This set of Class 12 Biology Chapter 5 Multiple Choice Questions & Answers (MCQs) focuses on “Chromosomal Theory of Inheritance-1”.
1. The lack of publicity of Mendel’s work was due to _______
a) lack of his ability to communicate
b) his deafness
c) lack of the availability of efficient communication methods
d) him being held captive in jail
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Explanation: Mendel had published his work back in 1865. The communication methods were not well developed and for people to recognize the importance of his work took more than half a decade after it had been published.
2. What was the reason for the scientific community not accepting Mendel’s proposal?
a) Mendel’s factors blended, but natural changes were somewhat discrete
b) Mendel’s factors were discrete, but natural changes blended
c) Mendel’s factors were discrete, and natural changes were also discrete
d) Mendel’s factors blended and natural changes also blended
View Answer
Explanation: Mendel’s laws of inheritance were based on the assumptions of factors/genes being discrete. However, most of the changes observed in nature exhibited the blending of characters. This led to the unacceptance of Mendel’s studies.
3. The nature exhibits ________ variation.
a) continuous
b) discontinuous
c) uniform
d) discrete
View Answer
Explanation: The variation observed in nature is mostly continuous. This arises from the complex genetic interactions which Mendel failed to observed in his experiments on pea plants.
4. What approach used by Mendel was utterly new?
a) Mathematics to study biological phenomena
b) Crossing of plants
c) Growing garden pea plants
d) Emasculation
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Explanation: People had performed crosses on garden pea plants before Mendel. But no one had applied a statistical and probabilistic approach to unveil the underlying phenomena. Mendel was the first to do so.
5. One of the significant drawbacks of Mendel’s work was _________
a) his study on pea plants
b) inability to show the factors being continuous
c) inability to isolate factors
d) inability to prepare proper notes
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Explanation: Mendel’s work suggested the existence of stable and discrete factors. This was completely shocking for the contemporary scientific world. A major drawback that lied was the inability to discover the factors and prove their existence.
6. Which of the following scientists was not responsible for the rediscovery of Mendel’s work?
a) de Vries
b) Correns
c) Tschermark
d) Putin
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Explanation: Mendel’s work was laid in papers before people could recognize it after 1900. This was achieved by the rediscovery of his work by three scientists: de Vries, Correns, and Tschermark.
7. The advent of microscopy in the 1900s allowed scientists to visualize _______
a) moon
b) cell division
c) electron
d) nucleon
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Explanation: Microscopy came into the picture around the 1900s. This allowed scientists to visualize cells and processes like cell division.
8. What were the colored bodies observed in the nucleus during the process of division called?
a) Chromosomes
b) Genes
c) DNA
d) RNA
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Explanation: Chromosomes means colored bodies/objects. The staining procedures allowed biologists to visualize the nucleus and chromosomes during the process of cell division.
9. Which pair of scientists to correlate chromosome movement during meiosis to Mendel’s predictions?
a) Crick and Watson
b) Newton and Einstein
c) Sutton and Boveri
d) Franklin and Wilkins
View Answer
Explanation: Sutton and Boveri, along with other scientists, had uncovered the complete movement of chromosomes during the process of cell division. They observed that these movements correlate with Mendel’s findings.
10. What was the contribution of Theodore Boveri and Walter Sutton to Mendel’s work?
a) Rediscovery of his work
b) Challenging Mendel
c) Reperforming Mendel’s experiments in lab conditions
d) Chromosome movement correlation with Mendel’s predictions
View Answer
Explanation: Theodore Boveri and Walter Sutton had unraveled the mechanisms underlying the chromosome movement during cell division. These movements were correlated with Mende’s laws.
11. What was the contribution of Correns, von Tschermak, and de Vries to Mendel’s work?
a) Rediscovery of his work
b) Challenging Mendel
c) Reperforming Mendel’s experiments in lab conditions
d) Chromosome movement correlation with Mendel’s predictions
View Answer
Explanation: These three scientists helped in the rediscovery of Mendel’s work in the 1900s. Mendel’s work was published in 1865 and long forgotten.
12. Why is the chromosome behavior during cell division similar to the gene behavior?
a) Chromosome learns from gene
b) Gene learns from chromosome
c) Chromosome contains gene
d) Gene contains chromosome
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Explanation: The chromosome is composed of many genes. Hence the behavior of gene was similar to the observed movement of the chromosome during the process of cell division.
13. What is called an equational division?
a) Mitosis
b) Meiosis
c) Mitrosis
d) Cleavage
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Explanation: Mitosis results in the equal division of the chromosomal content of the cell. Hence it is also called equational division. The mitosis results in the production of two daughter cells from one parent cell with the exact chromosomal content as in the parent cell. This is ensured by a duplication event in the synthesis phase prior to the mitosis phase.
14. Genes occur in pairs.
a) True
b) False
View Answer
Explanation: Genes are present on chromosomes. Each diploid cell has a set of two chromosomes. Thus, genes also occur in pairs. The pair of genes are called alleles if they code for a different protein. Usually, one copy of gene is enough to code for a functional protein. Hence the other copy is kept silent. This results in the dominant and recessive nature of the genes.
15. Chromosomes occur in pairs.
a) True
b) False
View Answer
Explanation: Each diploid cell has a set of chromosomes. Thus, chromosomes occur in pairs. The pair of chromosomes can be either identical or differ in specific loci. If the chromosomes differ in specific loci, they are called homologous chromosomes.
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