism
  5. Interspecific competition

10.  Study the population growth curves shown below: [3]

  1. Identity curves A and B.
  2. Mention the conditions responsible for the curves A and B.
  3. Which one of them is considered a more realistic one and why?

 

Chapter 15: Biodiversity and Conservation

1.  Assertion: Habitat loss and fragmentation cause driving animals and plants to extinction.

Reason: The most dramatic examples of habitat loss come from tropical rain forests.

  1. Both assertion and reason are true, and reason is the correct explanation of the assertion.
  2. Both assertion and reason are true, and reason is not the correct explanation of the assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false. [1]

2.  Assertion: Species diversity on earth is not uniformly distributed but shows interesting patterns.

Reason: It is generally highest in the tropics and decreases towards the poles.

  1. Both assertion and reason are true, and reason is the correct explanation of the assertion.
  2. Both assertion and reason are true, and reason is not the correct explanation of the assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false. [1]
3.  Assertion: Sacred forests are protected by tribal communities due to religious sanctity.

Reason: These forests are without any human impact.

  1. Both assertion and reason are true, and reason is the correct explanation of the assertion.
  2. Both assertion and reason are true, and reason is not the correct explanation of the assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false. [1]
4.  What is IUCN Red List? Give its main aim. [2]
 
5.  A particular species of wild cat is endangered. In order to save them from extinction, which is a desirable approach in situ or ex situ? Justify your answer. [2]

6.  What is the significance of the slope of regression in a species–area relationship? [3]

7.  Identify the levels of biodiversity in India represented by
  1. Diversity among amphibian in Eastern and Western Ghats.
  2. 50,000 strains of rice in India.
  3. Presence of deserts, mangroves and coral reefs of India. [3]

 

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