Question

The thread-like structures present in the nucleus are

• A. nucleolus
• B. chromosomes
• C. genes
• D. ribosomes

Answer 1

The correct option is B

chromosomes

The correct option is option B.

Explanation of the correct option:

1. The thread-like structure located inside the nucleus of cells of plants and animals is called a chromosome.
2. The term chromosome was first coined by German anatomist Henrich Wilhelm Waldeyer in 1888.
3. Each chromosome is composed of DNA wrapped tightly by proteins called histones
4. Each chromosome contains a constriction point called the centromere, which divides the chromosome into two arms or parts.
5. The short arm of the chromosome is termed as the 'p arm' and the long arm of the chromosome is termed as the ‘q arm’.
6. Chromosomes replicate during the cell cycle to form a pair of sister chromatids.
7. The number of chromosomes present in each organism differs, in humans 23 pairs of chromosomes are present i.e. 46 chromosomes.

Explanation of the incorrect options:

Option A:

1. Inside the fluid matrix of the nucleus (nucleoplasm), contains one or more spherical structures which are not surrounded by any membrane called nucleolus.
2. It is the site for the synthesis of ribosomal RNA.

Option C:

1. The sequence of nucleotides in DNA or RNA located in the chromosome is responsible for the transmission of characters from parents to offspring.
2. The segment of the DNA chromosome that has coding information or it can actively undergo transcription.

Option D:

1. The granular structures present inside the cell are called ribosomes (composed of RNA and protein not surrounded by any membrane).
2. The eukaryotic ribosomes are the 80S and prokaryotic ribosomes are 70S.

Final Answer: the thread-like structures present in the nucleus are chromosomes.