Plus Two Zoology Previous Year Question Paper March 2018

Time: 1 Hour
Cool off time : 10 Minutes
Maximum : 30 Score

General Instructions to Candidates :

  • In addition to the writing time of 1 hour, there is a 10-minute ‘cool off time’ for Botany and Zoology. Additionally, there is a five minute preparation period at the end of the Botany examination and before the start of the Zoology examination.
  • During the ‘cool off time’ and ‘preparation time’, you are not permitted to write your answers or talk with others about anything.
  • During ‘cool off time’, familiarize yourself with the questions and prepare your answers.
  • Read questions carefully before answering.
  • Only internal choice is allowed and all questions are compulsory.
  • Selecting a question means answering all the sub-questions from that question.
  • The answer sheet itself should include calculations, graphs, and figures.
  • Malayalam version of the questions is also provided.
  • Give equations wherever necessary.
  • Except for non programmable calculators, electronic devices are not allowed in the Examination Hall.

Answer all questions from 1 – 3. Each question carries 1 Score. (Scores: 3 × 1 = 3)

Question 1.
Name the cells in testes which synthesize and secrete the androgens.
Answer:
Interstitial cells or Leydig cells

Question 2.
Different contraceptive methods are given below. Pick out the odd one.
a) CuT
b) Saheli
c) Multiload 375
d) Lippes loop
Answer:
b) Saheli

Question 3.
Expressed sequences in the gene are called
a) Introns
b) Mutons
c) Exons
d) Cistrons
Answer:
c) Exons

II. Answer any nine questions from 4 – 14. Each question carries 2 Scores. (Scores: 9 × 2 = 18)

Question 4.
In a classroom discussion, a student said that the sex of the baby is determined by father. Analyse the statement and give reason for it.
Answer:
Chromosome pattern of human female is XX and male is xy
Haploid gametes produced by female contain only X chromosome while male produces either x or y.
Hence father determines sex of a child

Question 5.
Different contraceptive methods are used to control population explosion. Summarise the natural method and barrier method of contraception.
Answer:
a) Natural methods:
Periodic abstinence, Coitus interruptus, etc

b) Barrier method:
Use of condoms, diaphragms, etc

Question 6.
DNA is tightly packed structure and is found as units called nucleosomes.
a) Explain the concept of nucleosomes.
b) Differentiate between euchromatin and heterochromatin
Answer:
a) Nucleosomes are histone octamer, in this negatively charged DNA wrapped around it.

b) Euchromatin:

  • Here, chromatin region is loosely arranged and they are transcriptionally active Heterochromatin:
  • Here, Hchromatin region is densely packed and transcriptionally inactive

Question 7.
Plus Two Zoology Previous Year Question Paper March 2018, 1
a) Observe the above cross and name the phenomenon.
b) Write down the theoretically given explanations of the phenomenon.
Answer:
a) Incomplete dominance
b) It is the blending of characters, that lead to the production of intermediate flower colour-pink.
In this less efficient enzyme is produced.

Question 8.
Complete the boxes with the suitable words given below:
[Analogus, Homologus, Convergent evolution, Divergent evolution]
Plus Two Zoology Previous Year Question Paper March 2018, 2
Answer:
A – Homologous organ
B – Divergent evolution
C – Analogous organs
D – Convergent evolution

Question 9.
Explain the factors affecting the Hardy-Weinberg equilibrium.
Answer:

  • Gene flow
  • Genetic drift
  • Mutation and
  • Natural selection

Question 10.
Innate immunity is a non-specific type of defense and consists of four types of barriers. Categorize the barriers and give one example for each.
Answer:
i) Physical barriers:
It includes skin or mucous coating of respiratory system

ii) Physiological barriers:
Acid in stomach or saliva

iii) Cellular barriers:
It includes natural killer cells and monocytes

iv) Cytokines barriers:
It includes interferon

Question 11.
Complete the table given below:
Plus Two Zoology Previous Year Question Paper March 2018, 3
Answer:
A – Salmonella
B – common cold
C – plasmodium falciparum
D – elephantiasis

Question 12.
Consumption of drug and alcohol affects the persons mental and physical health very badly. List the warning signs of alcohol or drug abuse.
Answer:

  • Drop in academic performance
  • Lack of interest in personal hygiene
  • Depression
  • Withdrawal symptoms

Question 13.
Identify the disadvantages of RNA over DNA as a genetic material and explain it.
Answer:

  • Hydroxyl group of RNA is reactive and easily degradable
  • RNA is catalytic and highly reactive
  • Mutation takes place at a faster rate
  • Presence of uracil makes RNA less stable

Question 14.
Complete the table with appropriate terms.
Plus Two Zoology Previous Year Question Paper March 2018, 4
Answer:
A – Aspergillus Niger
B – bacterium
C – cyclosporine A
D – Monascus purpureus

III. Answer any three from 15 – 18 questions. Each question carries 3 scores. (Scores: 3 × 3 = 9)

Question 15.
Observe the graph and answer the following questions:
Plus Two Zoology Previous Year Question Paper March 2018, 5
a) Name S, A, Z and C in the graph.
b) Name the scientists who explained Species – Area relationship.
Answer:
a) S – Species richness
A – Area
Z – Regression coefficient
C – Y Intercept

b) Alexander Von Humboldt

Question 16.
a) In lac Operon lactose act as inducer molecule. Evaluate the statement and explain it.
b) Observe the diagram of lac Operon and identify labelled parts A, B, C and D.
Plus Two Zoology Previous Year Question Paper March 2018, 6
Answer:
a) Lactose that binds with repressor and make structural modification hence it cannot bind with operator therefore lactose switch off Lac Operon act as inducer.

b) A – Repressor mRNA
B – Bete galactosidase
C – Permease
D – Transacetylase

Question 17.
Sexually transmitted disease (STD) are mainly transmitted through sexual contact.
a) Name any two example of sexually transmitted disease.
b) Explain any two methods adopted to prevent STDs.
Answer:
a) Gonorrhea, syphilis
b)

  1. Avoid sex with multiple partners
  2. Always use condoms during coitus

Question 18.
Hemophilia, Sickle cell anemia, and Phenyl Ketonurea are Mendelian disorders.
a) What do you mean by Mendelian disorder?
b) Which one of the above is an example of inborn error of metabolism? Mention the cause of the disorder.
Answer:
a) Mendelian disorder is determined by a mutation in a single gene
b) Phenylketonuria.
It is an autosomal recessive trait in which lack of enzyme for the conversion of phenylalanine to tyrosine.

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