Q1
mcq
1 mark
Choose the set of sex determining chromosomes that indicates the correct sex of the respective organism.
- A. Homozygous sex chromosomes (ZZ) determine female sex in birds
- B. XO type of sex chromosomes determine male sex in grasshoppers
- C. XXY condition in humans, as found in Turner Syndrome, determines male sex
- D. Homozygous sex chromosomes (XX) produce male sex in Drosophila
Correct Answer: B —
Solution
XO type of sex chromosomes determine male sex in grasshoppers. In the XO type of sex determination, males have only one X chromosome (X O) and females have two X chromosomes (XX). Therefore, option B is correct. Option A is wrong because in birds, ZZ is male and ZW is female. Option C is wrong because XXY in humans is Klinefelter syndrome, not Turner syndrome; Turner syndrome is XO and female. Option D is wrong because in Drosophila, XX is female and XY is male.
Q2
mcq
1 mark
Given below is a list of steps Meselson and Stahl carried out in their experiment to prove that DNA replication is semi-conservative. Select the option that gives the correct sequence of steps followed by them.
(i) Bacteria transferred to a $N_{14}$ medium and sampled every 20 minutes.
(ii) All bacteria contain hybrid DNA ($N_{14}$ DNA and $N_{15}$ DNA).
(iii) Bacteria grown in $N_{15}$ medium for many generations.
(iv) All bacteria contain $N_{15}$ DNA.
(v) Bacteria contain either all $N_{14}$ DNA or all hybrid DNA.
- A. (ii) (iv) (iii) (i) (v)
- B. (i) (ii) (v) (iv) (iii)
- C. (iii) (iv) (i) (ii) (v)
- D. (iv) (iii) (ii)
Correct Answer: C —
Solution
The correct sequence in Meselson and Stahl’s experiment is: (iii) bacteria grown in $N_{15}$ medium for many generations, (iv) all bacteria contain $N_{15}$ DNA, (i) bacteria transferred to a $N_{14}$ medium and sampled every 20 minutes, (ii) all bacteria contain hybrid DNA ($N_{14}$ DNA and $N_{15}$ DNA), and (v) bacteria contain either all $N_{14}$ DNA or all hybrid DNA. So the correct option is C. This sequence shows the shift from heavy nitrogen to light nitrogen and the appearance of hybrid DNA after one generation, supporting semi-conservative replication.
Q2
mcq
Given below is a list of steps Meselson and Stahl carried out in their experiment to prove that DNA replication is semi-conservative. Select the option that gives the correct sequence of steps followed by them.
- A. (ii) (iv) (iii) (i) (v)
- B. (i) (ii) (v) (iv) (iii)
- C. (iii) (iv) (i) (ii) (v)
- D. (iv) (iii) (ii) (v) (i)
Correct Answer: C —
Solution
The correct order of steps is: (iii) bacteria grown in $N_{15}$ medium for many generations, (iv) all bacteria contain $N_{15}$ DNA, (i) bacteria transferred to a $N_{14}$ medium and sampled every 20 minutes, (ii) all bacteria contain hybrid DNA ($N_{14}$ DNA and $N_{15}$ DNA), and (v) bacteria contain either all $N_{14}$ DNA or all hybrid DNA. Hence, option C is correct. This is the sequence followed by Meselson and Stahl to demonstrate semi-conservative DNA replication.
Q3
mcq
Identify the option that gives the correct type of evolution exhibited by the two animals shown, living in the same habitat in Australia.
- A. Convergent Evolution
- B. Disruptive Selection
- C. Divergent Evolution
- D. Homologous Ancestry
Correct Answer: A —
Solution
The correct answer is Convergent evolution. The two animals shown are unrelated but live in the same habitat in Australia and develop similar body forms due to similar environmental pressures. Such similarity in unrelated organisms is called convergent evolution. Divergent evolution refers to different forms arising from a common ancestor, and homologous ancestry refers to shared origin, so those are not correct here.
Q4
mcq
A human male decides to adopt a surgical method for contraception. Identify the point in the diagram where a cut would be made and tied.
- A. Point S
- B. Point R
- C. Point Q
- D. Point P
Correct Answer: B —
Solution
In male surgical contraception (vasectomy), a small cut is made and the vas deferens is tied and cut. In the given diagram, the point representing the vas deferens to be cut and tied is Point R. Therefore, option B is correct.
Q5
mcq
Which of the following options correctly matches the name of the hormone to its site of production in the human body?
- A. P-i, Q-iii, R-ii, S-iv
- B. P-i, Q-iv, R-iii, S-ii
- C. P-iii, Q-iv, R-i, S-ii
- D. P-ii, Q-iii, R-i, S-iv
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Q6
mcq
Which of the following seeds have remained alive for the longest period?
- A. Phoenix dactylifera
- B. Striga asiatica
- C. Mangifera indica
- D. Yucca gigantea
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Q7
mcq
Select the options which is/are incorrect statement(s) with respect to T-lymphocytes in the human body.
- A. (i) and (iv) only
- B. (iii) only
- C. (iv) only
- D. (iii) and (iv) only
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Q8
mcq
Human settlement often leads to habitat loss which leads to fragmentation, forming smaller patches of habitats. Select the statements that describe how a small patch differs from a large patch of the same habitat.
- A. (ii), (iii) and (iv) only
- B. (ii) and (iv) only
- C. (i) and (iii) only
- D. (i), (ii) and (iii) only
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Q9
mcq
Identify the option that does not exhibit a parasitic relationship.
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Q11
mcq
Polymerase chain reaction. Which of the following statements are correct with reference to the illustration given above?
- A. (i) and (iii) only
- B. (ii) and (iii) only
- C. (ii) only
- D. (i) only
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Q12
mcq
DNA profiles of the child and three individuals 1, 2 and 3 who claim to be the parents of the child are given below. Select the option that shows the correct actual parent/parents of the child.
- A. Individual 1 and 3
- B. Individual 1 and 2
- C. Individual 2 and 3
- D. Individual 1 is the only parent of the child amongst 1, 2 and 3
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Q13
mcq
Assertion (A): In humans the genotype with all the dominant alleles $(AABBCC)$ will have the darkest skin colour.
Reason (R): In a polygenic trait, phenotype reflects the contribution of each allele.
- A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- C. Assertion (A) is true, but Reason (R) is false.
- D. Assertion (A) is false, but Reason (R) is true.
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Q14
mcq
Assertion (A): The number of white winged moths decreased drastically after industrialisation in England.
Reason (R): Effects of industrialisation were more marked in rural areas of England.
- A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- C. Assertion (A) is true, but Reason (R) is false.
- D. Assertion (A) is false, but Reason (R) is true.
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Q15
mcq
Assertion (A): More and more children in metro cities of India suffer from allergies and asthma due to sensitivity to the environment.
Reason (R): Modern day lifestyle and a protected environment in early life has resulted in lowering the immunity.
- A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- C. Assertion (A) is true, but Reason (R) is false.
- D. Assertion (A) is false, but Reason (R) is true.
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Q16
mcq
Assertion (A): The Mediterranean orchid Ophrys uses sexual deceit to get pollinated by a species of bee.
Reason (R): The female bee changes its colour depending on the temperature of the area.
- A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- C. Assertion (A) is true, but Reason (R) is false.
- D. Assertion (A) is false, but Reason (R) is true.
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Q17
short answer
2 marks
(a) Explain the process of the development of a male gametophyte in an angiosperm.
(b) Why is it called a male gametophyte ?
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Q18
short answer
2 marks
(a) Write the first step the primary effluent undergoes when it enters the secondary treatment plant and state the purpose.
(b) What is the level of B.O.D indicative of in the secondary treatment plant ? Mention its significance.
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Q19
short answer
2 marks
Given below is a food web that involves nine organisms.
(a) Identify two producers and two carnivores shown in the food web.
(b) Is it possible to make an ecological pyramid depicting this food web ? Give reason in support of your answer.
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Q20
short answer
2 marks
Illustrate with the help of an example how introduction of an alien species turns invasive and causes decline of an indigenous species.
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Q21
short answer
2 marks
(a) ဂ to detect recombinant DNA.
Explain the method.
OR
(b) Expla
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Q21
short answer
2 marks
d to detect recombinant DNA. Explain the method.
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Q21
short answer
2 marks
Explain how recombinant DNA technology is used to detect a disease even before any clinical symptom appears.
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Q22
short answer
3 marks
(i) How many types of RNA polymerases are there in a eukaryote cell? Mention which one of them transcribes hnRNA.
(ii) Write the changes that hnRNA undergoes before it leaves the nucleus as mRNA.
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Q22
short answer
3 marks
The length of DNA in any cell is far greater than the dimension of its nucleus. Explain how this enormous DNA is packaged in a eukaryotic cell.
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Q23
short answer
3 marks
Expand and explain the following techniques used in
(a) GIFT
(b) ZIFT
(c) IUI
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Q24
short answer
3 marks
Given below is a diagrammatic sectional view of a seminiferous tubule. State the developmental process of:
(a) (i)
(ii)
(iii)
(b)
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Q25
short answer
3 marks
(a) Darwin's limitations have been identified by modern biologists. Mention the limitations identified.
(b) Name and state the most accepted theory of evolution in modern times.
(c) Mention any two ways the limitations of evolution are explained in modern biology.
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Q26
short answer
3 marks
(a) Name the category of drugs represented by the chemical structure given above.
(b) If the methyl group is substituted by acetyl group we get a bitter crystalline compound. Name the compound.
(c) Name the natural source of these compounds.
(d) State the harmful effects of this class of drugs on the human body.
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Q26
short answer
By acetyl group we get a bitter crystalline compound. Name the compound.
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Q26
short answer
Name the natural source of these compounds.
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Q26
short answer
3 marks
State the harmful effects of this class of drugs on the human body.
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Q27
short answer
3 marks
(a) Write the scientific name of the nematode that infests the tobacco plants and the part that it infests.
(b) How is Agrobacterium used to protect tobacco plant from this attack?
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Q27
short answer
(a) Write the scientific name of the nematode that infests the tobacco plants and the part that it infests.
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Q27
short answer
3 marks
(b) How is Agrobacterium used to protect tobacco plant from this attack?
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Q28
short answer
3 marks
Explain the following population interactions with the help of one example each:
(a) Brood Parasitism
(b) Co-evolution of mutualists
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Q29
short answer
The following pedigree chart shows the inheritance of a genetic disorder up to three generations of a family. Observe the chart and answer the questions that follow.
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Q30
short answer
The diagram shows the life cycle of a pathogenic protozoan.
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Q31
long answer
5 marks
(a) Answer the following questions with respect to recombinant DNA technology:
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Q31
long answer
5 marks
OR
(b) Answer the following questions based on Bt-crops:
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Q32
short answer
5 marks
Protein synthesis requires the services of all three types of RNAs, namely t-RNA, m-RNA and r-RNA. Explain the role of each of them during the process of protein synthesis in prokaryotes.
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Q38
short answer
1 mark
Is the disease sex-linked or autosomal as per the chart? Give reasons in support of your answer.
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Q39
short answer
1 mark
Is it a recessive or a dominant disorder?
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Q40
short answer
1 mark
probability of their daughter being a sufferer of this disease?
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Q41
short answer
1 mark
disease, what will be the probability of their daughter being a sufferer of this disease?
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Q43
short answer
1 mark
Write the changes the parasite undergoes in the liver.
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Q44
short answer
1 mark
Write the changes the parasite undergoes when it enters the RBC.
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Q45
short answer
1 mark
At which stage during the life cycle of the pathogen does the e ? Name the disease and the toxic substance responsible for these symptoms.
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Q47
short answer
Why is plasmid considered to be an important tool in rDNA technology? From where can plasmids be isolated? (Any two sources)
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Q49
short answer
DNA technology cannot proceed without restriction
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Q51
short answer
Why do farmers prefer to grow Bt cotton crop than genetically un
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Q53
short answer
Write the possible phenotype and genotype of $F_1$ generation.
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Q54
short answer
State the laws of Mendel that are proved true by the $F_1$ generation.
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Q55
short answer
Mention the $F_2$ phenotypic ratio along with their possible phenotypes.
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Q56
short answer
Write the genotypes of the male and female gametes produced by $F_1$ progeny.
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Q57
short answer
Double fertilisation is an event unique to all flowering plants. Explain the process.
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Q58
short answer
Give a reason for the following: A seed of an orange has many embryos.
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Q59
short answer
Give a reason for the following: Cashew is a false fruit but Guava is a true fruit.
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