PRINCIPLES OF INHERTANCE AND VARIATION

 

Class: 12 (2025-26)

CLASS TEST

TIME: 2 HOURS	M.M.: 50

General Instructions:

• This question paper contains 22 questions.

• All questions are compulsory.

• Q.1 to 5 (Multiple Choice Questions (MCQs)): 5 questions. Each question carries 1 mark.

• Q.6 to 7 (Assertion Reason Questions): 2 questions. Each question carries 1 mark.

• Q.8 to 11 (Very Short Answer Questions): 4 questions. Each question carries 1 mark.

• Q.12 to 16 (Short Answer Questions): 5 questions. Each question carries 2 marks.

• Q.17 to 21 (Long Answer Questions): 5 questions. Each question carries 5 marks.

• Q.22 to 22 (Competency Based Questions): 1 questions. Each question carries 4 marks.

Topics Covered:

• Principles of Inheritance and Variation

 

Q.NO.	QUESTIONS	MARKS
MULTIPLE CHOICE QUESTIONS (MCQS) Questions 1 to 5 (5 questions × 1 mark each)
1	In Mendelian inheritance, which law states that alleles of different genes assort independently of one another during gamete formation? A. Law of Segregation B. Law of Dominance C. Law of Independent Assortment D. Law of Recombination	1
2	A plant with genotype TtYy is crossed with a plant with genotype Ttyy. What is the probability of obtaining an offspring with genotype TtYy? A. 1/4 B. 1/2 C. 1/8 D. 1/16	1
3	Which of the following genetic disorders is caused by a mutation in a single gene? A. Down Syndrome B. Turner Syndrome C. Sickle Cell Anemia D. Klinefelter Syndrome	1
4	In a dihybrid cross involving two heterozygous parents (AaBb x AaBb), what is the expected phenotypic ratio in the F1 generation? A. 9:3:3:1 B. 1:1:1:1 C. 3:1 D. 1:2:1	1
5	A woman with blood group AB marries a man with blood group O. What is the probability that their child will have blood group A? A. 0% B. 25% C. 50% D. 75%	1
ASSERTION REASON QUESTIONS Questions 6 to 7 (2 questions × 1 mark each) Instructions: The following questions consist of two statements – Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below: A. Both A and R are true, and R is the correct explanation of A. B. Both A and R are true, and R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true.
6	Assertion (A): In Mendelian inheritance, the F2 generation shows a phenotypic ratio of 3:1 in a monohybrid cross.  Reason (R): The F1 generation produces gametes with two different alleles in equal proportions.	1
7	Assertion (A): Codominance results in offspring with a phenotype that is distinct from both parents.  Reason (R): In codominance, both alleles in a heterozygote are fully expressed.	1
VERY SHORT ANSWER QUESTIONS Questions 8 to 11 (4 questions × 1 mark each)
8	Define incomplete dominance with an example.	1
9	What is the phenotypic ratio observed in the F2 generation of a monohybrid cross? A. 3:1 B. 1:2:1 C. 9:3:3:1 D. 1:1	1
10	Explain why Mendelian inheritance patterns may not always be observed in all organisms.	1
11	Assertion (A): The law of independent assortment is always applicable.  Reason (R): Genes located on the same chromosome assort independently.	1
SHORT ANSWER QUESTIONS Questions 12 to 16 (5 questions × 2 marks each)
12	Explain Mendel's law of segregation using the concept of alleles.	2
13	How does incomplete dominance differ from codominance? Provide an example of each.	2
14	Describe the significance of test crosses in genetic studies.	2
15	Compare the mechanisms of sex determination in cockroaches and Drosophila, highlighting one key difference in their chromosomal systems.	2
16	Explain how polygenic inheritance contributes to continuous variation in traits.	2
LONG ANSWER QUESTIONS Questions 17 to 21 (5 questions × 5 marks each)
17	Explain the significance of Mendel's dihybrid cross experiment in establishing the Law of Independent Assortment. Discuss how this principle is violated during gene linkage.	5
18	A plant with genotype AaBb (where A=Tall, a=dwarf; B=Red flowers, b=white) was test crossed. The progeny showed 42% parental types and 8% recombinants each for Ab & aB. (a) Calculate the map distance between these genes (b) Explain why the recombination frequency isn't 50%	5
19	Compare and contrast incomplete dominance and codominance using specific examples. How do these phenomena challenge Mendel's principle of dominance?	5
20	Explain the phenomenon of pleiotropy with a suitable example. Discuss how pleiotropy influences the inheritance patterns of genetic disorders and provide insights into its implications for genetic counseling.	5
21	Describe the chromosomal theory of inheritance with experimental evidence. How did Morgan's work with Drosophila provide crucial support for this theory?	5
COMPETENCY BASED QUESTIONS Questions 22 to 22 (1 questions × 4 marks each)
22	Down syndrome, Klinefelter syndrome, and Turner syndrome are genetic disorders resulting from chromosomal abnormalities. Down syndrome is characterized by trisomy of chromosome 21, Klinefelter syndrome by the presence of an extra X chromosome in males (47,XXY), and Turner syndrome by the absence of one X chromosome in females (45,X). Analyze the genetic constitution and phenotypic characteristics of individuals with these syndromes. A. Explain how non-disjunction during meiosis leads to the chromosomal abnormalities observed in Down syndrome, Klinefelter syndrome, and Turner syndrome. B. Compare and contrast the phenotypic characteristics of individuals with Down syndrome, Klinefelter syndrome, and Turner syndrome. C. Evaluate the impact of these syndromes on fertility and reproductive health. D. Discuss the genetic counseling considerations for families with a history of these syndromes. E. Propose a strategy for early diagnosis and management of these genetic disorders.	4

 

Respiration infographic

 

JOINTS GANGWAR SIR

 

SEWAGE TREATMENT Gangwar sir

 

EVOLUTION CLASS XII BIOLOGY

 

GANGWAR SIR BAREILLY

BIOLOGY

Class: 12 (2025-26)

CLASS TEST

TIME: 3 HOURS	M.M.: 70

General Instructions:

• This question paper contains 33 questions.

• All questions are compulsory.

• Q.1 to 9 (Multiple Choice Questions (MCQs)): 9 questions. Each question carries 1 mark.

• Q.10 to 13 (Assertion Reason Questions): 4 questions. Each question carries 1 mark.

• Q.14 to 18 (Very Short Answer Questions): 5 questions. Each question carries 1 mark.

• Q.19 to 26 (Short Answer Questions): 8 questions. Each question carries 2 marks.

• Q.27 to 31 (Long Answer Questions): 5 questions. Each question carries 5 marks.

• Q.32 to 32 (Competency Based Questions): 1 questions. Each question carries 5 marks.

• Q.33 to 33 (Comprehension Based Questions): 1 questions. Each question carries 6 marks.

Topics Covered:

• Evolution

 

Q.NO.	QUESTIONS	MARKS
MULTIPLE CHOICE QUESTIONS (MCQS) Questions 1 to 9 (9 questions × 1 mark each)
1	Which of the following statements best explains the concept of adaptive radiation? A. It refers to the rapid evolution of a single species into many new forms B. It describes the migration of species to new habitats C. It is the process by which species become extinct D. It explains the convergence of unrelated species into similar forms	1
2	Which of the following is NOT a mechanism of evolution? A. Natural selection B. Genetic drift C. Mutation D. Photosynthesis	1
3	According to Darwin's theory of natural selection, which of the following is essential for evolution to occur? A. Variation within a population B. Acquired characteristics C. Uniform environment D. Stable population size	1
4	Which of the following best describes the bottleneck effect in evolution? A. A sudden reduction in population size leading to loss of genetic variation B. The migration of a small group to a new habitat C. The divergence of species due to geographic isolation D. The accumulation of mutations over time	1
5	Which of the following is an example of convergent evolution? A. The wings of bats and birds B. The forelimbs of humans and bats C. The tails of monkeys and apes D. The eyes of humans and octopuses	1
6	Which of the following best explains the role of mutations in evolution? A. They introduce genetic variation B. They always lead to beneficial traits C. They are the primary driver of natural selection D. They are the result of environmental changes	1
7	Which of the following is a key difference between Lamarck's and Darwin's theories of evolution? A. Lamarck proposed that acquired traits are inherited, while Darwin proposed natural selection B. Lamarck proposed natural selection, while Darwin proposed genetic drift C. Lamarck focused on genetic mutations, while Darwin focused on environmental factors D. Lamarck suggested that species remain unchanged, while Darwin suggested gradual change	1
8	Which of the following is true about genetic drift? A. It has a greater effect in small populations B. It is a directional process C. It always increases genetic variation D. It is driven by natural selection	1
9	Which of the following best describes the concept of homology in evolutionary biology? A. Structures in different species that have a common evolutionary origin B. Structures that perform the same function in different species C. The independent evolution of similar features in different lineages D. The process by which species diverge from a common ancestor	1
ASSERTION REASON QUESTIONS Questions 10 to 13 (4 questions × 1 mark each) Instructions: The following questions consist of two statements – Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below: A. Both A and R are true, and R is the correct explanation of A. B. Both A and R are true, and R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true.
10	Assertion (A): The fossil record provides complete evidence for the theory of evolution.  Reason (R): Fossils are preserved remains of organisms from past geological ages.	1
11	Assertion (A): Homologous organs support the theory of divergent evolution.  Reason (R): Homologous organs have different structures but similar functions.	1
12	Assertion (A): Natural selection acts on phenotypic variations in populations.  Reason (R): Phenotypic variations are always heritable.	1
13	Assertion (A): Genetic drift has a greater impact on smaller populations.  Reason (R): Genetic drift is a random change in allele frequencies over generations.	1
VERY SHORT ANSWER QUESTIONS Questions 14 to 18 (5 questions × 1 mark each)
14	Explain the significance of the Miller-Urey experiment in the context of chemical evolution.	1
15	Define Darwinian fitness in the context of evolution.	1
16	Describe one example of convergent evolution.	1
17	What role does genetic drift play in small populations?	1
18	How does the Hardy-Weinberg principle relate to evolutionary stability?	1
SHORT ANSWER QUESTIONS Questions 19 to 26 (8 questions × 2 marks each)
19	Explain how industrial melanism in peppered moths demonstrates natural selection.	2
20	Explain how embryological evidence supports the theory of evolution.	2
21	Define adaptive radiation and name the phenomenon observed in Darwin's finches.	2
22	Why is the Hardy-Weinberg equilibrium rarely observed in nature?	2
23	Explain how Bougainvillea and Cucurbita represent homology, despite their distinct appearances and functions.	2
24	Explain with an example how parallel evolution provides evidence for natural selection.	2
25	What is founder effect? How does it affect genetic diversity?	2
26	Explain how the discovery of fossils of Homo habilis and Homo erectus provides evidence for the evolution of modern humans.	2
LONG ANSWER QUESTIONS Questions 27 to 31 (5 questions × 5 marks each)
27	Explain Darwin's theory of natural selection with the help of suitable examples.	5
28	Discuss the three types of natural selection (stabilizing, directional, and disruptive) with suitable examples. How do these types of selection contribute to the process of evolution? Also, explain how the concepts of branching descent and natural selection form the foundation of Darwin's theory of evolution.	5
29	Describe the Hardy-Weinberg principle and explain the factors that can disrupt genetic equilibrium.	5
30	Trace the sequence of human evolution as per NCERT, highlighting the key features of each stage. Also, discuss the significance of cranial capacity in understanding human evolution.	5
31	Explain the concept of adaptive radiation with reference to the evolution of Darwin's finches.	5
COMPETENCY BASED QUESTIONS Questions 32 to 32 (1 questions × 5 marks each)
32	The Hardy-Weinberg principle states that allele frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. Consider a population of butterflies where the allele frequency for red wings (R) is 0.6 and the frequency for white wings (r) is 0.4. The population undergoes a sudden environmental change that favors white-winged butterflies, leading to a significant decrease in the red-winged population. Analyze the situation and answer the following questions: [1] What evolutionary mechanism is at play in this scenario? [2] How does this environmental change affect the allele frequencies in the population? [3] Predict the long-term impact on the genetic diversity of the butterfly population. [4] Discuss how the Hardy-Weinberg principle might be violated in this case. [5] Propose a conservation strategy to maintain genetic diversity in the butterfly population. A. Describe the concept of natural selection and its role in evolution. B. Explain how allele frequencies change in response to environmental pressures. C. Analyze the consequences of reduced genetic diversity on population survival. D. Evaluate the conditions under which the Hardy-Weinberg principle fails to apply. E. Suggest practical measures to preserve genetic diversity in endangered populations.	5
COMPREHENSION BASED QUESTIONS Questions 33 to 33 (1 questions × 6 marks each)
33	Evolution of Antibiotic Resistance The emergence of antibiotic-resistant bacteria is a classic example of evolution in action. When penicillin was first introduced in the 1940s, it could kill virtually all Staphylococcus aureus strains. Today, over 95% of strains are resistant. This resistance develops through natural selection - random mutations in bacterial DNA occasionally produce resistance genes. In an antibiotic-free environment, these mutations may be neutral or even harmful. However, when antibiotics are present, resistant bacteria survive and reproduce, passing on the resistance genes. The misuse of antibiotics accelerates this process by increasing the selection pressure. Horizontal gene transfer through plasmids further spreads resistance across bacterial populations. (1) Explain how the misuse of antibiotics contributes to the evolution of resistance in bacteria. (2) Compare and contrast vertical and horizontal gene transfer in the context of antibiotic resistance. (3) Propose a public health strategy to slow down the evolution of antibiotic-resistant bacteria.	6