Question 1

Which of the following statements best describes the structure of bacterial chromosomes?

Accepted Answer

They are circular, double-stranded DNA molecules compacted into a nucleoid and associated with DNA-binding proteins such as HU and H1.

Question 2

Which enzyme is primarily responsible for introducing or removing supercoils in bacterial DNA?

Accepted Answer

Topoisomerase

Question 3

A mutation in a plant results in the loss of all chloroplast DNA. Which cellular process would be most directly affected?

Accepted Answer

Photosynthesis, due to the loss of genes encoding ribosomal proteins and enzymes like rubisco

Question 4

Which of the following best explains why mitochondrial DNA (mtDNA) exhibits maternal inheritance?

Accepted Answer

mtDNA is inherited from the mother because the egg contributes the majority of cytoplasm, including mitochondria, to the zygote.

Question 5

Which of the following histones is NOT part of the nucleosome core particle?

Accepted Answer

H1

Question 6

What is the effect of histone acetylation on chromatin structure and gene expression?

Accepted Answer

It loosens chromatin structure, thereby promoting gene expression.

Question 7

A researcher digests chromatin with a restriction enzyme and observes DNA fragments of approximately 200 base pairs. What does this suggest about the chromatin structure?

Accepted Answer

The chromatin is composed of repeating nucleosome units, each protecting about 200 bp of DNA.

Question 8

Which of the following best describes the difference between euchromatin and heterochromatin?

Accepted Answer

Euchromatin is uncoiled and transcriptionally active, while heterochromatin is condensed and generally inactive.

Question 9

Which of the following is a function of telomeric DNA sequences?

Accepted Answer

They provide stability to chromosome ends and prevent erosion of functional genes.

Question 10

A forensic scientist is analyzing a DNA sample using (CA)n repeats. What is the significance of these sequences?

Accepted Answer

They are microsatellites, which vary in repeat number among individuals and serve as molecular markers.

Question 11

Which of the following statements about SINEs and LINEs is correct?

Accepted Answer

SINEs are short interspersed elements, while LINEs are long interspersed elements; together, they constitute about 30% of the human genome.

Question 12

Which region of the centromere is most critical for kinetochore fiber binding during cell division?

Accepted Answer

Region III

Question 13

Which of the following best explains the 'positional effect' in chromatin?

Accepted Answer

It describes the suppression of gene activity when a gene is relocated near heterochromatin due to chromosomal translocation.

Question 14

Which of the following is a unique feature of polytene chromosomes?

Accepted Answer

They are formed by multiple rounds of DNA replication without strand separation, resulting in visible banding patterns.

Question 15

Which of the following best describes the composition of a nucleosome?

Accepted Answer

An octamer of histones (two each of H2A, H2B, H3, and H4) with 146 bp of DNA wrapped around it.

Question 16

Which of the following is true regarding satellite DNA?

Accepted Answer

It is highly repetitive, consists of short sequences, and is often found in centromeric regions.

Question 17

Which of the following best explains why only a small portion of the eukaryotic genome encodes proteins?

Accepted Answer

Most of the genome consists of repetitive DNA sequences, including SINEs, LINEs, and satellite DNA.

Question 18

Which of the following is a consequence of abnormal DNA methylation patterns in cancer cells?

Accepted Answer

Gene silencing, uncontrolled cell growth, and resistance to cell death.

Question 19

Which of the following is a characteristic of lampbrush chromosomes?

Accepted Answer

They have extensive DNA looping and are associated with high levels of gene expression during prophase I of meiosis.

DNA Organization in Chromosomes

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