Class 12 ISC Biology Question Paper 2023

Maximum Marks: 70

Time Allowed: Three hours

(Candidates are allowed additional 15 minutes for only reading the paper.
They must NOT start writing during this time).

This paper is divided into four sections – A, B, C and D.

Answer all questions.

Section A consists of one question having sub-parts of one mark each.

Section B consists of seven questions of two marks each.

Section C consists of nine questions of three marks each, and

Section D consists of three questions of five marks each

. Internal choices have been provided in two questions each in Section B, Section C and Section D.

The intended marks for questions are given in brackets [ ].

All working, including rough work, should be done on the same sheet as and adjacent to the rest of the answer.

Answers to sub parts of the same question must be given in one place only.

A list of useful physical constants is given at the end of this paper.

A simple scientific calculator without a programmable memory may be used for calculations.

Section-A

Class 12 ISC Biology Question Paper 2023

Section-A

Question 1

Answer the following questions briefly.

Solution

(ix) Which one of the following enzymes is used to join DNA fragments? (a) DNA polymerase (b) Ligase (c) Primase (d) Endonuclease

Solution

(x) What type of ecological pyramid would be obtained from the following data? Secondary consumer: 120 gm Primary consumer: 60 gm Primary producer: 10 gm (a) Inverted pyramid of biomass (b) Pyramid of energy (c) Upright pyramid of numbers (d) Upright pyramid of biomass

Solution

Solution

(xii) Which one of the following factors is responsible for activation of protoxin into active Bt toxin of Bacillus thuringiensis? (a) Body temperature (b) Moist surface of midgut (c) Alkaline pH of gut (d) Acidic pH of stomach

Solution

(xiii) Give one significant contribution of each of the following scientists: (a) T.R. Malthus (b) R. Mishra

Solution

(xiv) Give a term for the following: (a) An ART in which eggs are removed from the ovary of the female, fertilised and then placed in her fallopian tube. (b) Fusion of male gamete and secondary nucleus in angiosperms.

Solution

(xv) Expand the following abbreviations: (a) NACO (b) PID

Solution

(xvi) Give a reason for each of the following: (a) Cattle avoid browsing on Calotropis plant. (b) DNA cannot enter directly into the host cell.

Solution

Section-B

Question 2

Give one difference between the following pairs: (i) Sites of maturation of B - Lymphocytes and T — Lymphocytes (ii) Sources of Opioids and Cannabinoids

Solution

Question 3

Briefly discuss any two methods by which plants avoid self — pollination.

Solution

Question 4

Mention the location and the function of Leydig cells.

Solution

Question 5

(i) What are vestigial organs? Give any one example of a vestigial organ in human body. OR (ii) State Hardy Weinberg’s principle. Give a mathematical expression for this principle.

Solution

Question 6

Riya went to the hospital to meet her sister who was undergoing some treatment. The hospital was crowded with patients suffering from various types of allergies, pneumonia and Ascariasis. Name the disease that Riya is most likely to get infected with. Give one reason for your answer.

Solution

Question 7

State the steps involved in the process of gene therapy for the treatment of ADA — deficiency.

Solution

Question 8

The pedigree chart given below represents the pattern of inheritance of sickle cell anaemia in a family. Study it carefully and answer the questions that follow. (i) What is the genotype of the father? (ii) What is the phenotype of the mother?

Solution

Section-C

Question 9

Discuss any three major causes of loss of biodiversity.

Solution

Question 10

Solution

Question 11

Draw a neat and well labelled diagram of L.S of an anatropous ovule.

Solution

Question 12

(i) Explain the process of sex - determination in grasshopper. (ii) What is the genotype of Tumer’s Syndrome? Mention any one symptom of this syndrome.

Solution

Question 13

With the help of neatly labelled diagrams, explain the different types of age pyramids of human population.

Solution

Question 14

Solution

Question 15

Solution

Question 16

Explain the components of the structural gene in Lac operon system in E. coli. How does the operon function presence of the lactolose

Solution

Question 17

Solution

Section-D

Question 18

Describe the mechanism of decomposition by explaining the various process involved in it.

Solution

Reach Us

SERVICES

CONTACT

(ix) Which one of the following enzymes is used to join DNA fragments?
(a) DNA polymerase
(b) Ligase
(c) Primase
(d) Endonuclease

(x) What type of ecological pyramid would be obtained from the following data?
Secondary consumer: 120 gm
Primary consumer: 60 gm
Primary producer: 10 gm
(a) Inverted pyramid of biomass
(b) Pyramid of energy
(c) Upright pyramid of numbers
(d) Upright pyramid of biomass

(xii) Which one of the following factors is responsible for activation of protoxin into active Bt toxin of Bacillus thuringiensis?
(a) Body temperature
(b) Moist surface of midgut
(c) Alkaline pH of gut
(d) Acidic pH of stomach

(xiii) Give one significant contribution of each of the following scientists:
(a) T.R. Malthus
(b) R. Mishra

(xiv) Give a term for the following:
(a) An ART in which eggs are removed from the ovary of the female, fertilised and then placed in her fallopian tube.
(b) Fusion of male gamete and secondary nucleus in angiosperms.

(xv) Expand the following abbreviations:
(a) NACO
(b) PID

(xvi) Give a reason for each of the following:
(a) Cattle avoid browsing on Calotropis plant.
(b) DNA cannot enter directly into the host cell.

Give one difference between the following pairs:
(i) Sites of maturation of B - Lymphocytes and T — Lymphocytes
(ii) Sources of Opioids and Cannabinoids

(i) What are vestigial organs? Give any one example of a vestigial organ in human body.
OR
(ii) State Hardy Weinberg’s principle. Give a mathematical expression for this principle.

Riya went to the hospital to meet her sister who was undergoing some treatment. The hospital was crowded with patients suffering from various types of allergies, pneumonia and Ascariasis.
Name the disease that Riya is most likely to get infected with. Give one reason for your answer.

The pedigree chart given below represents the pattern of inheritance of sickle cell anaemia in a family. Study it carefully and answer the questions that follow.

(i) What is the genotype of the father?
(ii) What is the phenotype of the mother?

(i) Explain the process of sex - determination in grasshopper.
(ii) What is the genotype of Tumer’s Syndrome? Mention any one symptom of this syndrome.