UPSC CAPF

Which of the following best represents the cells of a meristem of plant?

[amp_mcq option1=”Dense cytoplasm, thin cell wall, large nuclei and absence of vacuoles” option2=”Dense cytoplasm, thin cell wall, large nuclei and large vacuoles” option3=”Dense cytoplasm, thin cell wall, small nuclei and absence of vacuoles” option4=”Dense cytoplasm, thick cell wall, small nuclei and large vacuoles” correct=”option1″]

The correct answer is A) Dense cytoplasm, thin cell wall, large nuclei and absence of vacuoles.

Meristematic cells are undifferentiated plant cells that are actively undergoing cell division. Characteristics of these cells include dense cytoplasm, thin primary cell walls (as they are rapidly growing and dividing), relatively large and prominent nuclei (controlling the cell cycle), and usually small or absent vacuoles, which would otherwise occupy significant volume and potentially hinder rapid division.

Mature plant cells typically have thick cell walls and a large central vacuole that can occupy up to 90% of the cell volume. Meristematic cells are found in regions of active growth, such as root tips, shoot tips, and vascular cambium.

Lysosomes are sacs of the cell filled with digestive enzymes. These digestive enzymes are synthesized by

[amp_mcq option1=”Golgi bodies” option2=”smooth endoplasmic reticulum” option3=”rough endoplasmic reticulum” option4=”lysosome itself” correct=”option3″]

The correct answer is C) rough endoplasmic reticulum.

Lysosomal enzymes are hydrolytic enzymes that are proteins. Proteins destined for secretion or for inclusion in membrane-bound organelles like lysosomes are synthesized on ribosomes attached to the rough endoplasmic reticulum (RER). These proteins are then processed within the RER and subsequently transported to the Golgi apparatus for further modification and packaging into vesicles, which bud off to form lysosomes.

Golgi bodies are involved in modifying, sorting, and packaging proteins and lipids. Smooth endoplasmic reticulum (SER) is involved in lipid synthesis, detoxification, and calcium storage. Lysosomes themselves are membrane-bound organelles containing the digestive enzymes; they do not synthesize the enzymes.

Which of the following combinations correctly represents the genetic materials in prokaryotes and eukaryotes respectively?

[amp_mcq option1=”Nucleoid and Chromatin” option2=”Chromatin and Nucleoid” option3=”Nucleoid and Nucleolus” option4=”Nucleolus and Chromatin” correct=”option1″]

The correct answer is A) Nucleoid and Chromatin.

Prokaryotes (like bacteria) lack a membrane-bound nucleus. Their genetic material (usually a single circular chromosome) is located in a region of the cytoplasm called the nucleoid. Eukaryotes (like plants and animals) have a membrane-bound nucleus containing their genetic material, which is organized into multiple linear chromosomes composed of DNA wrapped around proteins (histones) forming a structure called chromatin.

The nucleolus is a dense structure found within the eukaryotic nucleus, involved in ribosome synthesis, not the primary form of the entire genetic material itself. Chromatin is the complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells.