Board Paper of Class 12 2017 Biology - Solutions

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Question 1
(a) Give a brief answer for each of the following:
(i) Why do Green plants start evolving CO₂ instead of O₂, at high temperatures?
(ii) Define Apomixis.
(iii) What is a Recon?
(iv) Why are the spores of Bacillus thuringiensis used as bio insecticide?

(b) Each of the following question(s)/statement(s) has four suggested answers. Choose the correct option in each case.
1. Initiation codon of protein synthesis in Eukaryotes:
(i) GUA
(ii) GGA
(iii) CCA
(iv) AUG
2. Type of interaction where an individual sacrifices its own welfare (life) for the benefit of another animal of its own species:
(i) Altruism
(ii) Scavenging
(iii) Protocooperation
(iv) Commensalism
3. Wings of Insect and Birds are examples of:
(i) Analogous
(ii) Homologous
(iii) Vestigial
(iv) Atavism
4. The pressure of the cell contents on the cell wall is known as:
(i) Wall pressure
(ii) Osmotic pressure
(iii) Turgor pressure
(iv) Diffusion pressure

(c) Give a scientific term for each of the following:
(i) An act of expelling the full-term foetus from mother’s uterus at the end of gestation.
(ii) Entry of pollen tube into an ovule through integuments.
(iii) An alternative form of the single gene which influences the same character and produces different expressions in different individuals of a species.
(iv) The study of human population covering all aspects and parameters.

(d) Expand the following abbreviations:
(i) MTP
(ii) IVF
(iii) HIV
(iv) DPD

(e) Name the scientists who have contributed to the following:
(i) Discovered the fossil of Cro-Magnon man.
(ii) Classified active and passive absorption of water by roots.
(iii) Reported Haemophilia.
(iv) Discovered double fertilization. VIEW SOLUTION

Question 2
(a) Differentiate between Apes and Man with respect to the following characteristics:
(i) Posture
(ii) Brow ridges
(iii) Cranial capacity

(b) Define protobionts.

(c) What is cognogeny? VIEW SOLUTION

Question 3
(a) Explain any three molecular (genetic) evidences in favour of organic evolution.

(b) Define biogenesis.

(c) Define fossils. VIEW SOLUTION

Question 4
(a) List any three drawbacks of Darwinism.

(b) State Hardy-Weinberg’s principle.

(c) Differentiate between Directional natural selection and Disruptive natural selection. VIEW SOLUTION

Question 5
(a) Give four anatomical differences between a dicot leaf and monocot leaf.

(b) Briefly describe the secretory phase of the menstrual cycle.

(c) Define:
(i) Menarche
(ii) Actinomorphic symmetry VIEW SOLUTION

Question 6
(a) Give a graphic representation of the Hatch Slack or C₄ cycle.

(b) Give two significant differences between:
(i) Transpiration and Guttation
(ii) Chlorophyll ‘a’ and Chlorophyll ‘b’

(c) Define the following:
(i) Amniocentesis
(ii) Polyembryony VIEW SOLUTION

Question 7
(a) Describe K⁺ transport stomatal mechanism.

(b) Draw a neat-labelled diagram of L.S. of anatropous ovule.

(c) Differentiate between the following:
(i) Spermatogenesis and oogenesis
(ii) Apocarpous ovary and syncarpous ovary. VIEW SOLUTION

Question 8
(a) Explain Pleiotropy with reference to phenylketonuria.

(b) Explain the mechanism of transcription in a prokaryotic cell.

(c) Explain Rh factor incompatibility during pregnancy. VIEW SOLUTION

Question 9
(a) Discuss the various In-situ and Ex-situ strategies for conservation of biodiversity.

(b) List any four applications of tissue culture.

(c) Mention the causative agent and the preventive measures for each of the following:
(i) Gonorrhoea
(ii) Pneumonia VIEW SOLUTION

Question 10
(a) Name the components of lac operon and discuss their role.

(b) Give the significance of transgenic animals.

(c) Give one significant difference between:
(i) Electroporation and Gene Gun
(ii) ECG and EEG VIEW SOLUTION