Question 1
Most alterations in the genes occur during ____________________
A. cell division
B. motility
C. anaerobic conditions
D. sunlight exposure
View Answer
Answer: Option A
Explanation:
There are mutations that alter the information of a single gene and then there are a whole range of alterations that chromosomes may be subjected to. Most of these alterations occur during cell division, when the chromosomal content is replicated and then distributed evenly among daughter cells.
Question 2
Mutations in which of the following genes lead to a rare form of muscular dystrophy?
A. lamin
B. tannin
C. gerotonin
D. rennin
View Answer
Answer: Option A
Explanation:
Lamin makes up the inner surface of a nuclear membrane. Mutations in the lamin genes (LMNA) lead to a rare form of muscular dystrophy (EDMD2). Patients of this disease have extremely fragile nuclei.
Question 3
Partial trisomy is the presence of _____ copies of a gene.
A. 1
B. 2
C. 3
D. 4
View Answer
Answer: Option C
Explanation:
Duplication occurs due to the presence of more copies of a gene than normal. Partial trisomy is the condition where a gene is repeated thrice, in place of two normal copies of the gene there are three copies.
Question 4
The chromosomal aberrations follow _____________________
A. chromosomal breakage
B. meiosis
C. mitosis
D. necrosis
View Answer
Answer: Option A
Explanation:
The chromosomal aberrations follow chromosomal breakage; hence their incidence increases by exposure to agents such as UV-rays, X-rays, viral infections that damage the DNA.
Question 5
The cry-of-the-cat syndrome is due to a defect in chromosome __________
A. 2
B. 4
C. 5
D. 9
View Answer
Answer: Option C
Explanation:
The cry-of-the-cat syndrome arises due to a deletion in human chromosome 5. This was elucidated by Jerome Lejeune while he observed a newborn with facial malformations and a cry resembling that of a suffering cat.
Question 6
The Philadelphia chromosome is the best studied example of ________________
A. inversion
B. translocation
C. deletion
D. duplication
View Answer
Answer: Option B
Explanation:
Philadelphia chromosome is the best studied example of translocation. It is a chromosome found in the malignant cells of leukemia patients. The Philadelphia chromosome was discovered in 1990 and is a shortened version of human chromosome 22.
Question 7
The translocated part of Philadelphia chromosome is found on chromosome ________
A. 4
B. 9
C. 11
D. 13
View Answer
Answer: Option B
Explanation:
The translocated part of Philadelphia chromosome i.e. shortened chromosome 22 is found on chromosome 9, which gets an addition of 600 extra amino acids encoding for protein kinase.
Question 8
Unlike the 23 pairs of chromosomes in human cells, chimpanzees have 24 pairs of chromosomes.
A. True
B. False
View Answer
Answer: Option A
Explanation:
Translocations have been proved to be important evolutionary agents. The 24 pairs of chromosomes present in chimpanzees, gorillas, and orangutans reveal striking similarity with the 23 pairs of chromosomes present in human cells.
Question 9
When was the first correlation between a chromosomal deletion and human disorder first developed?
A. 1963
B. 1973
C. 1983
D. 1993
View Answer
Answer: Option A
Explanation:
The first correlation between a chromosomal deletion and a human disorder was first discovered in 1963 by Jerome Lejeune, a French geneticist who had earlier discovered the chromosomal basis of Down syndrome.
Question 10
Which is not a type of chromosomal aberration?
A. mutations
B. inversion
C. translocation
D. duplication
View Answer
Answer: Option A
Explanation:
Chromosomal aberration refers to the change in number of chromosomes or any other associated errors. There are various types of chromosomal aberrations including inversions, translocations, duplications etc. Mutation however is a broader term.
Question 11
Which of the following is a rare genetic disorder?
A. Myeloma
B. Meningitis
C. Fanconi anemia
D. Breast cancer
View Answer
Answer: Option C
Explanation:
Fanconi anemia is a rare genetic disorder in which the chromosomes are highly unstable and prone to breakage. This disease results in decreased production of all types of blood cells.
Question 12
Zygotes containing chromosomal deletion are produced by ___________
A. apoptosis
B. abnormal mitosis
C. abnormal meiosis
D. necrosis
View Answer
Answer: Option C
Explanation:
Meiosis is the cellular process where a single cell divides twice to give rise to 4 distinct cells, the gametes. Zygotes containing a chromosomal deletion are a product of abnormal meiosis.